KCS-55A - Weird Issue

T

talkingbob

Pre-takeoff checklist
Joined
Oct 21, 2011
Messages
117
Display Name
Display name:
JonC
C172N (if that matters). Flew with KCS-55A+GNS430+autopilot (in NAV mode) for a cross-country flight and for the last 30 minutes of the flight, switched the AP to HDG mode and used the 55A's heading bug. Landed and went on with life.

Fast-forward three days and basically the 55A HSI seems to "drift" on the return flight and ended up not being able to use the GNS430 to fly in NAV mode, but instead used GPS for reference only and had to use the heading bug on the HSI to fly the correct course that the GPS said to fly.
As you can imagine, this resulted in a greater workload, since I had to manually adjust the heading bug if the plane got off course.

Has this happened to anyone else?
It appears that if there is an issue, a red "flag" should pop up on the HSI, but none did and the heading bug did an OK job and the AP flew it fine, even though the compass heading on the HSI was grossly wrong and in no way ever matched the "whiskey compass".

- Bob
 
Sounds like a remote gyro issue to me. The gyro, wiring, and interface to the head would be suspect.
 
We've had it with our 55A, plane goes in to the shop in January. Two GI275s to replace the HSI and AI, a GNC255 to replace the old King 197 and KNS80, and ditch the vac system.
 
Thank you everyone for your insights - I love this forum. You guys are GREAT!

The drift seemed to just happen at a specified rate - almost like a clock. It would go from North to West to South to East and then start over and all I was doing was flying straight and level...

It does drive the A/P in heading mode just fine, so I don't want to remove it. I guess I just will cease relying on it for anything other than a HDG bug that sorta works :(
Seems like kind of a waste of a GNS430 to have it linked to such a wonky HSI, but am starting to get the idea that these 55As are know to have many issues, so maybe I shouldn't be so surprised?
 
Previous owner had the gyro in my plane rebuilt a year ago. It crapped out on the broker when he was ferrying it to his location, so it was rebuilt again, I assume (hope for his sake) under warranty. He described the symptoms similar to the way you are. It's working now.... hopefully it stays that way for a while. Personally I'm in the chuck it when it fails camp. The something like 20lbs of components in that system.
 
You must log in or register to reply here.
Back
Top