1965 Cessna 150F flaps sticking problem

SPAJC

SPAJC

Pre-takeoff checklist
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May 15, 2014
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Spartanburg, South Carolina
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Jeff
So....i've had this happen several times now. A couple of times, the flaps would not retract and a couple of times, they would 't extend. Everytime I' ve spoken to the A&P about it, we couldn't duplicate the problem. So, I went out on a crappy weather day and pulled the inspection plates. I lubed the mechanisms related to the flaps per the A&P suggestion. They seemed to smooth out just a little bit. So today, nice and windy. Thought I'd go out and take advantage of some seemingly rare free time and get some practice. On my third approach, flaps at 20, smooth through touch-down and all, then they wouldn't retract again. So I taxi back to the ramp and park it. When I lubed everything up on the bad weather day, I extended and retracted the flaps numerous times. They stuck once and after some lube, didn't do it again. When they stuck, I found that I could apply just a little pressure to the flap and hit the switch and they would retract. After that, they worked fine again. So my thought was that the lubrication helped. Today when they stuck, I couldn't budge them. So I pulled the inspection plates and looked around again. Everything seemed fine, but no amount of pushing/pulling would help. It was really windy and worried about damage to the airplane, I didn't want to leave them extended, so, I pulled the plate that exposes the rear of the flap motor. Tapped it a couple times and it starts workng again. Prior to this, I checked the fuse, and observed that when you hit the flap switch, either way, you could hear the motor click, but nothing more would happen.

So my thought now is, bad flap motor. But, I start reading on the internet and see people with similar issues and people talking about micro-switches and limiters. I dont think my plane has limiters. So, anyone have any thoughts? Should I immediately replace the motor or is there something else that I should check before I spend the money? Any help would be greatly appreciated!

By the way, it has the simple up/down toggle switch. The motor will continue to run until you release the switch weather fully extended to 40 or fully retracted. The switch seems to work just fine. Thanks again!


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May need to clean the inside of the motors, if they have brushes, (can't recall) you may need to change them and dress the commutator.
 
Hit the flaps and check the voltage at the motor.
 
What does it do when they are retracted and you continue to run the motor??? I would think there must be switches to stop it in both directions, and they likely need some electrical contact cleaner sprayed into them.

Worn-out motor is also a good candidate. It's old.
 
I'm not sure what it would do if you held the switch too long....i read that it has a slip clutch to keep it from damaging the linkages/jackscrew or whatever else might be able to be damaged by letting it run.


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In my weirdo, uneducated in such things mind, I imagine the jackscrew disengaging from the motor or the "carriage" as i've heard it called, if i were to let it run too long....but i'm not sure if thats even possible...from what i read, basically it can run as long as you want it to without causing damage other than wear on the motor, but i've never let it go to see what would happen. The 150 I flew in training did the same thing as far as the motor running after fully extended/retracted. Its apparently normal and designed that way....


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I don't remember the last time I flew a 150, but I'd be shocked if the motor didn't have limit switches to shut it off in both directions. Time to look in the parts catalog and service manual.
 
What Scott said, and if those limit switches are all greasy and dirty chances are good they are sticking. Sometimes, a good cleaning with solvent will cure that.
 
My '66 172G has the same setup as the 150F. I'm pretty sure there are no limiters, I've checked into this before because mine just continues to run until I release the lever. The Service Manual for Cessna 100 series says in section 7-11 ELECTRIC WING FLAP OPERATIONAL CHECK. "B. Deliberately overrun flap motor at each end of stroke to make sure the transmission is free wheeling."

By chance are you a member of the type club? Someone there who I'm sure could help diagnose your issue.
 
There are two types of actuators that I'm aware of

#1 Has a free-wheeling type drive. These were originally installed on aircraft with the momentary up/off/down switch that is spring loaded to "OFF". These drives were not equipped with limit switches and you can still hear the motor running when the flaps hit the ends of tavel. (Flying a Cessna 205 that does it - completely normal)

#2 Were direct drive, no free-wheel slipper, originally installed in aircraft with the "pre-select" handle. All of these were equipped with limit switches on the cam mechanism in the instrument panel, and on the actuator in the wing to prevent over travel.


In 1972 an AD was issued that covered about 3/4 of the high winged cessnas with electric flaps, to correct the possibility of flap "slippage". Many required the installation of a "snubber". Others were required to install a different actuator jackscrew assembly.

Those that did not upgrade to the later part #s are required to inspect and lubricate on a schedule with grease containing molybdenum disulfied. (look at Aeroshell 33MS). The instructions are very specific. If a "scaling-like" appearance exists at the inspection the actuator is to be removed then jackscrew and nut soaked in solvent and re-greased.

http://rgl.faa.gov/Regulatory_and_G...11383ACCA8E3EF4E86256A34006319D9?OpenDocument


All that being said, I'd google both the 100 series service manual for your bird, and a parts manual. Find out which part # your motor is. If you get a "hard fail" check voltage at the motor. Because its either gonna be a switch issue, wiring, or the motor. If its in a "hard fail mode" and wont move via select switch, can you turn the black coupling between the motor and gearbox with your fingers?
 
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Havent tried that....but the first actuator you described is the exact description. We've complied with the flap AD also through inspection and such. The parts I did try to move by hand would not budge at all. Then after tapping the motor, it worked again. Thanks for all the info!!!! It appears I have some things to explore before I spend the $600 on a motor that I may not need. It works good, when it works, which is most of the time....but I don't want a flaky motor. Anyways, thanks again for all of the input! I have the parts catalogue and repair manuals, so research to begin


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And Greg, I'm not a member of the type club...but probly will be soon. Questions to be asked there as well. Thanks!


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SPAJC said:
Havent tried that....but the first actuator you described is the exact description. We've complied with the flap AD also through inspection and such. The parts I did try to move by hand would not budge at all. Then after tapping the motor, it worked again. Thanks for all the info!!!! It appears I have some things to explore before I spend the $600 on a motor that I may not need. It works good, when it works, which is most of the time....but I don't want a flaky motor. Anyways, thanks again for all of the input! I have the parts catalogue and repair manuals, so research to begin


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Google parts # or search on ebay can be helpful too.
 
So....after some trial, I have figured out that the flaps aren't sticking. When they seem to stick, they are actually losing power as opposed to "sticking" or jamming. I halfway expected that if they were jamming and the motor was still trying to run that it would pop the fuse...but that never happened. I finally got them to do it while not in flight and it is pretty clear that the motor loses power and winds to a stop. A couple of taps in the right spot under the wing...very light taps at that...and they work again. So I am thinking dirty or corroded connection somewhere. I am going to try the suggestion of contact cleaner on all of the connections and see what happens. Thanks for all of the input! It is much appreciated!


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If the motor has brushes, that is where you will likely find your problem.
 
Are the brushes something that can be cleaned by me or my A&P or does that require an overhaul?


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SPAJC said:
Are the brushes something that can be cleaned by me or my A&P or does that require an overhaul?


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You can do any work you please, for things not listed in FAR 43 you need an A&P to sign it off to return to service. I haven't had one of those flap motors in my hands for over 20 years so I don't remember the specifics to them, but all electric motors are very simple and cleaning them and changing brushes is typically a very simple operation. The parts will be available from any auto-electric shop.
 
Ok thanks! I've never disassembled an electric motor, but i'm more than happy and willing to try and learn. Appreciate the help!


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SPAJC said:
Ok thanks! I've never disassembled an electric motor, but i'm more than happy and willing to try and learn. Appreciate the help!


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Talk to your A&P and reference your manual, you'll do fine.
 
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