Phil,

Thanks for explaining this.....those of us who have never wrenched on a certified aircraft as an A & P often feel a little in the dark on the definitions

Couldn't agree with you more on the Rotax Rubber parts replacement......particularly on the rather expensive carb sockets.....Replaced mine at recommended time and found the condition of the old ones to be perfect...except for that telltale smell of fuel they picked up. Same-same on the carb diaphrams. Both of these items were as pliable as the new ones and there were no cracks anywhere.

Thinking that use, environmental exposure etc have a lot to do with useful length of service.