RPM Drop in 912ULS
I have an issue with the right engine on my AirCam. I would greatly appreciate any advice you could.
The issue has presented itself three times so far:
- Once, during a level flight at about 7,500 ft, and
- Again, after a touch-and-go at our home airport in Guaymaral (SKGY)
- Yesterday, in a testing flight over the airport.
All of these times, the engine was running at around 3,800 to 4,200 RPM, and suddenly, the RPM dropped to between 2,300 and 2,900. When I attempted to increase power, the throttle had almost no effect. After a minute or two, the engine recovers its full power.
For context, the carburetors were serviced entirely, and the mechanical fuel pumps on both engines changed after the first occurrence. The next occurrence was just two days after the service, during a touch-and-go at Guaymaral, right before entering the downwind leg. I landed immediately, and after a visual inspection for leaks or abnormalities, I restarted the engine, and all parameters appeared normal again.
After the second occurrence of the issue, I decided to inspect the tanks, piping, and electrical connections. However, nothing unusual was found during these inspections. The local mechanics are still uncertain about the root cause, though they are suggesting the ignition module might be the problem. I have my doubts about that diagnosis and am exploring other potential causes.
Do you have any ideas about what might be causing this sudden RPM drop and throttle response issue? I would greatly appreciate any advice or insights you can provide.
