Ignition woes - 914

So my AMO tells me one of the ignition units has failed and as a result when one of the units is turned off then there is no spark at all to cylinders 1 and 2 hence the EGT behaviour. 

Now the question is this… the aircraft is off home base. Part availability is at least 3 weeks lead time. 

would anyone consider ferrying the aircraft 40nm to home base with this situation? My gut says it’s probably safe but my brain says if another unit fails then I’m going to be flying a 2 cylinder aircraft. Not good. 

Desperately looking now for a used module or one to borrow to allow the ferry….

"I’m going to be flying a 2 cylinder aircraft. Not good"

I stand to be corrected - the ignition system, if correctly configured, is to top & bottom plugs. ie loss of one ignition module, will still have 4 cylinders running.

Note: Not advocating you fly with a defective system.😈

That’s an uncommon ignition module failure mode. 

Did you confirm it’s actually a module failure.  It’s easy to test, swap both connectors of both modules and do a mag test. If the problem moves to the other side, it’s a module failure. 

The timing of this failure is suspect. For me, a red flag is the area of work preformed by the shop on the engine. All the seals on the back of the engine involve removal of the ignition housing, the trigger coils are attached to that housing.  Did they damage a trigger coil or wiring? And did they check trigger coil gap clearance before closing it up?

I think I must get them to check the gaps before they install a new trigger coil assembly. Of course this still means pulling the engine again because there’s no room to work apparently. 

Of course the trigger coil assembly is one of the most expensive parts on the engine……. 1400USD give or take. 

I also find it bizarre that Rotax gmbh simply closes for parts etc for 3 weeks!

Hi Mike

I will not work on my holidays, don't know why Rotax would.  The typical procedure for many years is the close for a summer holiday season and also a Christmas break as well.  There are 15 distributors worldwide, those should carry all the required spares.  If they are out then you must wait.  A trigger assembly is not a common part to fail so I think I can understand someone not stocking them. 

On another note, there is no requirement to remove the stator or the triggers when you replace the seal.  The housing can be removed with them left in place, indeed that is the common practice.  The seal can be changed and the compete housing put back on the crankcase. 

Cheers