AA 763 engine failure on ground run

[JamesT73J]

http://www.airliners.net/open.file/1055376/L/
Looks rather dramatic, thankfully nobody was hurt. There's not many pictures of engines broken (for comparison) but I was rather surprised at what appears to have been evidence of a fairly nasty fire. The turbine part of the engine casing appears severely damaged.

[d2k73]

Happened yesterday, no1 engine was being tested and blew up!
http://photos.airliners.net/photos/photos/6/7/3/1055376.jpg

[misd-agin]

http://www.airliners.net/open.file/1055376/L/

Looks rather dramatic, thankfully nobody was hurt. There's not many pictures of engines broken (for comparison) but I was rather surprised at what appears to have been evidence of a fairly nasty fire. The turbine part of the engine casing appears severely damaged.

767-200ER. No tail skid.

No tail skid is one of the most obvious differences between the -200 and -300 models.

[cringe]

More pics at http://www.flickr.com/photos/lafd/sets/72157594153722446/

[JamesT73J]

Oops, corrected the title. What an interesting set of photographs from the firefighters.

Are these the remains of a turbine disc visible here, poking out of the casing?

http://www.flickr.com/photos/lafd/159079698/in/set-72157594153722446/

[BTSM]

767-200ER. No tail skid.

No tail skid is one of the most obvious differences between the -200 and -300 models.

He said re-arranging his anorak

[320DRIVER]

Personally, the most striking aspect is what seems to be fairly serious damage to the fuel tanks resulting in a significant fuel leak. Similar scenario to the AF Concorde.

Not something you'd like to see over the middle of the Pond. Good thing this was a ground run and not an in flight occurence. Possibly, the effect of this happening at normal airspeeds would result in a different trajectory for the expelled engine component so not sure if the damage would have been identical.

Looking forward to some comments from people in the know.

[FullWings]

I suppose that's what they call an uncontained failure... Glad I wasn't standing nearby. :ouch:

[Fernando_Covas]

Oops, corrected the title. What an interesting set of photographs from the firefighters.
Are these the remains of a turbine disc visible here, poking out of the casing?
http://www.flickr.com/photos/lafd/159079698/in/set-72157594153722446/
Which by the looks of things in this photo (http://www.flickr.com/photos/lafd/159079625/in/set-72157594153722446/) came from the left hand engine, sliced through the underside and embedded itself in the exhaust of the right engine. Scary stuff.

[boaclhryul]

Are these the remains of a turbine disc visible here, poking out of the casing?


Isn't that the outboard side of No. 2? Did it fail too? Hard to see how a disc from No. 1 would have travelled that path...

[320DRIVER]

Didn't pick that out, i.e. the damage on the opposite engine... if the initiating cause was common, i.e. one failure of one engine affecting the other, wouldn't that open a can of worms when it comes to maintaining the ETOPS approval for this airframe/engine combination?

[boaclhryul]

Sorry, missed the post from Fernando_Covas, it does look as though a No. 1 disc travelled across the belly and nearly through No. 2.

And (if I'd been thinking) No. 2 would have shown quite a bit of other damage if that was one of its discs...

[klink]

:eek:
Would be great to know what powersetting was applied!

(edit: wrote what Farnando wrote before..)

[JamesT73J]

Rest assured I won't make such an error again! To be honest I could care less about the exact type of aircraft (both have common powerplants with identical geometry to each other), I just thought it was an interesting picture, hence I put it initially in the spotter forum as I'd guessed that if there was any real mileage in it someone in the know would have already blogged it here in R&N.

I'm guessing that a failure of this nature is extremely rare (although that wouldn't console the poor buggers that experienced it), although I remember a thread some time ago about a 777 suffering an engine failure (again on the ground) and some expelled parts striking the opposite engine, though with only superficial damage caused.

The energy involved in sending a part out of one engine, through the fuselage, and almost straight through part of the other engine is mind boggling, but really illustrates some incredible engineering considering how long these things run for without any problems at all.

[gas path]

Hhmmmm!..........maybe that n2 vibration indication was genuine after all:eek: :suspect::E
..........both have common powerplants..........
CF6-80a for the -200 and CF6-80c2b6 for the -300
I know I'm going....i'll get me coat!

[barit1]

...
The energy involved in sending a part out of one engine, through the fuselage, and almost straight through part of the other engine is mind boggling, but really illustrates some incredible engineering considering how long these things run for without any problems at all.

It's not unheard of for a HP turbine disc, when loosed, to travel over 1 km. Slicing through aluminum belly skin is no obstacle at all.

Despite best efforts, it can still happen.


"Actually, Mr. Parkins," this visitor said brightly, after seeing the blue flame of an engine's exhaust, "you people are simply trying to contain and control fire, aren't you?"

"Yes," said Parkins, who had been up to his ears in trouble all week, "but that's simply all the devil has to do in h---, too, as I understand it."

(Mr. Horace Mansfield Horner, President, United Aircraft Corporation, in a 1952 briefing (http://www.ndu.edu/library/ic2/L52-095.pdf)on Jet Engine Production before the Industrial College of the Armed Forces)

[aintsaying]

Air NZ had a similar self destruction of a early manufactured turbine disk in Brisbane, Australia. This occured in flight!
Boeing had for several years quietly did engine strut stiffening without really explaning why.
The reason why became obvious from then on.
These photos show that this plyon has been strengthened, otherwise the enine would be sitting on the ground.

[lomapaseo]

Just a couple of coments to get this back on the proper track.

The cross aircraft damage is unique to a rebound off the runway, as is the fuel tank damage and ground pool fire.

Some account will need to be taken of this for ETOPs (single engine uncontained failure), but it would probably have negligible impact on ETOPS

[Loose rivets]

I realise that after much of my lifetime around aircraft, I have no idea what provision is made for a major fuel leak.

It seems here that an attempt has been made to catch some spill, but imagine several tons dumped round a hot and damaged aircraft.

[McGinty]

One hopes that those big white tanks in the background are not fuel tanks (they do not seem to have any spill control areas around them). But if they are not fuel tanks, then what are they?

[Pimp Daddy]

But if they are not fuel tanks, then what are they?
Water tanks at a guess, either for hanger use or for hanger fire system

[GotTheTshirt]

Lomapaseo,
May have been what happened here but not strictly true.
There have been instances of an uncontained failure hitting the opposite engine. As has been said the velocity that the bit leaves, especially the HP side has no problem in passing through a couple of skins of the cargo bay.:)
Dont forget the engine actually sits below the fuselage on many aircraft.

The one I remember was the DC10 in OKC. One engine let go and debris hit the opposite engine. And that was a fan failure !:} Fortunately he had a spare in the tail and amazingly the debris going back did not ingest into #2

Re Ful tank penetration after the BA B737 with the uncontained failure in UK that puntured the tank at the under wing inspection panels, the under wing inspections were beefed up.

[barit1]

...
The one I remember was the DC10 in OKC. One engine let go and debris hit the opposite engine. And that was a fan failure !:} Fortunately he had a spare in the tail and amazingly the debris going back did not ingest into #2
...

Actually it was National over NM, and landed at ABQ. See http://aviation-safety.net/database/record.php?id=19731103-0&lang=en

But you are right - a fan blade leaving the hub of #3 engine travelled under the fuselage and struck the accy section of #1. I believe that #2 did suffer minor FOD but kept running.

I believe the entire industry learned a good deal from various aspects of this accident, including flight crews NOT experimenting with the autothrottles!

[dannydick]

The cross aircraft damage is unique to a rebound off the runway, as is the fuel tank damage ...


What's your point?

So the 762 could sustain similar damage at V1! :eek:

I wouldn't fancy the chances of an a/c in that condition taking to the air and successfully limping back to the field. I suspect the outcome would be very similar to that of Concorde. :uhoh:

[barit1]

Exactly.

But with 2 donks vs 4, the risk is cut in half. :hmm:

[GotTheTshirt]

Barit,
Yes thats the one !! Had a senior moment over the location:)

I have the photos somewhere but on No 1 the compete gearbox sheered off held by the Hydraulic hoses and Generator cables !!
The No. 3 of course looked like a trick cigar ;)

Also a piece of debris hit one of the aft RH windows and a passenger departed the aircraft - again missing the No 2 engine:uhoh:

[Dash-7 lover]

I take it the aircraft will be an insurance write-off?...

[mono]

Don't be so sure Dash 7,

Visually it didn't look that bad. Though of course a proper survey would tell

[Creaser]

http://lafd.********.com/2006/06/boeing-767-engine-fire-causes-major.html

"Firefighters immediately applied firefighting foam and were able to control the fire within sixteen minutes."

Sixteen minutes seems a long time, what is the definition of "under control" in these circumstances?

Creaser

[mapper]

this may well have caused the plane to crash had it happend in flight
Is it reasonable to suggest that had this happened in flight:
1. The air stream would have constrained the fire to immediately behind the engine and not have affected the fuselage and wing as severely?
2. In spite of the blade exit velocity, the air stream might (possibly) have deflected a chunky blade aft of the other engine?
3. The fire handle may have been pulled more rapidly :) ?
thnx

[Belgique]

Anybody recall (or have a link to) the L-1011 or DC-10 take-off incident where #1's debris fodded #3 and I believe that the tail-mounted #2 also caught some. They got airborne, dumped and landed again without further trauma.
.
I recall reading the citation for an ALPA award for the crew. As I recall, that was an uncontained bounce off the runway surface into #3.
.
Happened some time within the last 7 years within the Continental US (IIRC it was between 99 and 2002).

[bubbers44]

The turbine blade that hit the right engine and the blades that caused the fuel leaks under the right tank had to bounce off the asphalt so if it was in flight probably would not have hit the right engine. Who knows what would have happened in flight if that turbine had passed through the fusilage. Thank God those pilots wrote up the left engine not delivering full climb power at high altitude requiring the full power runup.

[barit1]

Anybody recall (or have a link to) the L-1011 or DC-10 take-off incident where #1's debris fodded #3 and I believe that the tail-mounted #2 also caught some. They got airborne, dumped and landed again without further trauma...

This (http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001212X20894&key=1) one perchance.

[barit1]

The turbine blade that hit the right engine and the blades that caused the fuel leaks under the right tank had to bounce off the asphalt so if it was in flight probably would not have hit the right engine...

Don't bet on it. It was a heck of a lot more than a turbine blade sticking out of #2, and it cut quite a swath enroute.

[bubbers44]

I think a lot of turbine blades made the punctures on the right side. Only saw one make it to the right engine.

[747dieseldude]

:eek:
Would be great to know what powersetting was applied!



90%, according to this source:

http://www.flightglobal.com/Articles/2006/06/06/Navigation/177/207118/Pictures+GE+investigates+cause+of+American+Airlines+Boeing+7 67-200+uncontained+CF6-80A+engine.html (http://www.flightglobal.com/Articles/2006/06/06/Navigation/177/207118/Pictures+GE+investigates+cause+of+American+Airlines+Boeing+7 67-200+uncontained+CF6-80A+engine.html)


By the way, I imagine the results would be different, if this happened in flight, with the airstream taking all the debris back. The damage to the right engine could also have happened from debris bounced off the tarmac.
But, what would happen if this occured during the takeoff run, say around V1? Still not enough airstream to deflect all the debris, and still tarmac below to bounce off some debris back to the fuselage...
What do you think?

[SeldomFixit]

I'd have to agree that the cross engine and tank access panel damage is rebound and unlikely to have happened in flight. There have been enough large engine uncontained failures that haven't resulted in further structural damage to support this view.
Check your ADI's when parked on a gate. You'll usualy be 0.5 or so degrees nose up. Reason being that should there be a major fuel spill it can be directed back to the grated drains that often run spanwise across the back of a bay. A dedicated engine running probably couldn't accomodate that but at least you can take comfort in knowing that most major spills on bay WILL be directed away from the aircraft.

[DoNotFeed]

(quote from Flight)
General Electric is investigating the cause of an apparent uncontained engine failure which caused extensive damage to an American Airlines Boeing 767-200 at Los Angeles on Friday.

The aircraft (N330AA) was undergoing a ground run-up of the (left) No.1 engine when the problem occurred. The CF6-80A was being tested after the crew bringing the aircraft in from the New York reported abnormal power response from the engine during the flight.
(unquote)

First in a problem you should do a count on parts. We hat it too, sluggish power response and finally a blade was missing. Fortunatly the engine did not blow up on test.
Just as fun, once I asked the main difference between Pratts and GE's.

Answer: whether hear the loud bang when the Canadian cuffs or the Cowboy spreads the hot section over the runway.:ok:

Had this in flight, no problem securing the engine, after landing all parts (found)at atemperature you can touch them:}

[Hiflyer1757]

http://www.ntsb.gov/recs/letters/2000/A00_121_124.pdf

Sept 22 2000 USAir had a similar incident...same motors...same type high speed runup by mtc...except that the hpt stage 1 disk went up and over the aircraft into the river. AC was written off due to fire damage. N654US.

[lomapaseo]

........ snip.
But, what would happen if this occured during the takeoff run, say around V1? Still not enough airstream to deflect all the debris, and still tarmac below to bounce off some debris back to the fuselage...
What do you think?

From this postulated what if, I would suspect similar damage and outcome if below V1 and the aircraft stops on the runway. However, the window of risk vs hours of operation, is very small considering all causes of uncontained rotor failures.

[barit1]

So that no one misunderstands the gravity of this, it is not unusual for an uncontained failure of one low-mounted engine to cause secondary shrapnel damage to an opposite engine. The escaping projectiles are traveling so fast that slipstream has virtually no effect.

The object protruding from the outboard side of #2 engine in the LAFD photo appears to me to be a section of a HP turbine disc (a few hundred Kg) which left the #1 engine a very few milliseconds earlier, traveled horizontally under the fuselage, tore a gash in the belly, and almost tore completely thruogh #2. An instant double engine failure.

Fortunately, uncontained failures are VERY rare due to some of the highest design and maintenance standards in any industry. :ok:

[OVERTALK]

A dozen more detailed photos of the damage here (http://www.iasa-intl.com/folders/belfast/AA763EngineFire-3.htm)

[Globaliser]

Sept 22 2000 USAir had a similar incident...same motors...same type high speed runup by mtc...except that the hpt stage 1 disk went up and over the aircraft into the river. AC was written off due to fire damage. N654US.I'm not normally so anoraky, but as I'd looked this up for someone else: Technically the US Airways aircraft had CF6-80A2s, and this incident aircraft has CF6-80C2B2s.

[Sorry that information is the exactly wrong way around, as correctly pointed out by barit1 below. :O ]

The experts will know what the differences are, and if they make any difference!

[barit1]

I'm not normally so anoraky, but as I'd looked this up for someone else: Technically the US Airways aircraft had CF6-80A2s, and this incident aircraft has CF6-80C2B2s...


The other way around, I believe. N330AA (Friday's fire) was a 767-200 (-223 if memory serves) with CF6-80A2 donks - the baseline 767 for primarily domestic routes. N654US (US Airways PHL 9/2000) was a -200ER with -80C2B2's; bigger fan, an extra LPT and booster (LPC) stage for better SFC for international routes.

And that last batch of pix from OVERTALK leads me to correct my earlier statement of a double engine failure; the chunk of HPT disc from #1 JUST MISSED #2's turbomachinery, although I have no idea how. :eek:

In all likelihood #2 could have continued running.

[Globaliser]

Sorry, you are absolutely right. I looked back at what I'd written before (elsewhere) and realised that I'd managed to read it A over T. Thanks!

[barit1]

Report (http://www.aero-news.net/index.cfm?ContentBlockID=c9176564-53f0-46be-a307-9712da41498e&) says NTSB investigation underway.

[Volume]

Scary to see a full turbine disk having left the engine. During certification normally one third of a disk is seen as the worst case scenario, and even for such event a small risk of a catastrophic result is accepted.
I wonder whether the NTSB will analyse this event, as it was not during operation. I would be really interested in the chain of events of the breakup, it it is possible to determine it. Nomally you assume that the fracture of a turbine disk causes the failure, but the disk is in one piece this time.

[JamesT73J]

Scary to see a full turbine disk having left the engine. During certification normally one third of a disk is seen as the worst case scenario, and even for such event a small risk of a catastrophic result is accepted.
I wonder whether the NTSB will analyse this event, as it was not during operation. I would be really interested in the chain of events of the breakup, it it is possible to determine it. Nomally you assume that the fracture of a turbine disk causes the failure, but the disk is in one piece this time.

It looks that way in the LAFD pictures, but one of the shots that the person kindly provided above provides a different view:

http://www.iasa-intl.com/folders/belfast/AA763EngineFire-3.htm

There was an AD on the subject of cracking on the dovetail slots of HPT disks on the CF6-80, along with service bulletins from GE. Interesting as related reading:

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/ffb80a7e788c48b786256e46005a91c4!OpenDocument&ExpandSection=-4

[BAe146s make me cry]

James

Great pictures, certainly not what a CF6-80 should do on an EGR...
I can't believe that section of failed turbine disk wedged where it did!

BAe146?? AND Metallurgically flawed turbine disks?? :{ :{ :{

[BAe146s make me cry]

Come to think of it if those pictures haven't been reversed or messed about , it's O/B of #2 engine that has the wedged Turbine disk section!
#1 was the suspect engine right???:eek: Just think, the Speed & Inertia
of what took place! Lucky no AMTs were injured or worse...

BAe146??:{

[barit1]

Per the www.aero-news.net link above:

" ...the high-pressure turbine stage one disk on the number one engine, a GE CF6-80A2, broke into several pieces that were later found embedded in the fuselage, the number two engine, and scattered as far as 3,000 feet from the airplane. "

Once the stage one disc disintegrated, the stage two disc (still intact) had no means of support and rolled away at 10000 rpm. That is the intact disc seen at http://www.flickr.com/photos/lafd/sets/72157594153722446/ (LAFD photos)

[lomapaseo]

Scary to see a full turbine disk having left the engine. During certification normally one third of a disk is seen as the worst case scenario, and even for such event a small risk of a catastrophic result is accepted.
I wonder whether the NTSB will analyse this event, as it was not during operation. I would be really interested in the chain of events of the breakup, it it is possible to determine it. Nomally you assume that the fracture of a turbine disk causes the failure, but the disk is in one piece this time.

The so called small risk of catastrophe is averaged over all rotor stages and all operating conditions. If you parse the data down to just high pressure turbine disks it's more like 1 out of 2. I also believe that we will find the released disk pieces are 1/3, 1/2 and various other smaller bits. The piece with the most penetrating energy is the 1/3. But in the case of the high pressure (higher RPM) turbine the smaller pieces are actualy the most threatening since there are more of them emanating out in a spray pattern

[OVERTALK]

Engine on American Airlines Boeing plane blew apart during a check nearly two weeks ago, causing a fire and sending metal half a mile away.
An explosion that ripped apart the engine of an American Airlines jet during a ground test at Los Angeles International Airport this month was far more dangerous than first reported, new details suggest.
The blast was strong enough to hurl an 18-inch chunk of metal more than half a mile -- across taxiways, service roads and two active runways. Airport workers found the piece two days later, not far from the airport's perimeter fence.
The investigation into what caused the engine to explode has focused in part on tiny cracks found on a key piece of the turbine. An Air New Zealand jetliner lost the same kind of engine to similar cracks in late 2002 and was forced to make an emergency landing.
"It was pretty fortunate that no one was hurt," LAX spokeswoman Nancy Castles said, "and that no planes were taking off or landing at that time."
The Boeing 767 jet had arrived in Los Angeles on a regular flight from New York City. Its flight crew had reported some kind of mechanical problem, so the airline sent the plane to maintenance after it landed at LAX.
An airline spokesman would not discuss that initial problem in any detail, saying only that it was unrelated to the engine failure that followed.
Workers were still trying to figure out what was wrong with the airplane when they pushed the throttle for both engines, and one of them blew apart.
The explosion outside the American Airlines maintenance hangar on June 2 sparked a small fire that sent a column of dark smoke over the passenger terminals at LAX and drew most of the initial attention. The explosion -- officially an "uncontained engine failure" -- gutted the engine and blackened part of the airplane's fuselage.
It also blasted pieces of the engine onto a nearby runway -- and, in one case, clear across the southern airfield. The workers who found that piece half a mile away described it as a wedge of metal, 2 inches thick, and heavy.
Other pieces punched through the airplane's fuselage and wings and embedded themselves in its other engine, according to a statement released Tuesday by the National Transportation Safety Board. Robert Ditchey, an aviation consultant in Marina del Rey who once oversaw maintenance for Pan American World Airways, called that especially worrisome.
Airline engine systems, he explained, have extra shielding that's supposed to protect the rest of the airplane from that kind of damage. Pieces of the engine, he said, "are not supposed to penetrate the fuselage" under any circumstance.
Three maintenance workers who were on the plane when the engine blew escaped without injury. Nobody on the ground was hurt, either -- despite the blast of metal pieces across taxiways and service roads usually swarming with airport workers.
Two federal agencies are looking into the explosion: the transportation safety board and the Federal Aviation Administration. Both have offices here but, in a sign of how important this investigation is, both sent special investigators from their Washington, D.C., headquarters.
Their investigations will determine whether the flaw that destroyed the engine was an isolated problem or could affect other airliners still in service. "I don't think there's any indication right now that this is a systemic problem," FAA spokeswoman Laura Brown said.
Investigators have found evidence of "fatigue cracking" on pieces of a disk from the engine's turbine, the safety board said in its brief statement.
Such cracks can develop from a microscopic flaw in the metal and weaken engine parts against the extraordinary stress they must endure.
The same kind of engine, built by General Electric, was the subject of an FAA order in 2003 that required regular inspections for fatigue cracks. The order was prompted by the emergency landing of the Air New Zealand plane after one of its engines spun apart and damaged a wing.
Such cracks are rare, Ditchey said, and should be caught by the rigorous inspections -- "down to the last nut and bolt" -- that airlines put their engines through. The materials used to build an aircraft engine, he added, are "the highest tech of the high-tech. It doesn't get any fancier than that."
Investigators have shipped pieces of the turbine disk shattered in the LAX explosion to the transportation safety board's laboratory in Washington, D.C., for further tests. The engine itself was sent to an American Airlines maintenance center in Oklahoma.
Airline spokesman Tim Wagner said he did not know how long the airplane had been in service. He said workers were conducting a routine maintenance check known as a run-up to diagnose an unrelated issue when the engine broke apart.
The airline, Wagner said, is "still in the process of refurbishing the aircraft."
from link (http://www.dailybreeze.com/news/articles/3048421.html?page=2&c=y)

[JamesT73J]

Another photograph here, capturing the immediate aftermath:

http://www.airliners.net/open.file/1059747/L/

[Pilot Pete]

Another photograph here, capturing the immediate aftermath:
http://www.airliners.net/open.file/1059747/L/

Wow, I bet the ANZ pilots felt they had a lucky escape, with all that debris escaping!!

PP

[barit1]

...I have the photos somewhere but on No 1 the compete gearbox sheered off held by the Hydraulic hoses and Generator cables !!
The No. 3 of course looked like a trick cigar ;)
Also a piece of debris hit one of the aft RH windows and a passenger departed the aircraft - again missing the No 2 engine:uhoh:

The FAA has made an object lesson of this investigation - an excellent review of cross-discipline investigation techniques: National DC-10 (http://lessons.air.mmac.faa.gov/l2/NAL27/)

[aintsaying]

The early built turbine disks were cut by cutting tools which then made about 10 or so turbine disks. Then the cutting tools were replaced and another 10 or so turbine disks were cut from stock.
Apparently the disks that have been failing are the ones that were made/cut last before changing the cutting tools. So now when turbine disks are made, the cutting tools are replaced sooner. This apparently made for a better quality turbine disk. This was on the early CF6-80 A series engines.
When the disk let go on Air NZ's 767 out of Brisbane, Australia, the engine stopped rotating, from climb power, in 42 revolutions. We counted this on the engine casing.
The force of this sudden stop made the aircraft yaw so hard that the co-pilot hit his head against the pillar between the windows. There were rumors that he was knocked out, but I'm not sure about that one.
Boeing was glad they strengthened up the plylon struts coz the engine would have fallen off the wing and I guess the airframe would have been lost. They knew this because a few years before Air nz's incident, a similar disk departure happened during a maintenance ground run where the entire engine fell off the wing and sat on the ground.
Have you guys ever wondered why there is a 'dry bay' area in the wing just above the turbine's? Its so an uncontained turbine failure, should it happen into the wing, can be survivable.
Post#17.

[jondc9]

I recall a british air tours 737 that had an uncontained failure causing a fire , great damage and loss of life. type of engine was a pratt & whitney JT8d-?(15 or 17 or 9?).


I cannot recall what part of the engine broke apart, whether it was the compressor section or the turbine section.

Things can happen and really ruin your day. Engines on wings, next to fuel tanks scare me a bit in this scenario. Of course engines on the tail, near control cables can be messy too.


This article may be of interest:



Breakup of jet engine defies repair effort
By Matthew L. Wald The New York Times

Published: June 19, 2006


WASHINGTON U.S. investigators say they are deeply concerned about an engine breakup that nearly destroyed a Boeing 767 on the ground in Los Angeles on June 2 because the failure may be the third recurrence in six years of a problem they thought they had eliminated.

American Airlines mechanics were testing the engine after the crew of an earlier flight had reported that it was not performing properly. During the test, an internal disk came apart, slicing open a fuel tank in the left wing; the fuel spilled onto the ground, where it caught fire. One piece of metal was thrown 2,500 feet, or 760 meters, from the plane.

There were no injuries, and under the rules of the National Transportation Safety Board the event might not even qualify as an accident because there was no intention to fly the plane. But experts say that such "uncontained failures," so called because the engine cowling does not hold in the debris, resemble a roulette game.

"There's 360 degrees around, and it's really the luck of the draw which way the pieces come out," said John Goglia, a former member of the board and an aircraft maintenance expert. If the parts fly off in flight and hit the wing, where fuel is stored, or the fuselage, "the results could be pretty devastating."

The first such engine explosion occurred in July 1989, during a flight of a United Airlines DC-10. That engine was mounted in the tail, and the debris disabled the plane's hydraulic system. The crew brought the aircraft down in a field at the airport in Sioux City, Iowa, maneuvering only by varying the thrust on the two surviving engines; 111 people were killed.

The incident in Los Angeles is similar to one in September 2000 involving another Boeing 767, this one owned by US Airways, in Philadelphia. In both cases, mechanics were testing the engines by revving them toward full power when they broke up, leading to catastrophic fires.

In addition, an Air New Zealand 767 suffered an uncontained failure at 11,000 feet on a flight from Auckland to Brisbane, Australia, in December 2002. That plane landed safely. But as a result, in March 2003, the Federal Aviation Administration ordered inspections of the part involved. The agency believed that would solve the problem.

The Federal Aviation Administration is now investigating the failure in Los Angeles, said a spokeswoman, Laura Brown.

The engine in the incidents was a variant of the popular General Electric CF6.

Rick Kennedy, a spokesman for General Electric, said that about 3,400 of the engines were in service and that two- thirds of them had been inspected, with no problems found.

The engine involved in Los Angeles was not due for inspection, according to investigators.

The inspection interval is usually set at half the number of flights at which engineers think a problem will develop. The inspection limit now is 11,000 "cycles," or engine start-ups and shutdowns. Experts said that one likely outcome was that the government would require inspections at shorter intervals.

[barit1]

I recall a british air tours 737 that had an uncontained failure causing a fire , great damage and loss of life. type of engine was a pratt & whitney JT8d-?(15 or 17 or 9?).
I cannot recall what part of the engine broke apart, whether it was the compressor section or the turbine section...

Jon's looking for this one. (http://aviation-safety.net/database/record.php?id=19850822-0&lang=en) In this case it was the combustor--folks seem to forget the region between the HPC and HPT is a pressure vessel containing several hundred psi. :uhoh:

[lomapaseo]

Jon's looking for this one. (http://aviation-safety.net/database/record.php?id=19850822-0&lang=en) In this case it was the combustor--folks seem to forget the region between the HPC and HPT is a pressure vessel containing several hundred psi. :uhoh:

Looks to me like the commonality bewteen the two events is the location of a fuel tank access panel being in harms way for small parts which ricochet. It might be that the fuel tank access panel is weaker than the typical robust underwing skin.

[scarebus03]

Well this is why we (MX) do ground runs for fault confirmation. Sometimes the only way to confirm the fault is to run the engine and risk further damage to the engine or as in this case the airframe as well. Sometimes after performing all the required inspections for engine complaints and finding no faults the run up is the only way to ensure serviceability. In nearly all the manuals today it is stated "further operation of the engine for troubleshooting may result in further damage"

On the other hand with the pressures involved in our industry to get airplanes in the air the run up could be used to shortcut the longer inspection process.
I hope that this was not the case.

Better on the ground during maint. than in the air with pax,

Happy flying:)

SB03

[gas path]

lomapaseo
It was as a result of this accident, and other incidents that the fuel tank access panels located in vunerable areas were strengthend.

[NorthSeaTiger]

Is this a pic of the actual incident occuring ?


http://www.airliners.net/open.file/1059747/M/

[lomapaseo]

Is this a pic of the actual incident occuring ?
http://www.airliners.net/open.file/1059747/M/

I believe that it is a photo of the subject event.

I have a technical question on the visible fire.

It looks like the fire is above the ground level,?

It seems like that the engine burner flame was open to the outside and that the fuel visibly leaking from the wing in previous photos is ignited?

But does the photo above imply that the fuel leak never reached the ground before ignition?

[JamesT73J]

Knowing nothing about the lockout systems in the fuel for the CF6-80A or 767 I'd guess that until the fuel supply was shut-off there would have been a continual supply for the fire from the combustor(s).

[misd-agin]

I believe that it is a photo of the subject event.

I have a technical question on the visible fire.

It looks like the fire is above the ground level,?

It seems like that the engine burner flame was open to the outside and that the fuel visibly leaking from the wing in previous photos is ignited?

But does the photo above imply that the fuel leak never reached the ground before ignition?

Memory of the pictures was that the fuel leak was from the right wing inboard of the engine pylon. Those photos did not show obvious fire damage on that side of the a/c(memory).

This is apparently a picture taken with the engine burning while it is still rotating. The exhaust will be blowing the fire rearwards.

Fire warnings don't illuminate for internal engine fires. The fire warning system is for fires outside of the engine core and under the cowling. Actually heat sensors so bleed line failures can illuminate fire warning lights.

The following exchange highlights how the fire warnings system doesn't cover all possibilities -

(Paraphrased) - "your right engine has a fire in the tail section."
"we don't show anything on our instruments." (engine's shutdown)
"I'm telling you it's burning."
"Still? We don't show anything in here."
"Well it's getting worse. If it was me I'd get out of there."
"Ground, xxx is evacuating."

Tailpipe fire that damaged the engine and continued to burn after the engine was shutdown.

[jondc9]

not only does the fire warning/detection system miss fires outside the protected area (see former post) but so does the FIRE EXTINGUSIHING system. In previous posts I've mentioned seeing someone "shoot the bottle" for a fire outside the protected area...totally wasting the charge.

:-)

[barit1]

Knowing nothing about the lockout systems in the fuel for the CF6-80A or 767 I'd guess that until the fuel supply was shut-off there would have been a continual supply for the fire from the combustor(s).

I'm quite sure that fuel to the combustor stopped pretty quickly for two reasons:

1) Fuel limit schedules in any modern gas turbine are proportional to HPC exit pressure, and it was instantly dumped when the case was ruptured by HPT parts. Undoubtedly there was an instantaneous fireball, but I doubt the engine fire lasted more than a second or two.

2) The HP fuel pump is driven by the N2 gearbox, which came quickly to a halt.

[jondc9]

I understood that some 10,000 gallons of jet fuel was spilled in this 767 incident.

Wow

And while barit is right, there are reasons to think that the fuel may have stopped being pumped to the engine in question when it "blew up", one might also recall that electric fuel pumps are delivering fuel to the engine area, especially if the fuel line broke. This may have contributed to that amazing flame in the photo, but we cannot know for sure.

the fuel pump (mechanical) that is such a critical part of the engine almost certainly stopped briefly after the BOOM. But fuel under pressure to a broken line may have continued to be pumped until the fire procedures/emergency shut down checks were done and the fuel supply was cutoff at the wing valve.

regards

jon

[barit1]

Don't forget that engine oil burns well too, and since there were undoubtedly many broken oil lines this oil fire may have persisted long enough to help get the fuel tank spillage alight.

The wind is blowing pretty strong along the ramp too, a west wind if I interpret the sun angle correctly.

[javelin]

That's 36 tonnes of fuel - I very much doubt it !

Also, engine oil does not burn very well and there is usually only 5 gallons per engine so not really a factor :bored:

[Pilot Pete]

One of the previous photographs showed the aftermath and there was fuel still streaming from a rupture in the fuel tanks close to the engine. Perhaps this was feeding the fire until the emergency services extinguished it?

PP

[Beanbag]

I'd guess that the photo is from the first second or two of the incident - note the cloud of dust that looks to be about halfway between the camera and the aircraft, (parallax makes it appear to be in front of the burning engine). I'd guess that's from one of the ejected bits hitting the ground.

[lomapaseo]

I'd guess that the photo is from the first second or two of the incident - note the cloud of dust that looks to be about halfway between the camera and the aircraft, (parallax makes it appear to be in front of the burning engine). I'd guess that's from one of the ejected bits hitting the ground.

Looks like the dust cloud is not being affected by prevailing wind, so it might be from an engine exhaust??

[A330ismylittlebaby]

What about like when i saw them test the A380 blade off event where the engine contains the massive blade, can they not have that for every part of the engine.

This is the only thing that semi-worries me about flying right now

[barit1]

The only thing that has been demonstrated to contain a turbine disk rupture is the foot-thick reinforced concrete walls of a test cell ("test bench", in certain parts of the world.)

Even so, I'm not so sure I'd linger in the plane of rotation... :=

[nzmarty]

as the airnz uncontained turbine failure out of sydney a few years ago showed, a 767 CAN still fly heavy on one, and the damage to the aircraft didn't cause it to blow up. with respect, i think suggesting a high bypass fan engine that has gone out, will ignite fuel like an afterburning jet engine at take-off power such as the ones on concord, is not really a fair or reasonable comparison

[A330ismylittlebaby]

Yeah true, i was just thinking of all the fuel leaking, would that be ignited while flying?

[FridayNightPalma]

Looks scarily close to the fuel dump just in the background. Funny place to conduct an engine run test.

[rodthesod]

Looks scarily close to the fuel dump just in the background. Funny place to conduct an engine run test.
FNP

Couldn't agree more, if it is a fuel farm. Someone said earlier in the thread, they thought they were water tanks - but I don't think anyone's confirmed that.

rts

[gwillie]

http://www.bradenton.com/mld/bradenton/news/local/15299732.htm

[gwillie]

More detail included in LA Times coverage...
http://www.latimes.com/news/printedition/asection/la-me-engine18aug18,1,4664883.story?coll=la-news-a_section

[Pimp Daddy]

Someone said earlier in the thread, they thought they were water tanks - but I don't think anyone's confirmed that.

Been a long time since I've been to LAX but from the pics it looks like the aircraft was at the hanger area between taxiways C11 & C12.

If you look at the airport diagram (http://204.108.4.16/d-tpp/0608/00237AD.PDF) the fuel farm (marked Bulk fuel storage) is further west behind all the hangers. These are some pics of the LAX fuel farm (http://www.flickr.com/photos/lafd/sets/72157594155958369/).

These look much more like water tanks.

[Kiwiguy]

Just out of curiousity, what do these recent uncontained disc failures do for the demonstrated reliability of the CF6-80 in terms of ETOPS reliability ?

Anybody know if the reliability stats have been recalibrated for these recent failures ?

[barit1]

Inasmuch as the engines were deemed airworthy at the time of failure, I'm sure they will count toward overall model reliability statistics, with ETOPS implications. The fact they weren't operating for an intended flight doesn't count here.

But that's not the half of it. Uncontained failures always warrant some heavyduty introspection by the manufacturer, operator, and FAA to minimize future risk to ETOPS and non-ETOPS alike.

[Kiwiguy]

Mmmm well irrespective of whether the incident happens during ground runs or in flight, it all ought to count.

It does raise the question whether the CF6-80 met reliability expectations when new, but that the incidence of failure is now begining to climb as fleetwide fatigue sets in ?

Makes one wonder whether there ought to be a maximum age limit for the engine hardware in ETOPS flights ?

[pakeha-boy]

kiwiguy...yeah mate...just like the limitations on the Hawaian 737 that lost its top many years ago,and lets not forget the Alaska MD 80.....seems like it has to get catastophic before inspection programmes get the once over!!

[barit1]

The FAA's recent NPRM action can be seen here (http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/EAFCE1FFC771DC26862571CE005A95D2?OpenDocument).

Of interest is the FAA's use of the term "unsafe condition" without a quantative threshhold. The CF6-80 has, by any statistical measure, an outstanding reliability record, and the AD proposed will doubtless improve that record. GE would probably love to have their spare parts sales blossom as a result of hardware retirement, but that will create an economic burden on the industry that may raise ticket prices and drive more pax onto the highway. How much safer is that?

[lomapaseo]

The FAA's recent NPRM action can be seen here (http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/EAFCE1FFC771DC26862571CE005A95D2?OpenDocument).
Of interest is the FAA's use of the term "unsafe condition" without a quantative threshhold. The CF6-80 has, by any statistical measure, an outstanding reliability record, and the AD proposed will doubtless improve that record. GE would probably love to have their spare parts sales blossom as a result of hardware retirement, but that will create an economic burden on the industry that may raise ticket prices and drive more pax onto the highway. How much safer is that?


Oh I would say that there is a quantitative threshold..

At any given time, you are fliyng around with unknowns, about 10 times the number of known problems that you have. So while the reliability record might have been good up to the latest problem identification, you just can't go around ignoring the known stuff, figuring that it's not your turn today.

So you take the known stuff and with some data, (cracks per 1000 engines etc.) you extrapolate out how many more big bangs are likely to occur in the future if you do nothing. If you get an answer anywhere close to one that would indicate that you are using up all your average good reliability record in just a few months of exposure. Clearly not something that either the feds or the operators are prepared to absorb.

The problem with this latest problem is that it is so lethal that you have to err on the side of conservatism to avoid another one like the last one.

[barit1]

It's not a matter of "ignoring the known stuff" - the FAA is right to tighten the life management/inspection/rework cycle when a disc life problem is known. I'll bet GE is working overtime to implement a plan to make this problem a non-problem. Quick and competent response is mandatory on a safety issue such as this.

My earlier comment is that the FAA seems to have no public statistical standard re what is "safe" versus "unsafe". I defy anyone to tell me that we'll achieve a zero accident rate in our lifetime (or ever, for that matter). Does that mean that all commercial aviation is unsafe? The only reasonable question is "How safe is it?", and not "Is it safe?"

[barit1]

...Makes one wonder whether there ought to be a maximum age limit for the engine hardware in ETOPS flights ?

Rotating parts (discs, shafts) and other parts subject to cyclic loads DO HAVE hard life limits, generally expressed in operating cycles.

[lomapaseo]

My earlier comment is that the FAA seems to have no public statistical standard re what is "safe" versus "unsafe".

Does anybody?

I've never seen a light switch criteria, but I have worked with dimmer switches when somebody complains about the amount of light at the end of the tunnel

[John Farley]

An engineering source that I tend to trust has suggested to me that the engine run was carried out without the benefit of the normal max RPM controls.

While the end result could have been much worse the relevance of the incident to flight operations may turn out to be less than it appears at first sight.

[lomapaseo]

An engineering source that I tend to trust has suggested to me that the engine run was carried out without the benefit of the normal max RPM controls.
While the end result could have been much worse the relevance of the incident to flight operations may turn out to be less than it appears at first sight.

The RPM probably wasn't of much significance in the cause, considering the report that the disk already had extensive cracking in it beforehand.

[barit1]

The -80A (& early -80C2's) has an old-fashioned hydro-mechanical FCU, normally coupled to an analogue electronic override. But even with the electronics "off" there are two or three levels of overspeed protection, so I doubt that was a factor.

[vapilot2004]

Grounding urged for some GE engines

Los Angeles Times

Airlines should immediately ground dozens of commercial jets with a widely used General Electric engine that in June exploded in a parked Boeing 767 at Los Angeles International Airport, according to the National Transportation Safety Board (NTSB), which released its report Monday.

The report recommends inspection of the popular engine series for flaws that could cause an explosion. Engines that have been turned on and off more than 3,000 times and have not been serviced under post-2000 guidelines, should be inspected immediately.

The June 2 explosion at LAX occurred during a mechanic's ground check of an American Airlines jet whose pilots had reported engine trouble during the previous flight. There were no passengers on board the Boeing 767, and no one was hurt.

An FAA spokesman said the agency would review the board's recommendations and respond within 90 days.

Up to 1,155 engines on several widebodied aircraft, including Boeing 747s and 767s, McDonnell Douglas MD-11s and Airbus A300 and A310s, use the GE engines.



Seems a reasonable precaution. Anyone recall the outcome of the ANZ incident ?

[galaxy flyer]

Had similar cracks on the TF-39 (C-5) engines. Sounds about right, the AF buys them for the C-5 re-engining program and the NTSB recommends grounding. No one remembers that the DC-10 was doing fine until the AF bought the KC-10, then all hell broke lose with -10 crashing everywhere for awhile.

GF

[barit1]

Considering that the CF6-80 family is the current bestseller, check out the uncontained failure (http://aviation-safety.net/database/dblist.php?Event=ACEU) list and see if you think its rate is out of line with other, less numerous engines. :8

And I'll bet very few groundings will result - there are enough rotable spare -80's to keep the fleet going.

[barit1]

Had similar cracks on the TF-39 (C-5) engines. Sounds about right, the AF buys them for the C-5 re-engining program and the NTSB recommends grounding.

USAF is getting new engines with new discs. It'll be 20 years before enough cycles are accumulated to warrant inspection. Look at the KC-135 reengine program.

[fdr]

Actually it was National over NM, and landed at ABQ. See http://aviation-safety.net/database/record.php?id=19731103-0&lang=en
But you are right - a fan blade leaving the hub of #3 engine travelled under the fuselage and struck the accy section of #1. I believe that #2 did suffer minor FOD but kept running.
I believe the entire industry learned a good deal from various aspects of this accident, including flight crews NOT experimenting with the autothrottles!


and C/B's...:ugh: