Acs switch issue

[alaskan9974]

Anyone running into an issue with acs keyswitches bumping from both to one mag or all the way to the off position?

The detent is worn, or something happened to the spring that forces it back to both from start since just a nudge on the key sent it all the way off.

In flight I noticed it would sometimes be only selecting one mag, I assumed I forgot to switch to both but I watched it move from both as I brought the prop back in cruise seemingly randomly, must’ve been the vibration change. I had my mechanic replace the switch after that flight, hopefully the new one lasts longer than a few years. I filed an ASRS report and the flight school down the road that uses them also had never seen it fail in that manner

 

[sarangan]

Anyone running into an issue with acs keyswitches bumping from both to one mag or all the way to the off position?

The detent is worn, or something happened to the spring that forces it back to both from start since just a nudge on the key sent it all the way off.

In flight I noticed it would sometimes be only selecting one mag, I assumed I forgot to switch to both but I watched it move from both as I brought the prop back in cruise seemingly randomly, must’ve been the vibration change. I had my mechanic replace the switch after that flight, hopefully the new one lasts longer than a few years. I filed an ASRS report and the flight school down the road that uses them also had never seen it fail in that manner

Wow that's pretty scary. I have never seen it do that. Did the detents feel weak when switching between positions during runup?

 

[Magman]

There is a Recurrent AD that requires partial disassembly of the unit every 2000 hrs.

Maybe a spring was left out then?

 

[alaskan9974]

Wow that's pretty scary. I have never seen it do that. Did the detents feel weak when switching between positions during runup?

No, not that I noticed, I just bought this plane a year or two ago but didn’t feel like anything felt different.

 

[alaskan9974]

There is a Recurrent AD that requires partial disassembly of the unit every 2000 hrs.

Maybe a spring was left out then?

Possibly. Plane is relatively new to me but it only has 800 hours when they did the engine, and about 400 hours on the switch from install in 2018 I believe, switch has a 2014 manufacture date with no entry that I saw regarding disassembly. Hopefully was just a fluke, I did send them a message asking if they wanted it back and didn’t hear from them so it’s in my mechanics parts bin somewhere now.

 

[Gary Ward]

I updated my switch years ago. I wanted the diode across my starter solenoid. At the time the kit cost 18 bucks. One the cheapest updates I've done. The return spring is in the housing, not much you do there except replace the whole switch like your mechanic did.

There was nothing wrong with my switch. I wanted the diode on the solenoid and my airframe was approaching 2000 hours.
The instructions said to mark the screws with a red marker to indicate the switch has been upgraded.
The original screws were painted black.

It was fun getting it out and back in.

 

[Magman]

Cessna couldn’t tie it any tighter!