Guy hit and killed by prop

If aircraft didn't have impulse couplings this stuff would probably never happen, but whole lot of them can't support the starter vibrator.
 
Learn to hand prop safely and how an impulse works. Skills and knowledge that will help you be safer around propellers and cause you to not be in violation of 91.103 (knowing stuff relevant to safety of the flight).



(I made that last part up.)
 
Condolences to the widow and family of the pilot.

I always treat the prop like its hot. When I have to move it, I always move it forward only and only using the techniques I use when I'm trying to hand prop start. But for all any of us know, this particular pilot did those same things as well. There but for the grace...
 
Tantalum said:
haha @Paulie I was curious about the vacuum pump thing since in my mind's eye I was picturing a marine style impeller.. but at least if what I'm seeing is accurate the vanes just go in and out based on centrifugal force <- mind you that video kind of sucks but if you look at cutaways on Google it makes sense. There were a few I saw that were angled a certain way.. but if anything that angle would push the vanes into the shaft as it got into the narrow part of the cylinder

Who knows. I will say that I'd much rather spin a prop a half turn backwards than forwards. Never flown anything with a Rotax though.. maybe that's a whole different beast!
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A vacuum pump is not like a marine water pump. The vanes are flexible and don't want to flip over. There's no real problem turning a pump by hand in the wrong direction. You don't want to turn one that has canted vanes (i.e., one that specifies a rotation) at SPEED in the wrong direction.

With a hot engine, is master off, ignition off, enough to prevent an inadvertent start when you want to rotate the prop horizontal?
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NO! Always treat it as live.

First off, the MASTER has no bearing on anything. The engine will run all day with the master off. The only time that would make a difference is a few engines that have some electronic spark assist (rare).

Turning the fuel off with the mixture (or the valve) on shutdown doesn't mean that there's no fuel left when it dies. It just means that at the time the mixture got to a point where it wouldn't burn. You let that engine sit for a bit, there may be enough fuel there to have the engine fire a few times and that's enough to be dangerous.

Aircraft ignition switches are crap. You have no idea if it is working or not. On my old one you could do magchecks all day long. You could even turn the key to OFF and watch the engine die but remove the key (or just jiggle it) and one of the mags would come hot again.
 
Skip Miller said:
You are correct. But using a venturi in the slipstream is cheap and reliable. (NB does't work in icing conditions.)

The alternative (a funnel-like ram air device) would be less effective, particularly at low speeds. To get 5psi you would need a large air funnel = drag.

Aviation designers like low drag, cheap, and reliable.

-Skip
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You are correct, but I should have quoted the question which lead to Tom's reply to keep the context.

As most planes no longer use venturis (they also don't tend to work well until they have good air flow either), I was responding also to the question about not using pressure instead.

I also read someplace (and my information might well be incorrect for this statement) that jets also drive the "vacuum" instruments with positive pressure, as well as the planes I mentioned earlier.
 
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Juliet Hotel said:
Condolences to the widow and family of the pilot.

I always treat the prop like its hot. When I have to move it, I always move it forward only and only using the techniques I use when I'm trying to hand prop start. But for all any of us know, this particular pilot did those same things as well. There but for the grace...
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Yeah a lot of details aren’t known. From the way it sounds the engine did not actually start, it just turned over enough to wham into his head. I’m having a little trouble picturing exactly what happened.
 
Tom-D said:
BS propagated by those who believe old wives tales.
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Okay what specifically about those is an old wives tale? I left out the turn the prop backwards because people have varying opinions on that one but I personally do it anyway.

Should you not treat a prop like a loaded gun?? The prop is the most dangerous part of your aircraft, why wouldn't you give it the respect it deserves?

And before we go off into the weeds about what kind of engine is attached to the prop (Garrett, PT6, Rotax, Lycoming, Continental, etc) the advice given is a statement for personal safety.

My source is the NATA Safety 1st Professional Line Service Training as well as attending the Advanced Line Service regional workshop (and a few years of line service work).
 
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With Rotax one of the standard operating procedures for checking oil involves rotating the prop until the engine burps . It is safer though cause it requires 200 rpm to produce a spark so you would have to hand prop quite hard to get the required 200 rpm.
 
Tantalum said:
**here's a stupid question while we're on the topic of vacuum. How did vacuum become the standard? Seems like it would make more sense to use positive pressure to feed air driven instruments like a DG, etc. I would think a positive pressure system is far easier to construct and maintain..? there must be a reason, but it is not obvious
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A failed pump could then circulate pump bits through your instruments in a pressure system.
 
Tantalum said:
**here's a stupid question while we're on the topic of vacuum. How did vacuum become the standard? Seems like it would make more sense to use positive pressure to feed air driven instruments like a DG, etc. I would think a positive pressure system is far easier to construct and maintain..? there must be a reason, but it is not obvious
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Positive pressure is harder to keep clean. Pumps have oil, grease, rubber seals and such. These things are bad for the finely tuned instruments downstream if junk gets in the system.


On the original topic, C-182s are prone to this happening for some reason. My hangar neighbor nearly broke his hand a few months ago when his plane busted off while pulling the prop through before a cold start. The mag switch was the problem in his case.

I personally like to pull the prop through a couple times when it's cold. If I do, I always set the parking brake and treat the prop as if it's going to start when I pull it.
 
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overdrive148 said:
Always treat the prop like a loaded gun.
Do not touch the prop unless absolutely necessary.
Never reach through the prop arc for anything.
Only touch the prop with a flat hand.
(Line service tech experience)
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That’s the deal.

I’m going to try the shutdown mag check to see if I can incorporate it without a backfire.

As an owner/operator I mindfully locate the keys before touching the prop. I try to keep them visible either in the baggage door or the glare shield.

As a former modeler I was taught to treat the prop arc of a running engine as extending into infinity... I spend as little time as possible in it.


Sent from my iPad using Tapatalk Pro
 
Tantalum said:
**here's a stupid question while we're on the topic of vacuum. How did vacuum become the standard? Seems like it would make more sense to use positive pressure to feed air driven instruments like a DG, etc. I would think a positive pressure system is far easier to construct and maintain..? there must be a reason, but it is not obvious
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This question has already been answered by others, but one side benefit is that you can drive the instruments with manifold vacuum in a pinch if so equipped.

That said, with the proliferation of the electronic G5/D5/E5/etc it looks like vacuum driven instruments might not be long for this world.
 
Paulie said:
A

Can screw up vacuum pump. They don’t like going backwards.
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Nope. If it breaks turning backwards, it was worn to the point that it was going to break in flight before much longer. Better to have it break on the ground. The ONLY pumps I have replaced when they were broken were pumps that were very badly worn. Now you can buy pumps with inspection ports, and check them periodically. Takes five minutes at annual or whatever. Replace it when the gauges says to and you can turn that engine backwards all you want. In fact, sometimes during starting the engine will kick backwards and rotate a couple of turns, and when a mechanic is setting mag time he has to rotate the prop backwards and forwards.
 
Tantalum said:
**here's a stupid question while we're on the topic of vacuum. How did vacuum become the standard? Seems like it would make more sense to use positive pressure to feed air driven instruments like a DG, etc. I would think a positive pressure system is far easier to construct and maintain..? there must be a reason, but it is not obvious
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Like Tom says, it was a carryover from the venturi system. It also has the advantage of not having to filter the carbon residue out of the pumped air to feed the instruments. The pump has a carbon rotor and vanes to make it self-lubricating, and it is always producing a fine graphite dust as it wears.

That said, aircraft that fly at high altitudes often use the pump as a pressure pump instead. That's because the atmospheric pressure is much lower at altitude and the vacuum differential falls off, making the gyros perform poorly. That system has more filters and stuff to maintain.

Early vac pumps were wet pumps, using oil to lubricate and seal them, and using such a pump as a pressure pump was a sure way to wreck the gyros in a few minutes. There are still a few of those around in vacuum systems; they last a long time but make for an oily airplane belly.
 
Dan Thomas said:
Other way around.
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Best take another look.
The angle is very slight, but will push the vanes into the rotator when turned backwards.

Plus you are not going to turn it fast enough to harm it.

I've had them apart, and seen it in action.
 

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NO it can't another misconception. when you rotate a vac-pump backwards it pushes the vanes into the rotator and clear of the housing.
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This is probably the 5th time I have posted this story here - why do I persist, people insist on not listening.
I turned my prop backwards to accommodate the tow bar. I heard the distinctive 'snick' of breaking vac pump vanes. The pump was working when I landed. I was not convinced I broke vanes so I started it up and 0 vacuum. I shut it down, opened the pump and found busted vane or vanes (it was over 10 years ago). I r&r'd the pump and it was fine for 500hrs thereafter.

So YES you can break vanes by turning the prop (and pump) backwards.
Does it happen often? No. But that is not the question, the question is can you break vanes by turning prop backwards.
Does it mostly happen with worn vanes? Yes. But that is not the question, the question is can you break vanes by turning prop backward.
From a purely scientific myth-busting, 'Answer The Question' standpoint, YES you can bust vanes. I did.

Do you need to worry about this?
Probably only if you are using a non-owned airplane and don't want to take the (very small) chance of having to tell the owner you broke it.
Probably if you are a mechanic and don't want to take the chance of an owner coming back after maintenance, "the vac pump is reading zero after you worked on my airplane".
 
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Couple of thoughts -

Any prop that repeatedly stops vertical on a 4 cyl engine is very likely indexed wrong to the crankshaft. For six cylinder - not true.
Unless the vacuum pump vanes are exactly radial, there will be a wear point where they will self-lock and break if turned backwards.
Any prop is potentially loaded until at least one spark plug is removed from each cylinder.
Despite that famous picture of Amelia Earhart, the prop arc can be deadly.
 
Every pilot should be taught to hand prop during pilot training. When they find out how easily an engine can start by hand they become more careful when handling the prop.
 
Sad to hear.
It only takes a momentary lapse to end your days.
I chock the wheels and pull the prop from behind with the mags off.
Every time I go near the Cub.
Every time.
I've seen line monkeys reach up and grab a prop to pull an airplane, and it makes my 'nads shrivel every time I see it done.
 
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Stewartb said:
Every pilot should be taught to hand prop during pilot training. When they find out how easily an engine can start by hand they become more careful when handling the prop.
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Seems like they only start easily when you don't want them to. When I'm trying to prop start it? Sometimes I think I'd have better luck trying to grow roses on the moon.:D

I'm kidding. When I was doing banners I'd have to prop them regularly and I could get them going fairly easily. But never had much luck with the 450HP P&W on the Stearman. If that battery was dead, you weren't flying no way no how. I agree though, teaching good prop technique should be part of everyone's primary training. The problem there is one person's idea of good prop technique is another person's idea of flirting with certain death.
 
No offense, but CFI’s are usually not engine experts. They will usually just repeat what they’re told unless someone points out the correct method backed up with documentation. One of my instructors used to blend nicks on a prop with his car keys or whatever he could find. There’s a correct way to blend a nick on a prop if it’s under an acceptable size. Also, no reason to be touching a prop during a preflight. Treat the prop as if the mags are always “hot”. In fact, the only thing that keeps a mag from being hot is the small ground wire that’s attached to it. It can be easily broken, loose or perhaps not attached at all from the last person that worked on it. Respect the prop!
 
Warmi said:
With Rotax one of the standard operating procedures for checking oil involves rotating the prop until the engine burps . It is safer though cause it requires 200 rpm to produce a spark so you would have to hand prop quite hard to get the required 200 rpm.
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They forgot to tell me and my friends Rotax engine that. Either that or I can hand prop a Rotax at 200RPM.
I don't recommend hand propping them as a normal procedure, but stranded at a remote airport with a low battery after leaving the master on, it works just fine.

Brian
 
The recurring theme of 'experienced pilot struck by prop' does not make me go "He could not have been that experienced..."
Nor does it make me say "He obviously had a lapse that day..."
And certainly never, ever would I say, "That can't happen to me because..."

Like most other horrible events which I read about happening to experienced aviators - it makes me go, "Sheet! I better step up my game! This is happening to people who have been around airplanes a long time - being in the game 20, 30, 40 years does NOT give anyone immunity!"
 
Many here say there are safe ways to hand prop. I do believe with education on the matter there are “safer” procedures that drastically reduce risk, but I will never believe it’s an acceptable risk.
 
brcase said:
They forgot to tell me and my friends Rotax engine that. Either that or I can hand prop a Rotax at 200RPM.
I don't recommend hand propping them as a normal procedure, but stranded at a remote airport with a low battery after leaving the master on, it works just fine.

Brian
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Rotax 80 maybe ...
 
brcase said:
I can hand prop a Rotax at 200RPM.
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That. Don't forget that the crank is spinning faster than the prop.
A 912UL is not that hard - I doubt that the 100 hp is that much harder, but no one has brought one by for me to try.
 
Ryanb said:
Curious to get @jesse or @Ted DuPuis opinion on this situation.
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I don't generally go moving props without a reason and there often times isn't a good reason. If I have a reason to move the prop and I believe there is a chance the damn thing could fire on me - I would slowly move it backwards. If the vacuum pump fails it was about to fail anyways (I've never had one fail because of this).

Would I be terrified to move a prop forward and refuse to do it? No. I'd just take some caution...it's not hard for me to analyze what the likelihood of it firing is - and what I should do to prevent that. I do not default to moving props forward unless I have a good reason..and there really aren't any most of the time. My default is backwards.

I have owned an airplane that required you prop it everytime you start it...the more you do it...the more you respect the process. The first time the prop does something you didn't expect and gives you a good whack...you'll understand.

The only time I've been whacked by a prop was a kickback during hand propping. Prop leading edge just barely caught my finger nails ripping a couple of them off the fingers. Lesson learned? Pull harder and more through and don't let the damn thing kick back.
 
Capt. Geoffrey Thorpe said:
That. Don't forget that the crank is spinning faster than the prop.
A 912UL is not that hard - I doubt that the 100 hp is that much harder, but no one has brought one by for me to try.
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Bottom line is that it is much harder to get it going accidentally than your typical legacy GA engine...
 
Ravioli said:
Just take the mags out and you'll have no issues.

http://www.lightspeed-aero.com/
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that does not eliminate the danger. if the light speeds are wired correct, they should be wired hot to the battery through a switch and a fuse. they should never be wired through the master. a power switch failed hot will energize the module just like a failed ground on a mag.

bob
 
Here’s a good video with a detailed explanation of hand propping safely for anyone who cares to watch.

 
Ryanb said:
Here’s a good video with a detailed explanation of hand propping safely for anyone who cares to watch.

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Talking about safety around moving machinery with dangling hoodie drawstrings - What's wrong with this picture... :-(
 
Stewartb said:
Every pilot should be taught to hand prop during pilot training. When they find out how easily an engine can start by hand they become more careful when handling the prop.
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Years ago when I was teaching aircraft safety I'd do this demonstration.

Before the class I'd run the engine so it was warm, As I shut down I'd turn off the key and add a shot of prime as it spun down.
Then with the key off, mixture pull out, I turn the engine by hand until a mag was about to fire.
When the class was assembled, I'd tie the tail down, chock the wheels, and turn the key to the both position.

Then with every one watching I'd simply flip that prop passed the impulse coupling Click. and the engine would start right up spins a few seconds and shut down.

Every time I did this it was an OMG event for every one in the class.
 
Tom-D said:
Years ago when I was teaching aircraft safety I'd do this demonstration.

Before the class I'd run the engine so it was warm, As I shut down I'd turn off the key and add a shot of prime as it spun down.
Then with the key off, mixture pull out, I turn the engine by hand until a mag was about to fire.
When the class was assembled, I'd tie the tail down, chock the wheels, and turn the key to the both position.

Then with every one watching I'd simply flip that prop passed the impulse coupling Click. and the engine would start right up spins a few seconds and shut down.

Every time I did this it was an OMG event for every one in the class.
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Still waiting for you to tell me what about the initial list I put up is an old wives' tale
 
Tom-D said:
Best take another look.
The angle is very slight, but will push the vanes into the rotator when turned backwards.

Plus you are not going to turn it fast enough to harm it.

I've had them apart, and seen it in action.
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I've had them apart too, and I've turned the propeller to see which way the drive is turning, and it turns that pump so that the vane pressure is minimal: it tends to push the vane into the slot. Centrifugal force makes it work, and I suspect that the vacuum does as well. That angle is what breaks the pump when the vanes wear too short and the pump is turned backward. If they were as you claim, they wouldn't break like that.

There are clockwise and counterclockwise pumps. The angles are opposite.
 
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