Lost a mag in-flight today...

M

mtuomi

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dera
No. Lost it. Literally.

11781709_10153323733123673_1495738184460162186_n.jpg

Sure does wake you up I can tell you that.
 
Slightly rough running engine, 4 quarts of oil everywhere and a precautionary landing somewhere in Alabama.
 
Ouch! Glad you made it safely to a point that you could snap a pic. Is there more to the story? Looks like you're missing some hardware.
 
Wow! That is a long flight from Seoul. Good thing you didn't lose it over the Pacific... :wink2:
 
Looks like you lost some oil. The mag is right there in the picture. With all these mags falling off there is an AD to be issued somewhere.
 
The top clamp it seems have been missing for a while, something you dont really see on an early Arrow w/o taking the cowling off.

And yes, I know the mag is in the pic :p

I guess it needs an accident before they would consider an AD. There are a few different kinds of clamps for the mags which I learned today. I think they might've used a wrong kind. Im just glad it didnt happen an hr later to the flight, not much to land on in rural Alabama...
 
Curious if the correct clamp was installed as there are several out there that kinda fit.
 
bnt83 said:
Curious if the correct clamp was installed as there are several out there that kinda fit.
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Yep, the bottom one was the wrong type. Looks identical but the clamping point is a few mm off. So im guessing they had the wrong ones in there.

LH is a different design. We did check and they seem ok.
 
Geico266 said:
I've always wondered why we safety wire the oil filter on, but not the mags.
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Thats a very good question. Having 4qrts of oil on the windscreen made be think perhaps anything that opens up to the crankcase shld be safety wired...

I hope the plane owner has a bottle of whisky for me... I saved his 25k engine and initial comment was that I never should've taken off w that... :)
 
I think the lesson to learn from this is know how to divert.
Also, and I didn't do this but from now on I will - check out which airports on your way have services available. I got lucky this time with maintenance. Dont be me.
 
Geico266 said:
I've always wondered why we safety wire the oil filter on, but not the mags.
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Because the mag hardware is the clamp, 1 flat washer, 1 lock washer and a nut, for each post.

Half the the aircraft I inspect, some one left the lock washer off, or the lock washer is too well worn to be a lock washer.

I change them to a self locking type nut, and leave the lock washer off. never a problem after that.
 
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mtuomi said:
I guess it needs an accident before they would consider an AD. There are a few different kinds of clamps for the mags which I learned today. I think they might've used a wrong kind. Im just glad it didnt happen an hr later to the flight, not much to land on in rural Alabama...
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No AD, but I believe there is a service bulletin on using incorrect mag clamps.
 
Tom, it is a solution - until it is years later and the mechanic has had the mag off 6 times and still using the same self locking nut.
There's no cure for stupid :dunno:
 
The only option is to weld it on. :eek: :D
 
Wow, you handled it well, but that was an "interesting" flight.
 
Tom-D said:
Because the mag hardware is the clamp, 1 flat washer, 1 lock washer and a nut, for each post.

Half the the aircraft I inspect, some one left the lock washer off, or the lock washer is too well worn to be a lock washer.

I change them to a self locking type nut, and leave the lock washer off. never a problem after that.
Click to expand...

Curiosity question: as an A&P, how much latitude do you have to change out fasteners like that? (I'm not an A&P and I'd just like to know. This sounds like a really good idea.)

John
 
Another issue is the correct gasket and proper torque. Over tightening the nuts can crack the mounting flanges.

It's pretty simple, use the correct hardware, use the correct gasket and use a torque wrench set to the proper torque. Keep a bag of lockwashers on hand.

PS, sometimes I wonder if mechanics tend to dink with the timing too much, which would accelerate the wear on the nuts, washers, clamps and even the magneto mounting flanges.
 
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Dr. O said:
Tom, it is a solution - until it is years later and the mechanic has had the mag off 6 times and still using the same self locking nut.
There's no cure for stupid :dunno:
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There ya go, Ya gotta be smarter than the average nut.
 
jsstevens said:
Curiosity question: as an A&P, how much latitude do you have to change out fasteners like that? (I'm not an A&P and I'd just like to know. This sounds like a really good idea.)

John
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Like many other minor changes, we just do it and say nothing.

Any inspector that violates you for some thing like this is after you are a different reason. or just flexing their authority.
 
bnt83 said:
Another issue is the correct gasket and proper torque. Over tightening the nuts can crack the mounting flanges.

It's pretty simple, use the correct hardware, use the correct gasket and use a torque wrench set to the proper torque. Keep a bag of lockwashers on hand.

And how many mechanics do you see doing that?

PS, sometimes I wonder if mechanics tend to dink with the timing too much, which would accelerate the wear on the nuts, washers, clamps and even the magneto mounting flanges.
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If you comply with the maintenance many owners think is required every 500 hours, the mag will be off 4 times in the TBO of the engine, but in most cases the timing will be tweaked at each 100 hour or the annual which could be 15-20 times prior to overhaul.

In reality mag maintenance varies with every combination of A&P/ vs/ owner you can think of.
 
bnt83 said:
There are no documents that support using a self locking nut for this application.
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Not all of us need documentation to use common sense.
 
mtuomi said:
11781709_10153323733123673_1495738184460162186_n.jpg
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In a case like this, I'd be very careful on how the gears in the accessory case were inspected. I'll bet those gears did not disengage gracefully, if you know what I mean.
 
Tom-D said:
If you comply with the maintenance many owners think is required every 500 hours, the mag will be off 4 times in the TBO of the engine, but in most cases the timing will be tweaked at each 100 hour or the annual which could be 15-20 times prior to overhaul.

In reality mag maintenance varies with every combination of A&P/ vs/ owner you can think of.
Click to expand...

In the last couple of months we've had two airplanes whose magnetos had been ignored for 1300 hours or so. The engines didn't run right. All four mags were found to be beyond economical repair due to the filth that had accumulated in them and allowed internal arcing and so on. I'm seeing this sort of thing far too often. And new mags aren't cheap. The 500-hour checks are a bargain as far as I'm concerned.
 
Dan Thomas said:
In the last couple of months we've had two airplanes whose magnetos had been ignored for 1300 hours or so. The engines didn't run right. All four mags were found to be beyond economical repair due to the filth that had accumulated in them and allowed internal arcing and so on. I'm seeing this sort of thing far too often. And new mags aren't cheap. The 500-hour checks are a bargain as far as I'm concerned.
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Mags themselves are not here to blame. The humans who rebuild them, produce parts for them and install them are to blame. The magneto does not have conscience, will or thoughts. It cannot decide to commit suicide. It is incapable of any feelings or emotions.
The humans are always to blame for either improper manufacture of the replacement part, improper assembly or improper installation. If a mag fails (shreds itself) in under 300 hours, I call BS on the manufacturer's/rebuilder's QC.

So if a mag is manufactured/rebuilt properly, installer properly and maintained properly (every 500 hours), it should last a while. Too bad we don't get to enjoy this luxury.

Mtuomi, glad you got her down safely and very sorry that you're stuck in redneck hell but hopefully you'll be out of there soon.
 
BigBadLou said:
So if a mag is manufactured/rebuilt properly, installer properly and maintained properly
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That is three very big Ifs

We mechanics do not see the aircraft/system until there is a reason for the owner to bring it in.
If weren't for the annual requirement, we would never see many aircraft.
 
Dan Thomas said:
In the last couple of months we've had two airplanes whose magnetos had been ignored for 1300 hours or so. The engines didn't run right. All four mags were found to be beyond economical repair due to the filth that had accumulated in them and allowed internal arcing and so on. I'm seeing this sort of thing far too often. And new mags aren't cheap. The 500-hour checks are a bargain as far as I'm concerned.
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Yep, magnetos have several points of wear, and the distributor area needs the occasional dusting out. Thing is about adjusting timing by the case as time progresses is that it's the wrong thing to address. Points are what need adjusting with time, dwell affects timing. However if you address the timing issue by turning the case, you still have screwed up dwell and reduced performance from the coil. Too bad aircraft mags don't use an old GM points set that you could dial in with an Allen wrench through a window. Then you would never have to loosen those nuts and twist the case to bring the full timing set back to spec, you just set the timing mark and twist the wrench until you get the break.
 
Henning said:
Too bad aircraft mags don't use an old GM points set that you could dial in with an Allen wrench through a window. Then you would never have to loosen those nuts and twist the case to bring the full timing set back to spec, you just set the timing mark and twist the wrench until you get the break.
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The old cars used a dwell meter for that, and it would be suicide to try that on an airplane. The only method I'm aware of is to fix the rotor at the specified position (which can't be seen from outside the mag) and set the points there. Besides, I've never seen points that were much good beyond 1000 hours.

I wish E-Mag would get their stuff together and certify their units for OEM replacement. No points in there, and with a bit more work they could probably eliminate the distributor as well. Use the waste-spark system that has two coils for a four-banger and three for a six.
 
Dan Thomas said:
The old cars used a dwell meter for that, and it would be suicide to try that on an airplane. The only method I'm aware of is to fix the rotor at the specified position (which can't be seen from outside the mag) and set the points there. Besides, I've never seen points that were much good beyond 1000 hours.

I wish E-Mag would get their stuff together and certify their units for OEM replacement. No points in there, and with a bit more work they could probably eliminate the distributor as well. Use the waste-spark system that has two coils for a four-banger and three for a six.
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Mags are at the back of the engine, if it was designed for a simple adjustment window using the old style Allen tip on a spring shaft screwdriver, it wouldn't be a problem to set them with a dwell meter at all. However it would be unnecessary, you can just meter the point break and measure the gap. We adjust fuel servos with the engine running, and they are even closer to the prop.

But yeah, an electronic replacement with its own alternator is far overdue.
 
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"The top clamp it seems have been missing for a while, something you dont really see on an early Arrow w/o taking the cowling off."

Another Reason I like my Comanche so much. Open up the cowl for every pre-flight. Touch the mags, exhaust nuts, inspect security of control cables and a hoses and a myriad of other things, right in front of you. I've caught a loose ignition harness at the mag, oil cooler hose laying against an exhaust pipe and other less trivial items.
 
comanche pilot said:
Another Reason I like my Comanche so much. Open up the cowl for every pre-flight. Touch the mags, exhaust nuts, inspect security of control cables and a hoses and a myriad of other things, right in front of you. I've caught a loose ignition harness at the mag, oil cooler hose laying against an exhaust pipe and other less trivial items.
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Same here, love the accessibility on my Piper. Can't imagine flying a Cessna and only opening the oil dipstick door. I want to see the whole engine and check/touch things during preflight, otherwise I won't be happy.
Pilots can catch a LOT of things during a preflight or postflight inspection of the engine, before they turn into a full-blown engine failure in flight.
 
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