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Hello to everyone,

I’ve got a new to me 1971 Chaparral (M20E) and noticed that on takeoff, while accelerating through 35-40 mph IAS, the flaps drift up a few degrees. Confirmed it by setting takeoff flaps in the downwind, landing with that setting, and they drifted down the same amount as up. There’s very little slack in the flaps at either full up or full down, but a small amount in between. Flaps move in unison with each other. No issues extending them or retracting them. I can’t find any tolerance limits of play in the service manual. Has anyone else experienced this? Attached video shows the amount of play at indicated takeoff.

 

Thanks,

DV8

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Welcome aboard DV8! 
 

There is plenty of things to check on...

Most likely something has aged in the system...

Speaking of systems...

Did you mention if you have the electric or the hydraulic flaps?

Type of system will be helpful for giving insight...

Are you moving the flaps with just light hand pressure in the video?

There isn’t any tolerance... because normally flaps don’t do that at all... for either the electric or the hydraulic system...

PP thoughts only, not a mechanic...
 

Best regards,

-a-

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The fact that the flaps move in unison suggests an issue with the flap actuator.  Remove the last belly panel to expose the actuator for inspection.

Clarence

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On my 74 C, that symptom was caused by the deterioration/compression of the rubber spacer on the flap drive linkage.  Simple fix.

20210309_083906.jpg

Edited by Mooneymite
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7 hours ago, DV8Pilot said:

@Mooneymite Thanks! First item I'll inspect once I drop the belly pan.

While you are in there, you might as well grease the flap drive....this sometimes gets "overlooked" on annuals. Just unscrew this cap and fill it with the appropriate grease.  I think it's Aeroshell #6, but not positive.

20210309_164236.jpg

Edited by Mooneymite
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27 minutes ago, Mooneymite said:

While you are in there, you might as well grease the flap drive....this sometimes gets "overlooked" on annuals. Just unscrew this cap and fill it with the appropriate grease.  I think it's Aeroshell #6, but not positive.

20210309_164236.jpg

My M20J manual calls for lubing the ball screw every 100 hrs with Lubriplate 630-AA and the gearbox every 500 hrs with MIL-PRF-81322G (Aeroshell 22).

Skip

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  • 5 weeks later...

Update:

Using @Mooneymite’s suggestion we got into the belly pan and discovered the worn bushings. LASAR had them in stock; four required. Replaced them and returned to service. No idea how old the previous bushings were. The whole process took about 3 hrs from start to finish with most of the time being spent on removing and replacing the belly pan.D822F109-E28F-4188-B37F-EDC3371020D7.thumb.jpeg.3d88a17bd768802fec4f15283b2e5d82.jpegB07C58F9-C7E2-4061-9B64-95042551A339.thumb.jpeg.90ed2c066b0901a437e26778dafbac35.jpeg

E9CA3D5E-F7A2-4743-9F18-B7132FEC844A.jpeg

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