I've got the problem described below and maybe you could give me some hints where to look for possible causes.
Frame: Quadcopter (many successful flights before modifying the camera gimbal)
Hardware: APM 2.5
Firmware: ArduCopter V3.1.5
- Random, light twitches during flight
- Sudden altitude drop after a while in loiter mode
- Sudden roll to the left while hovering in stabilize mode, resulting in a crash
According to the information found here and the log, it could be a mechanical failure. I assume if I'd had a problem with a motor or an ESC, roll and pitch should show similar behavior in the log.
I'm also not sure if I can exclude a problem with the receiver or the PPM encoder.