Quote: carusoam
The enemies of the donut=weight, time and temperature. (not so much, hours flown or number of landings)
My guess...
The concern for donuts with only 50 hrs on them is.... The 50 hrs were the good hours when no compressive stress was placed on them and they were allowed to relax....
How many years out in the hot sun was 2,500# of airplane squeezing them down ever thinner and thinner???
Longer heavier mooneys are known/rumored to compress their donuts sooner than short / lighter mooneys.
Rubber is a visco elastic material. Viscous = slow flowing (years), Elastic = return to original form. Over time, the compression force of the weight of the airplane will shorten the height of the donut. Increased temperature will make it occur sooner. The elasticity is also lost (harden) as the age of the rubber increases.
On an active mooney, with only 50 hours, the donuts, were used for a year or less? On an inactive mooney, the 50 hrs does not tell much about how compressed or how old the donuts can be.
-a-
Although I'm not a mechanic, I do have them on condition that they do work. The circumstances are that the donuts were on a Mooney for 2 years then had a gear up landing. They were removed from the plane and have been inside stored up till now, therefore not subject to heat and downward pressures. I did call a Mooney service center and they said that would have no problem using them. In any event I'm going to copy my AME with your comments cause the final decision is his.
Thanks for your help
Eldon