172 flap motor

crash7

crash7

Line Up and Wait
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Crash7
Cross posting from AOPA boards:

Our club's 1971 172 flaps have been making a racket lately. Our mechanic took the motor out to test it. Makes a racket outside of the plane, too. I called Aircraft Spruce to order a new part. They said they'd have to call around, since it's a specialty part. No such luck.
Now what? Keep calling around?

Attached is a pic of the assembly. There's only 1 part # on the whole thing (printed on motor). So, I'm hoping it's a complete swap-out.
 

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A few years ago I bought a new flap motor from an a/c supply company in . . . . . . . .
(the midwest, somewhere; I can't remember). Does the name Wentworth strike any bells with anyone? Sorry I can't be more explicit. They shipped very quickly.

HR
 
Any aircraft salvage yard will have a bunch of them. They last a long time, so they're not a scarce item. If yours is shot it's either because it's really high-time and worn out, or really old and corroded, or wasn't looked after. I've seen these things go past 13,000 hours without a burp. The microswitches on them are far more trouble.

Dan
 
Lawreston said:
A few years ago I bought a new flap motor from an a/c supply company in . . . . . . . .
(the midwest, somewhere; I can't remember). Does the name Wentworth strike any bells with anyone? Sorry I can't be more explicit. They shipped very quickly.

HR
Click to expand...
Wentworth is an a/c salvage company. You probably did get your there. http://www.wentworthaircraft.com/
 
Yup; that's the place. We had the new part within a very short time. The frustration was that I had done the preflight and everything was fine. I taxied to the fuel depot, topped-off, my CFI came out and we were ready to go. When he was seated and I was doing final checks I lowered the flaps. Lowered was fine; it was retraction that quit only 10-15 minutes after all was fine before leaving my tie-down. End of planned flight.

HR
 
I've put a quote request in at Wentworth. We'll see what I get.

Oddly enough, the retraction of flaps has no problem. It's the extension. Even with the assembly out of the airplane.

<insert *sigh* smiley here>
 
crash7 said:
I've put a quote request in at Wentworth. We'll see what I get.

Oddly enough, the retraction of flaps has no problem. It's the extension. Even with the assembly out of the airplane.

<insert *sigh* smiley here>
Click to expand...


You had said it was noisy. Is it a gearbox issue, or a corroded screw-ball issue inside the jackscrew assembly? Or is it just a failed $10 microswitch that won't let it extend?

There's a microswitch at each end of the jackscrew. They shut the motor off when the jackscrew nut reaches the end of its travel. If the thing won't extend, the extend-stop switch might be shot. When it won't retract, it's the retract shutoff switch. The switch's contacts get dirtied up and don't close and the system thinks the nut is already extended or retracted, as applicable.

There are many dollars spent replacing parts that are just fine. It's often some peripheral issue that's preventing the operation of the component. This applies not only to flap motors but to alternators (failed regulator), radios (bad antenna cables or dirty contact strips in the tray), transponders (cracked or dirty antennae), starters (bad starter contactor) and many other items. I used to make my living remanufacturing air brake components for heavy trucks and off-road equipment, and about 75% of the cores returned had little or nothing wrong with them. $700 compressors were often replaced because their $19 governor was shot or a $12 drive coupling was slipping. We finally put troubleshooting brochures into every box, and asked the mechanic to read them first. Didn't often happen.

Dan
 
Preferred Air Parts wanted to sell me a non-working assembly for $175. No thanks. I've already got one of those.

The "noise" that we're hearing, sounds like the clutch slipping (like it does when flaps hit full extension, but you keep holding the switch down. The jack screw does turn, but VEEERRRRYYY slow. If I let up on the switch & hit it again a millisecond later, it usually extends fine. So, it looks like the motor doesn't shut off (at full extension). It just slips due to a clutch.

I welcome all opinions & idea. Still learning...
 
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