Customer got hit by a prop today.

Here is a question for the group. Would you volunteer to hold the prop mounted on a IO-540 when the TDC is at the 5 to 11 position?
Or would you rather allow the A&P to place the prop at TDC and get the hell out of the way?
 
OkieFlyer said:
If you work on stuff, there will be blood sooner or later. No matter how careful and safety minded we try to be, we are human, and humans ain't perfect. Manure occurs.
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Exactly!
 
Well, so if I'm understanding right, you do the compression check without securely holding onto the prop the entire time? I can't say I've ever done it like that and would have no faith that it wouldn't jump and bite someone... I use one hand to operate the gauge/valve and the other to secure the prop. I do make damn sure that there is no way the engine itself could fire on me (I disconnect all the plug wires). I've never seen anyone do it differently.

I will admit that I did once have the prop get away from me during a compression check. Can't remember how it happened other than something was pressurized that wasn't supposed to be. Doubt it'll ever happen again..scared the hell out of me.
 
Tom-D said:
Here is a question for the group. Would you volunteer to hold the prop mounted on a IO-540 when the TDC is at the 5 to 11 position?
Or would you rather allow the A&P to place the prop at TDC and get the hell out of the way?
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Given what you described, I will just never be involved in this process.
I will watch the experts do it from behind the prop and that is about it.
 
jesse said:
Well, so if I'm understanding right, you do the compression check without securely holding onto the prop the entire time? I can't say I've ever done it like that and would have no faith that it wouldn't jump and bite someone... I use one hand to operate the gauge/valve and the other to secure the prop. I do make damn sure that there is no way the engine itself could fire on me (I disconnect all the plug wires). I've never seen anyone do it differently.

I will admit that I did once have the prop get away from me during a compression check. Can't remember how it happened other than something was pressurized that wasn't supposed to be. Doubt it'll ever happen again..scared the hell out of me.
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Jesse, I'd not try the one handed trick on a 0-540 or a R-985. best to place at TDC and not get in the arc, because if bumped it will bite.
 
I helped my A&P do a compression check on our IO520 last year during our annual. I was shocked at how hard it is to hold the prop in place when air was applied. You're right, it's not bad when it's right at TDC, but move it just a bit and it really wants to spin. One with a reasonable amount of strength can certainly hold it, but it could get away from you if you're not expecting it.
 
Accidents happen, sounds like the customer just got a little scratch, wagering you learned something from this too, life goes on.
 
SixPapaCharlie said:
Given what you described, I will just never be involved in this process.
I will watch the experts do it from behind the prop and that is about it.
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I'm with ya on this one. I can't imagine I would ever need a "better look at the gauge" either, for chrissakes. The A&P knows how to read a gauge, and can tell me what it says.
 
midcap said:
So it's a leak down test I assume?
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It gets called that, but it's really a differential compression test. A leakdown is used elsewhere and involves bringing pressure up, shutting off the supply, and timing the pressure loss. A differential test involves a supply pressure (usually 80 psi) on the upstream side of a restricting orifice, and a second gauge on the downstream side that measures the pressure drop as the air leaks through rings or valves or cracks in the head or whatever. There will be no difference in the gauge readings if there is no leakage, and if there's leakage present the second gauge will read lower than the first, and a large leak will cause a much lower reading. So the mechanic (and owner) likes to see readings at least in the 70s.
 
Tom-D said:
Here is a question for the group. Would you volunteer to hold the prop mounted on a IO-540 when the TDC is at the 5 to 11 position?
Or would you rather allow the A&P to place the prop at TDC and get the hell out of the way?
Click to expand...


Held the prop on an O-540 in SF-260's numerous times. Center of the spinner is about 46" from the ground. O-435 on Stinson L-5's as well. Center of the prop hub is at about my ear height. Fiesler Fi-156, with an Argus As-10, where the center of the hub is more than a foot over my head. It takes a little care and coordination to make it happen without getting anyone bit.
 
I have never seen a compression check performed so this may be a crazy question, but isn't there a way to sling the prop in place with a belt or even stand of some sort?

I know if we had to something like that in a manufacturing environment we would have it locked in place before we would allow anyone around it. Of course, I do work for a large corporation and OSHA loves to fine our deep pocketed asses. Production be dammed when it comes to safety. So what if it takes a few extra minutes if it could save your or your friends life.

And please don't just dismiss the idea without at least exploring it honestly. Just saying
 
The accident chain was you let someone be in front of the propeller. Before starting the procedure you should have had him come stand behind you. The way I have seen comp check done safely twice is: One person works/reads the gauge, one person works the propeller. One guy used his leg to keep the prop in control before applying air pressure. Only after air pressure was released did the prop get released to it's own. Both people stood behind the propeller arc. When doing ground ops, all people are instructed to never go in front of the wing, evar. On the ramp I will never walk in front of the planes or if I have to it is with a good margin usually with a truck or light pole between me and the planes. Planes never can get to you when you are behind them.
 
Tom: Sorry you had to witness that. It made me think back as to how my A&P/IA has me 'assist' him on my airplane. I remove all the plug wires and the top plugs, I attach the tester adapter to the cylinder under test. He brings the piston in question to TDC and holds the prop from the side of the engine compartment with me standing to his side (further away from the prop). I hold the gauge so that he can see it while he jiggles. By placing himself between me and the prop, the situation you described becomes much less likely when I try to do something stupid...

Steve
 
yetti said:
The accident chain was you let someone be in front of the propeller. Before starting the procedure you should have had him come stand behind you.
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If he bumped into the prop why does it matter where he came from?
 
NavAir said:
Tom: Sorry you had to witness that. It made me think back as to how my A&P/IA has me 'assist' him on my airplane. I remove all the plug wires and the top plugs, I attach the tester adapter to the cylinder under test. He brings the piston in question to TDC and holds the prop from the side of the engine compartment with me standing to his side (further away from the prop). I hold the gauge so that he can see it while he jiggles. By placing himself between me and the prop, the situation you described becomes much less likely when I try to do something stupid...

Steve
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And if he ever slips he's hurt.
 
Craig said:
Held the prop on an O-540 in SF-260's numerous times. Center of the spinner is about 46" from the ground. O-435 on Stinson L-5's as well. Center of the prop hub is at about my ear height. Fiesler Fi-156, with an Argus As-10, where the center of the hub is more than a foot over my head. It takes a little care and coordination to make it happen without getting anyone bit.
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Anyone holding the prop is in the prop arc. It is much safer to place the piston at TDC and stay out of the prop arc while pressure is applied. When it does come off TDC in either direction nobody gets hurt, you simply try again at getting it exactly TDC.
anyone that tries to hold a prop while pressure is on the cylinder is placing them selves at risk.
 
There is no ands or ifs about this, you can not get hit by a prop if you are not in the prop arc, so stay the hell out.
 
I've seen a few A&Ps adjust something while an engine is running, like the idle mixture. This might be a common practice, but it makes me super nervous either way.
 
I'm not a mechanic, but I am a Safety Professional. I'd ask you what is the best practice for this task and was it being followed?

I'd also look into complacency, as I'm sure you've done this 1000 times with no issues.

There's probably a lot of variables, such as environment (was it hot?) Timing (how long had the shift been?) PPE (or lack their of) and expectations of the particular task.

I'd be willing to bet you guys don't fill out a Pre Job Safety Analysis before you begin?

For your protection and those working with you (whenever they may be) it would be a good idea for a JSA. You know.... to cover your...hind pots incase of a civil suit.
 
Challenged said:
I've seen a few A&Ps adjust something while an engine is running, like the idle mixture. This might be a common practice, but it makes me super nervous either way.
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Saw an A&P pull jumper cables off of a grumman yankee and screw the inspection cover back down with the prop running :o
 
OkieFlyer said:
If you work on stuff, there will be blood sooner or later. No matter how careful and safety minded we try to be, we are human, and humans ain't perfect. Manure occurs.
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I was changing a tire on the Navion once. I'd just finished and sat up straight and cracked my head on the flap hinge. Lots of blood but no other damage. Alas, this was in my tiedown at Oshkosh so it didn't go unnoticed. One of my "friends" went over to the metal working tent and english-wheeled a metal insert for my hat to protect me from further injuries.
 
Art VanDelay said:
Head wounds always bleed a lot. I'm betting he'll be fine with both one heck of a story and a scar to match. Biker chics dig scars !
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I can definitely attest to head wounds being massive bleeders but not the biker chick thing. However based upon that assertion, if I were to shave my head I'd probably be kidnapped by a whole gang of biker chicks.
 
Tom, no need to beat yourself up over this. Seems like others are more than willing to do it for you.
 
SmashTime said:
I'm not a mechanic, but I am a Safety Professional. I'd ask you what is the best practice for this task and was it being followed?

I'd also look into complacency, as I'm sure you've done this 1000 times with no issues.

There's probably a lot of variables, such as environment (was it hot?) Timing (how long had the shift been?) PPE (or lack their of) and expectations of the particular task.

I'd be willing to bet you guys don't fill out a Pre Job Safety Analysis before you begin?

For your protection and those working with you (whenever they may be) it would be a good idea for a JSA. You know.... to cover your...hind pots incase of a civil suit.
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OK you are the safety professional, tell us how to stop people from making mistakes.
the owner knew the dangers of being in the prop arc, he new the dangers of moving the prop when its under pressure ... yet he did.
 
GeorgeC said:
So, does this require an engine teardown?
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no, the prop didn't stop, after it hit him.
also this is a 0-200 continental, no AD just a service bulletin saying if the prop must be removed for repair, the iron parts should be checked for cracks. no the prop did not need to be removed for repair.
 
NavAir said:
He is standing to the side, behind the prop as well. Much lower chance of getting hit, especially in the noggin...
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When it jerks him, he will be pulled into the prop arc. happens every time
 
Tom-D said:
OK you are the safety professional, tell us how to stop people from making mistakes.
the owner knew the dangers of being in the prop arc, he new the dangers of moving the prop when its under pressure ... yet he did.
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I just told you how to take a large chunk of accountability off your shoulders.

If they wanna help, have them fill out your JSA. If you need a template or help, I don't mind helping you out.
 
SmashTime said:
I just told you how to take a large chunk of accountability off your shoulders.

If they wanna help, have them fill out your JSA. If you need a template or help, I don't mind helping you out.
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What makes you believe I am responsible for others action when they already know the consequences of their actions?
 
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