I noticed two flights ago that when I press either the control wheel steering button or the AP disconnect button (both on the yoke) that the KAP 140 autopilot in my TB20 plays up for most of the rest of the flight. Today in fact, after I pressed the AP disconnect button on the way to Gamston Airport (EGNE) it would not re-connect during the rest of the outbound flight nor later for the whole flight back to Elstree. It’s now completely broken: The autopilot fails to pass the trim test when I turn it on : Turn on AP, press the trim test button….10 second and many beeps later the AP power light flashes a few times and then the AP turns itself off. In other words I guess it reports that the self-test has failed.
Someone at Gamston said to me that the wires in the yoke are notoriously weak and that was almost certainly where the problem lay. Does that sound right to the techies here? Are they easily repaired? Does anyone know? What might it cost?
Thanks in advance,
Howard
The red disconnect switch on the yoke often fails. See here
King used an undersized one and the inductive load of the servo clutch solenoids burns the switch contacts out eventually.
That’s the easy option to start looking…
In the UK, there is IME only one shop which knows anything about autopilots: GAMA. And you need to make sure Harry Lees is actually available. The problem is that autopilot troubleshooting needs somebody who understands electronics.
Thanks Peter. I know an electronics engineer at Elstree. I’ll ask if he can replace the red switch with alternative part number that you identify. It might be a good start.
(Your KFC225 page is incredibly detailed. Honeywell need to engage you formally…)
Howard
Howard wrote:
(Honeywell need to engage you formally…)
Ha, that isn’t going to happen.
Yeah I know, but we can all dream :D
They approached me at EDNY 2 years ago, spoke to me at some length, took my details, and I never heard again.
I don’t know any background to that event.
IMHO they know exactly what the problems are but they don’t have anybody in-house who can get into the software, etc.
But that is the KFC225. Yours is different, with only a few shared problem areas. Frankly if you got 26 years out of it, that is very good. I reckon the crappy Globe motors wear out after a few k hours.
Avionicare at Southend did avionic work for me in the past, including nav-com replacement & repair, and work to the KFC200 in my Saratoga, all pretty successfully and for the price agreed. I like them a lot.
Thanks wsmempson. I’ll be talking to the people I know and extend outwards as necessary. Your recommendation of Avionicare is noted.
Howard
