Flap tuneup

flyfish1 · Post by **flyfish1** » Fri Mar 15, 2013 8:28 pm

I have been trying to work the slop out of my flap rigging on my M4-220.
I changed the hinge bushings and adjusted the cable tension. I also installed new springs. There still seems to be some verticle play at the bellcrank. Reading an earlier post by Jeremy he suggested rebushing the bellcrank. This sounds good but when I look at the parts drawing it does not show a bushing in the bellcrank. I would appreciate any clarification or advice. Thanks.

maules.com · Post by **maules.com** » Fri Mar 15, 2013 11:16 pm

Make sure the bracket holding the bellcrank is tight and is not stressed and moving under load. If so replace.
Check the bellcrank pivot holes for wear, a tiny bit is a lot at the flap.
Push or drill the bellcrank bushing out and replace with new or make one on a lathe with good fit to the pivot bolt. If bracket holes are worn, use next size bolt and enlarge holes to match.
The bellcrank should not move up and down when loading it.
Check the pushrod ends for snug fit and no wear.
Check no flat spots or ovaling of the various pulleys.
Rig the flaps by adjusting pushrods so bottom of flap is flush with wing bottom when upward pressure is applied to flap.

MikeW · Post by **MikeW** » Sat Mar 16, 2013 10:27 am

Jeremy,

To piggy back on this, my flaps can be pushed up by hand into a negative setting. This also has happened with the back of the wing covers pulling the flaps up into the negative. I don't remember them doing that before. Is this normal? 73 M5 wing

Mike

maules.com · Post by **maules.com** » Sat Mar 16, 2013 10:55 am

To get correct down flap angles, the pushrods must be adjusted such that flaps up and hand pressure up produces the bottom of flap on same plane as wing bottom.
Take into account there should be bump stop glued to the back of rear spar to protect from bell rank metal to metal contact.

MikeW · Post by **MikeW** » Sat Mar 16, 2013 11:58 am

OK, thanks. So the farthest I should be able to push is flush with wing bottom. Is this an unairworthy condition or something I can tune up next time plane is in shop. Thanks

Mike

maules.com · Post by **maules.com** » Sat Mar 16, 2013 2:38 pm

Impossible to know the airworthyness without looking.
May be only out of adjustment, or worst case the up position is excessive because the bell rank has worn through the wing spar.

MikeW · Post by **MikeW** » Sat Mar 16, 2013 4:46 pm

Thanks

aero101 · Post by **aero101** » Sat Mar 16, 2013 4:49 pm

Loose or incorrectly adjusted control cables is generally part of your problem as well... It's generally a combination of both the cables and the control rod which is what positions the bell crank properly. If you're able to push up on flaps to negative or reflex flaps (airloads will do this in flight as well) you are technically unairworthy as aircraft does not meet the specs of TCDS. Chances are when adjusted properly you'll pick up a couple MPH as well. The reflex flaps with that short wing will cause higher AOA on main wing resulting in a good bit more drag..

flyfish1 · Post by **flyfish1** » Sat Mar 16, 2013 5:56 pm

Thanks Jeremy,
When I get a chance I will take out the bellcranks and check for bushing wear and check the brackets.
Art H

MikeW · Post by **MikeW** » Sat Mar 16, 2013 5:58 pm

Thanks Aero,

Hadn't thought about the cruise aspect. I'll take it in next week and get them rigged up again. Hopefully i wont lose any ski season. Excellent down here this year

Mike

aero101 · Post by **aero101** » Sun Mar 17, 2013 3:27 pm

Yes, nice up here this year as well, though still pretty chilly...

Flap tuneup

Flap tuneup

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