When to change the donuts

[Fookz92]

My disks say ‘76 on them. Gear tolerances check within limits. We still going flying. 

[steingar]

I replace mine when my mechanic says to.

[LANCECASPER]

40 minutes ago, steingar said:

I replace mine when my mechanic says to.

I replace mine when my mechanic shows me that they are out of spec.

All 11 of mine were changed after buying the airplane in November 2015 and last January (2018) my mechanic just glanced at the mains and said they needed to be changed. We have a good working relationship, so I showed him the logs of when they were changed and asked if we could measure them according to the maintenance manual. They were in spec and still on the airplane.

[steingar]

1 minute ago, LANCECASPER said:

I replace mine when my mechanic shows me that they are out of spec.

All 11 of mine were changed after buying the airplane in November 2015 and last January (2018) my mechanic just glanced at the mains and said they needed to be changed. We have a good working relationship, so I showed him the logs of when they were changed and asked if we could measure them according to the maintenance manual. They were in spec and still on the airplane.

Were that me I'd be shopping for a new mechanic.

[LANCECASPER]

Just now, steingar said:

Were that me I'd be shopping for a new mechanic.

Not at all - I trust him with my life. He's forgotten more about Mooneys than most mechanics will ever know. He worked for Mooney for years and helped open the Mooney Factory Service Center back in the early 90's, but he is human. No matter how good your eyes are you need to measure to see if they're in spec. He's reasonable (yielding). He knows me well enough to know that if they were out of spec I wouldn't have tried to defer it. In fact, on his word I ordered 8 shock discs. Once we found that they were in spec I sold them on Mooneyspace.

All of that being said, I was surprised, though, in a little over two years how close to being out of spec that they were. I have Long Range tanks on a Long Body and at the time of the annual my tanks were full. They showed good resiliency though when we jacked up the airplane. 

[J0nathan225]

1 hour ago, LANCECASPER said:

Not at all - I trust him with my life. He's forgotten more about Mooneys than most mechanics will ever know. He worked for Mooney for years and helped open the Mooney Factory Service Center back in the early 90's, but he is human. No matter how good your eyes are you need to measure to see if they're in spec. He's reasonable (yielding). He knows me well enough to know that if they were out of spec I wouldn't have tried to defer it. In fact, on his word I ordered 8 shock discs. Once we found that they were in spec I sold them on Mooneyspace.

All of that being said, I was surprised, though, in a little over two years how close to being out of spec that they were. I have Long Range tanks on a Long Body and at the time of the annual my tanks were full. They showed good resiliency though when we jacked up the airplane. 

Those discs were then installed on my mains, replacing donuts that were 23ish years old if I recall. Front is still within specs though. Thanks again @LANCECASPER 

[Dave C C]

Hi fellow pilots!  This is my first post, but I have been a 1965 M20E owner for about 15 years. I have participated in owner assisted annuals every year with several excellent A&P/IA's.  I also have Aerospace and Mechanical engineering degrees and a fairly extensive shop.  This year I was very surprised to discover that the nose gear shock mounts were placed in service in 1970! And the mains last updated in 1990!  So quite possibly these might be the oldest and hardest shock disks in the fleet.  Needless to say, the airplane is standing much taller.  So the advice to find an experienced Mooney A&P shop is certainly justified.  I'm looking forward to greased landings from now on....

[carusoam]

15 years! 

Welcome aboard, Dave!

MS has only been around for about a decade... 

But, that doesn’t matter... you are here now!   

Best regards,

-a-