Where would the nose go?

[SoundBarrier]

Hi Everyone,

I was looking at the accident investigation report (http://www.ntsb.gov/publictn/2004/AAR0401.htm)for Midwest Flight 5418 a Beech 1900D which crashed after being over-loaded (using average baggage and pax weights at the time which, when calculated, were within limits) resulting in an aft C of G exacerbated by a limited downward deflection of the elevator after a rigging issue from maintenance.

Now with hind-sight, I put myself in the captains seat just after rotation, gear up and the nose starts pitching up despite full control column forward the nose continues to climb through, say 60 degrees, if I cut the throttles to idle would the nose pitch down at all given the engines are pretty much centre of the thrust line, or would the nose continue to rise given the aft C of G - now further aft due to the retraction of the gear- giving a similar disastrous end?
Here is an animation... youtube

Any thoughts or theories?

Thanks

[john_tullamarine]

Similar to a problem in Oz many years ago in which the crew performed a series of rolls and yaws to keep the thing flying while they clawed a bit of height sufficient to give them time to figure out a recovery.

As I recall not a cg problem but the pitch up was similar. With a cg problem the stability considerations make life very difficult for the non-FT pilot who has no familiarity with the differences.

The pilot is a PPRuNe contributor and there are posts on the event although I can't locate them at the moment. Will contact another contributor who will almost certainly be able to provide a link.

[SoundBarrier]

Thanks john that would be great!

[photofly]

Basic theory suggests that since the trim of an aircraft (whatever it be) is to fly a particular angle of attack, reducing thrust (and therefore speed) would have brought the nose down. Although depending on how far aft of limit the CofG was, the aircraft might have been loaded *not* to maintain a given angle of attack.

[By George]

A Canadian Ex-Pat pilot in Thai Airlines flying an A310 saved the aircraft with an aft C of G control problem. On take-off and losing control in pitch he rolled the aeroplane into a 60 degree bank and thus got the nose back down. I cannot remember the details but they eventually regained control and landed safely. He then went to work for SQ and I believe is now in the Middle-East. 'Reg' was his first name. Talking to him, it was indeed a fascinating story. I think it was caused by someone removing all the forward locker cargo. Very quick thinking on his part and a lucky outcome.

[B-757]

This accident was caused by incorrectly installed elevator cable..The crew did not have enough nose down-control available to compensate for the increasing pitch attitude.

[Tmbstory]

Sound Barrier:

I was a member of the crew in a Falcon 20F many years ago at Sydney airport that had this problem. It certainly got our attention. I will post the link to the article.

To start to answer your question, our nose went to about 70 / 80 degrees with full forward control column and I rolled the aircraft to the left but could not get the nose down until we closed the throttles. We did a series of these recoveries.

Regards

Tmb

[Old Smokey]

Hi John_T,

Yeah, it's been a while. Would the case you cite be a Turbo-Prop out of Sydney, after the tail cone filled with water after an overnight down-pour?

The pilot, who I know very well, did a series of vertical banks as the nose rose, until the water "sloshed" out due to his manoeuvres, and things became fairly normal again.

Thank goodness that the pilot was an ex RAAF Mirage pilot, who was well familiar, and competent with unusual attitudes at low level. Even so, he was an exceptionally good pilot:ok:

Regards,

Old Smokey

[Tmbstory]

SoundBarrier:
Others that may be interested:

"Dance of the Falcon"
The article that was posted in PPrune can be found at:

On Google: " PPRune The West: Plane Safe After Engine Trouble"

Internet: http://www.pprune.org/dg-p-general-aviation-questions/281726-west-plane-safe-after-engine-trouble-4.html

Tmb

[john_tullamarine]

ah .. Tmbstory... that was the username ... couldn't recall it for love nor money earlier .. early dementia, I guess.

trim of an aircraft (whatever it be) is to fly a particular angle of attack

a bit simplistic for the real world. If the cg moves too far back, the static stability reduces to a point where the stick force gradient flattens off and then reverses .. still flyable (for a little while, subject to mental workload and general stress) if the condition is recognised and the pilot has some knowledge of what techniques to use .. but the techniques required are quite different to normal stick and rudder stuff.

However, aviation history is littered with the bodies of folk who found out otherwise.

If the cg moves further back one gets to a condition of dynamic instability and all bets are off pending the funerals.

The certification rules give a bit of fat so, in the event of a modest aft limit excursion (and not too much in the way of peripheral problems .. turbulence and so forth) the lucky pilot may get away with it and the roll and yaw (further effect of roll type of thing) should help. It may be necessary to use some judicious asymmetric thrust and this sort of technique we used to use in the simulator for crew exposure to the problem.

OS .. where you been, good sir ? We thought you must have shuffled off the mortal coil ? A bit like the story of the DC3 with the load ambling down to the tail years ago. Not my sort of desired duty period but, then again, I'm getting to the stage where even the barest thought of excitement gets my pulse far higher than it should be ... quite happy to leave the hero stuff to those better equipped to handle it.

[photofly]

a bit simplistic for the real world. If the cg moves too far back, the static stability reduces to a point where the stick force gradient flattens off and then reverses ..Indeed.

Which is exactly what I meant by my next sentence "Although depending on how far aft of limit the CofG was, the aircraft might have been loaded *not* to maintain a given angle of attack."

Regardless, I'd suppose the answer to the o/p's question is 'yes'.

[SoundBarrier]

Thanks for all the replies, the detail from tmbstory was a particularly interesting read - but I'm sure not a fun time at all!
:ok:

[boofhead]

To bring the nose down in the event that the control column (stick) is at its forward most position (due to cg too far aft, stuck control column, etc):
Roll to 60 degrees or more of bank. This will cause the nose to drop and the bank can be maintained until speed is increased to the point of regaining elevator effectiveness. Do this on first recognising the problem. If delayed, the airplane will stall and recovery is doubtful.
Simultaneously reduce power. This will give a nose-down trim effect. It will cause a reduction in speed, which is not a good thing to have if the loss of control happens too close to the ground, but once the airplane is in the steep turn power can be restored.
Retract any flap.

The aim is to increase airspeed, and thus elevator effectiveness. A landing can be made at a high speed, flap up, but be careful to avoid a bounce since there will be little control left to recover.

[Tmbstory]

Boofhead:

In our case in the article of " Dance of The Falcon", we found that we needed to reduce the power to help get the nose below the horizon but then reintroduce the power to help recover before contact with the ground on the first recovery. We gained height after each time we used this procedure and eventually flew out of the problem.

Tmb

[Jane-DoH]

I saw a documentary on Flight 5481... I wondered why they didn't rock the wings in order to arrest the climb

[bubbers44]

I agree in an uncontrolled pitch up due either to cargo shift like a DC8 out of Miami about 20 years ago or runaway trim rolling into a steep bank is probably the only way to not stall. You can't reduce throttle because then you will stall anyway. Reducing flaps makes it worse so go full if that helps. Going around in circles trying to fix the situation isn't much fun but that is probably your only choice to have time to sort things out. That has always been my plan.

[ImbracableCrunk]

If the problem of uncontrollable pitch was caused by a jammed elevator, wouldn't the trim surface have a small but reverse effect? (i.e. It has now become a small elevator.)

[Tmbstory]

ImbracableCrunk:

THE Falcon F model has a variable- incidence horizontal stabilizer and that is used to trim the aircraft in pitch and is entirely electrical in its operation. In the F series the stabilizer is more powerful than in the D or E models. This was required to cope with the full span leading edge devices on the F model.

Tmb

[FlexibleResponse]

[QUOTE]Boofhead:

In our case in the article of " Dance of The Falcon", we found that we needed to reduce the power to help get the nose below the horizon but then reintroduce the power to help recover before contact with the ground on the first recovery. We gained height after each time we used this procedure and eventually flew out of the problem.

Tmb/QUOTE]

Tmbstory,
You were flying in this aircraft when this pitch-up event happened? Wow, that is some story indeed!

Well done sir!

[ImbracableCrunk]

THE Falcon F model has a variable- incidence horizontal stabilizer and that is used to trim the aircraft in pitch and is entirely electrical in its operation. In the F series the stabilizer is more powerful than in the D or E models. This was required to cope with the full span leading edge devices on the F model.

Tmb

I was thinking more of the B1900 situation with a fixed horizontal stab and a trim tab on the elevator.

[Tmbstory]

FlexibleResponse:

I was the Captain of the aircraft and took over the control at the first upset. The fact that we recovered was because of the excellent support of the other crew member and the ATC people.

It certainly is some story and it got our attention!

Tmb

[Tmbstory]

ImbracableCrumb:

Thanks for the clarification, it does make it clearer.

Rgds

Tmb