Piper18O
Pre-takeoff checklist
I have an stec 50 autopilot that does not hold altitude well at all. When I set it, I think it may be working, but the altitude will drift. Most of the time it enters a very very slow climb. after about 5 to 15 minutes it is about 200 feet high. Also I have a vsi that is reading incorrectly. When I climb, it will show that I am climbing 600 feet a minute, but in reality, I am only climbing about 350 or 400 feet per minute. It is constant on the reading error clear through the climb or decent regardless of how long the climb or decent is. Are these problems related, and what could be causing them?