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Flap Motor Question
Ok my flap motor quit again for about the fifth time. I've always cleaned the brushes and put it back together. Last time I ordered a new one and put it on the shelf. It is always because of a little grease on the brushes. This time I took the actuator arm (screw) out of the aircraft and cleaned the little threaded area that the motor gear turns. I sprayed it out real good with contact cleaner and got all the grease out. After cleaning the factory grease off the motors little gear I put the new motor on the arm and reinstalled it. During the test run I noticed that when it goes down and reaches the bottom the motor runs and the arm free wheels, when I take it up it and it reaches full up then the motor bogs down and quits while I'm still holding the switch up. I thought it was suppose to free wheel at the end of both directions.
I'm am loosing it? What's up guys? Added info: I've got between 350 - 400 hrs on the plane No the UHMW blocks are not tight on the rod. |
My solution?
Bobby,
It sounds like you're doing all the right things. It's no secret that these flap motors can be tempermental. I read many threads on here while building and rigging the flaps on my 7. When looking at the setup from Vans (OEM) I never really liked the idea of the "free wheeling" motor taking care of itself when reaching the ends of its travel. Consequently, I installed limit switches on the top and bottom of my system. The motor stops completely in the same place every time with no need for free wheeling. I'm at almost 300 hrs. and no problems so far.. (knock on wood). I have the schematic for the flap system if interested. It's very simple. Just a thought... C.... |
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Wow, that's crazy. How many hours do you have on the airplane?
I have about 350 now and haven't had any flap motor problems at all. One thing I've noticed is that a *LOT* of builders insist on torquing down the AN3 bolts that hold the various UHMW blocks in place with "standard" torque. This is absolutely not the correct thing to do as it will compress the UHMW blocks and put considerable drag on the flap system. When you disconnect the flap motor (which is sounds like you've been doing a lot of) how easily can you actuate the flaps by hand? |
It's probably the vintage of the motor more than anything... I know some folks who got their kits before I got mine (whenever you get the motor?) and they had to do this whole ritual several times.. Mine never quit in 300+ hrs and I never had to clean it etc.. I guess there was some change at some point and we just lucked out?
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Might need to
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Bobby,
The actuator is suppose to free wheel at both ends of its travel.... |
Adjustment? Maybe the flaps are binding motor up before reaching top. Unhook from flap mechanism and see if it freewheels at the top.
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I think if you add limit switches you're adding more complexity where you really don't need it. The RV-7 flap motor free wheels at both ends and if yours is not doing that there is an issue somwehere that needs to be fixed. Installing limit switches simply covers up the core problem, IMO.
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My experience
I've had trouble with my flap motor several times. Each time taking it apart and removing some black residue that looked like grease with alcohol and a Q-Tip from the motor and brushes as recommended. I had already cleaned out the excess grease from the gear housing previously, leaving just a minute amount on the gears (as per the manufacturer's recommendations).
This time I made sure to gently brush clean the motor internals with rubbing alcohol. I found that the Q-tip method is not thorough enough. The motor internals need to be soaked with a gentle solvent and paint brush. In particular I found grease residue in the brush holder... obviously when the brushes are seated back into their holders, what little remaining grease that remains in there will migrate down to the rotor contacts and mess things up. Time and heat will soften the grease and allow it to flow past the brushes onto the rotor contacts. In my case I had already ordered a new set of brushes, so I just replaced that assembly. I cleaned out my old brush set too, so now I have a spare set should I need it again, however I am hopeful that this is the last time. In summary, my recommendation is to do a thorough cleaning with alcohol and a small paint brush, especially with regards to the brush housing. That whole housing should be dunked in alcohol and gently brushed clean. |
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