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Flaps retracting on takeoff

Started by paullapoint, March 06, 2023, 08:06:40 AM

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  Is there a way to add more resistance to any of the flap deployment mechanisms ? The crank spins and they retract on their own to about 10 degrees if I don't hang on to the handle on takeoff. Seems likes getting worse. On landing, there is enough pressure from the air against them that they don't move from any set position.
  Also, is it normal to have to hold in a lot of right aileron when deployed past 33 degrees?   Thank You, Paul


Sounds like you have too much grease or oil on the jack screws. You don't need hardly any. Clean them off and run them back up and then down and clean them a couple more times as they will pick up more grease from the brass nuts inside the tubes. This a situation where too much of a good thing is bad. Jim

Kevin Dunn


On the holding aileron with flaps down. I've seen the flap gear box get loose and move side to side. When the flaps are at 30 degrees, it can cause one flap to go down further and raise the other. At that point you need aileron to offset the asymetric flaps.


Jason Stephens

Yup, we had that on Dad's Helio one time.


Thank You guys, I will give that a try. Paul


IYZ was right side heavy when the flaps were down when I got it.  Just had to re-rig one of the flaps and it's been great ever since.


I haven't tried to re-rig because it flies straight right up to the last two revolutions of the flap handle. When measuring flap angles on the ground,(I push up on them when measuring the angle as if it had air pressure against them) the left flap is actually about two degrees lower at forty than the right so I didn't think I should give it any more. It's heavy enough with full flaps that it takes both hands on yoke to handle gusty winds.

Jason Stephens

Do you have the trim tab on the Rt Aileron?  Seems like most of them need it.


  I do Jason and have the airplane trimmed to fly straight and level. It stays level in the pattern with flaps set up to about 13.5 cranks. It goes left with the last revolution or two of the flap handle, but when measuring degrees and eveness of the flaps on the ground, everything checks out-maybe even the left flap drooping a degree more than the right. I'm going to go through everything again to see if I'm missing something but I've heard that the prop wash does something to them when they're at 40 degrees ? Maybe it's worse on 391B with larger diameter prop? I was just wondering what others have experienced.  Thanks, Paul