Manual cowl flaps

Ken MacLean · #1 03-25-04, 08:52 PM

Has anybody had experience with Owen Bell's manual cowl flap STC? My rear cowl flap motor is acting up and this could be a good and permanent solution. My log books tell me the motor has received alot of attention over the years.

Thanks.

WebMaster · #2 03-26-04, 08:33 AM

I bit the bullet and replaced the motor with one of his motors. It is heavier looking. Hope it lasts

Dale Campbell · #3 03-26-04, 08:48 AM

I had problems with both of my cal. flap motors. I removed both and cleaned the oil out of them, mainly in the motor brush area. They get sticky and fail. I have had no problems since. Get a bench mounted magnifying glass with light and take them apart and clean them. They pick up a lot of oil because of where they are mounted. The easiest way to take them out, is to unplug wires, disconnect long shaft from flap linkage, remove end bearing on pilot side of shaft, and take out the whole assembly.
you can remove, clean and have them back in, in about a hour if you have done it before. On my 337H there is a tiny relay mounted to fire wall. Remove screw on one side only and loosen the other screw, do not take these wires off relay. they are tiny and will break easy so double check these wires when you put it back together after you clean motors.

Ken MacLean · #4 03-26-04, 02:40 PM

The rear cowl flap motor actually runs, but the shaft does not turn. The thinking is that the shaft is broken.

My question is this - rather than replace/repair the motor, as the logbooks attest has been done several times, what about simply eliminating the motor and its problems with a manual cowl flap conversion like that available from Owen Bell? Then all I would have would be a cable to push and pull to open and close the cowl flaps.

Has anyone done this conversion? Does it live up to expectations?

Thanks.

Dale Campbell · #5 03-26-04, 02:53 PM

Ken,
The problem on the rear cal. flaps is a shear pin that goes if you have a bind or if you block the flaps from closing. The pin is easy to replace. it is by the motor in the little arm.

Richard · #6 03-26-04, 09:37 PM

I had alot of problems with the rear as well. Researching the service manuals they call for a resister on the rear motor. This if for the braking. Couldn't find it.... looked on a friends 337... nope not there...... hmmm, aparently they get removed and not replaced. Cessna didn't list a part number.... so... I added one. No problems since. Without it, it was tempermental and would shear the pin off every 50 hours.

Used 200ohm 10watt resister. A 5 watt should be more than enough too....

It's attached to the positive 28V source then to the white wire on the motor. Every Skymaster I've seen has the white wire going straight to the 28V source. If you consult the service manual you will see the resister.

jimmuse · #7 03-26-04, 11:53 PM

Ken,

I had one on my '67 B shear because the shear pin didn't.

I saw a recommendation on Peter's board (I think) to use a small cotter pin as a shear pin, because it was a bit softer.

Jim