Originally Posted by airguy
Interesting how things work out...
I have the same ACS key switch in my plane, and for 260 hours it has worked flawlessly. This past weekend I experienced the same symptoms that were laid out here in this thread while starting up for an IFR training flight. If the key was rotated hard against the stop, the contactor dropped out. Back off just a hair and the contactor picks up and the starter engages.
I guess I'll replace the rotary key switch with two toggles and a pushbutton as others have recommended.
My starter has been flawless on the first attempt, since backing off the key rotation.
In case you want to try giving your ACS switch new life, Spruce sells an ACS service kit (Part #11-03654) for around $17 that replaces internal switch contacts and addresses an ACS service bulletin released back in 2008.
I'm expecting delivery of one of these kits any day.
I did confirm that my starter contactor "drops out" at full-clockwise rotation, so it is either an internal switch contact issue or a switch end-stop issue. I like the security of a key for the ignition and canopy.
I'm not convinced that toggles and push-buttons are immune to failures, too.