Thomas,
Start by saying that Im not a mechanic of any kind, nor am I an A&P, AI nor expert in this subject. These are my observations as an observer. As I understand it, the FAA wont allow a certificated airplane to be moved permanently into the experimental category. Plus, the only category available to you would be Experimental Exhibition and you dont want to go there. I think you can forget this option. The FAA seems to be only approving modifications approved by an FAA Designated Engineering Representative. You have to spend money to have the DER do a full evaluation and write-up of your proposed mod. That doesnt guarantee the FAA will then permit the mod, but, if you pick a DER with a good relationship with the FAA it should fly. The FAA may require you to put the plane in experimental status for a short time as you do flight testing on the modification. I saw a Coupe with a 3-blade composite prop at a national flyin a few years ago. It had to go through the experimental flight test (and I think it required specific tests and records kept) phase before approval. Does the Forney seat mod require any drilling in the spar? At this moment, I dont think the FAA will approve any spar drilling under any circumstances. Ill agree with Bill that moving the gascolator to the firewall is not an improvement. Ive never heard of a gascolator failing when the appropriate (easy to meet) ADs have been applied with the braces and, I think, brass fitting. The factory mounting location eliminates low spots and high spots and makes for a pretty unlikely-to-fail installation. The split elevator SHOULD be a no-brainer approval for the FAA. The FAA did **extensive** testing of the configuration when it was certificated. (Only God and *maybe* the FAA knows where those records are.) The split elevator is an obviously better installation with no downside. All it does is minimize trim changes when changing power, even from idle to full and visa versa. It doesnt change flying characteristics at all and only changes landing characteristics by returning planes with the 1320 pound STC (or D models) to the same landing speed as the 415-C. (The split elevator is often, however, an expensive modification. I flew 800 hours with the 9° limitation and had no fuss. This change never got near the top of my wish list.) Again, this is a non-expert opinion. Its what Ive seen and understood in trying to keep track of the modification process. Ed
