WingedFrog
Well Known Member
Last winter I started facing an unusual drop at run-up after starting the engine. It was with Circuit B off which I interpret as affecting circuit A. As the drop was about 300 accompanied with roughness and fluctuations I did not take-off and taxied back to my hangar. When I repeated the run-off at the hangar, the drop had disappeared and I went on and had a normal flight. The same problem reoccurred through winter months. When Spring flying came and during summer I had little trouble but still noticed some roughness after the engine started although it always disappeared at the run-up after taxiing. Came the colder months and I am again in the last winter situation so I decided to troubleshoot the ignition packs by switching the input from the generator between modules A and B. The roughness and drop appeared with A off this time! I concluded that the module A was faulty and decided to separate myself of $900 by ordering a new ignition module. Once the new module installed I had the same problem on the new module in position of A (i.e. with B off)!!!
I then did what i should have done first: looking at the schematics in the Heavy Maintenance manual (Fig 74-18) I concluded that I had misdiagnosed the module A and that the problem was likely coming from the generator, more specifically from one of the two trigger coils for ignition circuit A referenced as #2 on Fig 74-18.
I would appreciate some advice on this issue as my area does not have Rotax 912 specialists. My main concern now is how to access and troubleshoot these two coils. I am not sure the access is possible without removing the engine from its mount.
...In the mean time I have got an extra ignition pack for future failures!
I then did what i should have done first: looking at the schematics in the Heavy Maintenance manual (Fig 74-18) I concluded that I had misdiagnosed the module A and that the problem was likely coming from the generator, more specifically from one of the two trigger coils for ignition circuit A referenced as #2 on Fig 74-18.
I would appreciate some advice on this issue as my area does not have Rotax 912 specialists. My main concern now is how to access and troubleshoot these two coils. I am not sure the access is possible without removing the engine from its mount.
...In the mean time I have got an extra ignition pack for future failures!