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Old 02-06-2012, 07:17 PM
C-FAH Q's Avatar
C-FAH Q C-FAH Q is offline
Join Date: Dec 2008
Location: Ontario, Canada
Posts: 469
Default Flap Motor fix with Pics

So, once again I find my flap motor not wanting to go down, oh well, better than not going up after take off. I had cleaned the shaft of the motor before, but did not fully disasemble the unit to clean it out of grease.
So, out to the hanger I go to resolve this issue with hopefully a better result than the last time, it lasted 45 hours. First remove the flap assembly from the plane, hard to see in this pic, but there is quite abit of grease on the shaft. Some is good, but this was to much.

By grassy2040 at 2012-02-06

Remove the two screws from the top of the motor.

By grassy2040 at 2012-02-06

Gently pry off the motor cap

By grassy2040 at 2012-02-06

pull off center body that has the magnets, see on the top of the motor where the brushes contact the shaft, all gummed up with oily goop.

By grassy2040 at 2012-02-06

remove two allen screws from bottom of housing and remove screw unit

By grassy2040 at 2012-02-06

the larger hole was full of grease, this is what works up into the motor to stop the brushes from working properly. Clean out the excess grease.

By grassy2040 at 2012-02-06

Clean off as much grease as you can, but be sure to leave some on the shaft that comes out of the housing and atttches to your flap weldment. also, there are tiny bearings at each end of the motor, dont put anything in them to remove the grease in them. Clean off the ends of the brushes and shaft where the brushes touch. I used a light touch with a scothbrite pad. Assemble the unit, putting a drop of loc-tite on the allen screws( was on them when removed) be careful not to bend the little springs that hold pressure on the brushes. Some have diferent ways to hold these in when reassembling, I just used my fingers, no big deal. Re install and test, works fine. Hopefully doing the full grease removal will last a long time.

Best part, it was ony an hour job, start to finish.

This was how I did this fix and in no way am an expert. This info is worth what you paid for it. Use it wisely. Your mileage may vary

And now for something completely different.

By grassy2040 at 2012-02-06
Gary Wilcox
St.Thomas, Ontario. CYQS
RV7 Sold
C-FAH Q now N281CT
gwilcox3 @

Last edited by C-FAH Q : 02-07-2012 at 06:35 AM. Reason: Spelling
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Old 02-06-2012, 08:27 PM
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rv9av8tr rv9av8tr is offline
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Location: Portland, OR
Posts: 827

Thanks for the photo essay! Helpful indeed to see what you're getting into ahead of time.
Long-EZ built 1985 -> Sold 2007
RV-9A; N539RV First Flight: 7/2010
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Old 02-06-2012, 09:29 PM
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NickAir NickAir is offline
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Location: McMinnville, Oregon: HOME of the SPRUCE GOOSE
Posts: 540

Thanks for the photos Gary.

I am having mine act up on occasion lately. Need to clean it before it fails in a full down situation. Good post.

Simplicity is the ultimate sophistication.
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Working on a RV-4
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Old 02-07-2012, 04:18 AM
APACHE 56 APACHE 56 is offline
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Default Good show!

A most informative contribution to our knowledge base.

Thank you.
Don Stiver
RV8 "Little Pill" N6371S, Merritt Island, Fl.
BPE IO-390, Dual P-mag, MT 3-blade, AFP system
Steen Skybolt: Sold
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Old 02-07-2012, 04:35 AM
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islandmonkey islandmonkey is offline
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Default Nice One!

I agree with the others above. Thanks for taking the time and trouble to photograph this procedure and post it here. I have book marked it for future reference.

It is posts like this one that make this such a great site. Thanks Doug.
Anthony Johnston
Brit working in Zurich, Switzerland.
1500 hour pilot and ex instructor and examiner.
RV-4 s/n 4572 Emp Kit.
RV-3B s/n 11460 Emp Kit. (In storage).
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Old 02-07-2012, 06:08 AM
BillFear BillFear is offline
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Location: Sherrills Ford, NC (Lake norman area)
Posts: 432
Default Thanks for the write-up

Well just serviced this area during our first conditional. Yep, greased that shaft up real good. Well at least now we know what to expect! Thanks for taking the time to snap and post the pics!
Bill Fearheiley
Lake Norman, NC (14A)
RV7a N705RP (no longer own)
Contribution in for 2017, money well spent
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Old 02-07-2012, 06:12 AM
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bret bret is offline
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Location: Gardnerville Nv.
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Where did the grease come from? the comutator is at the other end of the worm gear? nice write up
7A Slider, EFII Angle 360, CS, SJ.
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Old 02-07-2012, 06:34 AM
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C-FAH Q C-FAH Q is offline
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Location: Ontario, Canada
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Default source

Originally Posted by bret View Post
Where did the grease come from? the comutator is at the other end of the worm gear? nice write up
As best as I could figure out, because the motor hangs upside down, it must get forced up into the housing when the actuator arm retracts and forced into the motor and just bleed down from the screw gear area, and gets flung around and finds the brush area. So, not sure exactly, but its there.
Gary Wilcox
St.Thomas, Ontario. CYQS
RV7 Sold
C-FAH Q now N281CT
gwilcox3 @
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Old 02-07-2012, 07:25 AM
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Pat Hatch Pat Hatch is offline
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Location: Vero Beach, FL
Posts: 915
Default Gear Box O-ring

Gary, did you happen to find the little O-ring that goes into the recess or counterbore in the gearbox? You can see this recess in your 6th picture down. I recently did this and was careful to re-insert the O-ring into this recess upon re-assembly. I think this O-ring is what is supposed to seal the grease and prevent it from getting slung out of the gearbox. I doubt if it does much in the way of preventing the grease from migrating through the motor bearing all the way to the commutator.

For what it's worth, I found no grease contamination in my motor, just the brush carbon tracks on the commutator that I cleaned up as you described. My flap motor operation has been flawless, I just did this cleaning as preventative maintenance during my last condition inspection. Just for background, Van's switched from the Motion System motors to the Pittman motors in 2002, and according to Van's newsletter about this problem, it was thought that the last of the Motion System motors were the culprits. I have one of these and mine appears to be fine; besides, the Pittman motors appear to be the exact same motor. I just think it was a change of ownership and not a change in the motor design. The blame has also been attributed to over-servicing the gearbox with grease in isolated instances. This grease contamination remains a mystery as far as I'm concerned.
Pat Hatch
RV-4 (Gone to RV heaven)
RV-6 (N44PH - Flying)
RV-7 (Sold)
RV-8 (Builder & Avionics Installer) Trim Relay Boards/Flap Actuators (Photography)
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Old 02-07-2012, 08:31 AM
RV7ator RV7ator is offline
Join Date: Jan 2005
Location: Boise, ID
Posts: 1,016
Default Usher's Take on the Actuator

Last week I spoke with Dean Trump, shop manager, Usher Industries. They have been making the flap actuator for upwards of 8 years. Van's asked them to replicate as identically as possible the Motion Industries product, which they did. The motor is unchange as far as specification; maybe the label and a few internal details are altered - like the "O" ring mentioned above.

Usher is convinced excess grease leads to contamination that gums the brushes/commutator. He suggested pulling the motor and mopping up as much grease as possible, leaving just a thin film on the gearing. As to how it migrates...?

I ordered a new motor/worm unit, $125, and a brush set, $25, (which includes the frame with brushes and a cool bushing to help slide the assembly onto the commutator). These are going on the shelf as spares to rapidly cure an AOG, which unfortunately seems to be a sore spot with RVs.

My personal take is that high starting loads on the motor cause a current flow exceeding specifications, arcs, and builds up conductive dust in the commutator gaps. That's, what I saw last time my flap motor failed to move. Grease, if it's there, simply helps gum up the works. That these units operate so small a percentage of flight hours calculates to a high failure rate, something the FAA would be all over if on certified ships.

John Siebold
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