Magneto question

[Oldsalt]

I had one of my magnetos shot out the other day and I slowly lost power until I had to make a forced landing in England.

I slapped my forehead later when I realized that I should've moved the mag switch from 'both' to whichever mag was still working. If I had done that, would I have been able to make it back, or would it not have made a difference?

[69th_Zeb]

Theoretically you should be able to shut off the offending mag and use the other.
I know on some piston aircraft engines, a single locked up mag will destroy the accessory gearbox downstream the gears and generate serial numbers in the oil pan. I've also heard of occasions were it caused the engine to stop completely.

-Z

[Oldsalt]

Theoretically you should be able to shut off the offending mag and use the other.
I know on some piston aircraft engines, a single locked up mag will destroy the accessory gearbox downstream the gears and generate serial numbers in the oil pan. I've also heard of occasions were it caused the engine to stop completely.

-Z

Wow, I've never heard of a failed mag destroying gears downstream, it must not happen very often. In reality while your performance is diminished, you should be able to fly all day on one mag if you have to.

I was wondering if they had modeled that in the sim or not. If they modeled two, then it should lose power, but be able to stay in the air. If they modeled only one and it failed, the engine should quit, but mine kept running for a quite a while.

[69th_Zeb]

Yeah, it's pretty rare. A lot of pilots and mechanics get complacent because there's dual ignition. Most mags fail internally at the cam/points/distributor and not at the drive end. That wouldn't cause engine failure. But if the drive adapter is installed incorrectly, the impulse coupling rivets get worn and fail,...or the unit gets hit by a bullet .....the broken gear may uncouple both mags causing instant shutdown. As of '92, the NTSB (US) has cited mag failure to be a cause or factor in 92 accidents involving 22 fatalities and 21 serious.¹

A few weeks back, I heard some misfiring and a low mag drop in our run-up area and the pilot took off anyway (might have fouled a plug idling around rich too, which can be cleared). Just a bit sketchy with all those moving parts.


¹The Magneto Ignition System, John Schwaner

[Baffin]

From someone who's been there... done that. Two war stories:

Owned a Cessna 172 and forgot to return the mags to "Both" after the runup. Full load, 4 souls... what an amateur mistake! RPM checked OK on takeoff and the craft felt normal until starting to climb after takeoff. With safe clearance from the treetops, my hands were full just staying away from the Vstall so I failed to check the switch until after the safe return landing at the departure field. This big, bad professional pilot felt quite foolish after that. Do the checklist, Lieutenant!

-----------------------

Some months after that, while on 1 mile final to Lincoln Muni (Nebraska) the engine just quit. That ain't right... Mags-Both, clear air (no icing), fuel-1/4 tank (Right where it's supposed to be). It was like a check-ride... do I stretch the glide or land in Farmer Brown's field? If my glide came up short, I would be on US route 34 challenging the 18 wheelers for right-of-way, so I had to find a field to glide into. Find a field? I'm in Nebraska... it IS a field!

So, I landed in some guy's pasture which was basically his back yard. Guess where he worked? At an FBO (Airplane service station) at Lincoln Municipal Airport! We quickly determined that I was out of fuel, so the helpful homeowner had some gas brought out so I could fly back to Lincoln. Our friendly FAA inspector was there to "help" so I was released to fly home with Mrs. Baffin and the Baffin kids and cats. What a day!

Back at the home drome, I had that plane inspected to find that the fuel gauge was in need of calibration, and that one of the magnetos, which was fine for a while after startup, had gradually failed as it warmed up during the flight down to about 10% output. As the mag deteriorated, I naturally just increased the throttle to compensate. Without a fuel flow gauge, there was no way to tell that anything was wrong. The faulty fuel gauge showed exactly the amount of fuel remaining that I had planned for but the increased throttle burned more fuel than was planned for. Magnetos can be sneaky!

I had the fuel gauge fixed, and the magneto replaced, but Mrs. Baffin refused to fly any more!

I suspect that I'm one of the very few pilots ever who ran out of gas and was not given a "Violation" by the FAA. They sent me a nice note explaining their agreement with me that
it just "wasn't my day!"

[Oldsalt]

Wow again, amazing stories.

That's great advice on check lists. I was a check list fanatic and probably added more items than needed, but I can't remember sh_t.

Having a fuel gauge and mag failure at the same time, was awfully bad timing, it seems that luck is your co-pilot. I wonder if statistics would show a difference between surviving a forced landing in a billiard table state like Nebraska verses mountainous ones like Colorado or California.

It's one thing finding an unplowed field that's large and flat enough, with no obstructions, ruts and holes to survive a forced landing on. But taking off from the same field, with your family no less, that's amazing! It's too bad it turned your wife off to flying, besides being scared, she should have also been impressed at how you handled it.

I'm just a PP, flew for 24 years and was lucky not having to deal with a serious problem and I flew planes built in the early 40's and 50's. I don't have any war stories, but I had what you might call a 'skirmish' story.

I was flying a Cub over the Santa Cruz mountains when the engine started coughing. I immediately told my front passenger to pull the carb heat control (difficult to reach with a passenger) and it cleared right up in about 10 seconds. No big deal, but I was amazed at how fast I reacted without thinking about it. Thankfully flight training is so thorough!

Btw, I can't imagine taking off with a misfiring engine, that's just crazy.

Do you have any war stories about having your mag shot out in CLoD and if so, what happened?

[Baffin]

I agree 100% about training! Even after we have the ticket in our wallet, it's real important to continue to practice simulated forced landings to go-arounds as well as accuracy landings at the home drome. (And in our CLoD sim too) I used to instruct mountain ops over the Reno / Lake Tahoe area out of SAC Executive back in the late 70's, and always emphasized the need for a plan and some practice in case the ol' prop ever quits spinning!

By the way, quit selling yourself short about "Only" a thousand hours in SEL tail-draggers... its about a thousand hours more than I've got. We all specialize according to our certificates and I have more respect for a good Private pilot than I do for a lousy Commercial pilot any day!

Since I elect to receive no text feedback on systems like Magnetos in CLoD, I can't advise on single Spark plug ops. If mine quit in the game, I never know the reason for the diminished performance. I just have to deal with it, just like in Lincoln.

[69th_Zeb]

That's a good one Baffin that I wouldn't have thought about. Maybe your humility will save my bacon someday. I like the fuel gauges on the super cubs that you can see. And yeah, sometimes pulling the carb heat too late will make it worse. Kinda scary.
I landed (under instruction) a 172 in Omaha once...close enough right? Everything looks safe from on high though then the cottonwoods and corn get close fast....but you can count on a water tower if you get lost and can't tune in to the nearest VOR.

I'm planning on overhauling our Luscombe project's C90 late winter, and I get uneasy about it. Mags are up there on the list too. They typically get neglected, and I don't trust the stamped dataplates. A lot of moving parts.

-Z