G'day,

Whilst going through my CPL KDR's with the ATO, he asked, what's the danger of taking off with a live magneto? Now obviously I know the danger of a live magneto on the ground - stay away from the prop! But in flight, the only thing I can come up with is that in the event of an emergency & a forced landing, you're unable to shut the maggy off and there's a danger of fire on impact if the forced landing doesn't go to plan.

Can anyone else shed some light?

thanks in advance,

Stew

In addition to what you said about not being able to shut the engine off after a forced landing, you could also not be able to safely disembark the aircraft after landing. And if that induces a fire, you could be in a whole world of pain

Seem's like a very odd question to ask as nearly all of us here know the danger on the ground, but I've never heard of a question like that being asked

Aaron

Also found this line in a document:

However, if for any reason ‘off’ is inadvertently selected, you should leave the switch at that position, select mixture to idle cut-off, and allow the engine to stop completely. Otherwise, accumulated unburnt fuel may ignite in the manifolds (backfire or exhaust explosion) and/or in the engine on the piston up-stroke causing kickback and possible mechanical damage.

www.casa.gov.au/wcmswr/_assets/main/fsa/1998/mar/22-25.pdf

Thanks Aaron. The ATO's question, having described the symptoms you get during run-up of a live magneto, went somewhere along the lines of - is it safe to take-off with a live magneto? He then used a hypothetical that it's your first job, you're returning to base and you've just done a run-up and found a live maggy, you call your boss to say you can't leave but he says don't worry about it, it's still working, just come back and we will get it fixed here. To which I replied no you can't take-off but could not really elaborate on why more than what I've written here in my first post.

I wouldn't take off because technically the magneto is unserviceable and if an accident or incident results, CASA will come looking for you and ask why you took off knowing the magneto was live, resulting in a potential end to your career in aviation

Bobby Tait, Rich Andrews, what do you blokes reckon?

Interesting question. Although technically the aircraft will fly with a live magneto, I think the problem would be with you fulfilling your responsibilities as pilot in command when checking the functioning of both mags, a required part of the pre-take-off checks.

Here's some regs to back up your decision to not take-off:
If your flight manual requires a magneto check and your magneto check indicates a "malfunctioning in any particular" you shouldn't take-off. Add the fact this is a "strict liability" offence (read: no excuses), and you can probably see, you are handing your bum to CASA on a plate if you take off.

That's my interpretation of the regs of the thing but I admit it would be a hard call under some circumstances. I won't say what I would do in this case, I just present what I think might be relevant regs for you, so you can make an informed decision as pilot in command.

Is that diplomatic enough?

Cheers,

Rich