NTSB Report on Another GE CF6 Engine Failure Resultng in Engine Separation Into Front and Rear Parts

NTSB (PDF file) ^ | December 12, 2000 | Jim Hall acting Chairman

[Lessismore]

Reports now indicate that the front part of the engine landed at the gas station, and that the rear part of the engine landed a few blocks away (this is the third small debris area on land). This separation of engine parts appears to be consistent with the on-ground incident referred to in the NTSB report, where the disintegration of a disk in the high pressure section of the engine separated the front and rear sections. Note also that in the Philadelphia incident the uncontained failure of the engine also damaged the front wing spar. This is because the high pressure section of the turbine is at the rear, under the leading edge of the wing.

[Rokke]

Stop it right now. You pre-empting a good 10,000 posts worth of conspiracy nonsense.

[skateman]

The only prob.... is that it was an Airbus that crahsed, not a Boeing 767.

[Fixit]

Same engines, different airframe.

[Lessismore]

Same GE engine. Same engine mounting on pylons under the wing. They are both wide-bodied twin-engine aircraft, and are very similar in form.

[Terrorista Nada]

F.O.D. kills (foreign object damage)

A simple monkey wrench left inside an engine air inlet cowling could have done this. F.A.A. will propose monkey wrenches are dangerous weapons and confiscate all monkey wrenches from A&P (airframe and powerplant) mechanics.

[John Jamieson]

Adequacy of HPT Stage 1 Disk Design and Continuing Airworthiness Program

As previously discussed, it is possible that the cracks in each of the three HPT stage 1 disks discussed in this letter were the result of surface damage. However, the Safety Board recognizes that there is no clear evidence of surface damage on the area of the US Airways disk from which the crack originated and, therefore, it is also possible that the crack in that disk initiated from an undamaged blade slot bottom. Further, metallurgical examination revealed that in the area immediately adjacent to the fracture origination point, the radius between the slot bottom and the forward and aft faces of the disk conformed to the engineering drawing requirements for that radius, suggesting that the area from which the crack initiated also conformed. This possibility raises concerns that the design of the slot bottom of the GE CF6- 80C2 HPT stage 1 disk may not provide an adequate margin of safety even when the disk is manufactured to specifications. Further, during the Safety Board’s examination of the separated disk from the US Airways airplane, it was found that many of the radii between the slot bottoms and the forward and aft faces of the disk either exceeded or were less than the engineering drawing requirements for this radius.

Appearently, the problem is still under investigation!

[Clinton's a rapist]

What do you think the chances are that the FAA will ground all aircraft with this engine type for overhaul/retrofit?

[John Jamieson]

They should. We sent 50-100 older planes to the desert somewhere. Somebody better plan on getting them flying if we can't use GE CF6's for a while.

[LibKill]

Hmmm. After seeing the wreckage and reports on TV, my dear old Dad (pilot with thousands of hours flight time) said that he thought it was an engine failure with the fan (front part) separating from the rear.

[KeyLargo]

Just like American 191 Chicago 1979

http://www.airdisaster.com/special/special-aa191.shtml

[Lessismore]

Appearently, the problem is still under investigation!

This is the NTSB recommendation. I haven't found anything definitive regarding what the FAA did in response.

[Lessismore]

Or the Sioux City, July 19, 1989, United Airlines DC-10 crash.

See http://www.ntsb.gov/speeches/former/hall/jh970912.htm for an interesting talk "Remarks of Jim Hall Chairman, National Transportation Safety Board to the International Society for Air Breathing Engines Chattanooga, Tennessee, September 12, 1997"

[El Gato]

How to explain that rather than, or in addition to, the wing being found in the bay, it was the vertical stabilizer. (Mayor reported a part of wing, but it could have been the Vert. Stab). Can't envision how the engine coming unglued would rip that off.

[El Gato]

What do you think the chances are that the FAA will ground all aircraft with this engine type for overhaul/retrofit?

Don't know, but the Air Force's KC-10 tanker, really just modified DC-10, uses a version of the same engine, although of course they give it a military designation. I don't think we can afford to ground them right now. (Verified with the guy in the next office, who was a KC-10 crew chief)

[Lessismore]

There was an interview with some fishermen on Fox 5 TV. They said that part of the wing hit the tail, causing parts of the tail to fall off.

My guess would be that if the engine failure cut the front wing spar, the outboard section of wing would fold backwards, upwards, and then separate. It might fold towards the fuselage far enough to hit the tail surfaces as it came off the plane.

An on-board explosion big enough to separate both one wing and the tail should have damaged the fuselage enough that there would be bodies in Jamaica Bay and between the bay and the main fuselage impact point. However, in interviews the crews recovering the tail and other parts from the Bay have said that there are no bodies in the Bay.

So either the tail was struck by wing parts following engine failure, or the tail was struck by wing parts following a small on-board explosion near the right wing root. I'd favor the former explanation at this point.

[Moonman62]

They should. We sent 50-100 older planes to the desert somewhere. Somebody better plan on getting them flying if we can't use GE CF6's for a while.

Usually what they do is just recall the ones that have a lot of hours on them

[7.62mm]

Just like American 191 Chicago 1979

If memory serves on this, the engine mount cracked when the engine was attached to the plane because the mechanics used an unapproved method of installing the engine. They used a fork lift to raise the engine into place and inadvertantly put too much pressure on the pylon mount, which cracked it.

The mount failed on takeoff, but the engine itself did not explode or disinteigrate.

Regards,

[lawdude]

"(this is the third small debris area on land)."

I heard some reporterette asking some high Mucky-Muck about the "third debris field". She seemed so proud to be able to use the new BUZZ TERM in her job. Betcha she asks for a raise!