Wed Feb 20, 2013 11:21 am
I've had some experience with 2 "all the bells & whistles" autopilots, the King KFC225 with flight director and KCS55 HSI. One was in a Mooney 231 that I flew extensively for a couple of years, and the other was in a T210 that I was partnered in for about a year. Both of these had altitude capture/hold, in addition to the usual nav/trak, heading/trak, etc. Both handled coupled approaches smoothly. Terrific boxes, when they worked well. When they glitched, they were as annoying as anything, and taught me not to trust even the most sophisticated of autopilots, which these were at the time.
I can't tell you how many times each glitched, but on the average, probably once every other flight. Most of the time, it was just shutting off without warning, and without any fault indication, other than the "on" light would go off, and the airplane would gradually drift from its heading or course or altitude if I didn't notice the light was out. Sometimes the autopilot would remain on, but one or the other of its axis would go offline, like it would stop holding altitude but stay on course, or lose its way but continue to hold altitude.
The single most unsafe glitch that occurred was in the Mooney, when late one night I was enroute to Newcastle from Laramie, and for no reason that I could ever determine, it suddenly commanded a hard right turn. I reacted too slowly to shut it off, and by then it had deviated about 90 degrees and lost altitude, enough that Center called and asked if things were OK. A later inspection by the avionics shop couldn't determine the cause.
As a result, I defaulted to only using the autopilot in either airplane, or in any other airplane I've flown with less sophisticated autopilots, when I need to look at a chart--no more coupled approaches! Otherwise, I just hand fly, and that works for me. My LRB doesn't have an autopilot, and I don't need one. Most of my flights are relatively short, only an hour or two, except for the occasional Angel Flight and the annual OSH flight, which is nearly 8 hours flight time. The expense of installing any autopilot is just more than I need, even if they all worked without fail.
Regarding putting a non-TSO'd autopilot in a certificated airplane, while it may be legal in CR (you'd want to make absolutely certain), it would make the airplane non-airworthy just about anywhere else, whether in the US, Canada, or Europe. I wouldn't recommend it.
Cary