Out of control pitch

[ahramin]

The 747 crash investigation pointing more and more towards a load shift, I thought maybe it's pop quiz time.

What are the three controls you have to control pitch, and what do you do if all three fail to get the nose down?

[DonutHole]

Im not expert so here are my best guesses

controlling pitch:

Power, Trim, Elevator

If all three fail Im thinking a roll inverted to get the nose down, but in reality if all three modes of controlling pitch fail Im thinking you're pretty screwed.

[CpnCrunch]

The other option you might have is to get your rear-seat passengers to lean forward and/or move some baggage forward. A while ago someone on this forum posted about using this method to get out of an apparently unrecoverable flat spin in a 172, as far as I remember.

[thatlowtimer]

Flaps...

[sidestick stirrer]

In the past, there has usually been only three reasons for incidents such as this.
-loaded outside of CofG, loaded differently than planned or a load shift during flight
-stabilizer not set for takeoff( the stabilizer is several times larger than the elevators)
-no or wrong flap setting, which also includes the leading-edge slats.
Each of these possibilities has at least one accident history.

[Colonel Sanders]

Also flight control locks left on. Remember that horrible video?

[DonutHole]

Runaway trim could and has caused accidents like this before

[iflyforpie]

IIRC, on some jets you can kill the inboard spoilers and use the speed brake handle in normal sense to control pitch.

[PilotDAR]

I was post maintenance check flying a C206, which I had previously flown. As a precursor to test flying I knew I would be doing in it, I did some stalls in various configurations. Flaps up stalls were fine at all power settings. With lots of power on, I casually extended the flaps. The nose went up, I pushed the control wheel in, the nose came up, I pushed the control wheel in, and it hit the nose down stop, and the nose still came up.

I retracted the flaps as quick as I could, and pulled off the power as the plane fell through a stall I could not prevent. I explored a little, and found that this C206 would fly full power, with 20 flap, and the control wheel hard against the nose down stop. Any more flap (40 available) and the nose was going up, and you could not stop it. It was only by the grace of god that someone had not attempted a full flap balked landing, they would have been all done. With power low, I could use the flaps for a normal landing.

Maintenance was instructed to re-rig the plane. Six re-rigs and check flights later I signed off on the plane as being controllable. It turns out that the H stab was on at the wrong angle of incidence, and it is not adjustable! Someone had rebuilt the plane from damage, and jigged it wrong! Just lucky that no one had ever got the combination of power and flaps which made the plane unflyable!

Now I check planes much more carefully when I check or test fly them.

[sidestick stirrer]

""Also flight control locks left on"

Isn't that what caused the crash of the very-first B-17 prototype?

[lownslow]

Yeah, the first B-17 was lost that way and led to Boeing's introduction of the airplane checklist (for real, prior to that all operations were done as common sense). Had they know. What their in enticing would do to FTUs of the future they may have gone with some other solution…

As for the OP, I would think when all else fails you could roll the plane to the point where the nose drops (doesn't have to be inverted) and your impending disaster would just become a steep turn.

LnS.

[DonutHole]

Of course it doesnt HAVE to be inverted, but if you are not inverted and you are pitched up and you roll it and the nose comes down.,,,

isn't that a spiral dive?

[ahramin]

Elevator, trim, and power. Exactly.

However, if the plane is pitching nose up uncontrollably and you roll it inverted ... where is the nose going to go now? Straight down.

The solution is to roll until you are no longer pitching up. Roll beyond that to get the nose down, roll towards level to get the nose up. You have now converted your bank angle into your pitch control. A Falcon 7x did this when they had a stab trim runaway and were able to keep the aircraft in the air long enough to recover the stab trim. Which is the whole point: it won't fix the problem, but hopefully it will keep you alive long enough to fix the problem. Try it next time you go flying Donut. Set the trim a bit nose up and then - without applying any elevator - roll the plane and play with the bank angle until you are maintaining altitude. If you find yourself inverted, stop and try it again.

[DonutHole]

What if I want to find myself inverted?

[ahramin]

That's fine, just wait until you resolve the pitch control problem first.

[DonutHole]

The explanation makes sense, I was thinking only in terms of extremes.

[High Flyin]

The solution is to roll until you are no longer pitching up. Roll beyond that to get the nose down, roll towards level to get the nose up. You have now converted your bank angle into your pitch control. A Falcon 7x did this when they had a stab trim runaway and were able to keep the aircraft in the air long enough to recover the stab trim. Which is the whole point: it won't fix the problem, but hopefully it will keep you alive long enough to fix the problem. Try it next time you go flying Donut. Set the trim a bit nose up and then - without applying any elevator - roll the plane and play with the bank angle until you are maintaining altitude. If you find yourself inverted, stop and try it again.

This is why I love these forums. A little bit of mindless reading exploring mishaps I didn't even know could happen could very well save your life in the future! If I hadn't read this and it happened to me, I would have no idea what to do. But I've now banked this info for later use.

I'm definitely going to try this one day. You just never know.