Not quite an engine failure...

SkyHog

Touchdown! Greaser!
Joined
Feb 23, 2005
Messages
18,431
Location
Castle Rock, CO
Display Name

Display name:
Everything Offends Me
But its a very disturbing feeling to be in the middle of the flare and see the propeller stop spinning out front of the airplane.

I was doing touch and goes today, and on one of the landings, my engine quit on me. I coasted off the runway and past the hold short line, and the engine started back up. As I taxiied back towards the hangar, the engine quit on me again. Both times it happened when the throttle was pulled to idle.

I started up again and got almost to the hangar and the engine quit again. At this time, I gave up, secured the airplane and walked to the hangar to grab the tow bar and manually tug my plane to the hangar (good lord my plane is heavy).

After talking to one of the other owners, we're thinking one of the mags went bad. I didn't even think about trying the mags separately, so I don't know. We're gonna have someone look at it tomorrow. Its a good thing it didn't happen in the air tho. Whew!
 
I've had that happen several times doing touch and gos in a POS Cessna 150 that I did my primary training in.

This was always during the winter. I always used carb heat. So I'm not sure what the deal was, But I eventually got to where I knew how to work the throttle just right to avoid it.

This almost sounds like your idle is set too low?
 
Seems to me it's a fuel delivery problem. What did the other owner say that makes you think it's a mag problem?
 
Richard said:
Seems to me it's a fuel delivery problem. What did the other owner say that makes you think it's a mag problem?

He said "well, if it only happens when the throttle is pulled to idle, it could be a bad mag."

Heh - I'm not so smart with this stuff. I assume he's right, because he is.
 
Could be a ton of things.

You need compresion, fuel, and ignition.

I'm sure the compression is fine.


I'm saying fuel delivery. If it happens when you pull it to idle I'd say either the mixture isn't right.. Or the idle is just too slow.

Could be a ton of things.

You need compresion, fuel, and ignition.

I'm sure the compression is fine.

I also doubt it's a mag. It's possible I suppose a t alow RPM the miss would be much more obvious..to the point to where it would quit running.

I'm saying fuel delivery. If it happens when you pull it to idle I'd say either the mixture isn't right.. Or the idle is just too slow.

Maybe it's too lean? ...colder temp means denser air...perhaps now that it's colder out the problem is more obvious with the mixture being set incorrectly, or the idle too low.


Let us know when you find out.
 
Last edited:
Didnt you say you recently had the idle lowered? I would start there. I noticed when you had it out here, the idle did seem a tad low when the power was pulled. not quite sputtering, but almost there.
 
SkyHog said:
He said "well, if it only happens when the throttle is pulled to idle, it could be a bad mag."

Heh - I'm not so smart with this stuff. I assume he's right, because he is.
No #1 rule of troubleshooting is to start with least expensive and easiest first. Before hopping straight to the mags I'd at least check fuel flow and spark plugs. Maybe accelerator pump is acting up. You didn't provide many specifics so it's all a WAG right now.

Oh yeah, let the learning begin... Jesse did mention air temp and density. Your at alt too...see where we're going with this?
 
Last edited:
Richard said:
No #1 rule of troubleshooting is to start with least expensive and easiest first. Before hopping straight to the mags I'd at least check fuel flow and spark plugs. Maybe accelerator pump is acting up. You didn't provide many specifics so it's all a WAG right now.

Oh yeah, let the learning begin... Jesse did mention air temp and density. Your at alt too...see where we're going with this?

ok - lemme try to give the best specifics I can (once again, I'm not very good at this stuff).

I thought at first, I pulled a stupid and pulled the mixture instead of the throttle, after coasting off the runway, I verified that it was not the mixture, as it was leaned properly.

The temperature was 6, with the dewpoint -16. I don't think that's a Carb Ice area, but I still used carb ice on approach (always turn it off on short final now).

The engine only died when the throttle was pulled towards full idle, which is set too low IMHO, but other owners disagree and wanted it set as low as it is.

I didn't do a lot of troubleshooting because I needed to get to class, and I also didn't want to be taking up the taxiway with the engine dieing, so I got towards the ramp and then pulled it manually back to the hangar.

Not sure what DA could matter, but using DA chart quickly, DA should have been around 4000ft, with field elevation of 5800. I always lean here anyways, but as a double check, after the first time the engine died, I used full rich mixture as a test.

I'm sure we'll find out whats up tomorrow. We have the mechanic coming to take a look if he's available.
 
SkyHog said:
He said "well, if it only happens when the throttle is pulled to idle, it could be a bad mag."

Heh - I'm not so smart with this stuff. I assume he's right, because he is.

Sounds more like you need to adjust the carb. If temprature drops signifigantly, you often have to do that, heck you need to do it reasonably often even in a moderate climate. While they're at it all uncowled, you might as well check the timing. Points wear and causes timing to change. Typically, this isn't signifigant. If those two simple items don't cure it, you may need to pull the carb and clean the idle metering circuit, could have a chunk of crud in it (doesn't take much) starving it of idle circuit fuel, and one you crack the throttle you go to the main metering circuit. Still not a big deal unless you have to use a shop that rapes you. If they're good people, might have them clean the carb on the first go at it, although I'd rather do it in three stages to find what the problem is. I list them in order of greatest probability/lowest cost first. It's not a biggie problem as it stands, but if it is crud in the fuel, you'll probably want to do something about that soon. IIRC you have a PA 28 and I don't think there's any bladders or sealant in those tanks, so it would probably just be changing out some rubber fuel lines that are deteriorating in the wing-fuselage area, those rarely get changed every 5 years.

PS As to Idle speed...You obviously don't want it too high so you throw crap all over the ramp and you have to stand on the brakes to hold position, but you dont want to go too low either. Most 4 cyl lyc engines don't appreciate running below 650. The only time you really have any need or desire to turn slower is with a seaplane, and I'm guessing your Cherokee isn't on floats. Some times in colder weather you need to even turn them up a bit to keep them smooth. You don't want it shaking, it tears up way too much stuff, read Christmas $$$$$ gone to the mechanics. Even idling 700-750 is fine if it smooths things out. Start there. If it's still not idling right at 725, dig further.
 
Last edited:
I'm with Henning -- while it could be a mag, or fuel feed, what happened to you is typical of a carb problem. In any event, get it seen to before you fly that plane again.
 
Michael said:
:hairraise: Must be for the thrill factor.

lol - silly brainless typing. My bad. That should read "carb heat."

heh

Ron Levy said:
I'm with Henning -- while it could be a mag, or fuel feed, what happened to you is typical of a carb problem. In any event, get it seen to before you fly that plane again.

Yeah, I grounded the plane. Its not going anywhere until we get it checked.

odd...I thought the automerge was being turned off. c'est la vie.
 
Last edited:
Nick;

I had a simular situation with a 182 25 years ago. On flare as I eased off the power the engine speed dropped below normal idle so I added just enough to mantain normal idle speed. Interesting the weather had changed drastically from very humid and warm to cool and dry. First thing I did was check the carb and that fixed the problem.

Let us know what comes of it

John
 
SkyHog said:
But its a very disturbing feeling to be in the middle of the flare and see the propeller stop spinning out front of the airplane.

I was doing touch and goes today, and on one of the landings, my engine quit on me. I coasted off the runway and past the hold short line, and the engine started back up. As I taxiied back towards the hangar, the engine quit on me again. Both times it happened when the throttle was pulled to idle.

I started up again and got almost to the hangar and the engine quit again. At this time, I gave up, secured the airplane and walked to the hangar to grab the tow bar and manually tug my plane to the hangar (good lord my plane is heavy).

After talking to one of the other owners, we're thinking one of the mags went bad. I didn't even think about trying the mags separately, so I don't know. We're gonna have someone look at it tomorrow. Its a good thing it didn't happen in the air tho. Whew!

Got into the habit of holding about 1000 RPM LDG in an AeroCommander 112A that did that to me on the rollout.

The shop eventually adjusted the idle.
 
I vote for carb icing or crud. I had this happen to me in the air (stop, start, stop, start, etc.), but it wasn't carb icing. It smoothed out right before I made my emergency landing (at the airport--it kept going long enough to bypass several emergency landing areas and make back it to the airport, and I had lots of altitude, too). Mechanic checked it with fine-toothed comb and it never happened again, hence the diagnosis of crud.

One lost mag wouldn't do it. Once I accidently set the mags on "right" instead of "both" after the mag check and when I finally discovered the error and set them to "both" I hardly noticed the difference. In fact I didn't notice the difference. I was operating at high density altitude and there was nothing unusual about the take-off at all.

Judy
 
judypilot said:
Once I accidently set the mags on "right" instead of "both" after the mag check and when I finally discovered the error and set them to "both" I hardly noticed the difference. In fact I didn't notice the difference. Judy

Ah, another candidate for an engine analyzer!

As to the original post, I think fuel too...crud, improper idle speed adjustment
 
Back
Top