Al, thanks for asking.
For just the two aircraft we exampled, we would recommend the five year replacement.
The REMOS was six+ years old with ~800+ hours total time (flight school ops for its first four years). Although we found no parts in imminent failure mode, it was clear that changing them was appropriate. Especially since the aircraft was in for both a rubber replacement and annual condition inspection (we are an authorized REMOS Service Center) and since the G-3 is an SLSA, and the REMOS manual defers to ROTAX, we could not sign-off the condition inspection without the rubber replacement. The customer was in agreement.
As for the AirCam, it is licensed as "Experimental" and the ROTAX five year replacement requirement would not have precluded us from signing off an annual inspection, "on-condition." We were not assigned the annual inspection (to be done later), just the rubber replacement, at the owner's request. However, this aircraft had not had ANY rubber parts replaced since birth, ten years ago... and it showed. It was most-certainly due, even though this aircraft had only 247 hours total time and had been hangared since new. Had we been asked to sign-off the annual, the rubber condition would not have allowed us to approve its return to service. By the way, the owner flew the AirCam 250 miles to us for this work, and in an AirCam, that's not a short flight. He trusted our evaluation.
So, we (FOXAerosport, Inc.), as an authorized ROTAX Repair Centre, can say... the five year replacement is somewhat overkill, but not by much. And TEN years (like the example AirCam) is waaay too long.
The risk of bypassing the five year replacement is subjective AND objective... depending on the aircraft's certification... and the A&P/IA or LSRM signing the logbook, and the owner's risk level.
FYI, any ROTAX trained technician that quotes a price of less than $3000 (parts and labor) for the five year replacement (except on the MOST SIMPLE installation) will either lose money, or the owner will be asked to pay more than he bargained for.
Also, please be sure the technician is ROTAX qualified.
I hope this helps.
ewg
