Extending the flaps (or retracting) in a turn

[russfarris]

Here's one I've only heard recently in almost 40 years of GA and airline flying.

"Never extend (or retract) the flaps in a turn, like base to final! If you have a flap asymmetery on the lowered wing, you could lose control!"
Extending flaps in a turn in the pattern was SOP in the Apache/Aztec, to counter the strong pitch up with flap extension.

I've had two flap asymmeteries, in 1977 in an Aero Commander 500 and another in 1999 on a 737-200, neither of which was a real problem.
On the Aero Commander one entire outboard flap segment retracted from full flaps - other than needing some aileron it was easy to manage.

Has anyone else ever heard this one? Russ Farris

[HA]

we used to have a bunch of Twin Comanches, no positive retraction for the flaps only springs, and they would stick a flap down often if you retracted them in flight (like a go around) which often made for interesting times. but that wasn't an extension problem.

I have heard the "don't put them down in a turn" thought before too, and I guess if you're really trying to minimize risk from the possible failure of one flap mechanism then it does make some sense. seems to me that an asymmetric flap problem was what caused Tsunami (homebuilt Reno racer) to crash in Pierre SD back in the '90's.

[Bill Hart]

What they teach us in the C-130 sim is if you are moving the flaps in a turn and have an asymmetry problem then it could be more difficult to identify in a timely manner.

[GAHorn]

Russ, as a professional pilot you already know this, but for others, ...it might be germaine to a specific aircraft. For example, an aircraft equipped only with spoilers instead of ailerons, might have an impossible situation arise if a wing cannot be lifted...the only method of correcting excessive-bank being to drop the opposite wing. (This contributed* to the famous B-52 accident in which a wing-over at low altitude was not correctable due to that aircraft's roll being controlled by spoilers only, and when fuel moved to the outboard-area of the low wing...no ability to lift that wing existed.)

For (hopefully) obvious reasons, handling notes and limitations of specific aircraft models should not be universally applied.

* (This is not the primary cause of the accident, but only a contributory one.)

[Jr.CubBuilder]

Hmmmmm I hadn't really thought about only one flap coming down before. I tend to drop mine to the second and third notches during my base and final turns for no specific reason other than it feels right and I don't get that sudden pitch up that normally happens when straight and level. Food for thought.

[Bruce Fenstermacher]

I think this is MUCH more critical in other aircraft specially those with motorized flaps and less control or hire speed than our 170.

Lets face it if you pulled the flaps and the plane all of a sudden turned left or right you would immediately and quickly drop the flaps.

Not sure I told this story here but likely I have. Once upon a time I was distracted during preflight. Of course I didn't realize I was distracted. The flight proceeded normally. A take off with a 180 degree turn on course and then about 10 minutes into the straight and level flight I decided to foul with the STC'd electric aileron trim my airplane had. When I looked out at the left wing trim tab my eyes were distracted bye that BIG RED aileron to flap lock that was still in place.

It took me a few seconds to regain composure and realize I had been flying the plane normally and there was no reason I couldn't turn around and go back and land normally. So that is what I did. I had plenty of control due I believe to an what was probably looser than spec aileron cables. I was basically controlling the aircraft with about half travel of one aileron and rudder. The other aileron was frozen level with the flap.

We things were going so unbelievably well on the long straight in final I decided to make that I thought no need to land with no flap speed and I pulled the first notch of flaps. Well guess what happens when your aileron is tied to your flap and you put your flap down. You got it you have a full length flap on one side. I immediately recognized the roll that I did not impart intentionally and it didn't take but nano seconds to figure out what ever I had just done I needed to undo. I immediately dropped the flaps leveled the aircraft and made a very nice no flap landing.

My point is I immediately recognized the dissymmetry and immediately and intuitively knew what to do because my hand was still on the handle. I think with our flap mechanism if you pulled flaps, even in a turn and the cable broke releasing a flap you would intuitively drop the flaps. Just my thoughts.

[15A]

Good point (confession) Bruce! NO ONE IS PERFECT
We always need to FLY THE PLANE regardless...
Back to the flaps, I pull 1 notch on downwind, second during the turn from downwind to base, then, if I feel it necessary, 3rd notch on final. I guess after flying my C-120 for so many years, I never did get the need for flaps...

[GAHorn]

..I was distracted ...BIG RED aileron to flap lock .. I pulled the first notch of flaps.....

You weren't distracted. Your brain was back home in bed. (BTDT)

Maybe you'd better think twice when pulling collective?

[170C]

And Bruce if you are like most of us, once you got the plane parked so you could remove the control lock, you looked around to see if anyone saw what you had done It would be my luck that that was when the ramp would be full of observers
HAPPY TURKEY DAY

[canav8]

Whats even more amazing is that you admit to it in a public forum. LOL. Those who have and those who will. Its kind of like my diamond club thread. Not proud but fishing to see if Im the only member. LOL D

[Bruce Fenstermacher]

And Bruce if you are like most of us, once you got the plane parked so you could remove the control lock, you looked around to see if anyone saw what you had done It would be my luck that that was when the ramp would be full of observers
HAPPY TURKEY DAY

Actually I announced on the unicom to the one person there, who I did not know, exactly what had taken place, that I was landing with a crippled aircraft and that he should be prepared to call 911 and render assistance. (he was sitting in his running aircraft). After landing and pulling on the ramp in front of this guy, who by know had shut down and gotten out of his plane, I cooly stepped out of the plane removed the gust lock, waved at the guy, jumped back in my plane and took off. After all I was now late for lunch.

Whats even more amazing is that you admit to it in a public forum. LOL. Those who have and those who will. Its kind of like my diamond club thread. Not proud but fishing to see if Im the only member. LOL D

I firmly believe I've learned things from others mistakes and I might not have heard of them without their confession. I do my best not to make my own or repeat others mistakes. But when I do make a mistake at the right time and place I'm not ashamed to confess so others hopefully can learn. I think that is part of being a professional pilot.

In this case I never put two gust locks on again, one was sufficient. My gust locks always have a red flag hanging from them to attract attention because I know as hard as I might try I may be distracted again.

[cessna170bdriver]

Correct me if I'm wrong, but don't A-models and ragwing flaps use spring force and air loads for retraction, relying on the cables only for extension? If this is the case, I could see where the flaps could go asymmetric. B-model flaps are interconnected so as to be positively extended AND retracted by cable tension. Is there a failure mode that could cause asymmetric flaps in a B-model? If so, are there documented cases of it occurring?

[GAHorn]

Miles, Bruce's earlier ride only had a 170A datatag.

[Bruce Fenstermacher]

Miles as George said, think of my first 170 as a '52 B Model and you'd be very accurate. You are correct in thinking Miles that in my gust lock story had I had true A model the effect the lock would have been different, most likely allowing the aileron and flap to go down on that side but not up past neutral.

No one has said there ever was an asymmetric deployment of the flaps in a 170. This discussion started with other aircraft and how that might relate to how one might want to fly an aircraft. The discussion of course naturally boiled down to what might happen with a 170.

[Luvjet]

I had this very thing happen in my 170A back in 1975 . Turning base into a grass strip with full flaps, the left flap completely retracted with the right flap still at 40. It's been a long time, but I don't remember the plane being uncontrollable however I did retract the right flap almost immedietely . Yes, I have since replaced all of the cables.