C-5 accident at Dover AFB

[barit1]

Originally Posted by cwatters

Planes don't usually go far without a tail. There is usually quite a rapid pitch nose down when the tail falls off (sometimes to inverted). Since it didn't go in nose down that kinda rules out the tail breaking off at any significant altitude. I guess we'll have to wait for the reports.

The classic example of the loss of only 50% of the horizontal tail. Nothing at all like this C-5 accident.

[212man]

If you watch this clip it may give you an idea of how readily tail planes can detach during a heavy landing:

http://www.airdisaster.com/download/md80.shtml

[broadreach]

More speculation, nothing to do with why it happened nor with how the emergency was handled, rather what happened after the aircraft hit the ground. This accident has been one of the most densely covered photographically so there's plenty to look and wonder at.

If Mr Mike Cowan's (he is mentioned as a crash witness in jondc9's last post) estimate of an aoa of 45-50° is even approximately correct, the nose would have come down like a hammer from what, the equivalent of five-seven stories? Would that in itself not have been sufficient to shear most of the structure just ahead of the heavy cargo, i.e. just aft of the nose section? And, if that's the case, not surprising flight deck crew were "pinned" down and had to be extracted by the rescue team. I hope they recover quickly and fully.

Nitpicking perhaps but what's had me puzzled is, was the gear down or not? Several posts and the ABC report suggest a "belly landing", and sliding on wet (or dry) grass over sandy, frangible soil. But, that close to touchdown, would the gear not have been extended? Surely better, despite the speed penalty, than a gear-up landing?

Pics from starboard show what what appear to be those bogies swivelled completely around in line with the direction of slide. And the port gear doors are shown still slightly ajar. Look closely and one can pretty much see where the port wing tipped over and dug in just before the aircraft came to a halt; had the aircraft been bouncing along on its belly surely that wing would have hit the ground much sooner and at a much higher speed, with hotter consequences than just some fuel sprayed out to port.

So, was the gear down or not? If so, what difference did it make?

[rpbrown]

I heard from one of our pilots who knows the AC that they had inadvertent thrust reverser deployment at takeoff power and were trying to return - probably not enough power to make the approach heavy weight.

[757manipulator]

I heard from one of our pilots who knows the AC that they had inadvertent thrust reverser deployment at takeoff power and were trying to return - probably not enough power to make the approach heavy weight.

Inadvertent? does this mean or imply they deployed reverse by mistake?...or to clarify the news in the reverser activated without command?

(of course this is asking for clarification on pure speculation)

[RatherBeFlying]

If so, most likely uncommanded

A B-732 in Cranbrook suffered an uncommanded reverser deployment on go-around and lost control in 1978; so did a Lauda Air B-763 in 1991.

We should also note that post-Cranbrook modifications to the reverser interlock system may have played a role in last winter's overrun at MDW.

Against that grim background, it's a brilliant achievement to get an a/c back on the ground without loss of life after an uncommanded reverser deployment

[KC135777]

Originally Posted by rpbrown

I heard from one of our pilots who knows the AC that they had inadvertent thrust reverser deployment at takeoff power and were trying to return - probably not enough power to make the approach heavy weight.

I don't believe it was full t/r deployment...I was told it was a t/r 'unlocked' light...which requires a precautionary shutdown of the engine. A full blown t/r deployment would be emergency shutdown required (T-handle).

can't get slow, back side of the power curve---right?! hmmmm.....

[patrickal]

Originally Posted by 212man

If you watch this clip it may give you an idea of how readily tail planes can detach during a heavy landing:
http://www.airdisaster.com/download/md80.shtml

If you watch the clip that 212man linked to, you can also see the fuselage buckle just in front of the wing as the nose smacks down. A little faster rate of descent and this MD-80 may have suffered the same fate as the C-5 and broken into 3 pieces.

[212man]

Thanks Patrick,
sadly, small post = small observation but actually there is a lot of useful info in that video. High vertical rates of descent tend to split aircraft in fairly specific areas, and the empenage attachment is one of them. The cockpit bulkhead another.

[archae86]

Ground-level pictures

A colleague forwarded me a Powerpoint file containing nothing save a couple of dozen photos apparently taken at ground level in early morning light, thus fairly soon after the event. From that set, here is a view of the tail section which may help those familiar with the structure see the failure points:
C-5 tail
This photo of hand-held spraying appears earlier than the truck foaming shown elsewhere in video. To my eye, the spray appears directed more toward the pylon from which an engine departed than toward the fuel spill, but no hint of fire is apparent.
Hand Spray
This view of the main portion may clarify the separation point, appears to be just aft the last row of a set of passenger seating.
side_aft
This view of an early portion of the gear tracks may suggest that the C-5 landing gear's oft-discussed but little-used low California Bearing Ratio capability may have been helpful this day.
gear tracks
This view shows the large caster angle of the main gear at rest, with a deployed slide that must not have been used.
main gear and slide

[Earl]

Back in the early 90's a C-5 crashed at Ramstein AB if I remember correctly.
Wasnt the final report due to T/R deployment?

[galaxy flyer]

Earl:

Yes, it was. Many mods to improve reliability and better fault indications since.

GF

[jondc9]

Ah, thrust reversers and deployment (uncommanded) inflight.


I recall that Douglas actually took their planes up, at a critical moment deployed reversers and showed that the plane could be controlled.

I understand (correct me if I am wrong , please) that boeing makes a mathematical calculation on the effect of a reverser and the ability of the plane to be controlled.

Does anyone know what Lockheed does/did for the C5?

It sure does sound like the plane got a little bit behind the power curve. Does anyone know what the flap settings should be at super heavy weight and loss of one or two engines on approach?

Does anyone know (for a fact please) if the C5 can "dump" fuel?


On some of the planes that I have flown if you "lose an engine" during the approach, you reduce your flap setting...how about the C5?


jon

[ironbutt57]

You can make it in a 767 as well if the t/r deploys after liftoff, but it takes full rudder and lots of aileron applied in a "timely" fashion..

[lomapaseo]

Originally Posted by jondc9

Ah, thrust reversers and deployment (uncommanded) inflight.
I recall that Douglas actually took their planes up, at a critical moment deployed reversers and showed that the plane could be controlled.
I understand (correct me if I am wrong , please) that boeing makes a mathematical calculation on the effect of a reverser and the ability of the plane to be controlled.
Does anyone know what Lockheed does/did for the C5?
It sure does sound like the plane got a little bit behind the power curve. Does anyone know what the flap settings should be at super heavy weight and loss of one or two engines on approach?
Does anyone know (for a fact please) if the C5 can "dump" fuel?
On some of the planes that I have flown if you "lose an engine" during the approach, you reduce your flap setting...how about the C5?
jon

A few comments

No where Have I seen anything but unsubstantiated third and 4th hand rumor about uncommanded inflight reverse. I have read 2nd hand rumor about a reverser unlock light, which is still protected from deployment by backup systems.

The present tense use of what Boeing does or does not do relative to protecting against uncommanded deployment is not correct. Lessons have been learned by all manufacturers and regulatory agenciesd and are reflected in today's (present tense ) designs

What Lockheed did (past tense) may have been of interest for the C5 but only if the facts relate it to this accident. Right now, as far as I understand, the report from the crew is that an engine flamed out/was shutdown.

I still have no idea why this was not routinely handled by the crew and if there might have been another system failure.

[galaxy flyer]

Yes, the C-5 can dump fuel. At his fuel load, about 9000# per minute.

Normally, a heavy weight OEI return would be flown at 40% (apx 16 degrees) of flap vice 100% or 40 degrees at normal weights. Vref would be around 168 or a bit more. The plane, at heavy weights can be "underpowered" on a OEI return, but is quite controllable, if the speed is closely monitored and power is applied correctly. Getting slow is likely to be very scary or non-survivable. Could that have happened--maybe, but the crew was highly experienced and knew what the stakes were. Sims are done quarterly, emphasize OEI work. NOT to imply any faults on the crew, we simply do NOT know what happened.

The thrust reverser, as opposed to FAA-certified planes of like vintage, does NOT mechanically pull the throttle to idle in the event of an uncommanded T/R deployment. With a T/R deployed, they would have shutdown the engine and landed on three. IF a T/R deployed, it would have a either a crash OR a routine return on three. GE and Lockheed have done major work on the T/R installation since the RMS accident and it has been pretty reliable since. While a T/R was the cause of that accident, no other plane has been found with an identical fault, seems to be a one-time event.

A two-engine inoperative landing, assuming they got to a safe altitude (DOV about 1000 feet) would have required careful handling, a willingness to apply near T/O power on the operating engines and good planning. It is possible to return heavy on two, but worthy of a DFC on the part of the crew and the handling pilot. Losing two during liftoff would have been a certain disaster, IMHO. Two engine returns, in the sim, are managable at around 730K weight, but in real life, demand skill and a bit of luck. A perfect sim performance is just like a perfect operation on a cadaver. You will be flying with a bootful of rudder AND full scale rudder trim AND T/O power. There is absolutely no room for error.

From many sim sessions and several three-engine landings, these guys did pretty well with what they had. They got real, real close to the runway with an obviously very sick plane and landed it without fatalities. It had to be very, very damaged, beyond a simple engine-out to result in a crash landing. I await the investigation for the real answer, not idle speculation.

There is something missing in the open news as on now. NO news there.

GF

[411A]

News at ten

From a knowledgeable guy on the scene...

"The C-5 flew into a huge flock of seagulls right after lift off and they lost #2 engine immediately, and were losing power on #1 and #3 engines. Evidently the other engines failed as they were turning final - and at the high gross weight it became a brick. The pilots did a hell of a job just getting it down wings level. Note that in the pictures there are no sliding tracks or marks of any kind in the dirt. The C-5 evidently hit hard, the tail broke off and the rest of the plane bounced high and landed several hundred yards from the tail and stopped right where you see it without sliding."


Seems consistant with other folks on the scene.
Time will tell.

[archae86]

Ground marks

Originally Posted by 411A

Note that in the pictures there are no sliding tracks or marks of any kind in the dirt. The C-5 evidently hit hard, the tail broke off and the rest of the plane bounced high and landed several hundred yards from the tail and stopped right where you see it without sliding.

This picture is one of a set taken at ground level very shortly after the event. In the sequence, it appears to have been taken in the direction away from the main section, from a position a bit beyond the tail section's resting point.
gear tracks
an AP overhead picture published in the New York Times a couple of days ago appears to show clear tracks documenting a gradual transition to sideways movement over the distance from the tail resting point to the main section as the marks left by the forward section get farther and farther to the right of the main track. I don't have that picture, though this relative close up shows the last portion of the gear marks:
final slide
I not trying to pick nits over how much sliding is "no sliding", just to fill in the available information.

[galaxy flyer]

Thanks 411A

That scenario, without any inside knowledge, sounds much more believable than the news and uninformed speculation. Indeed, a very scary situation.

GF

[lomapaseo]

Originally Posted by 411A

From a knowledgeable guy on the scene...
"The C-5 flew into a huge flock of seagulls right after lift off and they lost #2 engine immediately, and were losing power on #1 and #3 engines. Evidently the other engines failed as they were turning final - and at the high gross weight it became a brick. The pilots did a hell of a job just getting it down wings level. Note that in the pictures there are no sliding tracks or marks of any kind in the dirt. The C-5 evidently hit hard, the tail broke off and the rest of the plane bounced high and landed several hundred yards from the tail and stopped right where you see it without sliding."
Seems consistant with other folks on the scene.
Time will tell.

The pictures I have, show extensive slide out of the fuselage after the initial touchdown where the tail broke off. It is only as the aircraft came to a stop that the nose section appears to have broken and skewed away from the fuselage. Also in the pictures I do not see any evidence of bird strikes to the wing leading edge, nose cowls or fan blades of Pos 1 engine.

Quite surprising though that dead bird carcases are not being reported found on the runway ala Elmendorf. Do you suppose the investigators are being that secretive to withhold such overt common cause evidence from all other aviators, or do you suppose that this is just a rumor?