JPA Posted July 1, 2019 Report Share Posted July 1, 2019 I just bought a 1978 J model mooney, when I'm in the taxiway a minimum hollow feels quite that is an indication to change the donuts? Quote Link to comment Share on other sites More sharing options...
kortopates Posted July 1, 2019 Report Share Posted July 1, 2019 23 minutes ago, JPA said: when I'm in the taxiway a minimum hollow feels quite that is an indication to change the donuts? I have no idea what that means, but the test for the donuts is in the service manual which measures how compressed they are by the gap at the top. The other very useful indication, although not in the SM is to jack up the aircraft and see if the donuts will fully expand with the weight off such that you can't turn them easily by hand after a few minutes. Or If you see cracking in the rubber, you don't have to look any further. You can also look at the date code, that includes a 2 digit year code. if 10+ years you are likely due. 1 Quote Link to comment Share on other sites More sharing options...
JPA Posted July 1, 2019 Author Report Share Posted July 1, 2019 Thanks.Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
orionflt Posted July 1, 2019 Report Share Posted July 1, 2019 Welcome, where you from JPA?, how about a bit of an introduction Brian 1 Quote Link to comment Share on other sites More sharing options...
Bravoman Posted July 2, 2019 Report Share Posted July 2, 2019 I understand that with the long bodies with the extra weight and normal usage five years is about the time to look to change the donuts. This is something I myself would err on the side of being conservative on since the shock absorption of the Mooney system is marginal to poor at best and it is IMO cheap insurance to preserve the airframe, tank seals etc. Quote Link to comment Share on other sites More sharing options...
carusoam Posted July 2, 2019 Report Share Posted July 2, 2019 Welcome aboard JPA! Things to know about donuts... Their molding date is right on their exterior... month and year... make sure you are reading them right side up... (lesson from Hank) Their installation date is in your log book... find how long they have been in there... They wear based on time under compression... and how much weight they are holding up... Long Bodies get five or so years... Short Bodies May get 10 years... The Maintenance Manual has a Specific and clear method of measuring the compression... there are lots of pics around here for old vs. new donuts... So it doesn’t really matter what it feels like over a minimum hollow... go ahead and fill that in, use the edit function... They’re rubber donuts, not coil over shocks.... There is a difference in feel between new and old donuts. Taxi slowly...hold the elevator back... know the elevator isn’t going to help very much either... unless you are going really quickly... Have you seen the price of donuts yet..? Fill in your plane details and a pic, when you get a chance... PP thoughts only, not a mechanic... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
RobertGary1 Posted July 2, 2019 Report Share Posted July 2, 2019 18 hours ago, Bravoman said: I understand that with the long bodies with the extra weight and normal usage five years is about the time to look to change the donuts. This is something I myself would err on the side of being conservative on since the shock absorption of the Mooney system is marginal to poor at best and it is IMO cheap insurance to preserve the airframe, tank seals etc. That’s an old wives tale. I’ve seen 15 year old donuts measure just fine. Some mechanic needed to make a boat payment. -Robert Quote Link to comment Share on other sites More sharing options...
MBDiagMan Posted July 3, 2019 Report Share Posted July 3, 2019 I would start by checking tire pressure. Quote Link to comment Share on other sites More sharing options...
JPA Posted July 3, 2019 Author Report Share Posted July 3, 2019 I have no idea what that means, but the test for the donuts is in the service manual which measures how compressed they are by the gap at the top. The other very useful indication, although not in the SM is to jack up the aircraft and see if the donuts will fully expand with the weight off such that you can't turn them easily by hand after a few minutes. Or If you see cracking in the rubber, you don't have to look any further. You can also look at the date code, that includes a 2 digit year code. if 10+ years you are likely due. Thanks for answer, what I tried to say is if it’s normal to feel hard the taxiway, I was thinking about the Donuts.The plane is very clean and beautiful.Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
JPA Posted July 3, 2019 Author Report Share Posted July 3, 2019 Welcome, where you from JPA?, how about a bit of an introduction Brian Thanks, well I am from Panama City panama, I had a Cessna XP with lots of gadgets but without speed so I jumped in to a Mooney. I just arrived from wisconsin 2 days ago it was a long trip but amazing trip 2083 NM. So any recommendation I will appreciate very much.Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
JPA Posted July 3, 2019 Author Report Share Posted July 3, 2019 Welcome aboard JPA! Things to know about donuts... Their molding date is right on their exterior... month and year... make sure you are reading them right side up... (lesson from Hank) Their installation date is in your log book... find how long they have been in there... They wear based on time under compression... and how much weight they are holding up... Long Bodies get five or so years... Short Bodies May get 10 years... The Maintenance Manual has a Specific and clear method of measuring the compression... there are lots of pics around here for old vs. new donuts... So it doesn’t really matter what it feels like over a minimum hollow... go ahead and fill that in, use the edit function... They’re rubber donuts, not coil over shocks.... There is a difference in feel between new and old donuts. Taxi slowly...hold the elevator back... know the elevator isn’t going to help very much either... unless you are going really quickly... Have you seen the price of donuts yet..? Fill in your plane details and a pic, when you get a chance... PP thoughts only, not a mechanic... Best regards, -a- Thanks a lot I will check them tomorrow but manny thanks a lot your recommendation and tips I will check tomorrow all details.Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
JPA Posted July 3, 2019 Author Report Share Posted July 3, 2019 I understand that with the long bodies with the extra weight and normal usage five years is about the time to look to change the donuts. This is something I myself would err on the side of being conservative on since the shock absorption of the Mooney system is marginal to poor at best and it is IMO cheap insurance to preserve the airframe, tank seals etc. Thank you! Sent from my iPhone using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
kortopates Posted July 3, 2019 Report Share Posted July 3, 2019 2 hours ago, JPA said: Thanks for answer, what I tried to say is if it’s normal to feel hard the taxiway, I was thinking about the Donuts. The plane is very clean and beautiful. Sent from my iPhone using Tapatalk Because of the firm donuts, as opposed to pneumatic struts used on most other planes, the mooney feels very firm which is entirely normal. Mooney pilots can't really tell by feel when its time to change them, but they are very likely to notice the change after getting new donuts, or perhaps after riding in someone else's Mooney. 1 Quote Link to comment Share on other sites More sharing options...
Mcstealth Posted July 3, 2019 Report Share Posted July 3, 2019 20 hours ago, JPA said: Thanks a lot I will check them tomorrow but manny thanks a lot your recommendation and tips I will check tomorrow all details. Sent from my iPhone using Tapatalk Don't mind him. He thinks he knows it all. Well, he does know most. Quote Link to comment Share on other sites More sharing options...
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