The engine went above its maximum RPM
What ArduPilot says:
- Engine: Above redline RPM
The filtered engine speed from the RPM sensor rose above ICE_REDLINE_RPM, the highest speed the maker allows. Unless ICE_OPTIONS bit 1 disables it, a governor now lowers the throttle until the speed is back under the limit, and lets go once it has fallen below 90% of it.
What to do, most likely first
The propeller is too small or too fine for the engine, which then over-revs at full throttle.
CheckIn the log the RPM climbs past the limit in level flight at full throttle, and in a dive.
FixFit the propeller the engine's maker recommends, or lower
THR_MAX.ICE_REDLINE_RPMis set below what the engine is meant to reach.FixSet it to the maker's maximum, and check that the RPM sensor counts right (its scaling).
Parameters to look at
| Parameter | What it is |
|---|---|
ICE_REDLINE_RPM | RPM of the redline limit for the engine |
ICE_OPTIONS | ICE options |
ICE_RPM_CHAN | RPM instance channel to use |
THR_MAX | Maximum Throttle |
The code that sends it
Engine: Above redline RPM
libraries/AP_ICEngine/AP_ICEngine.cpp AP_ICEngine::update() · Open in ArduPilot Copter-4.7.1