Flap Tolerances

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bkozura
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Name: Bret Kozura
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Flap Tolerances

Post by bkozura »

Hello all,

The other day I noticed one of my flaps hung slightly lower and had a little bit more play when moving it compared to the other. Is there anywhere that states a tolerance for the amount of play that is allowed? Particularly in the torque tubes or center tube?

Thanks
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6643
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Name: John C
Location: KLCI, NH
Aircraft Type: 1946 C140/C90
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Re: Flap Tolerances

Post by 6643 »

Did it hang lower when they are retracted, or when deployed? A little play is acceptable when deployed, but when you lift them up (as the air load will) they need to be even. When retracted they should be against the flap stops, and even. The stops are adjustable.
bkozura
Posts: 4
Joined: Wed Aug 28, 2019 12:54 pm
Name: Bret Kozura
Aircraft Type: 1946 C-140
Occupation-Interests:
Contact:

Re: Flap Tolerances

Post by bkozura »

Thanks for the help, John. It hangs slightly lower when retracted but no noticeable difference when deployed. There is play when both deployed and retracted. Without having a chance to take a look inside yet, I was just curious how much, if any, play was allowed.
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6643
Posts: 2443
Joined: Tue May 01, 2018 7:00 am
Name: John C
Location: KLCI, NH
Aircraft Type: 1946 C140/C90
Occupation-Interests: A&P, semi-retired
Contact:

Re: Flap Tolerances

Post by 6643 »

When retracted the springs should hold them firm against the stops. If they are "loose", something is wrong. Fix it before flutter causes the wing to fail. If they're uneven when retracted, adjust the stops.

When deployed, the air load pushes then up against the mechanism. The amount of play is not critical, as long as they are even. The fittings on the flaps are slots. As long as they don't look like a slot with a big hole in the center, they're probably OK. If they wear unevenly you'll get uneven deployment and the plane will roll on deployment: not good...
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