Intermittant Rough Running 914F
in 912 / 914 Technical Questions
7 years ago
Hi All
I have a 914F in my HK36-TTC Motorglider. It is running roughly intermittently.
So far - the history...
- Got hot briefly in climb out. Running hot time approx 5 minutes. Hot but not over red line as power reduced and speed increased. Cause - broken cowl flap cable.
- Repaired cowl flap cable and flew 3 circuits. On 4th circuit on downwind, engine made a "pop" noise and stopped (stalled). Prop windmilling. Forced landing carried out. Engine examined including spark plugs (looked normal), checked for oil leaks, checked turbo impeller, checked carby sync and operation. No faults found. Ground run of engine to full power ran normally.
- Flight test. 4 circuits. All normal. Left airport for longer run - on climb into next controlled airspace step - ran very roughly. Not taken into boost region for climb. Smooth running on power reduction. Engine shut down and restarted normally (remember this is a motor glider). Still ran rough when more than low cruise power applied. Determined that engine ran normally if turbo control switched off.
-Needed to ferry back to maintenance facility intending to try spare TCU and/or sensors. Ferry flight, started normally. Operated with turbo control off (carefully). After 10-15 minutes, rough running returned.
TCU downloaded after engine stop with no abnormal numbers. Intending to download again tomorrow now its back in the maintenance hangar and see if anything new or out of limits.
Thought I'd post here to see if anyone had seen anything like this and had any suggestions.
My background - rated to work on my own engine but still learning. Access to LAME advice and talking to the local rotax agent tech guys too.
Thanks
Cath
I have a 914F in my HK36-TTC Motorglider. It is running roughly intermittently.
So far - the history...
- Got hot briefly in climb out. Running hot time approx 5 minutes. Hot but not over red line as power reduced and speed increased. Cause - broken cowl flap cable.
- Repaired cowl flap cable and flew 3 circuits. On 4th circuit on downwind, engine made a "pop" noise and stopped (stalled). Prop windmilling. Forced landing carried out. Engine examined including spark plugs (looked normal), checked for oil leaks, checked turbo impeller, checked carby sync and operation. No faults found. Ground run of engine to full power ran normally.
- Flight test. 4 circuits. All normal. Left airport for longer run - on climb into next controlled airspace step - ran very roughly. Not taken into boost region for climb. Smooth running on power reduction. Engine shut down and restarted normally (remember this is a motor glider). Still ran rough when more than low cruise power applied. Determined that engine ran normally if turbo control switched off.
-Needed to ferry back to maintenance facility intending to try spare TCU and/or sensors. Ferry flight, started normally. Operated with turbo control off (carefully). After 10-15 minutes, rough running returned.
TCU downloaded after engine stop with no abnormal numbers. Intending to download again tomorrow now its back in the maintenance hangar and see if anything new or out of limits.
Thought I'd post here to see if anyone had seen anything like this and had any suggestions.
My background - rated to work on my own engine but still learning. Access to LAME advice and talking to the local rotax agent tech guys too.
Thanks
Cath
