hotrod180 wrote:Cary wrote:....any airplane which was authorized for spins that has an Avcon conversion loses its authorization, because the folks in Kansas didn't go through the necessary STC testing process.....
A guy I used to know bought a C150 Aerobat with an Avcon 150hp conversion. It either wasn't placarded properly, or (more likely) he didn't pay close enough attention, but after he bought it he griped about it no longer being aerobatic. Other than "intentional spins prohibited", it was still approved for for all the maneuvers listed in the POH so I didn't see the problem. But thinking about it now, perhaps the empty weight went up enough and/or the CG shifted enough to take it out of the utility category and into normal?
There is no placard requirement; it's in the STC. I hadn't bothered to look at the STC, but my IA pointed it out to me. So I added a "spins prohibited" placard to mine, just to make it clear in case I were to lend my airplane to a friend, since otherwise all 172s are authorized to be spun in the utility category.
I don't know whether the 150hp STC for the Aerobat affected the category (might have, I just don't know), but personally, I'd have been hesitant to do other permitted aerobatic maneuvers--it's too easy to screw up an aerobatic maneuver and have it fall into a spin, and adding a bunch of weight and moment to the front of the airplane could adversely affect other maneuvers as well.
I know that there are pilots who do aerobatics in non-aerobatic airplanes. Although most aerobatic maneuvers performed properly don't put excessive stress on the airframes, it's the screwed up maneuvers which can do that. To me, it's the epitome of stupid pilot tricks, to do prohibited aerobatics in a non-aerobatic airplane--
or for that matter, to do aerobatics at all without proper training. I'm just a tad sensitive about this issue, of proper training for aerobatics. Here's the story:
My Daddy died when the P-51 he was flying fell out of the top of a victory roll, because he hadn't had proper aerobatic training yet. He had been a heavy twin driver (B-25s and C-47s) in WWII and joined the Wyoming Air Guard after the war. The Army Air Corps was unloading a flock of P-51s on the Guard units all across the country, and of course, all of the kids in the Guard at that time wanted to fly them. All that was required to transition was 4 hours in an AT-6, and then several hours in the P-51.
His first hour in the P-51 was just in the pattern, doing take-offs and landings. The second hour was to introduce high speed flight, so he and his instructor (in another airplane--they were all single seaters) headed east from Cheyenne, climbed only to 12,000' MSL, and flew around for awhile, so that he could get used to the high stick forces involved at 400 mph. Then they headed back, and his instructor told him to follow him through with a victory roll. Like any good student, and with the military background, he did what he was told, but he stalled it in the process at the top of the roll. The airplane fell into a spin. Witnesses in another flight observed that he made a valiant effort to stop the spin, and that he'd succeeded in stopping the rotation but plowed into the ground, because there wasn't time to pull out.
Here's the issue: a P-51 loses altitude at the rate of about 2500' per rotation in a spin and takes about 2 1/2 turns to stop rotation with full anti-spin control input. Simple math: the rotation takes about 6250' to stop. They were flying at 12,000' MSL, which in that part of Wyoming (near Hillsdale) is only 6300' AGL.
If you're going to spin an airplane, get good instruction, do it from a sufficiently high altitude, and realize that if you don't recover it properly in time, you can die.
Cary
