Temperature-related landing gear issue

[Philip S]

1976 M20C model here. Last winter I had a gear issue where on departure I would get a "gear unsafe" alert light and warning horn after raising the gear. Sometimes this would result in a low voltage alarm from the gear motor continuing to run, but not always. It is clearly temperature-related as it does not happen in warmer temps, happens intermittently around the 50-60F range, and happens fairly consistently below 50F. I know its not simply a switch problem, as on one occasion when I continued my departure despite the alarm, my cruise speed was about 10 knots slow. When I slowed to gear speed at altitude and recycled the gear to the up and locked position and the alarm quit, my cruise speed returned to normal. I am fairly certain that the gear is not fully retracting as a result. I sent it to two local mechanics last year who have Mooney experience. The first refused to leave the plane outside in the cold to test the gear, as his hangar is heated and he didn't want to jack the plane up outside, but he found no issues in the heated hangar. The second, who evaluated the gear later in the spring when it was warmer, could not replicate the issue and said all the measurements were in tolerance. I have done several low passes with a Mooney pilot ground observer who can see no issue from outside, but again it was warm then and I didn't get a warning during the low passes. The issue resolved itself over the summer, but now that temperatures are cold again it has returned. On a recent flight I took off at about 65F without issue, and only had the issue return when I was visiting the DC area. It promptly resolved on my return flight to warmer temps. I suspect a donut issue as based on the serial numbers they are original to the airplane, and temperature tends to alter the expansion properties of rubber, particularly old rubber, rather dramatically.  I've never had an issue with the gear coming down or locking properly. Yet. Anyone had experience with this issue before? Sound like donuts? My debate is between continuing to investigate, versus simply replacing the donuts. I called my A&P who can't take a look until March. If anyone knows another experienced Mooney mechanic in the southeast who can check me out sooner I'll be all for it. 

[Hank]

That's what myn1970 C did back in 2011-2012-ish. One winter intermittent, summer great, next winter got worse. Check your pucks on a cold morning.

Also, if you look at the edge of your pucks, the manufacturing date is molded in. Mine were installed upside down, I thought they read "09-1996" but it turned out to be "06-1969". Have had no trouble in the decade since replacement. Taxiing became more comfortable, and I swear my landings got smoother . . . .

Good luck with yours! Let us know how things go.

[Ragsf15e]

5 minutes ago, Hank said:

That's what myn1970 C did back in 2011-2012-ish. One winter intermittent, summer great, next winter got worse. Check your pucks on a cold morning.

Also, if you look at the edge of your pucks, the manufacturing date is molded in. Mine were installed upside down, I thought they read "09-1996" but it turned out to be "06-1969". Have had no trouble in the decade since replacement. Taxiing became more comfortable, and I swear my landings got smoother . . . .

Good luck with yours! Let us know how things go.

I believe you, but I’m wondering how the pucks affect the gear retracting?  Did you have a squat switch that wouldn’t compress to allow retraction to happen?  Other than the squat switch I can’t figure out how the pucks can do that?

[PT20J]

There is a specification on how far the pucks should be compressed with full fuel measured at the collar at the top of the stack. It should be in the service manual. For my M20J it is 0.60" max.

You can test the squat switch theory by temporarily disabling it on a cold day when you have previously replicated the issue and see if that fixes it. 

[Pinecone]

If you get up to DC area in the winter, get in touch with @jetdriven at KGAI.