One aviation accident that is completely avoidable.

[kortopates]

My shutdown checklist includes putting the keys on the glareshield.  It sucks on hot sunny days, though, they get hot real fast  
I get paranoid about the best way to move the prop.  Turning it backwards means you're grabbing onto the leading edge, so if it somewhat kicks forwards, it could drag you into the prop.  Turning it forwards means a spark is more likely with a hot mag, but then you're pulling on the face of the blade, so if it kicks forwards it won't pull you in.
I wonder if the safest way would be turning it backwards while standing behind the prop (on the left side).  Then you could pull it by the rear face of the blade, and you wouldn't get pulled in if it turns.  It's kind of an awkward place to stand, though

It can’t pop turning backwards!


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[Marauder]

3 hours ago, PTK said:

Kathryn's Report says "...The plane was grounded and running when Kramer was hit in the head by the plane's spinning propeller..."

http://www.kathrynsreport.com/2018/07/cessna-182p-skylane-n1311s-fatal.html

My guess is that he forgot the nose wheel chocks. Left it running, had his parking brake on or possibly his wife on the brakes. Got out and got hit when he reached under to pull the chocks.

[jaylw314]

16 minutes ago, kortopates said:

It can’t pop turning backwards!


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That doesn't mean I'm not paranoid about it!!

[jaylw314]

12 hours ago, DonMuncy said:

Not if you do it quickly. Don't try this with the engine running very fast; but at idle, I have never had it happen, and I do it at every shut- down.

I think it'd be better to go ahead and shut down the engine if your going to do a P-lead check.  If you have a hot mag that is also weak, or there is anything else wrong with your air/fuel mix, the engine will begin to stumble even though it's running on the hot mag.  If you don't let the engine come to a complete stop, how will you tell the mag is actually hot?  I think it makes more sense to shut it down completely as in the Bendix ignition switch AD, and do that once every couple weeks.  If you're worried about leaving unburnt fuel in the cylinders, just start the motor up for a minute after the P-lead check, then do a normal shut down.

[jaylw314]

8 hours ago, teejayevans said:

Doesn’t the runup sequence accomplish the same thing, instead of turning off both, you turn 1 off at a time. If P lead was broken and mag was not turning off, you would not get RPM drop, etc

I think the idea is that the runup checks it before the flight, but there could be enough vibration during the flight to create a new issue like a broken P-lead.

Also, some ignition switches have been known to fail in the OFF position, which is not tested during the runup.

[kortopates]

17 minutes ago, jaylw314 said:

I think it'd be better to go ahead and shut down the engine if your going to do a P-lead check.  If you have a hot mag that is also weak, or there is anything else wrong with your air/fuel mix, the engine will begin to stumble even though it's running on the hot mag.  If you don't let the engine come to a complete stop, how will you tell the mag is actually hot?  I think it makes more sense to shut it down completely as in the Bendix ignition switch AD, and do that once every couple weeks.  If you're worried about leaving unburnt fuel in the cylinders, just start the motor up for a minute after the P-lead check, then do a normal shut down.

You'll be able to sense the engine is dying right away. Since it takes longer than what you allow with a quick flip of the key to the off, soon as you have the key back on Both the engine resumes running just fine. It does not need to come to complete stop for you to sense you have removed the spark for a second and the engine is dying. You might need a demonstration by your A&P or someone that's experienced.

Its a shame though that you weren't taught this during your primary instruction since its a safety issue before you go push the plane back into its parking place or hangar. But not all CFI's know this unfortunately.

Incidentally, shutting down the engine with the ignition key potentially creating a dangerous conditions with fuel still in the cylinder ready to be lighted off with a single release of an impluse coupling. But yes the key would have to be left in too.

Edited July 30, 2018 by kortopates

[jaylw314]

15 minutes ago, kortopates said:

You'll be able to sense the engine is dying right away. Since it takes longer than what you allow with a quick flip of the key to the off, soon as you have the key back on Both the engine resumes running just fine. It does not need to come to complete stop for you to sense you have removed the spark for a second and the engine is dying. You might need a demonstration by your A&P or someone that's experienced.

Its a shame though that you weren't taught this during your primary instruction since its a safety issue before you go push the plane back into its parking place or hangar. But not all CFI's know this unfortunately.

When I had a weak right mag, I had done the Bendix switch AD check, and I noticed when I shut down, turning the switch to off resulted in the engine spinning down with a fair amount of vibration and heaving, and taking a few seconds to come to a stop.  When I turned the switch to the weak right mag, the prop spun did the same thing for the first few seconds, then started coughing every few seconds as the right mag fired intermittently.  When I mentioned this to my instructor (who's also an IA), he was the one who suggested waiting for the engine to fully stop during the p-lead check, since restarting the engine at that point is trivial anyway.

[ShuRugal]

16 hours ago, triple8s said:

I heard from a friend who was there that he shut down and was out at the front and moved the prop after engine was shut down. The key was not turned off, supposedly he barely moved the prop and it popped once. I have moved the prop after shut down to give clearance with the tug and been fussed at by a few folks for touching the prop. I generally place the key in eye shot of the front of the plane so I know it is indeed out and off, however my mechanic always fusses anytime someone touches the prop on aircraft around his shop he says a broken p-lead is all it could take. 

 

14 hours ago, kortopates said:

Exactly right, but there is a genuine need to move the prop by both mechanics and pilots - you just gave an excellent and very common example of needing to move the prop to hook up the the tug or tow bar. So how do we safely move the prop without getting hurt from it in case the p-leads are not grounded? Mechanics are taught to turn the prop backwards when moving it - this will prevent the impulse coupling from releasing.  

 

13 hours ago, carusoam said:

Like two factor authentication...

Two factor kill the engine and make sure it stays that way...

1) when turning off the engine... drain the fuel from the line with the mixture knob pulled all the way out...

2) To top that off... key out of the ignition... in plain sight..

I have learned with age... pulling the mixture, some times leaves the key in the ‘both’ position...  (add that to the final checklist)

 

13 hours ago, toto said:

I always turn the ignition to "off" momentarily before switching back to "both" and pulling the mixture. This was taught by my primary instructor, and while it hasn't prevented a catastrophe (yet), I do it by rote.

 

This is something that I am trying to add into my shut-down checklist.  Well, I have added it, remembering to do it is the hard part, my hand keeps pulling mixture by muscle memory.

 

8 hours ago, teejayevans said:

Doesn’t the runup sequence accomplish the same thing, instead of turning off both, you turn 1 off at a time. If P lead was broken and mag was not turning off, you would not get RPM drop, etc

It does, but it does not protect against the possibility that a p-lead vibrated loose in flight.

 

5 hours ago, Raptor05121 said:

Has anyone hand propped a Mooney? We've tried it once on my 3-blade, and it never got even close. When starting my plane normally with the high-speed SkyTec, she turns over about 4-5 blades before it lights off. When my starter died away from home, my CFI tried for about 15 minutes to get it. Even with me holding the SoS, it would go one compression and stop. Never got even close to popping off. It seems to me that the SoS is superior in starting and superior in ground safety (given my experience).

 

I was going to mention the same thing:  it seems that impulse couplers are at least as much of safety hazard as they are a benefit for easy starting.  SoS might be a PITA to hand prop, but unless you have the SoS unit engaged, it won't retard the timing and it won't supply a spark...

[aviatoreb]

1 hour ago, kortopates said:

It’s testing that the P-lead is not grounded before shutdown. Everyone SHOULD have been taught this by their instructor - preferably primary!

 

Doing the run up test it too but after any flight you need to re-test that the p-leads are STILL not grounded before getting out and grabbing the prop!

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Clearly I was not....

But I am hear doing my best to continue to be humble and to learn from my fellow aviators.

[kortopates]

3 minutes ago, aviatoreb said:

Clearly I was not....

But I am hear doing my best to continue to be humble and to learn from my fellow aviators.

Good for you and Sorry Erik if I came off a little too strong but its not your fault you didn't get that training but its such a huge safety factor before we get out and grab our prop to push back etc. we should all be doing it. As well as turning the prop backwards when we must.  I myself didn't learn the safe way about turning the prop backwards till A&P school. I wish one of my instructors had enlightened me much earlier. 

The critical thing is the engine doesn't need to restart to kill you, its just needs one good pop! Those that have been Mooney owners for over 15 years may recall and a very good A&P that used to work at Dugosh whose account was on the old Mooney list years ago. He got hit in the head by a single pop. Although he survived the massive head injury, it was not without a long convalescent period and permanent brain injury. He tried to return to work for a short time but it didn't work out. One pop is all that it takes. And this event continues to repeat time and again. Don't let it happen to you.

[carusoam]

Brain injuries take a long recovery period (measured in years or decades) for those that have the opportunity to recover...

Try to avoid brain injuries when able... 

I bet origami would make a real interesting class for people with TBIs...

PP thoughts only, not a cognitive therapist... I have worked closely with a few...

Best regards,

-a-

[Seth]

8 hours ago, Raptor05121 said:

Has anyone hand propped a Mooney? We've tried it once on my 3-blade, and it never got even close. When starting my plane normally with the high-speed SkyTec, she turns over about 4-5 blades before it lights off. When my starter died away from home, my CFI tried for about 15 minutes to get it. Even with me holding the SoS, it would go one compression and stop. Never got even close to popping off. It seems to me that the SoS is superior in starting and superior in ground safety (given my experience).

I saw a C-172 at a flight school hand prop by a big burly guy who yelled at the pilot what to do (he was the owner).  It fired right up.  I forget if they went for the flight or over to maintenance.  knowing the flight school, it likely went for a flight.

 

-Seth

Edited July 30, 2018 by Seth

[aviatoreb]

2 hours ago, kortopates said:

Good for you and Sorry Erik if I came off a little too strong but its not your fault you didn't get that training but its such a huge safety factor before we get out and grab our prop to push back etc. we should all be doing it. As well as turning the prop backwards when we must.  I myself didn't learn the safe way about turning the prop backwards till A&P school. I wish one of my instructors had enlightened me much earlier. 

The critical thing is the engine doesn't need to restart to kill you, its just needs one good pop! Those that have been Mooney owners for over 15 years may recall and a very good A&P that used to work at Dugosh whose account was on the old Mooney list years ago. He got hit in the head by a single pop. Although he survived the massive head injury, it was not without a long convalescent period and permanent brain injury. He tried to return to work for a short time but it didn't work out. One pop is all that it takes. And this event continues to repeat time and again. Don't let it happen to you.

I'm not the least bit offended.  I am quite happy to be reading this thread and a bit horrified that I have been blissfully unaware of this possibility and just dumb lucky that nothing bad has happened all this time....  This one so it seems simply a blaring hole in my knowledge set.   I will be changing my procedures immediately and henceforth regarding ignitions, moving my prop etc accordingly.  Thank you all for the FYI.

PS I am not exactly a newbee - nor a pro - somewhere in between - IFR and commercial rated, 12 years and 1200 hrs, but that's one of my big things of being here, is I KNOW there is still more to learn.  This one is very very simple and yet clearly important.

Edited July 30, 2018 by aviatoreb

[DXB]

Two questions come to mind:

1) If I turn the ignition switch to off and then quickly back to on, I definitely get a backfire - I learned this the hard way in the early days and now understand why.  I'm careful during my mag check not to  accidentally switch to off. Am I missing something when folks advocate doing something similar to check for p lead grounding?

2) I've heard that turning a prop backwards is a terrible idea because it can easily kill a dry vac pump by turning the vanes opposite their intended direction.  Am I wrong here?

 

 

[DonMuncy]

Dev,

Is your C a carburetored model. I don't know whether that would make a difference. 

[DXB]

16 minutes ago, DonMuncy said:

Dev,

Is your C a carburetored model. I don't know whether that would make a difference. 

Yes a carb'd C model  - honestly I don't understand fuel injection systems well enough to know whether they'd do the same. 

[EricJ]

1 hour ago, DXB said:

 

1) If I turn the ignition switch to off and then quickly back to on, I definitely get a backfire - I learned this the hard way in the early days and now understand why.  I'm careful during my mag check not to  accidentally switch to off. Am I missing something when folks advocate doing something similar to check for p lead grounding?

 

At idle there's so little fuel flowing that not much will make it out the exhaust by momentarily switching the mags off.   At runup rpm there's a lot more, and a backfire (and potential muffler damage) is more likely.   At idle it's pretty much a non-issue and you can still easily tell that the ignition is being turned off.

Edited July 30, 2018 by EricJ

[kortopates]

Two questions come to mind:
1) If I turn the ignition switch to off and then quickly back to on, I definitely get a backfire - I learned this the hard way in the early days and now understand why.  I'm careful during my mag check not to  accidentally switch to off. Am I missing something when folks advocate doing something similar to check for p lead grounding?
2) I've heard that turning a prop backwards is a terrible idea because it can easily kill a dry vac pump by turning the vanes opposite their intended direction.  Am I wrong here?
 
 

The vacuum pump concern is one of those OWT's. Nothing to be worried about there - your safety is far more important.
Eric answered your first. At idle RPM it's not an issue if you don't delay going back to both.


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[Guest]

6 hours ago, kortopates said:

It’s testing that the P-lead is not grounded before shutdown. Everyone SHOULD have been taught this by their instructor - preferably primary!

 

Doing the run up test it too but after any flight you need to re-test that the p-leads are STILL not grounded before getting out and grabbing the prop!

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Paul, 

I’m confused, isn’t the test to confirm that the “P” leads are grounded in the “Off” position and the magnetos aren’t live?

Clarence

[Guest]

11 hours ago, Raptor05121 said:

Has anyone hand propped a Mooney? We've tried it once on my 3-blade, and it never got even close. When starting my plane normally with the high-speed SkyTec, she turns over about 4-5 blades before it lights off. When my starter died away from home, my CFI tried for about 15 minutes to get it. Even with me holding the SoS, it would go one compression and stop. Never got even close to popping off. It seems to me that the SoS is superior in starting and superior in ground safety (given my experience).

I’ve hand started a number of planes during my career in maintenance.  Your Mooney should be fairly easy, correct amount of fuel and healthy magnetos is the key.  Cessna 185 & 206 amphibious models are harder to reach because of their height, however their Bendix 1200 magnetos make it a breeze to start.  You only have to pull it through the compression stroke slowly.

Its still not something for everyone to try.

Clarence

[kortopates]

Thanks Clatence for pointing out my typo - that should have been ungrounded rather than grounded when we move to Off quickly to test.

When a p-lead breaks (or perhaps switch contacts are failing) it prevents grounding the mag in the Off position so that the coil can't induce a current.


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[jaylw314]

1 hour ago, EricJ said:

At idle there's so little fuel flowing that not much will make it out the exhaust by momentarily switching the mags off.   At runup rpm there's a lot more, and a backfire (and potential muffler damage) is more likely.   At idle it's pretty much a non-issue and you can still easily tell that the ignition is being turned off.

In the past, I've tried this at 900 RPM, and I've managed to give myself a pretty good backfire a couple times.  I usually try to idle above 800 RPM, because the motor just gets too bouncy below that.  Maybe I should try doing this again below that.

[whiskytango]

2 hours ago, DXB said:

Two questions come to mind:

1) If I turn the ignition switch to off and then quickly back to on, I definitely get a backfire - I learned this the hard way in the early days and now understand why.  I'm careful during my mag check not to  accidentally switch to off. Am I missing something when folks advocate doing something similar to check for p lead grounding?

2) I've heard that turning a prop backwards is a terrible idea because it can easily kill a dry vac pump by turning the vanes opposite their intended direction.  Am I wrong here?

 

 

I have heard the same warning about damaging the vanes in a dry vacuum pump as a result of turning the prop backwards from an A&P, and never do it.  Dry vacuum pumps have always seemed to have 2 strikes against them at all times, so why make things worse?

[kortopates]

In the past, I've tried this at 900 RPM, and I've managed to give myself a pretty good backfire a couple times.  I usually try to idle above 800 RPM, because the motor just gets too bouncy below that.  Maybe I should try doing this again below that.

It does happen to folks learning how to do it by going to slow or to fast an RPM. My suggestion, less than 1000rpm, do it as quick as you can to show yourself you'll avoid backfire. Then slow it down progressively just enough you can feel the engine dying. Thats all you need. Its only on Off for a fraction of a second.



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[DXB]

25 minutes ago, jaylw314 said:

In the past, I've tried this at 900 RPM, and I've managed to give myself a pretty good backfire a couple times.  I usually try to idle above 800 RPM, because the motor just gets too bouncy below that.  Maybe I should try doing this again below that.

Yeah I've had a backfire too at a low RPM, I think it was around 1100 rpm which is where I normally idle per my POH.  It was actually when formally complying with the 100AD for the Bendix ignition. I can't recall if I had it maximally leaned out or not - leaning more or a lower rpm might have prevented it, but I've been gun shy about trying again ever since.