Oh, THIS Shouldn't Be Happening

LauraE51

LauraE51

Pre-takeoff checklist
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Nov 24, 2013
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272
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Modesto,CA
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Laura
Tried to practice some touch and goes yesterday, just to feel more comfortable after being away for awhile. I started the rental, my favorite C172P with 180HP, taxied down to the run-up area, and did my pre-flight list. The plane had just been through a 100 hr inspection and i was the first to fly afterwards. Run it up to 1700RPM; right magneto, very little drop. Oh, this is good. Left magneto, engine quits (or at least tried to quit). I did this two more times and each time the left magneto seemed to be completely AWOL. Now, a less sane pilot would probably say, "Hey! i've got one good mag and i'm only staying in the pattern. Let's go." The sane me said, "let's taxi back to the ramp and report a squawk, which is what i did.

I didn't log the .2 hours.
 
It's harder to taxi back than to rationalize it and take off. You done good in my book. Did you try to burn it off?
 
iflyvfr said:
It's harder to taxi back than to rationalize it and take off. You done good in my book. Did you try to burn it off?
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I am betting it is more then just a "burn off"....

P lead maybe???:dunno:
 
If you are going to rationalize flying after a problem ,why do the run up? You did fine,I might have tried to clear the mag in case of a fouled plug.
 
roncachamp said:
Did you pay for the .2 hours?
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I was just going to address this. I would definitely log it, but tell them at the rental desk that they better not charge my account for that 0.2. I've done that before when I rented a plane that had a very bad vibration during run up.
 
N801BH said:
I am betting it is more then just a "burn off"....

P lead maybe???:dunno:
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A broken P-lead would let the engine run, not stop it. The one magneto is dead, or maybe they replaced the mag switch and accidentally grounded the wire for that mag. Or, maybe, they did mag work and reversed the P-lead and its shield when connecting them to the mag. Could indeed be a P-lead...
 
172sp don't perform that well on one mag if say you were to do a run up and then not get it back to the both position. Not to say I would know how. On the other hand I would never fly the planes just out of maintenance.
 
Dan Thomas said:
A broken P-lead would let the engine run, not stop it. The one magneto is dead, or maybe they replaced the mag switch and accidentally grounded the wire for that mag. Or, maybe, they did mag work and reversed the P-lead and its shield when connecting them to the mag. Could indeed be a P-lead...
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I didn't say BROKEN...:no::no:
 
Why on gods earth wouldn't you log the .2? A flight so full of experience you opt to post here and share. I'd say it's right up there in the top 10 .2's in your logbook and you decide NOT to log it?

Legally, you taxied out there with the intention of flight. It's legit and legal. It's also the right thing to do. Go put it in the book.

That's MY .02
 
roncachamp said:
Did you pay for the .2 hours?
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No. they were quite apologetic and offered another plane. i took the events as an omen and will fly next week instead. the plane spent the afternoon in the shop.
 
Captain said:
Why on gods earth wouldn't you log the .2? A flight so full of experience you opt to post here and share. I'd say it's right up there in the top 10 .2's in your logbook and you decide NOT to log it?

Legally, you taxied out there with the intention of flight. It's legit and legal. It's also the right thing to do. Go put it in the book.

That's MY .02
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Thanks. i think i will now.
 
Why didn't you log the 0.2? You taxied with the intention of flying.

Edit: Nevermind. Already covered.
 
I don't log aborted flights because I don't see the point. Sure, it's legal, but I didn't learn anything.

I've also never been charged. And when it occurred during lessons, my instructor didn't charge me either (it would have been reasonable).

The "little drop" part indicates the other mag wasn't doing much. You want normal drops -- on a 172, around 75-100 RPM. More or less merits further investigation.
 
I wouldn't log it either but that's me.

I've had this happen twice, once a fouled plug that I couldn't burn clean, and once an alternator that died. Neither time did I pay for the hobbs time. Any FBO would be crazy to try and charge someone for that, but I suppose they're out there.
 
Not much to add but in case anyone is tallying the votes....

This exact scenario happened to me. I didn't log the time and I didn't pay for the time.
 
Logging and paying are two separate issues.

With that said, compare two flights; one normal and one with a mechanical ground turn back.

The normal flight takes .2 to get to the runway and back from the runway after the flight. Everyone here logs that .2 despite not much going on except normal stuff.

The ground turn back is normal right up to where you use your skill and experience to suss out the pertinent information and make a really tough decision...one that could actually be life or death.

Why would you log the normal and routine but not the one where experience is being built? I'd log it just to highlight those days and put a remarks comment describing what happened. It's not even really about the .2 IMO.
 
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I've returned 2 planes to the FBO in the same day. I'm happier to do that than to fly a plane that might not get me back.
 
MAKG1 said:
I don't log aborted flights because I don't see the point. Sure, it's legal, but I didn't learn anything...
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I think I've learned something on every aborted flight. There's always some new way for stuff to break. In the OP's shoes, I would log it, and the symptoms, then pursue the cause and fix with the FBO and log that once he gets it.
 
yetti said:
On the other hand I would never fly the planes just out of maintenance.
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???

So if a plane you want just comes out of maintenance, you'd sit around and wait for someone else to fly it before you'd check it out?

I'm guessing airplane ownership is not in your future.
 
Dan Thomas said:
A broken P-lead would let the engine run, not stop it. The one magneto is dead, or maybe they replaced the mag switch and accidentally grounded the wire for that mag. Or, maybe, they did mag work and reversed the P-lead and its shield when connecting them to the mag. Could indeed be a P-lead...
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However, P-leads are a thin cheap, mostly overlooked and neglected piece of wire typically as old as the airplane that drapes all over stuff that eventually will chafe through, or crack from heat and age, and ground out, shutting the mag down.

The P-lead is the first place I look for any sporadic mag failures, tracing from the mag to the switch. If I get to the switch without finding a glitch in the wire, 80% of the time the problem will be in the switch, especially Bendix key switches.
 
Fearless Tower said:
???

So if a plane you want just comes out of maintenance, you'd sit around and wait for someone else to fly it before you'd check it out?

I'm guessing airplane ownership is not in your future.
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:rofl::rofl::rofl: That's for sure. Heck, pretty much every time I flew my plane it was, 'just out of maintenance.':rofl:
 
That's the kind of pickey pilot rental people hate. They have two mags on the plane for a reason if one fails the plane will fly on the other. What's next return to the ramp for a full ashtray or some other lame reason. Don't be such a wimp, real pilots fly and take planes with all sorts of problems, they might not live long but their not wimps.
 
Don't Mech's do a runup before returning airplanes to the line for rental? Seems something so obvious should never been given to a Rental Customer... And if not, maybe the FBO should have a practice of flying the airplane before making it available for rental.:dunno:
 
Sometimes they do.

I've picked up an airplane from annual before, with a cracked oil filter. Obviously not run up.

Note that a problem that shows up right after annual might possibly be coincidence. Maybe the mag/lead/whatever broke on engine start. Lots of stuff shakes around.
 
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FlySince9 said:
Don't Mech's do a runup before returning airplanes to the line for rental? Seems something so obvious should never been given to a Rental Customer... And if not, maybe the FBO should have a practice of flying the airplane before making it available for rental.:dunno:
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Brief maint run ups don't always show a problem, sometimes mechanics fly them for the return to service, but not typically. As for FBO staff, really they should before they rent it out, but again, this is not typical.
 
yetti said:
On the other hand I would never fly the planes just out of maintenance.
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Unless you think the other renters are more capable than you of dealing with a mechanical problem if one arises, isn't it unfair to have them shoulder all the perceived risk without your doing your share?
 
bbridges51 said:
Now, a less sane pilot would probably say, "Hey! i've got one good mag and i'm only staying in the pattern. Let's go." The sane me said, "let's taxi back to the ramp and report a squawk, which is what i did.
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Not just that, but when you're operating on a single mag you're operating at reduced power. That's the reason for the mag drop. It would take a special kind of fool to take off with a bad mag. Most of those fools don't bother checking mags, I suspect.

bbridges51 said:
No. they were quite apologetic and offered another plane. i took the events as an omen and will fly next week instead. the plane spent the afternoon in the shop.
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Hmmm...omen?

bbridges51 said:
Tried to practice some touch and goes yesterday, just to feel more comfortable after being away for awhile.
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I suspect you were nervous in the first place about flying, and used the bad ag as an excuse to scrub flying for the day. Trust me, we've all been there before. The best way to change that mild anxiety into healthy respect would have been to jump into that other 172 and fly. I promise that after the first circuit in the pattern you'd have been fine. Gotta leave that comfort zone every once in a while.

Now if you question the FBO's maintenance practices, well that's a different story.

Fly safe.
 
You made the right call. Good job! That's exactly what the runup is for.

I wouldn't take off with one mag. Other pilots might, but it's their life on the line, not mine. I'm all about reducing risk.
 
fiveoboy01 said:
I wouldn't log it either but that's me.
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I'm the same way. Don't care if I learned anything or not, looks dumb putting time in the logbook with no T/O or landing logged. If anything I'll just remember it and tack the .2 on the next flight I do.
 
This happened to me once when I was with my instructor. He had me turn to the bad mag and run up the engine to just below redline for a minute or two. I guess they can get carbon built up on them which causes them to loose their effectiveness and somehow, from the heat of the engine, burns that carbon off and cleans it up. After doing that, we checked both mags again at 1800 rpm and they were fine.
 
rachelk.tailwinds said:
This happened to me once when I was with my instructor. He had me turn to the bad mag and run up the engine to just below redline for a minute or two. I guess they can get carbon built up on them which causes them to loose their effectiveness and somehow, from the heat of the engine, burns that carbon off and cleans it up. After doing that, we checked both mags again at 1800 rpm and they were fine.
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A little different from what the OP experienced. When you isolate the mag with a fouled plug the engine will run rough (i.e. only one of cylinders is not firing) but will not cut out, as decribed by the OP.

But yes, if one of the mags is rough, bringing the power up on both mags and leaning the mixture will cause the temperature inside the cylinder to increase enough to "cook off" whatever lead/carbon has built up. Plugs probably still need a good cleaning though.
 
jordane93 said:
At the school I work at, we don't charge for the hobbs if the student came back due to maintenance.
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I've never heard of a place that does charge if the aircraft does not leave the ground. There may be such places but they would not get my business more than that one time.
 
rachelk.tailwinds said:
This happened to me once when I was with my instructor. He had me turn to the bad mag and run up the engine to just below redline for a minute or two. I guess they can get carbon built up on them which causes them to loose their effectiveness and somehow, from the heat of the engine, burns that carbon off and cleans it up. After doing that, we checked both mags again at 1800 rpm and they were fine.
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He should have had you do it on both mags. You find the issue when you are on just one mag but you cure it on both.
 
What C-172P has 180HP?

Good on you for turning around. Go log it.
 
Gucci Pilot said:
I'm the same way. Don't care if I learned anything or not, looks dumb putting time in the logbook with no T/O or landing logged. If anything I'll just remember it and tack the .2 on the next flight I do.
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Same here. While the time spent taxiing and running up counts towards my flight time if I leave the ground, if I don't leave the ground I do not log it. I also do not add it to a later flight. The idea that "well there was the intent to fly" is pure silliness in my mind. The flight just became a ground run up. That is all it was. Just like the countless ones (and countless hours) I have done on everything from Cessna 150s to L-1011s.

To each their own. I guess.
 
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