Hypothetical - Flap failure

FredFenster

FredFenster

Pre-takeoff checklist
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Talking with my instructor the other day, we did a landing with no flaps to simulate a flap failure. I asked him what would happen if for some reason only one side failed to extend, would the airplane roll or yaw? He wasn't sure, said it would probably yaw. Thinking about it more after I left, I'd think one flap would act like an aileron and make it roll. Anyone know for sure?
 
FredFenster said:
Talking with my instructor the other day, we did a landing with no flaps to simulate a flap failure. I asked him what would happen if for some reason only one side failed to extend, would the airplane roll or yaw? He wasn't sure, said it would probably yaw. Thinking about it more after I left, I'd think one flap would act like an aileron and make it roll. Anyone know for sure?
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Some CFI's I've ridden with (BFR, etc.) advocate being fully configured on the base leg. Their reasoning is more altitude to deal with something bad like asymmetric flap deployment. I go to full flaps just after rolling out of the downwind to base turn.

An asymmetric flap deployment on short final would be interesting. Then again, I've never heard of it hapenning.
 
FredFenster said:
Talking with my instructor the other day, we did a landing with no flaps to simulate a flap failure. I asked him what would happen if for some reason only one side failed to extend, would the airplane roll or yaw? He wasn't sure, said it would probably yaw. Thinking about it more after I left, I'd think one flap would act like an aileron and make it roll. Anyone know for sure?
Click to expand...

In the event of split flaps or failure of both flaps to extend have the bridge ring down FLANK on the engine order telegraph. Also call down to central control and inform the Engineering Officer Of the Watch (EOOW) of the emergency and ask for max turns. In each of the two Maneuverings the Propulsion Plant Watch Officer (PPWO) will supervise the watch team consisting of a Reactor Operator (RO) and two Throttlemen (one for each screw) to answer the Flank bell. Until ordered by the EOOW they have to assume it is just a regular Flank bell and use normal heat up rates. The RO takes the lead and adjusts coolant flow through the reactor to ensure that power to flow limits are not exceeded and that steam demand is not increased so fast as to cause excessive swell in the steam generators causing carryover of liquid into the steam piping. (Flank is typically 150 RPM on the screws. Depending on the aircraft carrier's current weight you can add 20 plus RPM to that number. Also by calling the EOOW, if the emergency is bad enough he can authorize emergency heat up rates which will allow the ROs to raise the average reactor coolant temperatures for each reactor to the top of the higher bands more quickly than if he/she is restricted to normal heat up rates. This higher primary temperature gives you higher steam generator temperatures, therefore higher steam pressure to make the ship accelerate faster.) This will give you 10-15 knots of additional wind across the flight deck to help make up for the aircraft having to approach at a higher airspeed.

Oh wait, you wanted to know how the PILOT handles split flaps...my bad!

I was flashing back to a dark night in the Northern Arabian Gulf (the U.S. military name for the Persian Gulf) when a F-14 was having a bad night.

Jim
 
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One of the nice things about the X-Plane simulation platform is that you can try this stuff out. Async flap deployment is one of the failures we throw at people during tradeshows when they're flying the sim. Experienced pilots immediately retract the flap they just added...less experienced pilots start babbling about a "heck of a crosswind" :)

A friend of mine experienced this in a 172 while he was a CFII at Riddle.
 
coma24 said:
A friend of mine experienced this in a 172 while he was a CFII at Riddle.
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Don't they have like the best maintained airplanes there?

A 50 year old decapitated dog rarely sees such a failure.
 
I was taught early on to never change flap setting in a turn.

For me, its a habit, and one I've tried to teach my students.

Why? With no bank in place, the unintended roll (and/or yaw) from a split flap condition might be caught in time. If you were already banked to 30º or so and the flaps either increased or decreased the bank, it might be more confusing as to what was going on, and if they increased the bank, you'd be that much closer to a really unusual attitude.

I'll stipulate that in any given pilot's career, its extremely unlikely to ever happen.

But it does happen, so might as well attempt to diminish the effects if it does.
 
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Allegedly, during the Aerostar certification, the test pilot landed with one flap fully deployed (40 degrees) and the other retracted. Can't verify it and maybe he used differential power to keep it level - something you can't do in a single.
 
FredFenster said:
would the airplane roll or yaw? He wasn't sure, said it would probably yaw
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And bank.

The wing with the extended flap would be generating more lift (akin to an aileron). Increased lift production equals increased induced drag, which would "pull the wing back," creating adverse yaw. In such a situation, you'd want to equalize the flap setting, either by retracting them if the extended one is functional or extending them if the retracted one is functional.
 
bnt83 said:
Don't they have like the best maintained airplanes there?

A 50 year old decapitated dog rarely sees such a failure.
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They do a very good job of maintaining their aircraft, but they also put a lot of hours on their aircraft.

I have an ex-ER Socata Tampico. They put 1,000 hours a year on the bird during the five years they owned it. The next owner put 400 hours on it in 12 years. I've put 200 on it in 2.5 years. Plus, as a primary trainer the flap system saw a LOT of use!

Jim
 
Find a new CFI. He doesn't know what as symmetric flap deployment will do to an airplane??

One of the airplanes I've flown had a procedure;
Uncommanded roll/yaw - Return flap/slat lever to previous setting
 
Split flaps are something every CFI should discuss with students. It's the reason that electric flaps are put in in increments (when going into slow flight, for example, or setting up for a stall). Better to catch a split flap condition at 10° than at 30°.

I've never known anyone who had a split flap, but I doubt that it is so uncommon that we shouldn't prepare our students for it.
 
A friend had a catastrophic split-flap accident. A Cessna 185 on floats, and the left flap down cable snapped right after the airplane lifted off the water. It rolled violently and dug in a wing and cartwheeled into the water.

A DeHavilland Twin otter had a flap pushrod break about 15 years ago in Vancouver. On floats, again, this time on approach. It rolled into the water and killed some folks.

The Electras I worked on had jackscrew-operated flaps, and had flap assymetry detectors to stop and lock the whole system if the flaps got even a little bit out of sync.

Dan
 
Thinking about it, I am reasonably confidant in saying that I've never had any "instruction" on the use of flaps.

That's probably atypical.:dunno:
 
FredFenster said:
Talking with my instructor the other day, we did a landing with no flaps to simulate a flap failure. I asked him what would happen if for some reason only one side failed to extend, would the airplane roll or yaw? He wasn't sure, said it would probably yaw. Thinking about it more after I left, I'd think one flap would act like an aileron and make it roll. Anyone know for sure?
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Happened to me once putting the flaps up after a stall recovery and it was roll (just like you would think). Coincidentally it was my first real multiengine lesson and I thought for a minute he had failed the engine even though he said we were not going to do that the first lesson. But then I thought from what I read that engine failures created yaw, besides someone had let me fly around on one engine informally before and it didn't feel like what I was feeling.

It was in a Twin Comanche if anyone is curious. The only time I ever flew the airplane. I moved away shorty after this happened.
 
When flying mooneys , usually into short fields, 2000 ft. Or so, I would always put full flaps and gear down on downwind, 70 mph, never in a turn. By the time I was on final, I was set up just right. Mooney's , like Taylorcrafts like to go on and on if your speed is very great over the fence. I was always told if one flap only deployed it was probably a roll and die situation. On a longer field I would full flap on final.
 
Capt. Geoffrey Thorpe said:
Both.
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Yup. BTDT. Best bet at that point is to retract the working flap to match the stuck flap (if possible) and land with symmetrical albeit partial flap extension. If you have to land asymmetric, best bet is to climb up and do a controllability check to determine a good approach speed for adequate control before landing, and then don't slow below that speed until touchdown ("fly it on").

And a CFI-A really should know this.
 
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bnt83 said:
"Results of the study indicated that while at takeoff power, with one flap extended to 30 degrees and the other flap fully retracted, the ailerons would have had sufficient authority, "though marginally," to counter the resulting moment at a 70-knot true airspeed."
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I hate reading statements like this...that one condition, that one particular day, the pilot just wasn't able to overcome the challenge that chance rolled out.
 
And once you get it into a controllable state, stop messing with it. Taught a very experienced Navion CFI that one. Same for the gear. There are like 14 steps in trouble shooting the Navion gear failure in the checklist. What's omitted from is that once you get the THREE GREEN indication in the process, don't touch the GEAR HANDLE, don't touch the FLAPS, don't touch the HYDRAULIC CONTROLS, don't touch the WOBBLE PUMP.
 
RhinoDrvr said:
Find a new CFI. He doesn't know what as symmetric flap deployment will do to an airplane??

One of the airplanes I've flown had a procedure;
Uncommanded roll/yaw - Return flap/slat lever to previous setting
Click to expand...

On big Boeings, the non flyer monitored the flap position indicator while in transit and at the first sign of a split, the flaps were stopped and left alone till landing.
 
JohnAJohnson said:
On big Boeings, the non flyer monitored the flap position indicator while in transit and at the first sign of a split, the flaps were stopped and left alone till landing.
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Actually the flaps have protections. If a split or asymmetric is sensed the flaps will stop.

Airbus has a similar protection as well with WTB (wing tip brakes) that will stop a split or asymmetric condition.
 
RotorAndWing said:
Actually the flaps have protections. If a split or asymmetric is sensed the flaps will stop.

Airbus has a similar protection as well with WTB (wing tip brakes) that will stop a split or asymmetric condition.
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Good to know. Sounds like needed technology. I should have stipulated that my experience was on the old birds, 707, KC-135A, etc.
 
3393RP said:
I hate reading statements like this...that one condition, that one particular day, the pilot just wasn't able to overcome the challenge that chance rolled out.
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The report also stated that Vx was 99KIAS and Vy was 120. The testers forgot to simulate those conditions and left us to only assume results would duplicate their findings at 70KIAS, which is presumptuous IMHO.
 
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