Different engines possible?

[Ernie Martin]

Morne, I draw the line on changes that I or a competent A&P/IA can easily determine to not adversely affect other elements of the aircraft, either because of its simplicity or because numerous such changes have already been effected without problems.

A different engine with significantly greater horsepower or one with radically different characteristics (read: diesel powered and water cooled) would be acceptable to me only if there have been dozens of such installations spanning several years and they have been without trouble.

Two other thoughts.

First, it's possible that I'm more conservative than most, because a) I fly mostly my family and principally over water, and b) I spent 19 years on communications satellites, where the designs had to be perfect since you can't fix a satellite once in orbit.

Second, my opinion is based not just on good engineering principles, but on hands-on observations. For instance, I recently assisted in the replacement of the rubber/metal motor mounts of the rear engine, a process that showed how cramped and well designed are all of the elements associated with the engine. The engineering effort that went into the design of all mounts, control cables, hoses, etc., must have cost millions in 1960s dollars, and I just cannot believed that kind of robust design can come from an STC. Just think of the consequences if a throttle control cable fails on take-off or landing, because the STC design gave short thrift to that element. And you, being an early user, are the guinea pig.

Not for me. I'm not a test pilot.

Ernie Martin