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Newsweek Daily Beast Article - Is The Boeing 737 Unsafe?  
User currently offlineg38 From United States of America, joined Oct 2009, 229 posts, RR: 0
Posted (2 years 4 months 5 days 23 hours ago) and read 25291 times:
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Someone sent me this article on 737 being prone to problems. I responded by listing for them the number of aircraft that have been built and the number of hours flown compared to the number of accidents. The aircraft's record speaks for its self, that it is infact, one of the safest airliners ever built.

Still I though I would share this article and see what you all though. Personally I find myself rather annoyed by it.


http://www.thedailybeast.com/newswee...eet_morning&utm_term=Cheat%20Sheet

85 replies: All unread, showing first 25:
 
User currently onlineStitch From United States of America, joined Jul 2005, 30542 posts, RR: 84
Reply 1, posted (2 years 4 months 5 days 23 hours ago) and read 25259 times:
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My personal view is that if it was unsafe, regulators around the world wouldn't certify it for passenger operation.

User currently offlineBoeingGuy From United States of America, joined Dec 2010, 2969 posts, RR: 7
Reply 2, posted (2 years 4 months 5 days 23 hours ago) and read 25127 times:

You guys tell us.


How many 737NGs are flying?

How many have crashed due to a fault of the airplane (e.g. not a runway overrun because the pilot flared too long, or a crash due to spacial disorientation or lack of situational awareness)?


That should answer your own question.

Sensationalism, Sensationalism.........


User currently onlinenomadd22 From United States of America, joined Feb 2008, 1828 posts, RR: 0
Reply 3, posted (2 years 4 months 5 days 23 hours ago) and read 24980 times:

Clive Irving has a long habit of jumping on technical bits he doesn't understand or really want to understand if it would get in the way of him getting another sensationalistic headline. His stories aren't research. They're pick and choose former employees of this and that company or organization who will support his expert wannabe opinions.


Andy Goetsch
User currently offlineseabosdca From United States of America, joined Sep 2007, 5308 posts, RR: 4
Reply 4, posted (2 years 4 months 5 days 22 hours ago) and read 24852 times:

The article contains a wide variety of errors, oversimplifications, and misstatements, while brushing off the fact that the 737's actual in-service safety record is quite good, particularly if you take dodgy operators out of the mix.

User currently offlineAWACSooner From United States of America, joined Jan 2008, 1882 posts, RR: 1
Reply 5, posted (2 years 4 months 5 days 22 hours ago) and read 24787 times:

Sure Boeing's are unsafe...and Airbus's tails snap off.

User currently offlineikramerica From United States of America, joined May 2005, 21472 posts, RR: 60
Reply 6, posted (2 years 4 months 5 days 22 hours ago) and read 24776 times:

The 737 is one of the 5 least safe passenger aircraft families that Boeing currently produces!!  


Of all the things to worry about... the Wookie has no pants.
User currently offlineikramerica From United States of America, joined May 2005, 21472 posts, RR: 60
Reply 7, posted (2 years 4 months 5 days 22 hours ago) and read 24741 times:

Quoting seabosdca (Reply 4):
The article contains a wide variety of errors, oversimplifications, and misstatements, while brushing off the fact that the 737's actual in-service safety record is quite good, particularly if you take dodgy operators out of the mix.

That's an important point. Once an aircraft reaches 25 years old and goes through multiple owners to end up with a third tier carrier outside the developed world, you really can't fairly assess safety anymore, as there are too many other factors involved: does that airline have properly trained mechanics? pilots? proper inspections? use genuine replacement parts? etc...



Of all the things to worry about... the Wookie has no pants.
User currently offlineBoeingGuy From United States of America, joined Dec 2010, 2969 posts, RR: 7
Reply 8, posted (2 years 4 months 5 days 22 hours ago) and read 24533 times:

Quoting AWACSooner (Reply 5):
Sure Boeing's are unsafe...and Airbus's tails snap off.

My boss put it very succinctly. Nobody builds unsafe airplanes, not Boeing, not its competitors. Sometimes good airplanes have a bad day, but no current airplanes are unsafe.


User currently offlinejetblueguy22 From United States of America, joined Nov 2007, 2752 posts, RR: 4
Reply 9, posted (2 years 4 months 5 days 22 hours ago) and read 24360 times:
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What a joke of an article. If planes were dropping out of the sky like fly's i may give him credit. But this is just someone looking for a story where there is none. He listed what 5 events? There are 10,000 of em made. That though a little higher than Boeing would like is far from unsafe.
Blue



You push down on that yoke, the houses get bigger, you pull back on the yoke, the houses get bigger- Ken Foltz
User currently offlinemax550 From United States of America, joined Nov 2007, 1147 posts, RR: 0
Reply 10, posted (2 years 4 months 5 days 22 hours ago) and read 24308 times:

I thought the part at the end really shows how badly the author wants to make the 737 sound unsafe. It's just a list of incidents with a total of 1 fatality that were entirely unrelated to the problems pointed out in the article. Surprised he didn't bother to include the TK 738 at AMS and the ET 738 in Lebanon, among others.

Quote:
Take comfort: survivability rates are very high even in violent crashes during landing (as long as there’s no fire). But the newest models of the 737 Next Generation series have suffered shattered fuselages, which makes passenger evacuation difficult – for example, emergency slides are often unusable.

December 2009, Kingston, Jamaica: An American Airlines 737-800 splits open after running off the runway during a rainstorm. All 154 passengers survive, some with injuries.

August 2010, San Andrés Island, Colombia: An Aires Airlines 737-700 rips apart after landing in an electrical storm. One passenger dies, 30 injured.

July 2011, Georgetown, Guyana: A Caribbean Airlines 737-800 ruptures after running off the runway in a rainstorm; 163 passengers survive, some injured.


User currently offlineSuperCaravelle From Netherlands, joined Jan 2012, 233 posts, RR: 0
Reply 11, posted (2 years 4 months 5 days 22 hours ago) and read 23871 times:

Quoting Stitch (Reply 1):
My personal view is that if it was unsafe, regulators around the world wouldn't certify it for passenger operation.

Not necessarily true in my opinion (should stress it's not my intention to divert the thread into a which aircraft is safe and which isn't debate) but yes for the case of the 737. The fact that a staggering number of 737's from three generations are flying around everyday with a minimum of incidents and accidents speaks for itself. This writer is just seeking for an article.

Quoting max550 (Reply 10):
July 2011, Georgetown, Guyana: A Caribbean Airlines 737-800 ruptures after running off the runway in a rainstorm; 163 passengers survive, some injured.

The way this is formulated tells you everything. One would expect a certain number of dead people after the statement "163 survive", otherwise he would've surely wrote "all survive"? Oh wait, they did all survive. The writer is intentionally ambiguous and shows his article has nothing to do with journalism (presenting facts, with probably an opinion afterwards, clearly separating facts an opinion), but everything to do with sensationalism (appeal to the audience first and foremost, in any way possible. Facts are not important).

Nothing to see here, move on.

[Edited 2012-03-19 11:34:40]

User currently offlineRoseflyer From United States of America, joined Feb 2004, 9489 posts, RR: 52
Reply 12, posted (2 years 4 months 5 days 21 hours ago) and read 23476 times:

He measures safety on very few parameters that have any meaning.

First he says that because the 737 has ADs, then it is not safe. All commercial airplanes have Airworthiness Directives. More common airplanes have more ADs because as the statistics play out, less common failures will happen and ADs will come from them as more Service Bulletins are created.

The article analyzes skin thickness and claims that Boeing used a thinner skin to save weight. On the 737NG, the skin is actually stronger than on the A320 which was a required enhancement when it was certified up to 41,000ft.

The article ignores structural problems and rapid decompressions on airplanes other than 737s.

The article comments on the 737 having the market to itself prior to the A320. That is completely wrong. Early on the DC9 was more popular than the 737 and the DC9/MD80 family was always what the 737 was intended to compete against until the 737NG.

There are many more problems with the article. I usually try to read into articles to see if there is any truth behind it, but on this article, despite trying to appear as a technical well researched document falls pretty flat on useful information. The only practical information is that airplane structure is complex and that at times it fails.

In general this article is all about being sensational. The FAA is by far and away more strict now than it ever has been before. Nothing that is certified today is unsafe. I think it is very unfortunate that a magazine like Newsweek actually published this.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineSSTeve From United States of America, joined Dec 2011, 693 posts, RR: 1
Reply 13, posted (2 years 4 months 5 days 21 hours ago) and read 23209 times:

Newsweek's just a tabloid now. You can probably turn the page from this article and read about Snooki and the Hunger Games delightful teen actors. If you want a weekly newsmagazine that's not a tabloid, BusinessWeek (despite the coupling plane cover) and the Economist would seem to be better options.

[Edited 2012-03-19 11:51:19]

User currently offlineMountainFlyer From United States of America, joined Jul 2005, 474 posts, RR: 0
Reply 14, posted (2 years 4 months 5 days 21 hours ago) and read 22973 times:

Quoting Roseflyer (Reply 12):
I think it is very unfortunate that a magazine like Newsweek actually published this.

  

Unfortunate, but not surprising.

I think someone should do a study on the public's fixation on the perceived dangers of flying. Why is it every time two planes clip wings at an airport, you hear about it on the national news? More people die on bicycles than airplanes, yet when was the last time you read an article about that? Perhaps it's because of the general mystery of flying, and one of the areas where you put your entire trust in the manufacturers, mechanics, pilots, etc., and have almost no control yourself of the situation. I don't know, but it is such an irrational fear. Most fears are irrational. Did you know that more people are killed by cows than sharks?



SA-227; B1900; Q200; Q400; CRJ-2,7,9; 717; 727-2; 737-3,4,5,7,8,9; 747-2; 757-2,3; 767-3,4; MD-90; A319, 320; DC-9; DC-1
User currently offlineSASMD82 From Netherlands, joined Mar 2007, 726 posts, RR: 0
Reply 15, posted (2 years 4 months 5 days 21 hours ago) and read 22799 times:

With so many 737s flying around safely and with many more on order, I bet there is no real problem......

User currently offlineContnlEliteCMH From United States of America, joined Mar 2005, 1455 posts, RR: 44
Reply 16, posted (2 years 4 months 5 days 21 hours ago) and read 22424 times:

Quoting SSTeve (Reply 13):
Newsweek's just a tabloid now.

And how! I generally disapprove of refusal to evaluate an article on its merits because of its author or its publisher, but as soon as I clicked on the link and saw Newsweek I immediately said "Oh. Newsweek." About 20 years ago I subscribed to this magazine for about a year, and read it thoroughly while riding the bus to/from my engineering college co-op job. Even then I thought it was tabloid-ish, but it had some decent articles and I liked the commentaries even though I agreed with virtually none of them.

Now... ugh. It's become the Discovery networks of magazines: no content pertaining to the name of the channel you're watching. Maybe the Discovery network and Newsweek can collaborate on a reality show entitled "Useless Media Producers."

This paragraph from the article is noteworthy:

There are two important safeguards that stand between safety and disaster: technology on the one hand and airline safety checks on the other. And the problem is that as the technology of fuselage design has evolved over several decades, the 737’s has not. As a result, the final responsibility for our safety has moved from Boeing to the maintenance and safety checks carried out by the airlines and supervised by the FAA. So far this final safety net has mostly worked—the flaws have been caught before they caused a fatal crash. But that’s no cause for complacency: an aging design with chronic problems remains our most frequently flown plane today.

The author implies that the final responsibility for our safety SHOULD be with Boeing, but it has been displaced to airlines who operate each airframe. This implication is simply incorrect and no amount of pie-in-the-sky fantasy about engineering can obviate the need for periodic inspections. Safe operation of a commercial airliner has *always* been shared by the OEM and the operator and both parties understand this relationship.

He is correct that the aging design has chronic problems that must be addressed. That's why there are AD's, which allow other operators to learn from the inspections of others and to take action to *avoid* problems, not remedy them. AD's are not evidence that the 737 is unsafe; rather, they show that the author's belief in OEM-as-ultimate-safety-guarantor is completely out of step with how the industry actually operates, and that the airplane can continue to be operated safely so long as the knowledge contained in AD's is acted upon properly.

The 737 is no Comet. THAT airplane had a fatal design flaw.

[Edited 2012-03-19 12:29:00]


Christianity. Islam. Hinduism. Anthropogenic Global Warming. All are matters of faith!
User currently onlineRara From Germany, joined Jan 2007, 2055 posts, RR: 2
Reply 17, posted (2 years 4 months 5 days 20 hours ago) and read 21642 times:

Al Jazeera did a similar story:

https://www.youtube.com/watch?v=IaWdEtANi-0

Obviously the 737 isn't unsafe, as is demonstrated thousands of times every day. Still, I wouldn't completely dismiss any concern. The pressure to safe costs which management exerts on engineering these days is staggering. At some point, this could become a potential threat to safety, and in this case it's best to find out about it early.



Samson was a biblical tough guy, but his dad Samsonite was even more of a hard case.
User currently offlineBoeingGuy From United States of America, joined Dec 2010, 2969 posts, RR: 7
Reply 18, posted (2 years 4 months 5 days 20 hours ago) and read 21367 times:

Better call Newsweek to get on another story. The 767 is unsafe too:

http://www.upi.com/Top_News/US/2012/...to-land-at-SFO/UPI-83401332175298/

Oh my gosh, the sky is falling.


User currently offlinejetpilot From United States of America, joined May 1999, 3130 posts, RR: 29
Reply 19, posted (2 years 4 months 5 days 20 hours ago) and read 20683 times:

If we knew everything about aircraft structures and could foresee how they would react in the real world then we wouldn't need inspections. But since we can't predict the future we have mandatory inspections to catch things such as corrosion and skin cracks.

It's interesting that the author states the fuselage was taken from the 727 but the 727 didn't share the same issue as the 737.


User currently offlineBoeingGuy From United States of America, joined Dec 2010, 2969 posts, RR: 7
Reply 20, posted (2 years 4 months 5 days 20 hours ago) and read 20472 times:

Quoting max550 (Reply 10):
Quote:
Take comfort: survivability rates are very high even in violent crashes during landing (as long as there’s no fire). But the newest models of the 737 Next Generation series have suffered shattered fuselages, which makes passenger evacuation difficult – for example, emergency slides are often unusable.

December 2009, Kingston, Jamaica: An American Airlines 737-800 splits open after running off the runway during a rainstorm. All 154 passengers survive, some with injuries.

August 2010, San Andrés Island, Colombia: An Aires Airlines 737-700 rips apart after landing in an electrical storm. One passenger dies, 30 injured.

July 2011, Georgetown, Guyana: A Caribbean Airlines 737-800 ruptures after running off the runway in a rainstorm; 163 passengers survive, some injured.

Shattered fuselages? What does he expect? The AA 737 ran off the end of the runway at relatively high speed. It didn't shatter. It broke and the 737 fuselage was so robust that everyone survived that tremendous force on the airplane.

That can happen when airplanes go to places they aren't designed to go at higher speeds. And as he points out, in these three spectacular events - none of which were the fault of the airplane design - the 737's structure protected the passenger such that only one was last out of over 400. A lesser built airplane would not have protected the passengers so well.

You run off the end of the runway, hop over a ditch and end up on the beach just short of concrete blocks. Everyone walks away with bruises. What kind of idiot would have the audacity to suggest the airplane is unsafe?


User currently onlinenomadd22 From United States of America, joined Feb 2008, 1828 posts, RR: 0
Reply 21, posted (2 years 4 months 5 days 19 hours ago) and read 19853 times:

Newsweek picked the story up, but Conde Nast (Esperanto for "overrated fluff") is the source.


Andy Goetsch
User currently offlinemax550 From United States of America, joined Nov 2007, 1147 posts, RR: 0
Reply 22, posted (2 years 4 months 5 days 19 hours ago) and read 19173 times:

Quoting jetpilot (Reply 19):
If we knew everything about aircraft structures and could foresee how they would react in the real world then we wouldn't need inspections. But since we can't predict the future we have mandatory inspections to catch things such as corrosion and skin cracks.

Exactly, and I believe WN was fined $7.5m or so for not performing required fuselage inspections which the author never mentions.

Quoting jetpilot (Reply 19):
It's interesting that the author states the fuselage was taken from the 727 but the 727 didn't share the same issue as the 737.

The last 2 paragraphs on page 3 say that the fuselage skin was thinned from the 727 because the engines were barely powerful enough. He also implies that aircraft fly more cycles now than they used to. I have no idea if either of those is true but that seems to be his reasoning for focusing on the 737 v. 727. True or not it fits with the rest of the article, a bunch of claims with very little evidence to back them up.

Then there are the two paragraphs about the aft pressure bulkhead. He's concluded it's a chronic problem based on one (or five, he's not clear) AD from 2001.

If I didn't know any better when I read the article I would have come to the conclusion that the 737 is extremely unsafe but incredibly lucky. The chronic skin problems and the aft pressure bulkhead problems have combined to cause a total of 3 incidents with one fatality over 31 years. It's a pretty flimsy case to base an article about how problematic an airframe is.


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9489 posts, RR: 52
Reply 23, posted (2 years 4 months 5 days 19 hours ago) and read 18752 times:

Quoting max550 (Reply 22):

The last 2 paragraphs on page 3 say that the fuselage skin was thinned from the 727 because the engines were barely powerful enough. He also implies that aircraft fly more cycles now than they used to. I have no idea if either of those is true but that seems to be his reasoning for focusing on the 737 v. 727. True or not it fits with the rest of the article, a bunch of claims with very little evidence to back them up.

If he is talking about skin thickness, then yes the original 737 had less skin thickness than the 727. The reason was that the 727 was certified to 42,000ft. The 737 was only certified to 37,000ft since it was intended for short haul operations with the average stage length of about 1 hour. Max certified altitude determines skin thickness as it is responsible for the pressure differential and fatigue loading. Boeing changed this with the 737NG as average stage length increased to about 2 hours and the additional altitude was useful for optimization of range/payload and flexible route planning.

It wasn't because of engines being barely powerful enough, but rather lower operating and max certified altitude.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineDocLightning From United States of America, joined Nov 2005, 19371 posts, RR: 58
Reply 24, posted (2 years 4 months 5 days 18 hours ago) and read 18616 times:

Quoting BoeingGuy (Reply 18):

Oh my gosh, the sky is falling.

No no. It's just raining airliners.  


User currently onlineUTAH744 From United States of America, joined Jul 2009, 195 posts, RR: 0
Reply 25, posted (2 years 4 months 5 days 18 hours ago) and read 18955 times:

See the posting I made last year.




UTAH744 From United States of America, joined Jul 2009, 160 posts, RR: 0
Reply 9, posted Wed Jan 26 2011 17:20:10 your local time (1 year 1 month 3 weeks 1 day 21 hours ago) and read 2154 times:



http://seattletimes.nwsource.com/news/local/737/

In 1996 I was living in the Puget Sound area and the Seattle Times did an excellent multi part piece on the Boeing 737 ruder PCU. If you have the time read all of the articles, or just go to part 5 which tells of the relationships between Boeing, NTSB and the FAA. Much of the delays on fixcing the rudder PCUs was due to Boeing (or cost reasons) and the FAA (conflicting mandates - protect flying public & advance aviation industry.)

As to how close the FAA was to grounding the B737's a friend in gthe FAA told me he had heard that it was being considered. After reading all of the articles you sure hope they were considering such an action. I now have not even a second thought about riding on a B737.



You are never too old to learn something stupid
User currently offlinemax550 From United States of America, joined Nov 2007, 1147 posts, RR: 0
Reply 26, posted (2 years 4 months 5 days 18 hours ago) and read 18891 times:

Quoting Roseflyer (Reply 23):
If he is talking about skin thickness, then yes the original 737 had less skin thickness than the 727. The reason was that the 727 was certified to 42,000ft. The 737 was only certified to 37,000ft since it was intended for short haul operations with the average stage length of about 1 hour. Max certified altitude determines skin thickness as it is responsible for the pressure differential and fatigue loading. Boeing changed this with the 737NG as average stage length increased to about 2 hours and the additional altitude was useful for optimization of range/payload and flexible route planning.

It wasn't because of engines being barely powerful enough, but rather lower operating and max certified altitude.

That sounds much more plausible. Naturally no mention of that in the article.

Here's the exact quote from the article: One of the most respected authorities on aging airplanes and metal fatigue is Prof. Tony Ingraffea of Cornell’s School of Civil and Environmental Engineering. His extensive investigation of the Aloha 737’s shattered fuselage, part of a long study published in the 1990s, is a classic aviation text. Looking back at the 737’s origins, he explains that the available engines were barely powerful enough for the new model. The designers needed to save weight; to do so, they used an aluminum alloy for the fuselage skin that was only .036 inches thick (the width, for example, of a guitar string).

So perhaps he had bad sources, although it seems he had already drawn a conclusion before writing the piece which tends to steer what sources you end up with.


User currently offlinedave2 From United States of America, joined Sep 2011, 29 posts, RR: 0
Reply 27, posted (2 years 4 months 5 days 18 hours ago) and read 18855 times:

The 737 is a safe plane. I have flown in them many times. The only problem I remember had to do with the servo drive was suspect in a few crashes. Boeing put out fixes back in the 1980s for the aircraft. To the best of my knowledge, all other crashes have not been due to a flaw in the aircraft.

User currently onlinebikerthai From United States of America, joined Apr 2010, 2063 posts, RR: 4
Reply 28, posted (2 years 4 months 5 days 18 hours ago) and read 18655 times:

Quoting max550 (Reply 22):
conclusion that the 737 is extremely unsafe but incredibly lucky.

Sometimes it's better to be lucky than good.  
Quoting max550 (Reply 26):
The designers needed to save weight; to do so, they used an aluminum alloy for the fuselage skin that was only .036 inches thick

Haven't seen .036 skin on an airplane. Have seen .040 skin on an airplane though. All in context of course. The .040 skin was in a chem-milled pocket with thickness at the fastened joints much higher. You'll be surprised how tough even a .032 aluminum skin is . . . go figures . . .

bt



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlineflashmeister From United States of America, joined Apr 2000, 2900 posts, RR: 6
Reply 29, posted (2 years 4 months 5 days 17 hours ago) and read 17785 times:
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The choice of images should tell you everything you need to know about this "piece of journalism". If they were serious about approaching this topic objectively, they might have included photos of aircraft of the same vintage as those being discussed (i.e. Classics and NGs). Instead, they only show -200s, which do indeed look old, tired, and obsolete. New NGs are none of those things.

User currently offlineCubsrule From United States of America, joined May 2004, 22717 posts, RR: 20
Reply 30, posted (2 years 4 months 5 days 15 hours ago) and read 15680 times:

Quoting ikramerica (Reply 7):
Once an aircraft reaches 25 years old and goes through multiple owners to end up with a third tier carrier outside the developed world, you really can't fairly assess safety anymore, as there are too many other factors involved: does that airline have properly trained mechanics? pilots? proper inspections? use genuine replacement parts? etc...

And, if a 25 year old aircraft is well-maintained by a reputable operator or operators for that time period, it can be as reliable as or more reliable than a newer one. LA didn't have 732s (most ex-LH examples) falling out of the sky, and for much of the 2000s, NW saw better dispatch reliability on the DC-9s than on the 32xs.



I can't decide whether I miss the tulip or the bowling shoe more
User currently offlineBCEaglesCO757 From United States of America, joined Mar 2011, 242 posts, RR: 2
Reply 31, posted (2 years 4 months 5 days 15 hours ago) and read 15433 times:

Wow.

This article was obviously done with no research or knowledge regarding aviation and aeronautics.

Though a very reliable car.......I bet the author thinks honda accords driven by the average american driver are safer and maintained better than the average 737.

But that is me.


User currently offlinepenguins From United States of America, joined Mar 2010, 267 posts, RR: 0
Reply 32, posted (2 years 4 months 5 days 14 hours ago) and read 15034 times:

It seems like someone needs a story. I guess sales are down.

User currently offlinesolarflyer22 From US Minor Outlying Islands, joined Nov 2009, 976 posts, RR: 3
Reply 33, posted (2 years 4 months 5 days 14 hours ago) and read 14586 times:

I don't think if you look at the fatigue failures per cycle (on ave) vs. other airframes it would be any higher. I guess the only question in my mind is, do airlines that operate the 737NG have to repair the aft bulkhead or cracks in the fuselage more often than a typical A320 operator? My answer is no if only for the fact that the 737 has to have comparable maintenance costs to the A320 otherwise, they'd have a lot less market share. If airlines were constantly repairing the skin, inspecting it or replacing the bulkhead regularly, you'd know it long before an accident or AD was released.

I did find the testing without G loads and the wingbox a little bit of a shortcut by Boeing but I am pretty sure a well maintained 737 can go 100,000 cycles no problem.


User currently offlinecontext From United States of America, joined Jul 2009, 37 posts, RR: 0
Reply 34, posted (2 years 4 months 5 days 13 hours ago) and read 14061 times:

I suppose someone was looking to tease out the exact point at which reporting ended and libel began...

User currently onlineTigerguy From United States of America, joined Aug 2010, 895 posts, RR: 0
Reply 35, posted (2 years 4 months 5 days 13 hours ago) and read 13935 times:

Well, I flew on a 737 on Saturday. Either I'm posting from the dead, or there's some other explanation...   


On the occasion of United overtaking Frontier as my most-flown airline, I say...let's get friendly.
User currently offlineBlueSky1976 From Poland, joined Jul 2004, 1869 posts, RR: 4
Reply 36, posted (2 years 4 months 5 days 13 hours ago) and read 13845 times:

I don't know why people would even bother reading this crap... Clearly, someone at Newsweek needed a "filler" article due to lack of other "news" to report on.


STOP TERRORRUSSIA!!!
User currently onlineghifty From United States of America, joined Jul 2010, 890 posts, RR: 0
Reply 37, posted (2 years 4 months 5 days 12 hours ago) and read 13687 times:
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This is awful. As a noobie aviation enthusiast, someone who understand basic statistics (normality of samples, etc.), and as an editor-in-chief of a small newsaper, this is extremely offensive.

I still don't see why people like reading these kind of crap. Driving your car, heck riding the train, is more dangerous than a B737, or any other airplane, will ever be. Ridiculous.

Quoting flashmeister (Reply 29):
The choice of images should tell you everything you need to know about this "piece of journalism". If they were serious about approaching this topic objectively, they might have included photos of aircraft of the same vintage as those being discussed (i.e. Classics and NGs). Instead, they only show -200s, which do indeed look old, tired, and obsolete. New NGs are none of those things.

I want to say there use of old pictures is intentional. So that they can sensationalise.. I mean, come on, they wrote about one aviation disaster involving the airplane... that landed safely with only one loss of life and performed admirably given the circumstances... and made it sound like a flying metal deathtrap. Next thing you know, people are going to be calling the A320 some sort of bird-strike magnet because of the Miracle on the Hudson River. !! I'm irked.

[Edited 2012-03-19 20:43:46]


Fly Delta Jets
User currently offlinevegas005 From Switzerland, joined Mar 2005, 319 posts, RR: 0
Reply 38, posted (2 years 4 months 5 days 10 hours ago) and read 12653 times:

I have flown the 737 numerous times and I too believe it is a safe plane. My only issue is it seems to ride "rough"; my most turbulent flights have all been on 737 varieties. I flew LAS_ORD once and the plane basically felt like we were riding down a rocky road the entire flight.

User currently offlineCM From , joined Dec 1969, posts, RR:
Reply 39, posted (2 years 4 months 5 days 8 hours ago) and read 11715 times:

Quoting vegas005 (Reply 38):
My only issue is it seems to ride "rough"

Riding "rough" is predominantly a byproduct of low wing loading. To a much lesser degree, wing stiffness plays a role as well. The 737NG has lower wing loading than the A320, and from around line number 800 on, it also has a stiffer wing. LAS - ORD is not a short flight, but if there were a lot of empty seats and you were flying in good chop (especially later in the flight), the 737NG is capable of delivering a rough ride. I doubt if you would have noticed the difference in an A320 under the same conditions, but a 737 Classic would not have felt as bumpy.

BTW - the A320 stiffened their wing this year in order to accommodate "sharklets"' so no real difference there anymore.


User currently offlineDaysleeper From UK - England, joined Dec 2009, 838 posts, RR: 1
Reply 40, posted (2 years 4 months 5 days 7 hours ago) and read 11242 times:

Wondered how long it would be before an American media outlet had the guts to say this as questions have been asked about the 737’s safety outside of the US for some time. This article/video springs to mind. – And yes, I’m aware the SW incident was on a classic.

Personally I don’t know what to think, but the fact Boeings own QA staff thought the problems serious enough to turn whistle blower certainly does raise some questions. As for the conduct of the FAA and Boeing …. LOL


User currently offlinefaro From Egypt, joined Aug 2007, 1533 posts, RR: 0
Reply 41, posted (2 years 4 months 5 days 7 hours ago) and read 11117 times:

In all good faith, someone should indicate to Mr Irving the presence of the this thread; never too late to learn from one's mistakes...

Faro



The chalice not my son
User currently offlineBurkhard From Germany, joined Nov 2006, 4384 posts, RR: 2
Reply 42, posted (2 years 4 months 5 days 6 hours ago) and read 10959 times:

An aircraft is as safe as the schedule for inspections requires the necessary steps and these instructions are followed. From this event we have learned that a well defined series of aircraft, several 100 if I'm not mistaken, needs some additional inspections. That's it.

It is obvious, that with an aircraft produced in such numbers one learns more about the product, and that more unlikely events really happen. I'm very sure that the same will also apply to the A320 family once it is older. But with every lesson learned, aircraft get safer if the lessons are taken serious, and I have no doubt that the major airlines take them serious.

I fly 737s without any hesitation, even classics...


User currently offlinesoon7x7 From , joined Dec 1969, posts, RR:
Reply 43, posted (2 years 4 months 5 days 6 hours ago) and read 10907 times:

WN is a type specific airline. It only flies 737's and none exercises them more than WN. Southwest also happens to be one of the safest and most successful carriers flying today. All to good management and airframe selection. While their airframes have had some burps, it only goes to prove how robust the plane is. Need one say anymore?...'cept....believe none of what you hear and half of what you see...

User currently offlinedc9northwest From Switzerland, joined Feb 2007, 2269 posts, RR: 7
Reply 44, posted (2 years 4 months 5 days 6 hours ago) and read 10897 times:

"The 737 is VERY unsafe. That's why Russia, Brazil, Australia, Mexico, China, Japan, the EU and the US banned it.

In fact, the 737 is to blame for Hurricane Katrina, the massive tsunami in 2004 AND the alien invasion of 2013.

I've personally died twice or thrice on my 68 flights on 737s."

I haven't read the whole article, but this is what I expect it to say.


User currently offlineAA777 From United States of America, joined May 1999, 2544 posts, RR: 28
Reply 45, posted (2 years 4 months 5 days 4 hours ago) and read 9990 times:
Support Airliners.net - become a First Class Member!

Isn't it THE best selling jet ever?

The other thing is check out its perfomance in heavy cross winds vs. the 320's.... I'm not a fan of all that oscillation that can happen due to the FBW system in the 320.

I'd say its safe to say this guy doesn't know what he's talking about!


User currently offlinemax550 From United States of America, joined Nov 2007, 1147 posts, RR: 0
Reply 46, posted (2 years 4 months 5 days 4 hours ago) and read 9730 times:

Quoting Cubsrule (Reply 30):
And, if a 25 year old aircraft is well-maintained by a reputable operator or operators for that time period, it can be as reliable as or more reliable than a newer one. LA didn't have 732s (most ex-LH examples) falling out of the sky, and for much of the 2000s, NW saw better dispatch reliability on the DC-9s than on the 32xs.

Or the AQ 732's. Why weren't they falling out of the sky for the 20 years AQ continued operating them?

Quoting Daysleeper (Reply 40):
Personally I don’t know what to think, but the fact Boeings own QA staff thought the problems serious enough to turn whistle blower certainly does raise some questions. As for the conduct of the FAA and Boeing …. LOL

There are questions and it's good to keep looking into these issues to keep the plane as safe as we possibly can.
This piece however doesn't raise questions, it accuses the 737 of being problematic and unsafe because it uses an old fuselage design which was made flimsily to save weight and the cost of designing a new plane. The evidence of that are four incidents over 31 years, one of which was caused entirely by corrosion, one by corrosion plus high cycles, and two that are potentially related to the frame and a lack of inspections and improper maintenance.

This guy may have a few valid points, the problem is that his judgement is so clouded by making the 737 appear totally unsafe that it's hard to put much stock in the few legitimate problems he brings up.


User currently offlineDaysleeper From UK - England, joined Dec 2009, 838 posts, RR: 1
Reply 47, posted (2 years 4 months 5 days 3 hours ago) and read 9456 times:

Quoting max550 (Reply 46):
The evidence of that are four incidents over 31 years, one of which was caused entirely by corrosion, one by corrosion plus high cycles, and two that are potentially related to the frame and a lack of inspections and improper maintenance.

I’m not sure what incidents your referring too, but the preliminary findings for Flight 812 indicate faulty manufacturing.

Quoting NTSB:


Inspections conducted around intact rivets on the removed skin section forward of the rupture revealed crack indications at nine rivet holes in the lower rivet row of the lap joint. X-ray inspections were performed on the skin located forward of the rupture location, and revealed gaps between the shank portions of several rivets and the corresponding rivet holes. Upon removing selected rivets, the holes in the upper and lower skin were found to be slightly offset relative to each other and many of the holes on the lower skin were out of round.


User currently onlinebikerthai From United States of America, joined Apr 2010, 2063 posts, RR: 4
Reply 48, posted (2 years 4 months 5 days 3 hours ago) and read 9031 times:

Quoting Daysleeper (Reply 47):
Flight 812 indicate faulty manufacturing.

Max550's point exactly. The fault was in the manufacturing, not a design flaw. If you want assign blame to that incident, blame that on the inspection process an not the basic design of the 737 itself as the article is trying to do.

Don't know if it's urban myth, but way back when, I was told that the older generation were often over design/built because analysis was not as precise and designers often design with greater margins just to take out the uncertainty. Now with better analysis, we seem to be pushing the margins closer to the line than be fore. If this is the case, then from a structure stand point, one could argue that the older designed frame are much safer than the newer ones. But as everyone is pointing out, safety includes more than structures, and advancements in other aspects of flight have made newer designs "safer" than the older ones.

bt



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlinemax550 From United States of America, joined Nov 2007, 1147 posts, RR: 0
Reply 49, posted (2 years 4 months 5 days 2 hours ago) and read 8779 times:

Quoting Daysleeper (Reply 47):
I’m not sure what incidents your referring too, but the preliminary findings for Flight 812 indicate faulty manufacturing.

Which would be discovered through more frequent and more rigorous inspections. Just like the cracks on the A380 have been found and are being dealt with the same way. The existence of cracks caused by a manufacturing defect doesn't make the design unsafe, it just requires more attention be paid to the parts that are affected.

And yes, the two incidents I'm referring to were the WN flights.


User currently offlineDaysleeper From UK - England, joined Dec 2009, 838 posts, RR: 1
Reply 50, posted (2 years 4 months 5 days 2 hours ago) and read 8455 times:

Quoting bikerthai (Reply 48):
Max550's point exactly. The fault was in the manufacturing, not a design flaw. If you want assign blame to that incident, blame that on the inspection process an not the basic design of the 737 itself as the article is trying to do.

Don't know if it's urban myth, but way back when, I was told that the older generation were often over design/built because analysis was not as precise and designers often design with greater margins just to take out the uncertainty. Now with better analysis, we seem to be pushing the margins closer to the line than be fore. If this is the case, then from a structure stand point, one could argue that the older designed frame are much safer than the newer ones. But as everyone is pointing out, safety includes more than structures, and advancements in other aspects of flight have made newer designs "safer" than the older ones.

Indeed, the problem highlighted in the video I linked too is that the design of the NG is dependant on parts being manufactured by CNC allowing for much tighter tolerances to be stipulated. It was discovered by Boeings own QA inspectors that this wasn’t happening , and AHF Ducommun were making parts such as bare straps and fuselage chords by hand which were consequently out of specification,

The conduct of Boeings managers after being made aware of this is what really concerns me as if they dismiss the concerns of their own inspectors which are able to present indisputable evidence that dangerous, even potentially deadly parts were being fitted to 737s. A further concern is that there is also clear evidence that documents were being falsified, and still, Boeing took no action to stop these parts being fitted, instead opting to dismiss their own inspectors which had highlighted the problem.

What I remain unsure about is just how dangerous these Aircraft will be. As many here have pointed out it isn’t as if it’s raining 737NG’s – However, as these Aircraft were manufactured between 1996 and 2004 then many won’t have reached the number of cycles or flight hours required for the defects to cause a problem.

Incidentally, I agree that the 737 doesn’t have an inherent design flaw. It doesn’t need too, any aircraft that isn’t manufactured properly or is manufactured using defective parts could be dangerous. In fact, as one of Boeings own managers pointed out. Where the defective straps and chords are fitted is difficult to access and infrequently inspected – so no one is likely to know it’s dangerous. Well until it fails in flight.

[Edited 2012-03-20 07:27:01]

User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 51, posted (2 years 4 months 5 days 2 hours ago) and read 8290 times:

Quoting Daysleeper (Reply 50):
The conduct of Boeings managers after being made aware of this is what really concerns me as if they dismiss the concerns of their own inspectors which are able to present indisputable evidence that dangerous, even potentially deadly parts were being fitted to 737s.

It is extremely unlikely that a line inspector has enough stress and engineering knowledge to determine if the issue is dangerous. All they can tell is if it's in or out of spec. It's entirely possible that, out of spec, it's still completely within requirements. In order to figure out if it's dangerous you'd need a full engineering disposition, the results of which, funny thing, *never* come up when this particular issue is discussed.

It's almost certainly not deadly, on its face, unless multiple defective parts are on the same aircraft AND they're all out of requirements AND they all fail at the same time.

Tom.


User currently offlineDaysleeper From UK - England, joined Dec 2009, 838 posts, RR: 1
Reply 52, posted (2 years 4 months 5 days 1 hour ago) and read 8038 times:

Quoting tdscanuck (Reply 51):
It is extremely unlikely that a line inspector has enough stress and engineering knowledge to determine if the issue is dangerous. All they can tell is if it's in or out of spec. It's entirely possible that, out of spec, it's still completely within requirements. In order to figure out if it's dangerous you'd need a full engineering disposition, the results of which, funny thing, *never* come up when this particular issue is discussed.

Line inspectors / QA staff did indeed point out that parts which were out of specification and had false records were being used in production. It was then an internal audit team which reported back to senior management that “misrepresentation of the manufacturing process jeopardises the integrity” and “the severity of this situation cannot be ignored” _- I’d assume that an audit team are able to determine how dangerous this situation was.

There is no defence for this, there are video’s and photos taken at AHF Ducommun that prove they breached regulations and shipped parts to Boeing to be used on the 737 that were out of specification. There is also proof that Boeing were aware of this, and that documents certifying these parts had been falsified and still they continued to fit the parts to aircraft.

I agree however that how dangerous these out of spec parts will be is open to interpretation.


User currently offlinemax550 From United States of America, joined Nov 2007, 1147 posts, RR: 0
Reply 53, posted (2 years 4 months 5 days 1 hour ago) and read 7955 times:

Quoting Daysleeper (Reply 50):
The conduct of Boeings managers after being made aware of this is what really concerns me as if they dismiss the concerns of their own inspectors which are able to present indisputable evidence that dangerous, even potentially deadly parts were being fitted to 737s. A further concern is that there is also clear evidence that documents were being falsified, and still, Boeing took no action to stop these parts being fitted, instead opting to dismiss their own inspectors which had highlighted the problem.

Valid points and an article exposing that would be totally valid. The article we're discussing is, for the most part, about something entirely different though. It's about how the 737 is a dangerously flawed and problematic design, mostly because it's an old design. I don't think anyone here agrees with that.

Quoting Daysleeper (Reply 50):
As many here have pointed out it isn’t as if it’s raining 737NG’s – However, as these Aircraft were manufactured between 1996 and 2004 then many won’t have reached the number of cycles or flight hours required for the defects to cause a problem.

Not only is it not raining NG's, AFAIK not a single NG has had an incident related to the flaws pointed out in the article.
Many of WN's 733's are nearly the same age as the early 73G's (N632SW, the plane from flight 812 was delivered in 1996) yet aren't having the same problems.


User currently offlineDaysleeper From UK - England, joined Dec 2009, 838 posts, RR: 1
Reply 54, posted (2 years 4 months 5 days 1 hour ago) and read 7669 times:

Quoting max550 (Reply 53):

Valid points and an article exposing that would be totally valid. The article we're discussing is, for the most part, about something entirely different though

The video highlights problems with the manufacture of 737 fuselage components from 1996 to 2004. And although the frame involved in the incident at Yuma was a classic, it was manufactured in 1996. I mean, the Boeing QA inspector actually states one of the problem’s she witnessed were that line workers couldn’t get rivet holes to line up, so they were re-drilling and forcing them to fit – It could still be co-incidence, but given what the NTSB found on their inspection, I doubt it.


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9489 posts, RR: 52
Reply 55, posted (2 years 4 months 5 days ago) and read 7497 times:

Quoting Daysleeper (Reply 52):

Line inspectors / QA staff did indeed point out that parts which were out of specification and had false records were being used in production. It was then an internal audit team which reported back to senior management that “misrepresentation of the manufacturing process jeopardises the integrity” and “the severity of this situation cannot be ignored” _- I’d assume that an audit team are able to determine how dangerous this situation was.

There is no defence for this, there are video’s and photos taken at AHF Ducommun that prove they breached regulations and shipped parts to Boeing to be used on the 737 that were out of specification. There is also proof that Boeing were aware of this, and that documents certifying these parts had been falsified and still they continued to fit the parts to aircraft.

I agree however that how dangerous these out of spec parts will be is open to interpretation.

As Tom mentioned there is a much more in depth process for dealing with such problems. Also, I think it would not be the audit team who would decide on if the parts are safe or not. It is up to the engineers responsible for that part of the airplane. They may have been involved, but that is not necessarily true. Management and quality do not have the authority to decide if a part is safe or not, they can only determine if it meets the engineering drawing requirements or not.

The issue they are finding is when a part does not meet the drawing requirements and the supplier did not notify of the problem. This is an every day occurrence and is called an escapement. It can happen when a process isn't being followed, a new machine is added to a process, a tool is out of tolerance, a dimension is misread, etc. What happens when the escapement is found is that it goes through an engineering evaluation to determine what to do. Engineering will make the call if the part is acceptable as is, or if it needs to be reworked or replaced. As a result of the engineering decision, a recovery plan is made. Many times it is to accept the part as is because there is no detrimental result, but sometimes it can have massive repercussions. It can involve replacing parts in production, retrofitting parts in service. It can get as severe as having an Airworthiness Directive issued to fix airplanes in the fleet.

The second process is related to non-conforming parts. This is very common and every plane has parts on it that do not meet the drawing. Tolerances build and usually in design there is the ability to add a shim or washer or trim a part so that it will work. Again engineering makes the call on what is acceptable and not quality assurance or quality investigators. It always goes through engineering and engineers who have a special certificate with authority to approve such parts have to approve on the final decision.

The processes can take some time, or they can happen very quickly when in a rush. Engineering, quality, and manufacturing all have to agree. It isn't the case of a manager tells someone to install a part because we are in a hurry and the part gets on the airplane. People get fired for doing that and it is a very serious problem that puts the Production Certificate in jeopardy.

Rarely does the media understand how these processes work. The article you presented does point out a case where there were some problems and sometimes resolution is not smooth.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineRoseflyer From United States of America, joined Feb 2004, 9489 posts, RR: 52
Reply 56, posted (2 years 4 months 5 days ago) and read 7474 times:

Quoting Daysleeper (Reply 54):
I mean, the Boeing QA inspector actually states one of the problem’s she witnessed were that line workers couldn’t get rivet holes to line up, so they were re-drilling and forcing them to fit

How do you know that re-drilling holes and having to rework parts is unsafe?



If you have never designed an airplane part before, let the real designers do the work!
User currently offlinemax550 From United States of America, joined Nov 2007, 1147 posts, RR: 0
Reply 57, posted (2 years 4 months 5 days ago) and read 7292 times:

Quoting Daysleeper (Reply 54):
The video highlights problems with the manufacture of 737 fuselage components from 1996 to 2004. And although the frame involved in the incident at Yuma was a classic, it was manufactured in 1996. I mean, the Boeing QA inspector actually states one of the problem’s she witnessed were that line workers couldn’t get rivet holes to line up, so they were re-drilling and forcing them to fit – It could still be co-incidence, but given what the NTSB found on their inspection, I doubt it.

We're talking about 2 different things here. Sorry for the misunderstanding.
The video you linked makes valid points and appears well researched. The article linked to in the OP is not. The author of that article mentions the manufacturing flaws once on the first page and then moves on to the design flaws in the 737 fuselage, namely thin skin prone to cracking, unsafe joints in the skin (the Achilles Heel of the 737), and an aft pressure bulkhead that could crack during hard landings. All of those problems can be dealt with through inspections and maintenance.
The manufacturing defects are a different and more serious matter and I don't want it to sound like I'm dismissing them. The problems brought up in the Newsweek article are what I take issue with.


User currently offlineDaysleeper From UK - England, joined Dec 2009, 838 posts, RR: 1
Reply 58, posted (2 years 4 months 5 days ago) and read 7255 times:

Quoting Roseflyer (Reply 56):
How do you know that re-drilling holes and having to rework parts is unsafe?

I didn’t say it was, I just said that it’s a co-incidence that there is a 737 with a hole in its roof that also has rivet holes that didn’t properly line up.

Quoting Roseflyer (Reply 55):

The issue they are finding is when a part does not meet the drawing requirements and the supplier did not notify of the problem. This is an every day occurrence and is called an escapement. It can happen when a process isn't being followed, a new machine is added to a process, a tool is out of tolerance, a dimension is misread, etc. What happens when the escapement is found is that it goes through an engineering evaluation to determine what to do. Engineering will make the call if the part is acceptable as is, or if it needs to be reworked or replaced. As a result of the engineering decision, a recovery plan is made. Many times it is to accept the part as is because there is no detrimental result, but sometimes it can have massive repercussions. It can involve replacing parts in production, retrofitting parts in service. It can get as severe as having an Airworthiness Directive issued to fix airplanes in the fleet.

I’m really not sure what your trying to say here, yes I understand that an occasional part might slip through QA and not be to specification or may require some re-work. But that is not what was happening here, by AHF’s own admission less than 10% of the parts they supplied to Boeing were manufactured to the certified standard. The rest had false documentation to say that were.


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9489 posts, RR: 52
Reply 59, posted (2 years 4 months 5 days ago) and read 7208 times:

Quoting Daysleeper (Reply 58):

I’m really not sure what your trying to say here, yes I understand that an occasional part might slip through QA and not be to specification or may require some re-work. But that is not what was happening here, by AHF’s own admission less than 10% of the parts they supplied to Boeing were manufactured to the certified standard. The rest had false documentation to say that were.

I explained the process for how to deal with the problem of parts not matching the drawings. Whether it was a falsified document or a cutting tool out of tolerance, the process for dealing with it is the same. That process is exactly what would have happened.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineEagleboy From Niue, joined Dec 2009, 1794 posts, RR: 2
Reply 60, posted (2 years 4 months 5 days ago) and read 7175 times:
Support Airliners.net - become a First Class Member!

Quoting ikramerica (Reply 6):
The 737 is one of the 5 least safe passenger aircraft families that Boeing currently produces!!

Love it!


User currently offlineHiFlyerAS From United States of America, joined Jul 2011, 923 posts, RR: 2
Reply 61, posted (2 years 4 months 5 days ago) and read 7175 times:

As someone that flies on 737 Classic and NG aircraft on a regular basis I was somewhat concerned after reading the article. I could tell that it was not giving the whole story and I'm glad that I found this thread on a.net to put it all in perspective!

User currently offlineRoseflyer From United States of America, joined Feb 2004, 9489 posts, RR: 52
Reply 62, posted (2 years 4 months 5 days ago) and read 7115 times:

Quoting Daysleeper (Reply 58):
Quoting Roseflyer (Reply 56):
How do you know that re-drilling holes and having to rework parts is unsafe?

I didn’t say it was, I just said that it’s a co-incidence that there is a 737 with a hole in its roof that also has rivet holes that didn’t properly line up.

You said earlier:

Quoting Daysleeper (Reply 50):
The conduct of Boeings managers after being made aware of this is what really concerns me as if they dismiss the concerns of their own inspectors which are able to present indisputable evidence that dangerous, even potentially deadly parts were being fitted to 737s.

I never saw any indisputable evidence that there were dangerous or deadly parts being fitted on 737s. I saw evidence that parts not meeting engineering drawings were being fitted on 737s. Those are completely different statements. The article you linked actually did a good job of not jumping to the conclusion that parts not meeting drawing requirements meant that airplanes were unsafe. Inherently all parts should conform to drawings, but not conforming to drawings does not necessarily mean they are unsafe. From all that is stated in the article it could have been a situation where there were problems with parts, but engineering found them acceptable which is why only a handful of the parts were rejected.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineDaysleeper From UK - England, joined Dec 2009, 838 posts, RR: 1
Reply 63, posted (2 years 4 months 5 days ago) and read 7102 times:

Quoting Roseflyer (Reply 59):
That process is exactly what would have happened.

Perhaps what *SHOULD* have happened, but going on the evidence in this case it isn’t what actually happened.


User currently offlinesoon7x7 From , joined Dec 1969, posts, RR:
Reply 64, posted (2 years 4 months 4 days 12 hours ago) and read 6556 times:

Driving cars is considerably more risky than a flight on a 737, yet we all don't give it a second thought...much less a first...so whats all the hubbub?...journalists suck, they are looking to guild their own throne....So what else is new?  

User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 65, posted (2 years 4 months 4 days 11 hours ago) and read 6536 times:

Quoting Daysleeper (Reply 52):
There is no defence for this, there are video’s and photos taken at AHF Ducommun that prove they breached regulations and shipped parts to Boeing to be used on the 737 that were out of specification.

There's no defense *for AHF Ducommon*...if Boeing looked at the parts and determined they met requirements (a very different thing than meets spec) then Boeing's position is completely defensible.

Quoting Daysleeper (Reply 52):
There is also proof that Boeing were aware of this, and that documents certifying these parts had been falsified and still they continued to fit the parts to aircraft.

And, if the parts went through engineering disposition process (which is what happens to *all* know discrepancies) then there is absolutely nothing wrong with that.

Quoting Daysleeper (Reply 54):
I mean, the Boeing QA inspector actually states one of the problem’s she witnessed were that line workers couldn’t get rivet holes to line up, so they were re-drilling and forcing them to fit

That's what you do if you have misalignment...either shim it back into alignment or oversize the holes (this option is designed right into the part) so that they new larger hole is aligned. Provided it's done per process, this is a completely acceptable and normal way of addressing a manufacturing discrepancy.

Tom.


User currently offlineDaysleeper From UK - England, joined Dec 2009, 838 posts, RR: 1
Reply 66, posted (2 years 4 months 4 days 5 hours ago) and read 6324 times:

Quoting tdscanuck (Reply 65):
There's no defense *for AHF Ducommon*...if Boeing looked at the parts and determined they met requirements (a very different thing than meets spec) then Boeing's position is completely defensible.
Quoting tdscanuck (Reply 65):
And, if the parts went through engineering disposition process (which is what happens to *all* know discrepancies) then there is absolutely nothing wrong with that.
Quoting tdscanuck (Reply 65):
That's what you do if you have misalignment...either shim it back into alignment or oversize the holes (this option is designed right into the part) so that they new larger hole is aligned. Provided it's done per process, this is a completely acceptable and normal way of addressing a manufacturing discrepancy.

Tom.

The design stipulated that the parts needed to be manufactured by CNC to ensure they met tolerance, and more importantly the standard to which they were certified. This was not happening, they were instead being made by hand, so no matter how much re-work Boeing line workers did they were never going to be able to meet the certified standard. Mis-alignment is also just one defect, the documents detail numerous other problems some of which such as the material being too thin would be very hard to fix.

In regards to Boeing’s accountability; line managers prevented workers from filing non-conformance reports due to the volume of problem parts. They also knowingly allowed non-certified parts with false documentation to be fitted to aircraft – And that’s without going into their conduct towards their own staff when they decided these issues were serious enough to involve the FAA.


User currently offlinedynamicsguy From Australia, joined Jul 2008, 868 posts, RR: 9
Reply 67, posted (2 years 4 months 4 days 4 hours ago) and read 6295 times:

Quoting Daysleeper (Reply 50):
Indeed, the problem highlighted in the video I linked too is that the design of the NG is dependant on parts being manufactured by CNC allowing for much tighter tolerances to be stipulated.

The story you linked to was already discussed to death at the time. The program made plenty of assertions which weren't supported by the evidence which they used. The audit report which you refer to and which was available on the program's website showed 3 problems - that the production planning did not match the process used, that the company had billed Boeing for the cost of tooling for CNC processes when cheaper tooling for hand forming would have been sufficient for the process they were using, and that they had lost some of the expensive tooling which Boeing had paid for. There was nothing in the audit report about the parts not being made to spec, or that there was a safety problem. This suggests that the parts did not need to be CNC manufactured to meet the engineering.

The credibility of that program is about as low as this Newsweek article. It certainly had an agenda to push.


User currently onlinebikerthai From United States of America, joined Apr 2010, 2063 posts, RR: 4
Reply 68, posted (2 years 4 months 4 days 3 hours ago) and read 6211 times:

Quoting Daysleeper (Reply 66):

The design stipulated that the parts needed to be manufactured by CNC to ensure they met tolerance,

Designers rarely if ever specify that a part have to be CNC. We provide a required tolerance, and it's up to the supplier to decide what processes they use to meet that tolerance.

Quoting dynamicsguy (Reply 67):
This suggests that the parts did not need to be CNC manufactured to meet the engineering.

  

In most case now-a-days CNC is preferred because there is limited up-front tooling cost. However, if the contract goes to a company with limited CNC capacities (for various reasons) high accuracy tooling is a viable option.

This is also true with CMM inspection.

We are finding this out as we subcontract to places like India. Although these company do have CNC and CMM machine to perform the work, they may not have sufficient quantities to meet rate, so they build high accuracy tooling to supplement their NC work. This is possible because the labor cost and tooling cost is much cheaper over there.

bt



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlineDaysleeper From UK - England, joined Dec 2009, 838 posts, RR: 1
Reply 69, posted (2 years 4 months 4 days 3 hours ago) and read 6177 times:

Quoting dynamicsguy (Reply 67):
The story you linked to was already discussed to death at the time. The program made plenty of assertions which weren't supported by the evidence which they used. The audit report which you refer to and which was available on the program's website showed 3 problems - that the production planning did not match the process used, that the company had billed Boeing for the cost of tooling for CNC processes when cheaper tooling for hand forming would have been sufficient for the process they were using, and that they had lost some of the expensive tooling which Boeing had paid for. There was nothing in the audit report about the parts not being made to spec, or that there was a safety problem. This suggests that the parts did not need to be CNC manufactured to meet the engineering.

Can you provide links to those threads? - Or proof that the assertations made by the Boeing staff featured in the video are false?

Edit

Quoting bikerthai (Reply 68):
Designers rarely if ever specify that a part have to be CNC. We provide a required tolerance, and it's up to the supplier to decide what processes they use to meet that tolerance.

Quoting dynamicsguy (Reply 67): This suggests that the parts did not need to be CNC manufactured to meet the engineering.

If thats was the case then why bother making just some of them on the CNC? If it wasn’t required and as you point out significantly cheaper then why not just make them all by hand?

Also, why did they go to so much trouble to keep two sets of books? And then fake documentation?

And finnaly You have to ask why Boeing sent an audit team to AHF in the first place, if the parts met specification and tolerance then why did they investigate them?

[Edited 2012-03-21 06:44:23]

User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 70, posted (2 years 4 months 4 days 2 hours ago) and read 6134 times:

Quoting Daysleeper (Reply 66):
The design stipulated that the parts needed to be manufactured by CNC to ensure they met tolerance, and more importantly the standard to which they were certified. This was not happening, they were instead being made by hand, so no matter how much re-work Boeing line workers did they were never going to be able to meet the certified standard.

1) The design didn't stipulate they had to be CNC (see other replies).
2) All OEM's have a production certificate that includes a non-conformance process. If the part goes through that process and is dispositioned as such then it is certified for use on the airplane, *regardless of what was wrong with it entering the process*.

You seem to believe that a part has to match spec or it can't be used or can't be certifed; that's just not correct and, in fact, a huge number of parts on all aircraft have something wrong with them when they enter the production system. When these are caught they're dispositioned and dealt with appropriately; this is normal, safe, and completely certified.

Quoting Daysleeper (Reply 69):
If thats was the case then why bother making just some of them on the CNC? If it wasn’t required and as you point out significantly cheaper then why not just make them all by hand?

Rate. Suppliers have to hit a certain rate. CNC is fast but, if you don't have enough CNC tools, you can't make rate. If you do it all by hand you're wasting your expensive and fast CNC tool by having it do nothing. Maximum rate, in many cases, will be a combination of both.

Quoting Daysleeper (Reply 69):
Also, why did they go to so much trouble to keep two sets of books? And then fake documentation?

I don't think anybody is defending the supplier for double-bookeeping; you're just jumping from "the supplier did something wrong" to "Boeing must have done something wrong because they used parts from a supplier that did something wrong" without showing that Boeing didn't actually following Boeing's processes to deal with parts manufacturing issues.

Quoting Daysleeper (Reply 69):
You have to ask why Boeing sent an audit team to AHF in the first place, if the parts met specification and tolerance then why did they investigate them?

1) OEM's audit all their suppliers from time to time.
2) Nobody is claiming the parts met spec or tolerance, just that they met requirements after engineering disposition. I feel the need to repeat: "meets spec" and "meets requirements" are NOT the same thing.

Tom.


User currently offlineDaysleeper From UK - England, joined Dec 2009, 838 posts, RR: 1
Reply 71, posted (2 years 4 months 4 days 1 hour ago) and read 6070 times:

Quoting tdscanuck (Reply 70):
You seem to believe that a part has to match spec or it can't be used or can't be certifed; that's just not correct and, in fact, a huge number of parts on all aircraft have something wrong with them when they enter the production system. When these are caught they're dispositioned and dealt with appropriately; this is normal, safe, and completely certified.

What I believe isn’t relevant, I’m simply going on the evidence provided by Boeings own staff and industry experts which participated in the report. I have already stated how dangerous Boeings conduct turns out to be is open to interpitation. The expert’s and the staff members on the Audit team believe it could lead to premature failure. In fact, they were so concerned over the safety of the aircraft and so disgusted with how Boeing handled the issues they raised they were willing to risk not only their jobs, but there entire career’s to try and resolve it.

Quoting tdscanuck (Reply 70):

1) OEM's audit all their suppliers from time to time.
2) Nobody is claiming the parts met spec or tolerance, just that they met requirements after engineering disposition. I feel the need to repeat: "meets spec" and "meets requirements" are NOT the same thing.

1)The two members of Boeings staff which instigated this report were the members of the actual audit team sent to AHF, they categorically state that they went because parts arriving at Boeing were not up to standard. It was not a routine audit.

2)Dynamicsguy claimed exactly that. I also feel the need to repeat that if the requirement were being met then why did they fake the documentation or accept fake documentation? Why breach regulation when they could just update the requirement?


User currently onlinebikerthai From United States of America, joined Apr 2010, 2063 posts, RR: 4
Reply 72, posted (2 years 4 months 4 days ago) and read 6025 times:

Quoting Daysleeper (Reply 69):
If thats was the case then why bother making just some of them on the CNC? If it wasn’t required and as you point out significantly cheaper then why not just make them all by hand?

Now you are getting into the nitty gritty of business models.

At the beginning of a program, there is not enough airplanes delivered to warrant spending up-front money for expensive tooling, so CNC is a good way to produce parts.

If the program is a success, and you get more order, you can 1) create additional tooling to make rate or 2) buy more CNC machines. Companies just don't keep CNC idle waiting for business. So, tooling may be expensive but new CNC machines are even more expensive, may take longer to acquire, and may become a liability if that business dry up.

It becomes a business decision and not an engineering decision. My note on difference in cost, between CNC vs tooling and handwork, varies depending on regions and politics. In East and South Asia, manual labor may be cheaper, in N America and Europe, automation may be the way to go. We engineers rarely make these business decisions . . .

bt



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlineRoseflyer From United States of America, joined Feb 2004, 9489 posts, RR: 52
Reply 73, posted (2 years 4 months 3 days 19 hours ago) and read 5858 times:

Quoting Daysleeper (Reply 66):

The design stipulated that the parts needed to be manufactured by CNC to ensure they met tolerance, and more importantly the standard to which they were certified. This was not happening, they were instead being made by hand, so no matter how much re-work Boeing line workers did they were never going to be able to meet the certified standard. Mis-alignment is also just one defect, the documents detail numerous other problems some of which such as the material being too thin would be very hard to fix.

Drawings specify inspection requirements based on what process is used. For example, for forgings inspect per document X, for castings inspect for document Y. I have never seen a drawing specify a requirement to be manufactured by CNC. Drawings may specify to machine a part and then inspect per penetrant inspection process XX. Whether it is by hand or it is by CNC does not matter if the tolerances are met.

Also parts aren't certified, designs are certified. There's no certification plan that a piece of sheet metal must have specific dimensions. It is designed to have whatever dimensions the engineering and stress analysis indicate it has to have. Any change to the build paperwork of the airplane is reviewed to see if it affects certification. Redrilling holes or adding shims to make a part fit does not affect certification. The part might not meet drawing requirements, which means it must be assesed on whether it is acceptable or must be rejected, but again that is not a certification question. I'm not an expert on structural certification plans, but there are guidelines for what counts and what does not. Changing spacing of frames or replacing lap joints might affect certification, but nothing at the detail level being talked about here is a certification issue.

Quoting Daysleeper (Reply 71):

2)Dynamicsguy claimed exactly that. I also feel the need to repeat that if the requirement were being met then why did they fake the documentation or accept fake documentation? Why breach regulation when they could just update the requirement?

Again this is two separate questions. Is the part acceptable for use and does the part meet the drawing requirement are separate questions. Claiming that the part did meet the drawing requirements, when it does not is a problem, but as stated before there is a review process that is used to check to see if the part is acceptable for use. Boeing does not accept parts that do not meet drawing requirements unless they are reviewed by engineering. Boeing does not want suppliers to send parts that don't meet the drawing requirements and continuously submitting parts that do not meet drawing requirements might result in loss of contracts and other penalties.

Also updating a requirement is not a simple easy process. For a supplier to initiate a change to the drawings, they have to request it and it may or may not be approved and can take some time.

If you want to know what the consequences of fake documentation are, look at the Koito seat problems. The documentation from certification testing was falsified. The second it was found out, those seats were no longer able to be delivered on new airplanes because the engineering analysis showed that they did not meet the certification requirements. CO had about a dozen brand new 737s sitting in Seattle awaiting delivery for months, but because they didn't have certified seats, the planes were sitting in limbo until new seats could be attained.

Quoting Daysleeper (Reply 71):

1)The two members of Boeings staff which instigated this report were the members of the actual audit team sent to AHF, they categorically state that they went because parts arriving at Boeing were not up to standard. It was not a routine audit.

The reports indicate that there were parts being rejected. Many were accepted, but some were rejected. That implies that they did go through the nonconforming parts process. Accepted but via the nonconformance process or rejected are red flags that lower the quality rating on a supplier and will trigger an audit or some other form of corrective action.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlinedynamicsguy From Australia, joined Jul 2008, 868 posts, RR: 9
Reply 74, posted (2 years 4 months 3 days 18 hours ago) and read 5791 times:

Quoting Daysleeper (Reply 69):
Can you provide links to those threads? - Or proof that the assertations made by the Boeing staff featured in the video are false?
AlJazeera: 'investigation' On Boeing Due Wed

The program's website had a copy of the draft audit report. The worst it said was that there was a "quality problem", which was true, but does not make it unsafe.

Quoting Daysleeper (Reply 71):
What I believe isn’t relevant, I’m simply going on the evidence provided by Boeings own staff and industry experts which participated in the report

As I said, be wary of the agenda of the people making the program. The Boeing staff were the staff who had been sacked. The experts were not independent - they all came from the legal team of those sacked employees. My impression of the program was that the journalists did very little work - they presented the story which was gift wrapped for them.


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 75, posted (2 years 4 months 3 days 13 hours ago) and read 5675 times:

Quoting Daysleeper (Reply 71):
I also feel the need to repeat that if the requirement were being met then why did they fake the documentation or accept fake documentation?

Because a build-to-print supplier has no idea what the requirements are. They only know what the drawing says. If they build parts that don't match the drawings, they'll get parts rejections, audits, and eventually lose their contract.

Quoting Daysleeper (Reply 71):
Why breach regulation when they could just update the requirement?

Because they can't update the requirement. They don't know what it is and, even if they did, they don't have the authority or capability to update it.

For a straight part-shop supplier, only the OEM knows the actual loads and operating environment for a structural part. As a result, only the OEM can disposition an off drawing part. This is also important for multi-site structural parts like stringers or clips...a particular type of out-of-tolerance problem may be completely acceptable at one location and totally unacceptable at another. The supplier has no idea what location any particular part is going to end up in; the OEM does.

Note that this is quite different for build-to-spec or "partner" suppliers, but that's not the type of supplier in this case.

Tom.


User currently offlinecoolum From United Arab Emirates, joined Jul 2008, 51 posts, RR: 0
Reply 76, posted (2 years 4 months 3 days 6 hours ago) and read 5524 times:
Support Airliners.net - become a First Class Member!

http://www.kansas.com/2010/10/16/154...g-seeks-info-in-whistleblower.html

Some more background info regarding the boeing whistleblower video.



Coolum
User currently offlineDaysleeper From UK - England, joined Dec 2009, 838 posts, RR: 1
Reply 77, posted (2 years 4 months 3 days 2 hours ago) and read 5418 times:

Quoting Roseflyer (Reply 73):
Drawings may specify to machine a part and then inspect per penetrant inspection process XX. Whether it is by hand or it is by CNC does not matter if the tolerances are met.

This is incorrect. Under PMA federal regulation requires details on how a part is manufactured and stipulates that subsequent part be manufactured the same way in order to be installed upon a type certificated aircraft.

As an example of this, consider a bolt. One could be manufactured with the specified material, to the exact dimensions stipulated but then incorrectly heat treated. The result would be a part that would meet all aspects of the specification, but be considerably weaker. Therefore it is critical that manufacturing process be considered in a part specification.

Quoting Roseflyer (Reply 73):
Also parts aren't certified, designs are certified. There's no certification plan that a piece of sheet metal must have specific dimensions. It is designed to have whatever dimensions the engineering and stress analysis indicate it has to have.

Again, incorrect. See above.

Quoting Roseflyer (Reply 73):
The reports indicate that there were parts being rejected. Many were accepted, but some were rejected. That implies that they did go through the nonconforming parts process. Accepted but via the nonconformance process or rejected are red flags that lower the quality rating on a supplier and will trigger an audit or some other form of corrective action.

The failure of Boeings internal QA procedures are what started all this, had they been to standard then their own staff wouldn’t have needed to turn whistle blower. Just one example of how badly it failed is the fact they allowed parts with false documentation to be used. This is a clear breach regulation outlined in Part 21, subsection 3 of federal code covering Aeronautics and Space. To me, examples like this are indefensible - The regulation is there for a reason, people have died because of such breachs.

Quoting dynamicsguy (Reply 74):
The program's website had a copy of the draft audit report. The worst it said was that there was a "quality problem", which was true, but does not make it unsafe.

These parts are Primary Structural Elements, and to quote Boeing “The failure of a PSE would likely result in the catastrophic failure of the airplane” So, for these components to have “quality” problems is fairly significant.

Quoting dynamicsguy (Reply 74):
As I said, be wary of the agenda of the people making the program

A fact is a fact .
Incidentally did you manage to find the links you mentioned above that disprove all of this? I have genuinely been searching to try and get another viewpoint on it but have come up with nothing


User currently onlinenomadd22 From United States of America, joined Feb 2008, 1828 posts, RR: 0
Reply 78, posted (2 years 4 months 3 days 2 hours ago) and read 5393 times:

Quoting Daysleeper (Reply 77):

As an example of this, consider a bolt. One could be manufactured with the specified material, to the exact dimensions stipulated but then incorrectly heat treated. The result would be a part that would meet all aspects of the specification, but be considerably weaker. Therefore it is critical that manufacturing process be considered in a part specification.

Nonsense. Strength is obviously part of the specification. Micromaniging the manufacturing process would destroy any chances the vendor had to make improvements or come up with inovations. The customer can farm out an exact way of making something, but most stuff depends on the vendor determining the best method of meeting the requirements.

[Edited 2012-03-22 07:01:37]


Andy Goetsch
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 79, posted (2 years 4 months 3 days 2 hours ago) and read 5379 times:

Quoting Daysleeper (Reply 77):
Under PMA federal regulation requires details on how a part is manufactured and stipulates that subsequent part be manufactured the same way in order to be installed upon a type certificated aircraft.

A supplier is prefectly free to change manufactuing methods at any time provided the end part meets the drawing requirements. Unless the drawing actually says "CNC this part" (which is extremely unusual and doesn't appear to apply in this case) then the supplier is welcome to use alternate manufacturing methods if they produce the same result.

Also, this isn't about PMA...PMA is for a supplier to build individually certified spare parts. It doesn't apply to parts built for OEM.

Quoting Daysleeper (Reply 77):
As an example of this, consider a bolt. One could be manufactured with the specified material, to the exact dimensions stipulated but then incorrectly heat treated. The result would be a part that would meet all aspects of the specification, but be considerably weaker.

Heat treatment would be part of the specification. Spec includes a *lot* more than just material and dimensions. A part incorrectly heat treated would not meet all aspects of the specification.

Quoting Daysleeper (Reply 77):
The failure of Boeings internal QA procedures are what started all this, had they been to standard then their own staff wouldn’t have needed to turn whistle blower. Just one example of how badly it failed is the fact they allowed parts with false documentation to be used.

There is NOTHING wrong with allowing a part with false documentation from the supplier IF the part goes through the production-certificate approved engineering disposition process. It's inefficient as hell and the OEM's hate it for that reason, but it's perfectly legal, normal, safe, and acceptable.

Quoting Daysleeper (Reply 77):
These parts are Primary Structural Elements, and to quote Boeing “The failure of a PSE would likely result in the catastrophic failure of the airplane”

That's a very interesting quote, since it functionally says the aircraft isn't airworthy. Failure of *a* PSE cannot result in catastrophic failure of the airplane or the design itself doesn't meet the intent of the FARs.

Tom.


User currently onlinebikerthai From United States of America, joined Apr 2010, 2063 posts, RR: 4
Reply 80, posted (2 years 4 months 3 days 2 hours ago) and read 5377 times:

Quoting Daysleeper (Reply 77):
Under PMA federal regulation requires details on how a part is manufactured and stipulates that subsequent part be manufactured the same way in order to be installed upon a type certificated aircraft.

Haven't read much in terms of regulations but I have read a few process specs. Typically regulations can be quite broad even when they seem very specific.

The above example stipulate that parts shall be manufactured the same way. But it does not specify what "same" is. Consider the drilling of a hole per a drilling specification. The regulation may consider that drilling per that specification is considered the "same way". However the specification does not specify whether the driller is a machinist or a robot, with a hand drill or a drill press, using a tool or through CNC as long as the drill bits meet the requirements, the drill speeds are appropriate and the drilling equipment/tools are certified.

But the regulation or specification probably does differentiate among holes drilled by a drill bit, punched by a die, or cut via a laser cutter. In many cases, the engineered design will allow for the different processes. In those cases the processes gets rolled up in to "the same" category by the engineering drawing and get final approval by the regulatory agency in the end.

bt



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlineDaysleeper From UK - England, joined Dec 2009, 838 posts, RR: 1
Reply 81, posted (2 years 4 months 3 days 1 hour ago) and read 5325 times:

Quoting tdscanuck (Reply 79):
There is NOTHING wrong with allowing a part with false documentation from the supplier IF the part goes through the production-certificate approved engineering disposition process. It's inefficient as hell and the OEM's hate it for that reason, but it's perfectly legal, normal, safe, and acceptable.

That’s great in theory. But the principal complaint in this report, and the very reason that Boeings own QA staff went to the FAA was because these procedures were not being followed, and this in their opinion compromises the safety of the aircraft.

Quoting tdscanuck (Reply 79):
. Unless the drawing actually says "CNC this part" (which is extremely unusual and doesn't appear to apply in this case) then the supplier is welcome to use alternate manufacturing methods if they produce the same result.

I’m going to hold off discussing this point for a while. I stand by what I said in that the manufacturing process is part of the specification, but I’m still trawling through the regulations in order to expand upon that.


User currently onlinebikerthai From United States of America, joined Apr 2010, 2063 posts, RR: 4
Reply 82, posted (2 years 4 months 3 days ago) and read 5262 times:

Quoting Daysleeper (Reply 77):

As an example of this, consider a bolt. One could be manufactured with the specified material, to the exact dimensions stipulated but then incorrectly heat treated.

Bad example. If the bolt is incorrectly heat treated, then it would not meet all spec and requirements because for the most part the heat treat process (and the correct application there off) is part of the requirements. As far as strength is concern, batches of bolts are regularly tested. Batches with bolt samples that do not meet spec (specially with respect to strength) are discarded.

Where fasteners are concern, we tend to have more problems with finishes. Bad finishes are harder to detect and problem don't show up until you see corrosion on an already delivered aircraft.

And to be sure, we do get fasteners that are deformed or do not meet dimensional requirements all the time (you just can't inspect every faster in a batch). But hopefully the mechanic installing those fasteners will discard them if they find them. All those issues are more QA related and may not necessarily be spec related. It is a trade off - proof testing every fastener is impractical. Although for critical applications, Engineering sometimes do require each bolt to be proof tested.

Quoting Daysleeper (Reply 81):
I stand by what I said in that the manufacturing process is part of the specification,

In this we agree. Although some specifications may be more broad than others.

bt



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlineRoseflyer From United States of America, joined Feb 2004, 9489 posts, RR: 52
Reply 83, posted (2 years 4 months 3 days ago) and read 5229 times:

Quoting Daysleeper (Reply 77):
Quoting Roseflyer (Reply 73):
Drawings may specify to machine a part and then inspect per penetrant inspection process XX. Whether it is by hand or it is by CNC does not matter if the tolerances are met.

This is incorrect. Under PMA federal regulation requires details on how a part is manufactured and stipulates that subsequent part be manufactured the same way in order to be installed upon a type certificated aircraft.

As an example of this, consider a bolt. One could be manufactured with the specified material, to the exact dimensions stipulated but then incorrectly heat treated. The result would be a part that would meet all aspects of the specification, but be considerably weaker. Therefore it is critical that manufacturing process be considered in a part specification.

I am not incorrect and also have no idea why you are quoting PMA requirements because we are talking parts certified in the type design. PMA is for aftermarket parts, and the FAA requires them to be similar to the original parts. However if an OEM engineer wants to change the original part manufacturing process, they are free to do so.

As someone who has created drawings for parts used on airplanes, I know the process. For a machined part, here are the drawing notes regarding manufacturing that I would typically use

1. Machine Part from Aluminum Spec XXX
2. Heat Treat per Spec XXX
3. Apply primer per spec XXX
3. Penetrant inspect per spec XXX

I have never specified what type of machining process is used. That's overconstraining the manufacturer and may result in parts that cannot be built. The only process I care about is that it is machined since my stress analysis uses machining in its calculations. What type of machining does not matter since it does not affect the strength of the part, what would matter is if a supplier wanted to create the part from a casting or forging. If they wanted to do that, they'd have to submit a request for a design change, and I'd have to redesign the part including casting factors and adding draft angles etc.

Quoting Daysleeper (Reply 77):
The failure of Boeings internal QA procedures are what started all this, had they been to standard then their own staff wouldn’t have needed to turn whistle blower. Just one example of how badly it failed is the fact they allowed parts with false documentation to be used. This is a clear breach regulation outlined in Part 21, subsection 3 of federal code covering Aeronautics and Space. To me, examples like this are indefensible - The regulation is there for a reason, people have died because of such breachs.

As Tom mentioned, if it goes through the engineering disposition process, it can be used. The engineering disposition process can basically approve any part for the airplane and can overrule any drawing requirements as long as it does not impact certification requirements (review to check if certification requirements are affected is part of the engineering disposition process).

Quoting tdscanuck (Reply 79):
Quoting Daysleeper (Reply 77):
These parts are Primary Structural Elements, and to quote Boeing “The failure of a PSE would likely result in the catastrophic failure of the airplane”

That's a very interesting quote, since it functionally says the aircraft isn't airworthy. Failure of *a* PSE cannot result in catastrophic failure of the airplane or the design itself doesn't meet the intent of the FARs.

I agree that there is a contradiction here. No single failure can result in the inability for the crew to maintain safe flight and landing without exceptional pilot skill (FAR requirement). No single failure can be catastrophic otherwise the airplane is not airworthy, so "Failure of a PSE would likely result in the catastrophic failure of the airplane" is an incorrect statement.

[Edited 2012-03-22 09:53:58]


If you have never designed an airplane part before, let the real designers do the work!
User currently onlinebikerthai From United States of America, joined Apr 2010, 2063 posts, RR: 4
Reply 84, posted (2 years 4 months 2 days 22 hours ago) and read 5158 times:

Quoting Roseflyer (Reply 83):
I have never specified what type of machining process is used. That's overconstraining the manufacturer and may result in parts that cannot be built.

Just because you don't specify what type of machining process is used on our drawings, it doesn't mean that there are no processes out there that the supplier must follows. Often times it's a generic machining process or their own processes. Either way, these processes would have to be approved for use when the supplier is Qualified.

Quoting Roseflyer (Reply 83):
What type of machining does not matter since it does not affect the strength of the part,

In some cases it does . . . laser trimming can generate heat affected zone. (Although you don't usually laser trim aluminum.) Heat affected zone has different properties that must be accounted for.

bt



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlinedynamicsguy From Australia, joined Jul 2008, 868 posts, RR: 9
Reply 85, posted (2 years 4 months 2 days 17 hours ago) and read 5045 times:

Quoting Daysleeper (Reply 77):
The failure of Boeings internal QA procedures are what started all this

Why do you believe there was a failure in the internal QA procedures? The program presents evidence that parts were being rejected, which suggests that Boeing's QA process is working. Apart from that there are only anecdotes.

Quoting Daysleeper (Reply 77):
So, for these components to have “quality” problems is fairly significant.

To a layman this certainly sounds alarming. The reality is that for them to have used those words, and not something like it "safety of flight", means that it is likely just a quality problem. When we talk about a quality problem where I work it is usually something which impacts cost (in the cost of rework, repair or scrap) or schedule (the time required to disposition parts, or perform rework or repair, or to have to make a new part to replace a scrapped part).

Quoting Daysleeper (Reply 81):
but I’m still trawling through the regulations in order to expand upon that.

There is plenty of expertise here in the forum. The people you're disagreeing with all actually work in the industry and do this for a living.

Quoting Daysleeper (Reply 77):
Incidentally did you manage to find the links you mentioned above that disprove all of this?

It's all the the last thread on this subject which I linked to. The program had a website associated with it on which there is a copy of the draft audit memo. This is the document which the program relied heavily on as their "proof". I have not gone back to have another look so I haven't found the link, but I'm sure you can from the last thread.

If you actually read that document it does not support their claim of this being a safety problem, and in what it does not say it all but proves that the parts did not have to be manufactured using CNC processes. The audit document is more concerned with economic issues about Boeing having paid for more expensive tooling than was required for the processes actually used. There were certainly issues found relating to production planning and documentation which were significant, but not a massive risk to safety as the program's makers want you to believe.

I don't know if you've ever read or seen a journalist's report on a subject with which you're very familiar. If you have not, then when you do you will find it an eye-opening experience.


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