Rotax 912is Lane A dropout

[Gazunda61]

Hi,

 

Seeking advice on this problem please.

 

Have a 912is powered Bristell with 390 hours on the engine and have been experiencing a Lane A dropout on final at idle speed. Frustratingly we have been chasing this problem for a while. EMS says Ignition Fault Cylinder 1/2. Checked plugs, checked caps, checked air sensors, increased idle setting on throttle. Symptoms only appear on final, in the flare or shortly after touchdown. Reset Lane A on ground and it is returned  to ACT. Can't seem to fault it, nor understand why it only occurs near or on landing. All other electrical and engine parameters are stable. Any ideas?

 

Also, as we are Sydney based I would be grateful if anyone knows of a 'Rotax Guru' in the area that I can take the aircraft to for diagnosis.

 

Thanks,

 

Paul

[RFguy]

Howdy

I've heard of this from an aircraft on the sunshine coast. cant remember which..

I would be sure rotax have a diagnostic log in their box. This will contain the info....

Many engine shops, not sure about Berts, are generally low tech affairs and shy away from this data....

Talk to the factory .

 

is this at low idle or moderate power ? gather in a flare so it is occurring at idle stop ?

- glen 

[facthunter]

Hello factory. There's some  rot in my rotax. Sorry but to me, it's funny because it can't happen to the old stuff. ANY good LAME can troubleshoot them in a short time.   Nev

[sfGnome]

This is second hand information, but a bloke told me recently about problems he had with lane failures that would disappear when cycled. The problem in that case was a poor joint in one of the sensor cable connectors (don’t know which one). Something to look for if you haven’t already. 

[RFguy]

maybe some issue with a combination of higher vibration (low RPM) and less than perfect crimped connectors. someone must know at factory. 

[Gazunda61]

I'm leaning that way as well. Lower airspeed, higher AOA and turbulent airflow through the cowl leading to vibration. I'm going to pull the spark plug connectors and visually check the terminals.

[Gazunda61]

I should add that we had a diagnostic performed and the advice received was to increase the idle setting which did indeed solve the problem - temporarily.

[RFguy]

Putting aside spark plugs connections (I dont think that's the problem) 

---I'd ensure all the plug in connectors in ALL the harnesses  and plug in sensors are well seated and fixed down so they cannot free vibrate. You might cycle the harness and sensor connectors and inspect terminals under light and magnification .
Of course, I am guessing, but this would be my immediate checks

Edited August 26, 2023 by RFguy