Rotax 582 RPM fluctuating in cruise
in 2 Stroke Technical Questions
8 years ago
I've got an X-Air fitted with a 582 and today during a short flight we noticed that when setting cruise rpm (5400) the engine slowly ran back to around 5000 RPM. Initially I thought the instructor had accidentally nudged the throttle lever, but when the RPM was reset to 5400 the engine slowly ran back again to around 5000 RPM.
We cut the flight short and after landing checked the carbs - all looked well, carb bowls were full of fuel, clean and floats looked good. Carb needles set to third notch. Did a ground run and observed that if the RPM was set between 5200 and 5600 the RPM would slowly reduce by around 200 RPM and fuel pressure dropped from 0.3 bar to 0.28 bar, 5800 RPM and above the engine ran fine. Likewise below 5000 RPM the engine ran fine. On a static run, full power produces around 6100 RPM. The aircraft is configured with a 2 bladed DUC-Windspoon prop set at 16°.
The other issue is that we noticed from a previous flight that if the electric pump is switched off the fuel pressure drops below 0.2 bar. Previous owner advised that he kept the fuel pump on at all times in flight.
With speaking with the previous owner, they had had similar issues with RPM dropping like that, but it didn't occur all the time and this is the first time it's happened to me since buying the aircraft (just under five hours flown since purchase). Spark plugs were changed four hours ago and fuel filter was changed last week.
I've ordered a new mechanical fuel pump (Mikuni), but someone has suggested possible air leak between the engine and mechanical fuel pump.
Being new to microlights and 2-stroke engines this is all a bit of a learning curve. But wondering if anyone else has had similar issues with a 582 and whether there is anything else I should be checking?
We cut the flight short and after landing checked the carbs - all looked well, carb bowls were full of fuel, clean and floats looked good. Carb needles set to third notch. Did a ground run and observed that if the RPM was set between 5200 and 5600 the RPM would slowly reduce by around 200 RPM and fuel pressure dropped from 0.3 bar to 0.28 bar, 5800 RPM and above the engine ran fine. Likewise below 5000 RPM the engine ran fine. On a static run, full power produces around 6100 RPM. The aircraft is configured with a 2 bladed DUC-Windspoon prop set at 16°.
The other issue is that we noticed from a previous flight that if the electric pump is switched off the fuel pressure drops below 0.2 bar. Previous owner advised that he kept the fuel pump on at all times in flight.
With speaking with the previous owner, they had had similar issues with RPM dropping like that, but it didn't occur all the time and this is the first time it's happened to me since buying the aircraft (just under five hours flown since purchase). Spark plugs were changed four hours ago and fuel filter was changed last week.
I've ordered a new mechanical fuel pump (Mikuni), but someone has suggested possible air leak between the engine and mechanical fuel pump.
Being new to microlights and 2-stroke engines this is all a bit of a learning curve. But wondering if anyone else has had similar issues with a 582 and whether there is anything else I should be checking?
