1968 M20C Gear Biscuts

[MitchS]

I have been looking around here, and I'm not finding a specific answer to this, so if I'm missing something sorry!

I have a 1968 M20C and I'm coming up on my next annual.  My gear biscuits still look good, but I'm seeing signs/reports here that they should be replaced after __ years, or other similar bits of feedback.  But i"m having trouble finding that guidance, as well as I'm having trouble with what exactly kind of biscuits are there?  It appears that Lord makes them, but it appears that they are actually for E+ models, not the C.

Thoughts?  Links/Advice?

[smwash02]

In the manual there's a set of guidelines you can use to determine if they're airworthy. That said, mine passed even though they were 49 years old. (They got replaced)

'66 was the year they moved to the 'new' style and you'll want 11 of Lord J-11968-14

I'm not an A&P/IA, but in a C you can probably get 15 years out of them before you need to look into replacing them. Expect everyone to have a different answer. It depends on lots of factors -- climate, loading, how you land, etc as to how quickly they'll start to go out.

[MitchS]

Just now, smwash02 said:

In the manual there's a set of guidelines you can use to determine if they're airworthy. That said, mine passed even though they were 49 years old. (They got replaced)

'66 was the year they moved to the 'new' style and you'll want 11 of Lord J-11968-14

I'm not an A&P/IA, but in a C you can probably get 15 years out of them before you need to look into replacing them. Expect everyone to have a different answer. It depends on lots of factors -- climate, loading, how you land, etc as to how quickly they'll start to go out.

Awesome thanks!  I think I need to get one of those service manuals....it would help me become a more informed owner anyway.

Thankfully....my landings aren't usually too horrible....but it is loaded up quite often

[Guest]

You or your maintenance shop should have a maintenance manual for your plane.  If your plane has the old Firestone discs you will have 5 on the mains and 4 on the nose.  Lord discs have 4 on the mains and 3 on the nose.  

If you have Firestones you will need some conversion parts from Lasar, also your A&P will needs the compression tools to replace them.

The problem with lighter airplanes is the rubber goes rock hard long before they deteriorate, so the still meet the compression limits and appear OK.  New ones will improve the ride during taxi.

Clarence

[MitchS]

5 hours ago, M20Doc said:

You or your maintenance shop should have a maintenance manual for your plane.  If your plane has the old Firestone discs you will have 5 on the mains and 4 on the nose.  Lord discs have 4 on the mains and 3 on the nose.  

If you have Firestones you will need some conversion parts from Lasar, also your A&P will needs the compression tools to replace them.

The problem with lighter airplanes is the rubber goes rock hard long before they deteriorate, so the still meet the compression limits and appear OK.  New ones will improve the ride during taxi.

Clarence

Awesome, that helps!!

[Hank]

Landings are also better with new biscuits . . . When I replaced mine in Dec '13, they had the manufacture date of "06-69" molded into them. But they were upside down, and I somehow read it as "09-96" so I wasn't too worried.

Swap them out, you will like it [just not the price!].

[cliffy]

Wouldn't it be nice if we could still use the truck engine biscuits that Al Mooney used originally in the Mite?

Maybe $5 each!

[Guest]

1 hour ago, cliffy said:

Wouldn't it be nice if we could still use the truck engine biscuits that Al Mooney used originally in the Mite?

Maybe $5 each!

I wish that were true.  There is no supplier for them anymore.  A fellow in Ohio makes them in small batches$150.00 each for $900.00 per set.

Clarence

[par]

Had mine replaced just a few weeks ago during the annual. I've only done 2 landings since then but they were definitely some of my smoother ones. I can't really tell much a difference on the ground or notice any difference in the sitting height/angle. Either way, I will probably sell the plane before I ever have to worry about it again.

[Yetti]

I still think there is room for some enterprising person to make a conversion to firestone air bags

[cliffy]

The airbags might expand too much at altitude :-)