FluidFlow
Posts: 292
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 11:54 am

kalvado wrote:
FluidFlow wrote:
planecane wrote:

The 21 day repair is to replace the pickle forks with new ones. As lightsaber said, a reinforcement modification will be developed and installed on all aircraft BEFORE the cracks develop. This modification will certainly be far less expensive and time consuming. As lightsaber also said, once a repair is certified, a repair and reinforcement will be able to be done on aircraft with cracks that doesn't involve replacing the pickle forks with new ones. This will also be a less costly and time consuming repair.

They aren't just going to inspect and replace pickle forks when cracks are found for the rest of the 737NG service life.


Alright, that's good news.

Does anyone here has a rough estimation what a fix like this would cost? The development, testing and certification will probably cost a bit. Afterwards when it can be done on premise from the airline maintenance it should be rather cheap, a few hours of work.

Few hours including removal and reinstall of wing root fairing?


How long do you think it takes? My guess is <150 man hours. That's one week with 4 workers. I guess that is doable. That is only a few hours in my opinion on an issue like that, especially as the replacement takes 3 weeks, a repair/reinforcement should be quicker. Boeing will find a way to make this as quick as possible because if it needs to be performed on 6700 air frames it will cost alot.
 
Jacob2877
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 12:04 pm

Just out of curiosity, couldn’t there be 737ng that have the cracks under the specified 30k cycles? I am a nervous flyer and I am glad these checks are done now but my concern is flying on aircraft that has 24k cycles (for example) has cracks but no check was done and now something catastrophic can still happen.
 
MIflyer12
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 12:13 pm

Statistics. If the FAA thought there was a meaningful likelihood of cracking at 24K cycles vs. 26K they would have specified the lower count.
 
kalvado
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 12:18 pm

MIflyer12 wrote:
Statistics. If the FAA thought there was a meaningful likelihood of cracking at 24K cycles vs. 26K they would have specified the lower count.

will definitely be reviewed as most risky ones are inspected, and lower hour, lower risk ones may be due for inspection as well.
Potential risk factors mentioned so far are
-landing cycles
-winglet (cycles or hours?)
-short runway landings
(speculating)
-previous overweight landings
-average landing weight

SOmeone at FAA or Boeing is compiling all the data, that's for sure.
 
mjoelnir
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 12:41 pm

Jacob2877 wrote:
Just out of curiosity, couldn’t there be 737ng that have the cracks under the specified 30k cycles? I am a nervous flyer and I am glad these checks are done now but my concern is flying on aircraft that has 24k cycles (for example) has cracks but no check was done and now something catastrophic can still happen.


There is a regime in the AD for frames between 22,600 and 30,000 cycles, they have to be inspected inside of the next 1000 cycles.
 
minilinde
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 1:29 pm

VSMUT wrote:
https://check-in.dk/sas-finder-revnedannelser-i-to-fly/?fbclid=IwAR168aaEvCECJdeiZyooBsFeFUiN9JjuuybtBOKBXUJfI6juazpP9zmFSBM

2 SAS 737s now.


Most is a pay-wall. Could you share a qoute from the article?
 
VSMUT
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 1:34 pm

minilinde wrote:
VSMUT wrote:
https://check-in.dk/sas-finder-revnedannelser-i-to-fly/?fbclid=IwAR168aaEvCECJdeiZyooBsFeFUiN9JjuuybtBOKBXUJfI6juazpP9zmFSBM

2 SAS 737s now.


Most is a pay-wall. Could you share a qoute from the article?


No. I'm not paying the exhorbitant prices that site charges.
 
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par13del
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 2:14 pm

So if there are any NG's flying around that do not have winglets etc. would that a/c be a candidate for study to see if the cause can be traced to the additions?
If that is the case, is the extra fuel savings worth the cost of the repair, additional inspections and or shorter service life?
 
Leej
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 2:29 pm

Are these pickle forks used on other Boeing n/b, such as the 757 - or I guess anything that has winglets, 767 included? Are they being checked too?
 
kalvado
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 2:34 pm

Leej wrote:
Are these pickle forks used on other Boeing n/b, such as the 757 - or I guess anything that has winglets, 767 included? Are they being checked too?

This seems to be a more or less standard part of design. And no, engine failure on A-380 doesn't mean 737's engines must be checked as well, flat tire on my car doesn't mean your risk of getting a flat tire increased.
Same here, it is specific design of 737NG being looked at.
 
Leej
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 2:50 pm

kalvado wrote:
Leej wrote:
Are these pickle forks used on other Boeing n/b, such as the 757 - or I guess anything that has winglets, 767 included? Are they being checked too?

This seems to be a more or less standard part of design. And no, engine failure on A-380 doesn't mean 737's engines must be checked as well, flat tire on my car doesn't mean your risk of getting a flat tire increased.
Same here, it is specific design of 737NG being looked at.


Having a bad day? What a sarcastic reply! ' a more or less standard part of design' followed by 'it is a specific design'. A simple, no, I don't know, or I am sure they are checking would suffice. If it is a standard design, one would have thought that similar airframe types using said design would be checked too?
 
kalvado
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 2:59 pm

Leej wrote:
kalvado wrote:
Leej wrote:
Are these pickle forks used on other Boeing n/b, such as the 757 - or I guess anything that has winglets, 767 included? Are they being checked too?

This seems to be a more or less standard part of design. And no, engine failure on A-380 doesn't mean 737's engines must be checked as well, flat tire on my car doesn't mean your risk of getting a flat tire increased.
Same here, it is specific design of 737NG being looked at.


Having a bad day? What a sarcastic reply! ' a more or less standard part of design' followed by 'it is a specific design'. A simple, no, I don't know, or I am sure they are checking would suffice. If it is a standard design, one would have thought that similar airframe types using said design would be checked too?

Let me ask so: should an engine problem on Honda Civic cause checks on Honda Odyssey?
Both have piston internal combustion engine as a more or less standard part of the design. Except for one is 3.5L V6, the other is 1.5L L4, and spark plugs may be the only common part between the two.
 
Leej
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 3:08 pm

No - because they have different engines! Just like your idiotic comparison between an A380 engine and 737 engine. My case is thus: The 737 and 757 share (or very similarly) the same fuselage and framework, so one would assume similar structures wing to fuselage (pickle forks). You haven't made any attempt to shed any light in answering my question. Stop being a troll. If the subframe of my Honda Civic is the same (or similar) in design to your Odyssey, amd mine cracks, would, or should similar designs be checked? Why are you being so aggressive to a general question?
 
kalvado
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 3:20 pm

Leej wrote:
No - because they have different engines! Just like your idiotic comparison between an A380 engine and 737 engine. My case is thus: The 737 and 757 share (or very similarly) the same fuselage and framework, so one would assume similar structures wing to fuselage (pickle forks). You haven't made any attempt to shed any light in answering my question. Stop being a troll. If the subframe of my Honda Civic is the same (or similar) in design to your Odyssey, amd mine cracks, would, or should similar designs be checked? Why are you being so aggressive to a general question?

"share" is a relative term. Boeing said that neither MAX nor 737 classic are not affected. Parts are significantly different.
FOrk is part of wing to body attachement. Different wing - and different amount of force being transferred - requires different design.
I am not sure who is aggressive here. I am just giving examples of common parts- with designs being different enough. If you don't like these examples - feel free to read posts upstream where design differences within 737 type are discussed.
 
Leej
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 3:39 pm

Hooray - at last - a sensible reply! I know what the fork is. And, of course I know different forces and lots of other factors come in to play. You obviously totally missed the point of my post. So, to summarise, the NG has different forks to both the classic and the MAX. How easy that could have been explained in your first reply.
 
mjoelnir
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 3:46 pm

MIflyer12 wrote:
Statistics. If the FAA thought there was a meaningful likelihood of cracking at 24K cycles vs. 26K they would have specified the lower count.


As both 24,000 cycle and 26.000 cycle frames are to be inspected inside the next 1,000 cycles, as they are above 22,600 and below 30,000, could you explain what you are talking about?

And IMO we can first talk about statistics, when the current regime of testing has finished and brought results.
 
kalvado
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 4:05 pm

Leej wrote:
Hooray - at last - a sensible reply! I know what the fork is. And, of course I know different forces and lots of other factors come in to play. You obviously totally missed the point of my post. So, to summarise, the NG has different forks to both the classic and the MAX. How easy that could have been explained in your first reply.

How easy would it be if you read posts upstream... But nevermind..
 
rheinwaldner
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 4:17 pm

RickNRoll wrote:
ShamrockBoi330 wrote:
I know its only 5% of airframes tested, but Is this compounding the MAX issue for anyone?

Any word or rumours who the 5% belong to?
5% of tested is a lot.

Scaled up to the whole NG fleet, this means almost as many NGs grounded as MAXs.
Many things are difficult, all things are possible!
 
kalvado
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 4:24 pm

rheinwaldner wrote:
RickNRoll wrote:
ShamrockBoi330 wrote:
I know its only 5% of airframes tested, but Is this compounding the MAX issue for anyone?

Any word or rumours who the 5% belong to?
5% of tested is a lot.

Scaled up to the whole NG fleet, this means almost as many NGs grounded as MAXs.

Hopefully younger planes didn't develop the issue yet, so pro-rating current data to the entire NG fleet is unreasonable.
 
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lightsaber
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 4:24 pm

FluidFlow wrote:
planecane wrote:
FluidFlow wrote:
According to the Seattle Times there are now 36 aircraft grounded out of 686 tested. A repair station is now being set up in Victorville.

If the pickle fork is really affected on every single 737NG then this is a problem for Boeing because the pickle fork should last for the whole life time of the aircraft. I guess the repair costs and the compensation for the 3 weeks of grounding will probably be paid for by Boeing (product liability). As the NG is at the end of its production cycle, every single NG could be and probably will be over time affected. Thats over 6700 repairs over the next 10-20 years, which would be 1-2 aircraft per day, with a duration of 21 days for the repair, thats between 20-40 aircraft affected at the same time. So lets hope it is an isolated case only affecting a limited amount of pickle forks due to a bad delivery and not a construction fault effecting all of them.

Here is the source: https://www.seattletimes.com/business/boeing-aerospace/cracks-found-on-more-than-5-of-older-boeing-737s-in-pickle-fork-inspections/


The 21 day repair is to replace the pickle forks with new ones. As lightsaber said, a reinforcement modification will be developed and installed on all aircraft BEFORE the cracks develop. This modification will certainly be far less expensive and time consuming. As lightsaber also said, once a repair is certified, a repair and reinforcement will be able to be done on aircraft with cracks that doesn't involve replacing the pickle forks with new ones. This will also be a less costly and time consuming repair.

They aren't just going to inspect and replace pickle forks when cracks are found for the rest of the 737NG service life.


Alright, that's good news.

Does anyone here has a rough estimation what a fix like this would cost? The development, testing and certification will probably cost a bit. Afterwards when it can be done on premise from the airline maintenance it should be rather cheap, a few hours of work.

Which repair?

The pickle fork replacement is a 3 week job, almost certainly two shifts. Probably 15 ish people on overtime, so about 2,250 hours. Parts, management and such brings a pickle fork replacement to just under a million USD plus the equivalent lease cost.

The Permanent repair will be a 3 shift job at most, so 120 labor hours (including QA, parts crin and such). So maybe $100,000, much less at low wage MRO shops.

The temporary repair will be maybe 20 hours or less. So maybe $10,000. But this only allows flying for some limited time.

There is a reason the system is set up as it is.

For example, the first Embraer wing spar repairs were an equally huge deal. Equivalent scariness and cost. Eventually the root cause was found and only 62 aircraft were impacted: (warning, pdf):
http://services.casa.gov.au/airworth/ai ... 90-017.pdf

All the above are guesses, obviously.

Lightsaber
IM messages to mods on warnings and bans will be ignored and nasty ones will result in a ban.
 
ShamrockBoi330
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 5:44 pm

So 38 NGs now grounded according to multiple sources (10/10/19).... known tally so far;

Southwest x 2
SAS x 2
GOL x 11
Unidentified x 23
 
DDR
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 5:57 pm

ShamrockBoi330 wrote:
So 38 NGs now grounded according to multiple sources (10/10/19).... known tally so far;

Southwest x 2
SAS x 2
GOL x 11
Unidentified x 23


WN can't seem to catch a break when it comes to their all Boeing fleet. If just 2 are grounded, does that mean all the rest of the fleet has been inspected and no additional groundings will occur?
 
ShamrockBoi330
Posts: 109
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 6:19 pm

DDR wrote:
ShamrockBoi330 wrote:
So 38 NGs now grounded according to multiple sources (10/10/19).... known tally so far;

Southwest x 2
SAS x 2
GOL x 11
Unidentified x 23


WN can't seem to catch a break when it comes to their all Boeing fleet. If just 2 are grounded, does that mean all the rest of the fleet has been inspected and no additional groundings will occur?


From Reuters;

The U.S. Federal Aviation Administration last week told aircraft operators to inspect 165 older 737 NG planes for structural cracks within seven days, after cracking was found on a small number of planes. Nearly all the 165 jets were Southwest aircraft, officials said.

So not sure how far beyond this the tests went, for now!

But think latest is 38 grounded out of 810 per Boeing today.
 
DDR
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 6:22 pm

ShamrockBoi330 wrote:
DDR wrote:
ShamrockBoi330 wrote:
So 38 NGs now grounded according to multiple sources (10/10/19).... known tally so far;

Southwest x 2
SAS x 2
GOL x 11
Unidentified x 23


WN can't seem to catch a break when it comes to their all Boeing fleet. If just 2 are grounded, does that mean all the rest of the fleet has been inspected and no additional groundings will occur?


From Reuters;

The U.S. Federal Aviation Administration last week told aircraft operators to inspect 165 older 737 NG planes for structural cracks within seven days, after cracking was found on a small number of planes. Nearly all the 165 jets were Southwest aircraft, officials said.

So not sure how far beyond this the tests went, for now!

Thanks for that info Shamrock!

But think latest is 38 grounded out of 810 per Boeing today.
 
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Spacepope
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 6:24 pm

DDR wrote:
ShamrockBoi330 wrote:
So 38 NGs now grounded according to multiple sources (10/10/19).... known tally so far;

Southwest x 2
SAS x 2
GOL x 11
Unidentified x 23


WN can't seem to catch a break when it comes to their all Boeing fleet. If just 2 are grounded, does that mean all the rest of the fleet has been inspected and no additional groundings will occur?


No, it means only 2 have been discovered so far. More may be expected as inspections continue. There is no way WN has been able to inspect their entire fleet yet.
The last of the famous international playboys
 
kalvado
Posts: 2014
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 6:54 pm

Spacepope wrote:
DDR wrote:
ShamrockBoi330 wrote:
So 38 NGs now grounded according to multiple sources (10/10/19).... known tally so far;

Southwest x 2
SAS x 2
GOL x 11
Unidentified x 23


WN can't seem to catch a break when it comes to their all Boeing fleet. If just 2 are grounded, does that mean all the rest of the fleet has been inspected and no additional groundings will occur?


No, it means only 2 have been discovered so far. More may be expected as inspections continue. There is no way WN has been able to inspect their entire fleet yet.

Nor should they. Only ones with most cycles are to be inspected ASAP - unfortunately, WN didn't tell how many of their planes fit this category. Lower cycles should be done within few months - so there is a possibility for more groundings to come.
 
Jacob2877
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 7:14 pm

Your thoughts as I fly (And my family) southwest in a few weeks. If borderline cycle planes don’t quite fit the 30k -7 day deadline, how dangerous is it to fly these planes. They haven’t been inspected, they could be currently cracked just like the other 2 southwest flights that are grounded. Southwest has many 737-700 that easily are on the cusp but don’t need to be inspected yet.

Obviously the 2 that got grounded didn’t fall out of the sky. But I’m taking my family on a short vacation and safety is concerning. I also realize that FAA would have issued even lower cycles if they thought the problem called for it.

But with people sharing the Boeing AlJazeera video (about how bad Boeing has gotten) and with many forums on the web pushing for poor quality control at Boeing, I’m looking for some better reassurance. Thanks for any thoughts
 
n471wn
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 7:23 pm

DDR wrote:
ShamrockBoi330 wrote:
So 38 NGs now grounded according to multiple sources (10/10/19).... known tally so far;

Southwest x 2
SAS x 2
GOL x 11
Unidentified x 23


WN can't seem to catch a break when it comes to their all Boeing fleet. If just 2 are grounded, does that mean all the rest of the fleet has been inspected and no additional groundings will occur?[/quot


Shed no tears for WN’s shrinking fleet. First they are letting 19 leased aircraft go to United. Secondly they are retiring some NG’s built in 1999 that they own. Three have already left. And lastly the fully repaired and repainted aircraft involved in the nearly two year old accident still sits at VCV—N772SW. Makes no sense.
 
Dalmd88
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 7:27 pm

Leej wrote:
Are these pickle forks used on other Boeing n/b, such as the 757 - or I guess anything that has winglets, 767 included? Are they being checked too?


It is a similar design on the 767/757. Those fleet have had issues in the past, but I'm not aware of any AD's against the issue. I know at DL we have changed a few pickle forks on both the 767 and the 757. I have not heard of any being changed on the 737, the NG or even the old Classics we had. I also have not heard the results of the current AD inspections at DL. With the fleet size and the age of our fleet I would expect there may be some findings.

Lightsaber touched on the scope of work. It is a big job. I would see three weeks as the initial replacement. If the same crew did follow on replacements to other airframes I bet the turn time would get quicker.

I've never done a pickle fork replacement myself. When I did work sheetmetal at DL I never was on any of these big jobs. We always set them up as 12 hour crews usually 6 or 7 days a week until the job is done. If there are multiple aircraft to be done you are expected to stay on that schedule until the project is done with no extra days off if possible. Most just take the min required off days a month per FAA regs. I just can't do that. The huge OT check does not offset the lack of time away from work for me.
 
Northpole
Posts: 31
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 7:44 pm

minilinde wrote:
VSMUT wrote:
https://check-in.dk/sas-finder-revnedannelser-i-to-fly/?fbclid=IwAR168aaEvCECJdeiZyooBsFeFUiN9JjuuybtBOKBXUJfI6juazpP9zmFSBM

2 SAS 737s now.


Most is a pay-wall. Could you share a qoute from the article?


In short there are several articles in Scandinavian newspapers today saying about the same thing :
SAS has so far inspected 31 airplanes of the type 737 NG after FAA instructed / demanded inspections and SAS found that 2 aircrafts are affected ( and consequently grounded )
In total SAS has 58 aircrafts of this type
One of the two affected aircrafts will be repaired and the other will " go out of service "
 
VSMUT
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 7:50 pm

Northpole wrote:
minilinde wrote:
VSMUT wrote:
https://check-in.dk/sas-finder-revnedannelser-i-to-fly/?fbclid=IwAR168aaEvCECJdeiZyooBsFeFUiN9JjuuybtBOKBXUJfI6juazpP9zmFSBM

2 SAS 737s now.


Most is a pay-wall. Could you share a qoute from the article?


In short there are several articles in Scandinavian newspapers today saying about the same thing :
SAS has so far inspected 31 airplanes of the type 737 NG after FAA instructed / demanded inspections and SAS found that 2 aircrafts are affected ( and consequently grounded )
In total SAS has 58 aircrafts of this type
One of the two affected aircrafts will be repaired and the other will " go out of service "


Guess that makes at least 1x -600 or -700 then.
 
kalvado
Posts: 2014
Joined: Wed Mar 01, 2006 4:29 am

Re: 737NG Pickle fork issue

Thu Oct 10, 2019 7:51 pm

Jacob2877 wrote:
Your thoughts as I fly (And my family) southwest in a few weeks. If borderline cycle planes don’t quite fit the 30k -7 day deadline, how dangerous is it to fly these planes. They haven’t been inspected, they could be currently cracked just like the other 2 southwest flights that are grounded. Southwest has many 737-700 that easily are on the cusp but don’t need to be inspected yet.

Obviously the 2 that got grounded didn’t fall out of the sky. But I’m taking my family on a short vacation and safety is concerning. I also realize that FAA would have issued even lower cycles if they thought the problem called for it.

But with people sharing the Boeing AlJazeera video (about how bad Boeing has gotten) and with many forums on the web pushing for poor quality control at Boeing, I’m looking for some better reassurance. Thanks for any thoughts

Statistically speaking, old planes didn't got into a real trouble with these cracks - so likely newer ones have some time before the problem becomes big trouble. FAA did some evaluation, and believes risks are limited. EASA, which is also in the game, didn't say anything different.
Few weeks are enough time for Boeing and FAA to crunch the data and make their mind if more things need to be done ASAP. So no worry, you should be good.
If that helps, get a drink or two before the flight - and tell your wife that I allowed it. :D
 
Northpole
Posts: 31
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 8:00 pm

VSMUT wrote:
Northpole wrote:
minilinde wrote:

Most is a pay-wall. Could you share a qoute from the article?


In short there are several articles in Scandinavian newspapers today saying about the same thing :
SAS has so far inspected 31 airplanes of the type 737 NG after FAA instructed / demanded inspections and SAS found that 2 aircrafts are affected ( and consequently grounded )
In total SAS has 58 aircrafts of this type
One of the two affected aircrafts will be repaired and the other will " go out of service "


Guess that makes at least 1x -600 or -700 then.


I wld. assume so - don't know - hard to find details > all 58 "active" aircrafts will be inspected immediately acc. to SAS -( 31 already done)
3x600´s active
26x700´s active
29x800´s active
 
bob75013
Posts: 882
Joined: Tue Jun 23, 2015 5:05 pm

Re: 737NG Pickle fork issue

Thu Oct 10, 2019 8:16 pm

Jacob2877 wrote:
Your thoughts as I fly (And my family) southwest in a few weeks. If borderline cycle planes don’t quite fit the 30k -7 day deadline, how dangerous is it to fly these planes. Thanks for any thoughts



Well, zero NGs have fallen from the sky as a result of the pickle fork issue. So I'll answer your question with a question: What is the NG crash ratio as it relates to the pickle fork issue?
 
iamlucky13
Posts: 1070
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Re: 737NG Pickle fork issue

Thu Oct 10, 2019 10:10 pm

Leej wrote:
Are these pickle forks used on other Boeing n/b, such as the 757 - or I guess anything that has winglets, 767 included? Are they being checked too?


A similar large fitting between the center wing box and the fuselage frames, fork-shaped or otherwise, is pretty close to universal for low-wing passenger aircraft as far as I know, due to the loads in this portion of the airframe.

The details are custom to each airframe design, however, so whether or not there is a likelihood of similar cracks will be specific to the design.

Pickle forks have nothing directly to do with winglets, but it is being speculated here that winglets might be increasing the loads at the pickle forks in a way that might not have been sufficiently analyzed. Other possibilities include that the pickle fork is receiving more load than anticipated regardless of winglets, that there is a defect in the pickle fork itself (eg - incorrect heat treatment or dimensions), or that some of them have been getting damaged during installation.
 
marcogr12
Posts: 251
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 4:26 am

[quote="leghorn"]One has to wonder why this hasn't been found on ex-Ryanair planes. They've been sent to freight companies and have been used across Europe intensively on short hops. I guess they are heavily affected but at least the news comes during the low season.[/quote]
Not only on ex-FR ones but current ones also flying..FR has a fleet of 400+ 738s with high daily utilization doing lots of short hops..I am surprised no grounding or no inspection-findings have been mentioned on this huge fleet.
Flying is breathing..no planes no life..
 
FluidFlow
Posts: 292
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 5:23 am

lightsaber wrote:
FluidFlow wrote:
planecane wrote:

The 21 day repair is to replace the pickle forks with new ones. As lightsaber said, a reinforcement modification will be developed and installed on all aircraft BEFORE the cracks develop. This modification will certainly be far less expensive and time consuming. As lightsaber also said, once a repair is certified, a repair and reinforcement will be able to be done on aircraft with cracks that doesn't involve replacing the pickle forks with new ones. This will also be a less costly and time consuming repair.

They aren't just going to inspect and replace pickle forks when cracks are found for the rest of the 737NG service life.


Alright, that's good news.

Does anyone here has a rough estimation what a fix like this would cost? The development, testing and certification will probably cost a bit. Afterwards when it can be done on premise from the airline maintenance it should be rather cheap, a few hours of work.

Which repair?

The pickle fork replacement is a 3 week job, almost certainly two shifts. Probably 15 ish people on overtime, so about 2,250 hours. Parts, management and such brings a pickle fork replacement to just under a million USD plus the equivalent lease cost.

The Permanent repair will be a 3 shift job at most, so 120 labor hours (including QA, parts crin and such). So maybe $100,000, much less at low wage MRO shops.

The temporary repair will be maybe 20 hours or less. So maybe $10,000. But this only allows flying for some limited time.

There is a reason the system is set up as it is.

For example, the first Embraer wing spar repairs were an equally huge deal. Equivalent scariness and cost. Eventually the root cause was found and only 62 aircraft were impacted: (warning, pdf):
http://services.casa.gov.au/airworth/ai ... 90-017.pdf

All the above are guesses, obviously.

Lightsaber


Thanks for the guesses so we I was not that far off with my guess for the permanent repair with <150h.
 
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Aesma
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 10:05 am

JayinKitsap wrote:
Looking at the diagram @ leeham the red crack marking is across the lower outer bolt hole of the outer chord, possibly both bolt holes at this location. The primary normal loads are compression in the fork as it transfers the fuse forces down to the spar. However, this outer chord is connecting the fork to the skin of the aircraft. With the opening for the gear cutting the skin off below this there are a lot of 3D forces here. The downward shear at this bolt would cause high tension in this plate corner, coupled with the oscillation of the tail and fuse causing large cycle counts. Not good.

This plate probably needs to get thicker, possibly a stiffener added to cut out side bending effects and possibly a doubler plate on the shell at this pair of bolts.


Reinforcing all these, aren't you likely to cause other parts to now need reinforcing too, or at least study the effects of these changes ?
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LS83
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 10:20 am

Sorry if already mentioned...but Ryanair with over 450 of these aircraft in service I imagine a high number have encountered high cycles by now...any word from them?
 
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2nd2none
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 10:39 am

LS83 wrote:
Sorry if already mentioned...but Ryanair with over 450 of these aircraft in service I imagine a high number have encountered high cycles by now...any word from them?


Ryanair got at least 100 737-800 older than 12 years.
 
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Lingon
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 11:04 am

Northpole wrote:
I wld. assume so - don't know - hard to find details > all 58 "active" aircrafts will be inspected immediately acc. to SAS -( 31 already done)
3x600´s active
26x700´s active
29x800´s active


I got the impression from one article I read (Aftonbladet, credibility dubious) that the planes with lower number of cycles will be inspected when they get scheduled maintenance. Which seems perfectly reasonable.
 
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Erebus
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 12:14 pm

Leej wrote:
Are these pickle forks used on other Boeing n/b, such as the 757 - or I guess anything that has winglets, 767 included? Are they being checked too?


This is from a 787. If I'm not mistaken, I think those extensions at the corners are the "pickle forks" or at least do the same job. Maybe someone can confirm this?

Image

They exist on other aircraft too. There are pictures of this part on Airbuses as well.
 
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lightsaber
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 1:15 pm

iamlucky13 wrote:
Leej wrote:
Are these pickle forks used on other Boeing n/b, such as the 757 - or I guess anything that has winglets, 767 included? Are they being checked too?


A similar large fitting between the center wing box and the fuselage frames, fork-shaped or otherwise, is pretty close to universal for low-wing passenger aircraft as far as I know, due to the loads in this portion of the airframe.

The details are custom to each airframe design, however, so whether or not there is a likelihood of similar cracks will be specific to the design.

Pickle forks have nothing directly to do with winglets, but it is being speculated here that winglets might be increasing the loads at the pickle forks in a way that might not have been sufficiently analyzed. Other possibilities include that the pickle fork is receiving more load than anticipated regardless of winglets, that there is a defect in the pickle fork itself (eg - incorrect heat treatment or dimensions), or that some of them have been getting damaged during installation.

An excellent synopsis. I speculate the winglets add a frequency of stress that is close to the the natural resonance frequency of the pickle forks.

Or maybe I obsess that they look too much like a tuning fork.

Lightsaber
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BlackLion213
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 3:55 pm

Erebus wrote:
Leej wrote:
Are these pickle forks used on other Boeing n/b, such as the 757 - or I guess anything that has winglets, 767 included? Are they being checked too?


This is from a 787. If I'm not mistaken, I think those extensions at the corners are the "pickle forks" or at least do the same job. Maybe someone can confirm this?

Image

Those are pickle forks on the 787. They're part of the "11" section from FHI, from that view. The other pickle forks are on the "45" section from KHI. They differ from other legacy Boeing aircraft as they pointed upward as the others are pointed downward.
 
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Erebus
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 5:46 pm

BlackLion213 wrote:
They differ from other legacy Boeing aircraft as they pointed upward as the others are pointed downward.


I'm having a bit of a difficulty imagining this. Could you illustrate this better?
 
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Tugger
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 6:07 pm

Erebus wrote:
BlackLion213 wrote:
They differ from other legacy Boeing aircraft as they pointed upward as the others are pointed downward.


I'm having a bit of a difficulty imagining this. Could you illustrate this better?

Check out 9Patch's post #94 back on page 2. It shows an image of a downward one.

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mjoelnir
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 6:28 pm

I think, it is to early to speculate about the winglets as the culprit. Lots of older frames never had winglets. The SAS frame, not to be repaired, should be a 737-600, as they are being retired, and the 767-600 at SAS did not have winglets.
 
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Spacepope
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 6:49 pm

mjoelnir wrote:
I think, it is to early to speculate about the winglets as the culprit. Lots of older frames never had winglets. The SAS frame, not to be repaired, should be a 737-600, as they are being retired, and the 767-600 at SAS did not have winglets.


I recall a post earlier stating the SAS frame that was cracked and to be retired anyway in November as a -700.
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mjoelnir
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 8:30 pm

Spacepope wrote:
mjoelnir wrote:
I think, it is to early to speculate about the winglets as the culprit. Lots of older frames never had winglets. The SAS frame, not to be repaired, should be a 737-600, as they are being retired, and the 767-600 at SAS did not have winglets.


I recall a post earlier stating the SAS frame that was cracked and to be retired anyway in November as a -700.


Same argument, the 8 oldest 737-700 at SAS never had winglets
 
DYSK
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Re: 737NG Pickle fork issue

Fri Oct 11, 2019 8:51 pm

Spacepope wrote:
mjoelnir wrote:
I think, it is to early to speculate about the winglets as the culprit. Lots of older frames never had winglets. The SAS frame, not to be repaired, should be a 737-600, as they are being retired, and the 767-600 at SAS did not have winglets.


I recall a post earlier stating the SAS frame that was cracked and to be retired anyway in November as a -700.


From different sources in the nordic community the retired -700 was LN-RPK.

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