Stall From Switzerland, joined Apr 2004, 257 posts, RR: 0 Posted (8 years 9 months 2 weeks 2 days 10 hours ago) and read 4404 times:
Hello !
A couple of days ago a Swiss Avroliner had an uncontained engine failure. The first engine damaged the engine next to it and both engines had to be shut down . The problem took place at cruise altitude and cruise speed and the crew carried out an emergency landing without further problems.
I can't help to think that the outcome could have been worse if the uncontained engine failure had happened during t/o or initial climb. Can this aircraft (or any 4 engines aircraft) take off and climb at low speed with too inoperative engine on the same side ?
I thought that the engines were designed in a way that an explosion would not damage an other engine or the aircraft fuselage. Is it correct ?
Starlionblue From Hong Kong, joined Feb 2004, 15872 posts, RR: 66 Reply 1, posted (8 years 9 months 2 weeks 2 days 10 hours ago) and read 4335 times:
IIRC there was a thread about this a while ago, or at least it touched on the subject.
Something about four holers being able to climb (barely) with two engines inop, or at least one of the members said the A340 could do this (since the whole thing had also inevitably touched on the A340 being a slow climber). I do not know if it is a regulatory requirement.
Engines are designed to contain any fan, compressor or turbine blades that detach (and the resultant imbalances) within the cowling. This is tested thoroughly. Doesn't always work though.
But maybe APUs are not tested in such a way, which might explain the Avro
"There are no stupid questions, but there are a lot of inquisitive idiots." - from Citadel by John Ringo
Phollingsworth From United Kingdom, joined Mar 2004, 825 posts, RR: 6 Reply 2, posted (8 years 9 months 2 weeks 2 days 10 hours ago) and read 4292 times:
Two engine INOP rates of climb are very much dependent on loading and conditions. However, I doubt a MTOW A340 or B747 will achieve much of a positive rate of climb with say the number 1&2 or 2&3 engines out. Part of the problem is the resulting T/W is quite low, around 0.12, and the asymmetries are worse than twins with one engine out. There was the El-Al freighter that had both engines on one wing separate on climb out, it crashed into an apartment complex. At least if you physically loose and engine, vs. shutting it down, you don't have to worry about all of the drag they produce. Of course the more energy that is in the aircraft when the engines are lost the better. On the runway above V1 is the worst case scenario.
HaveBlue From United States of America, joined Jan 2004, 2069 posts, RR: 1 Reply 3, posted (8 years 9 months 2 weeks 2 days 9 hours ago) and read 4260 times:
There was Delta Flight 916, an MD-88 at Pensacola on July 7, '96 that had an uncontained engine failure on the starboard engine and killed 2 of the passengers in the cabin.
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 71 Reply 5, posted (8 years 9 months 2 weeks 2 days 7 hours ago) and read 4225 times:
PSA also had an uncontained failure back in the 1980s with the BAe-146. The newspaper reported that it put schrapnel in passengers' luggage in the overhead bins. Major bad scoobies!
I once saw the aftermath of an uncontained multiple-disk rupture on a CFM-56 mounted at number one position on a UA DC-8-73. It occurred at or near top of climb and the plane made an emergency landing at Reno Nevada.
The first stage fan stayed attached only because the inlet anti-ice ducts were strong enough to hold the intake ring cowl on. Aft of that, you could have crawled in the left side of the engine and out the right side. About a foot of it was completely missing.
Well, not entirely missing. Parts of it had peppered the left side of the fuselage and some of it had blown forward and been ingested by the number two engine. It got down safely. I don't know if the crew shut down number two or not. Well done to the crew and to the airframe manufacturer. It is also good fortune that it had not happened at number 2 or 3 position!
Thing I dislike most about non-revving is that they so often seat you in the turbine disintegration zone.
Happiness is not seeing another trite Ste. Maarten photo all week long.
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 71 Reply 7, posted (8 years 9 months 2 weeks 2 days 5 hours ago) and read 4142 times:
Yeah, sitting in the plane of the prop is another favorite. If you look at some older prop aircraft you will see big dents where they've slung ice. A separated prop blade goes where ever it wants until its energy is spent.
I think it was North Central that had a CV-580 hit some deer on landing in upper Michigan some years back. One blade went through between cabin and flight deck IIRC.
And don't get me started on helicopters! Never watch a helicopter, you'll become a witness!
I learned my lesson in the sawmill just before I took my first flying lessons. We had a 79" circular "cutoff" saw where all logs entering the mill were cut to eight foot lengths. (We cut only studs.) One day the motor burned out and they found another electric motor on the scrap heap. No one gave any thought to direction of rotation when they wired it. When they threw the switch the saw spooled right up backwards and of course, the arbor nut spun right off! We had a huge saw wobbling on a very short arbor shaft.
Some hero reached in and shut off the switch. I did a more sensible thing. I ran like hell 90 degrees to the plane of rotation!
Happiness is not seeing another trite Ste. Maarten photo all week long.
Tbanger From Australia, joined Jul 2004, 266 posts, RR: 0 Reply 8, posted (8 years 9 months 2 weeks 2 days 5 hours ago) and read 4139 times:
what happens if a prop blade on a prop plane detaches?
If one blade detaches from the hub in flight, the imbalance and vibration would be so severe that the aircraft would disintegrate very very quickly. If you are lucky, the other blades would quickly depart also, leaving you with a screaming overspeeding engine to worry about.
Propellers are often balanced in Mx to improve pax comfort and reduce engine isolator wear and tear. It can take just a few grams to imbalance a prop.
Aogdesk From United States of America, joined Jun 2004, 933 posts, RR: 4 Reply 9, posted (8 years 9 months 2 weeks 2 days 4 hours ago) and read 4128 times:
I don't know of all the measures that are taken in the design of an airframe/engine combo to contain the shrapnel, but the 757 has areas called 'dry bays' which are located inboard of the engine pylon. They would normally be wet fuel tanks, but in that particular area, they are dry just in case a disk decides to carve some leading edge metal on its departure from the a/c. Fuel + an uncontained failure = a hair raising experience.
Slamclick, I realize your saw predicament probably wasn't funny when it was happening, but its a priceless image in my head now....
Phollingsworth From United Kingdom, joined Mar 2004, 825 posts, RR: 6 Reply 12, posted (8 years 9 months 2 weeks 2 days 3 hours ago) and read 4094 times:
If one blade detaches from the hub in flight, the imbalance and vibration would be so severe that the aircraft would disintegrate very very quickly.
Wouldn't some of this happen on a turbofan too? Granted the imbalance would be much smaller, but severe are the vibrations?
Well the blade separating happened to and ASA Brasilia back in 1995 or so. The plane did not disintegrate; however, they were unable to continue flying it and the plane did crash, with fatalities.
As for TFs, the wing/pylon is supposed to be designed for this. In some older a/c the whole pylon was supposed to separate. This is now considered a bad idea, dropping engines in peoples yards is frowned upon. For some of the really big engines the thrust bearing will actually disintegrate, on purpose, saving the airframe while destroying the rest of the engine.
N243NW From United States of America, joined Jul 2003, 1494 posts, RR: 21 Reply 13, posted (8 years 9 months 2 weeks 2 days 3 hours ago) and read 4091 times:
So what if the prop strikes a bird or a deer (as mentioned by SlamClick) or some hail?
Although not directly related to the question, this reminds me of an incident that occurred to a Saab 340. A bird struck the nose of the aircraft just below the windscreen, which in turn broke the captain's wiper blade off the windshield wiper. The blade struck the prop of the #1 engine, which launched it through the left side of the passenger cabin, impaling a passenger in the leg. Talk about sitting in the "turbine disintegration zone!"
-N243NW
EMBQA From United States of America, joined Oct 2003, 9286 posts, RR: 13 Reply 15, posted (8 years 9 months 2 weeks 2 days 1 hour ago) and read 4067 times:
Although not directly related to the question, this reminds me of an incident that occurred to a Saab 340. A bird struck the nose of the aircraft just below the windscreen, which in turn broke the captain's wiper blade off the windshield wiper. The blade struck the prop of the #1 engine, which launched it through the left side of the passenger cabin, impaling a passenger in the leg.
N243NW-
We worked on that Saab here in Nashville. Boy what a mess..... Let alone the wiper arm being turned into a spear...the other birds the aircraft hit where then thrown into the now hole in the aircraft and entered the cabin, ingested into the engine adding to the smell and mess.
"It's not the size of the dog in the fight, but the size of the fight in the dog"
Greasespot From Canada, joined Apr 2004, 3050 posts, RR: 22 Reply 16, posted (8 years 9 months 2 weeks 2 days 1 hour ago) and read 4051 times:
It is more than a few grams. You can Blend up to about a inch of the tip of a C1 disk blade(going from memory) and leave it in service. As from props there can be some significant damage that can be blended out. It all depends on where it is. Near the tip lots...Near root very little. It is not because of balancing but because the root is the highest stress area.
I have a blade from a uncontained JT8D-15 failure on my desk. It nearly shook the Engine off the mount. The whole pylon had to be replaced and the fuselage area beefed up. It was on a freighter and on climb at 1500 feet at max weight.
Greasespot
[Edited 2004-08-13 02:22:32]
Sometimes all you can do is look them in the eye and ask " how much did your mom drink when she was pregnant with you?"
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 71 Reply 17, posted (8 years 9 months 2 weeks 2 days ago) and read 4040 times:
Thought about some more related items.
A few years ago I had the ice ingestion incident with a DC-9. Did not see it on the walkaround, not even looking out the cabin windows at the upper surface of the wing. Still a sheet of ice detached on rotation on the next flight and went through both engines. There were 30 C1 blades in each engine. 29 of the 60 needed replacement. One was torn nearly halfway, chordwise. None of the downstream stators or blades were damaged. I think we were very lucky. The surprising thing was that it was very smooth and for the whole flight we thought we'd blown a tire!
I know of a case where a nose locker came open in flight on a cabin-class twin and a pair of skis fell out and went through the prop. It took off a prop blade, which unbalanced the engine to the point where it broke the engine mount and it came off and took a horizontal stab with it. Very bad.
I saw a formula one race plane throw about half a blade at high speed. The vibration must have been pretty bad. The pilot pulled the power off and the nose up sharply. I assume he was trying to load up the prop and stop its rotation. The plane stalled, fell off on the right wing and he recovered flying straight at the bleachers. He pulled up again, stalled again and this time dove straight into the ground a little ways behind the crowd.
In 1976 Mercer Airlines lost a DC-6 (N901MA) in a bizarre chain of circumstances that began with throwing a prop blade on runway 16 at Burbank and ended on a golf course on the Sepulveda flood control basin near Van Nuys. Google this one, it makes fascinating reading and really illustrates the oft-stated truth that one single event does not cause the crash.
We don't pay much attention to these things because they so rarely malfunction, but anything that spins that fast has a lot of potential to do damage. Preflight carefully.
Happiness is not seeing another trite Ste. Maarten photo all week long.
Starlionblue From Hong Kong, joined Feb 2004, 15872 posts, RR: 66 Reply 18, posted (8 years 9 months 2 weeks 1 day 22 hours ago) and read 4012 times:
SlamClick, if you had that thing on the DC-9 you must have heard of the SAS MD-80 which "landed" on a field in Gottröra after taking off from ARN/ESSA. Ice sheets came off both wings and frelled both engines. Oops... Deicing checks were changed after that. The tech has to put a bare hand on the wing, not just check visually.
"There are no stupid questions, but there are a lot of inquisitive idiots." - from Citadel by John Ringo
Klaus From Germany, joined Jul 2001, 20859 posts, RR: 55 Reply 20, posted (8 years 9 months 2 weeks 1 day 14 hours ago) and read 3910 times:
Spitfire: Very nice indeed....but how to make that on a 747,340,...and A380 in the near future ???
Maybe it´s less critical because they´ve got wing-mounted engines that can´t be hit by ice detaching from the wing? If I´ve understood that correctly, the problem hadn´t been the aerodynamic change due to the ice but only its ingestion into the tail engines.
Starlionblue From Hong Kong, joined Feb 2004, 15872 posts, RR: 66 Reply 21, posted (8 years 9 months 2 weeks 1 day 13 hours ago) and read 3903 times:
Exactly as Klaus says. If a sheet of ice comes loose from a 747, 380, or 340 wing it won't be gobbled up by the engines. While the sheet of ice is still "attached" to the wing it's really no big deal. But if they HAD to check it, I'm sure they could use a ladder
I suppose ice could hit the stabilizer, but I don't imagine it would do much (or any) damage. We're not talking an iceberg coming loose here, just some chunks.
"There are no stupid questions, but there are a lot of inquisitive idiots." - from Citadel by John Ringo
Darkblue From United States of America, joined Sep 2003, 233 posts, RR: 11 Reply 22, posted (8 years 9 months 2 weeks 1 day 9 hours ago) and read 3836 times:
You can't have a discussion of blade-out scenarios without discussing the GE90. Let's do a quick calculation. A single GE90-115B blade weighs around 50lbs. I'll guess that the center of mass is around 3ft out from the center of rotation. Finally, the fan speed at takeoff is around 2500RPM. The radial force is therefore determined by:
F=m*r*w^2
F=50lbm*3ft*(2500rev/min)^2
After a couple unit conversions I find that the total load due to a single blade is 319,600lbf!
If I can count right, it appears from photos I've seen there are 22 blades in the GE90. This means that the loading on the fan hub at during is over 7 million pounds of force!
KDTWFlyer From United States of America, joined Jun 2004, 807 posts, RR: 1 Reply 24, posted (8 years 9 months 2 weeks 21 hours ago) and read 3727 times:
Isn't a blade out situation on UA flight 232's number 2 engine the cause for all that trouble? For some reason I found the turbine disintegration zone concept/phrase quite amusing .
25 KDTWFlyer: Darkblue, That is an amazing calculation.. How did you find out the RPM level at takeoff? Goes to show why jet engines are so damn expensive not to me
26 Meister808: KDTWFlyer: I believe there was something ingested on a previous flight, leaving a nick on a fan blade. About an hour into the flight the blade sheared
27 Air2gxs: The max RPM figures are always available in the maintenance manual. We use those for precision measurements during vibration surveys using a laptop co
28 SlamClick: Many air museums will have an old turbine engine cut away to show the internal workings. Take a look at the compressors (unless it is a Whittle-type e
29 MD11Engineer: Well, I´ve vboroscoped engines with compressor blade failures. The damage is usualy catastophic. Most of the scrap metal usualy gets blown out of the
30 Hugh3306: Very interesting discussion. A little known, but unnervingly common, cause of compressor failure is due to contamination (dirtiness) of the compressor
31 Infiniti757: Meister808, The cause of the failure on UA 232 was and intergranular discontinuity in on of the turbine discs. Basically a small defect in the metal w
32 EMBQA: Since we are talking about failures of spinning parts I think we should look at props too. These are a common cause of accidents in propeller driven a
33 Infiniti757: Sorry, reread the report, the prop damaged the tail as the engine left the airplane. Though that the prop lead to the engine leaving the airplane.
34 Darkblue: How did you find out the RPM level at takeoff? Yeah, I guess I should have listed my sources. For the most part I just estimated from the top of my he
35 BR715-A1-30: There was Delta Flight 916, an MD-88 at Pensacola on July 7, '96 that had an uncontained engine failure on the starboard engine and killed 2 of the pa
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