Customer got hit by a prop today.

GlennAB1 said:
Obviously "necessary precautions" were not taken, as there was accidental rotation.
"Take necessary precautions to prevent accidental rotation of the propeller while performing the differential pressure leak test" - That is a "Must" not "Should"
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Wrong again. he knows how to read the rules, you should try.
 
Norman said:
Yes. I simply don't let them near hot props.
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easy to say on line. but tell us how you know when they will do a move you don't anticipate ? You must be Clairvoyant
 
Tom-

Looking to avoid a repetition, is there some way the gauge could have been turned so the other person didn't have to look through the prop arc to read it? Perhaps next to you but behind the prop, or on the other side of the plane? He could then lean in to read all he wants but not put any of his body in the arc of the propeller or touch it.
 
GlennAB1 said:
No, you are to assume they will, and continually remind them, tape warnings to the prop, etc,. It's not that difficult.
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Get real, who would ever hang a sign on a prop that you are turning time after time during the test?
You train owners over years of special attention. And still they crash aircraft. People make mistakes even you can't stop that. So dump the idea you or I can do any thing about that.
 
Cap'n Jack said:
Tom-

Looking to avoid a repetition, is there some way the gauge could have been turned so the other person didn't have to look through the prop arc to read it? Perhaps next to you but behind the prop, or on the other side of the plane? He could then lean in to read all he wants but not put any of his body in the arc of the propeller or touch it.
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During an annual there really is no reason for them to see it at all. It's customary to show owners the results of the test to satisfy their curiosity. I allowed this owner to look at the other 3 cylinders readings and he made no attempt to touch the prop, this time he was going to pump the prop to see if it would increase. he never attained a good grip on the prop before pushing off TDC.
When you are going to hold a prop at TDC You always get a good grip prior to bringing the pressure up.
 
Dang dude, you're getting beat up! Hindsight being 20/20, yeah, maybe remind him to stay out of the prop arc, sure. . .but if you weren't perfect, you were a long way from careless, too. He kinda lulled you on the first three, sort of exhibited understanding of the situation that he might not really have had.

The safety Nazis will say all accidents are preventable, which is true in the physical sense. It just ignores the limits of human perception and psychology.
 
Tom-D said:
yes they are the same cylinder and crank throw. we were talking the 0-300 vs the 0-540 which has a 1 inch larger bore than the 0-300.
  • Bore: 5.125 in (130.2 mm)
  • Stroke: 4.375 in (111.1 mm)
  • Displacement: 541.5 in³ (8.9 L)
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So I figure that piston is applying about 1600 lbs of force at 80 psi to the crank. TDC would put the load thru the the crank into the case and not rotate, turning the prop would transfer that force out to the prop until you reach the max torque when the crank is at 90 degrees. Unrestrained that would give you a really good whack, that guy is lucky he didn't get really hurt.
 
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PaulS said:
So I figure that piston is applying about 1600 lbs of force at 80 psi to the crank. TDC would put the load thru the the crank into the case and not rotate, turning the prop would transfer that force out to the prop until you reach the max torque when the crank is at 90 degrees. Unrestrained that would give you a really good whack, that guy is lucky he didn't get really hurt.
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You don't get hit with the blade you are holding. typically you get hit with the next blade that will be 180 degrees of crankshaft travel later. by then the valves in the cylinder being tested have dumped the pressure. now the engine is rotating on momentum. yeah it will hurt ya.
 
PaulS said:
So I figure that piston is applying about 1600 lbs of force at 80 psi to the crank. .
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Pie X the R squared gives area X 80 = force X the arm. arm is stroke / 2 at 90 degrees to the bore of the cylinder. If geared, multiply the torque by the gear ratio.
 
Tom-D said:
Get real, who would ever hang a sign on a prop that you are turning time after time during the test?
You train owners over years of special attention. And still they crash aircraft. People make mistakes even you can't stop that. So dump the idea you or I can do any thing about that.
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What unadulterated BS! "People make mistakes so nothing can be done"--what a load of hooey! No wonder personal injury lawyers make so much money when there are such idiots around who make no attempt to mitigate any risk and claim that it's impossible to foresee a propeller turning and hitting someone in the head who's allowed to stand near it without any sort of clear direction by the person running the procedure. Just keep rationalizing how doing nothing to attempt to prevent this accident was the appropriate thing to do and I'll have to respond in kind yet again and the thread will continue for twenty pages. According to Tom there's no need to ever warn anyone over the age of ten when near something dangerous 'cuz "he knows it's dangerous." Yeah right.
 
Tom-D said:
You don't get hit with the blade you are holding. typically you get hit with the next blade that will be 180 degrees of crankshaft travel later. by then the valves in the cylinder being tested have dumped the pressure. now the engine is rotating on momentum. yeah it will hurt ya.
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then don't let go....hold the prop Tom. :ohsnap:
 
iu
 
Tom, you should get a job as a Hillary spokesman.
 
Cap'n Jack said:
Tom-

Looking to avoid a repetition, is there some way the gauge could have been turned so the other person didn't have to look through the prop arc to read it? Perhaps next to you but behind the prop, or on the other side of the plane? He could then lean in to read all he wants but not put any of his body in the arc of the propeller or touch it.
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Well Tom. How about answering this post. Still say there's no way anyone could do anything to prevent what happened? Common sense precautions for anyone with a lick of sense and yet he'll still come back and say no way. Just watch.
 
GlennAB1 said:
Obviously "necessary precautions" were not taken, as there was accidental rotation.
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So according to this logic if you have somebody else holding on to that prop and it accidental rotates (it happens) then "necessary precautions" were not taken. Going even further if he had twenty dudes hanging on and it turns he was not taking necessary precautions.
 
Tom-D said:
During an annual there really is no reason for them to see it at all. It's customary to show owners the results of the test to satisfy their curiosity. I allowed this owner to look at the other 3 cylinders readings and he made no attempt to touch the prop, this time he was going to pump the prop to see if it would increase. he never attained a good grip on the prop before pushing off TDC.
When you are going to hold a prop at TDC You always get a good grip prior to bringing the pressure up.
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Witmo said:
Well Tom. How about answering this post. Still say there's no way anyone could do anything to prevent what happened? Common sense precautions for anyone with a lick of sense and yet he'll still come back and say no way. Just watch.
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He did, please note the quote above yours in this post. The situation is different than what I read in the original post, where I didn't see that the other person grabbed the prop to move it deliberately.

I wonder if one could show the gauge as I described, and this would then make it more difficult (but by no means impossible) for the customer to grab the propeller to increase the pressure. Tom may then state that no one but him touches the prop, and the customer could ask him to swing it to see how the pressure changes.
 
Tom-D said:
he leaned in to better see the gauge and pushed the blade down,bring the piston off TDC and WACK.
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Tom-D said:
this time he was going to pump the prop to see if it would increase.
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So which was it? Did he inadvertently touch the prop trying to get a better look? Or did he deliberately grab the prop in an attempt to get a peak reading?
 
ifly4fun said:
So which was it? Did he inadvertently touch the prop trying to get a better look? Or did he deliberately grab the prop in an attempt to get a peak reading?
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It really doesn't matter. Tom was conducting the procedure and he didn't tell the owner anything, assuming that the owner knew enough not to do something that would get him injured. As it was, the owner did something that got him hurt and despite Tom's BS, could have killed him. Whether Tom encouraged him to get close by raising up the gauge for him to look at or whether he didn't, he should have at least reminded the owner to stay clear and not touch the prop. If rocking the prop was contemplated to see if the reading would improve, they should have discussed the way this was going to be done safely. Tom claims he was taken by surprise and I believe him but that just illustrates his poor supervision of an observer.
 
Cap'n Jack said:
He did, please note the quote above yours in this post. The situation is different than what I read in the original post, where I didn't see that the other person grabbed the prop to move it deliberately.

I wonder if one could show the gauge as I described, and this would then make it more difficult (but by no means impossible) for the customer to grab the propeller to increase the pressure. Tom may then state that no one but him touches the prop, and the customer could ask him to swing it to see how the pressure changes.
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You're likely not as familiar with standard maintenance procedures as some people in this thread, but please keep in mind that absolutely NOBODY does compression checks without securing the prop, except for Tom. This whole discussion is kind of silly, there is a safe way to do this, the safe way is what the manufacturer instructs, and it is the way that 99.9% of A&P IA's operate. Props that are being secured don't get away and hit people. Securing them is not a feat of extreme physical strength on any engine I've ever seen. Balancing a prop on TDC, pressurizing the cylinder, then letting people maneuver around the airplane with it in that condition is incredibly negligent.

You can head into any of the local shops and watch them do a compression check on any engine. If it's a one man shop (like BIE or CEK) then the A&P will hold the prop (preventing motion in either direction of the engine) and operate the gauges at the same time (this is how I do it, and I do compression checks a couple times a month). If it's a larger operation, like Silverhawk, you'll typically see one A&P secure the prop and the other will run the gauges (extra people are around, so they're used). The customer is allowed to look at the gauges (they'll bring you in the shop to show you). They make sure you are nowhere near the prop and they also have their guy securing it so there is no way it's going to get away and bite anyone.

If you want to see the whole procedure sometime, let me know!
 
jesse said:
You're likely not as familiar with standard maintenance procedures as some people in this thread, but please keep in mind that absolutely NOBODY does compression checks without securing the prop, except for Tom. This whole discussion is kind of silly, there is a safe way to do this, the safe way is what the manufacturer instructs, and it is the way that 99.9% of A&P IA's operate. Props that are being secured don't get away and hit people. Securing them is not a feat of extreme physical strength on any engine I've ever seen. Balancing a prop on TDC, pressurizing the cylinder, then letting people maneuver around the airplane with it in that condition is incredibly negligent.

You can head into any of the local shops and watch them do a compression check on any engine. If it's a one man shop (like BIE or CEK) then the A&P will hold the prop (preventing motion in either direction of the engine) and operate the gauges at the same time (this is how I do it, and I do compression checks a couple times a month). If it's a larger operation, like Silverhawk, you'll typically see one A&P secure the prop and the other will run the gauges. The customer is allowed to look at the gauges (they'll bring you in the shop to show you). They make sure you are nowhere near the prop and they also have their guy securing it so there is no way it's going to get away and bite anyone.

If you want to see the whole procedure sometime, let me know!
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Yes, I would like to see the procedure sometime, and other maintenance as well. I'd be happy to help in any way that doesn't create extra work for you.

You are correct, I am not familiar with the procedures, and that is why I didn't comment on what Tom was doing, but rather asked about ways to mitigate the potential risks in the future.
 
Does anyone here get paid on a per post basis?
 
jesse said:
You're likely not as familiar with standard maintenance procedures as some people in this thread, but please keep in mind that absolutely NOBODY does compression checks without securing the prop, except for Tom. This whole discussion is kind of silly, there is a safe way to do this, the safe way is what the manufacturer instructs, and it is the way that 99.9% of A&P IA's operate. Props that are being secured don't get away and hit people. Securing them is not a feat of extreme physical strength on any engine I've ever seen. Balancing a prop on TDC, pressurizing the cylinder, then letting people maneuver around the airplane with it in that condition is incredibly negligent.

You can head into any of the local shops and watch them do a compression check on any engine. If it's a one man shop (like BIE or CEK) then the A&P will hold the prop (preventing motion in either direction of the engine) and operate the gauges at the same time (this is how I do it, and I do compression checks a couple times a month). If it's a larger operation, like Silverhawk, you'll typically see one A&P secure the prop and the other will run the gauges (extra people are around, so they're used). The customer is allowed to look at the gauges (they'll bring you in the shop to show you). They make sure you are nowhere near the prop and they also have their guy securing it so there is no way it's going to get away and bite anyone.

If you want to see the whole procedure sometime, let me know!
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I do them several times a year, each time using only one hand. I never hold the prop with full pressure on or stand where I get hit if it moves. I'd rather "helpers" go sit in the corner till done.
 
bnt83 said:
I do them several times a year, each time using only one hand. I never hold the prop with full pressure on or stand where I'll get hit if it moves.
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Well, your situation is a little different than most. I suspect you'd be securing the prop if you weren't so unlucky.

Actually, I know that, since you taught me how to do it, and you taught me to physically secure the prop :)

It's really not even possible on a Continental to perform the compression check per the manufacturer's instructions without manually holding the prop. One of the steps has you moving the prop slightly back and forth while pressure is applied.
"To assure that the piston rings are seated and the piston is square in the cylinder bore, move the propellor slightly back and forth with a rocking motion, while applying the regulated pressure of 80 PSI to obtain the highest indication. Adjust the regular as necessary to maintain a pressure guage reading of 80 PSI"
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jesse said:
Well, your situation is a little different than most. I suspect you'd be securing the prop if you weren't so unlucky.

Actually, I know that, since you taught me how to do it, and you taught me to physically secure the prop :)

It's really not even possible on a Continental to perform the compression check per the manufacturer's instructions without manually holding the prop. One of the steps has you moving the prop slightly back and forth while pressure is applied.
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I do that about 40 PSI, set it, step out of the way and turn it up to 80. Take the reading then spray with soapy water looking for cracks, check the oil filler, exhaust and induction manifold for noise/air flow. Then onto the next.
 
ifly4fun said:
So which was it? Did he inadvertently touch the prop trying to get a better look? Or did he deliberately grab the prop in an attempt to get a peak reading?
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He said later he was going to. he didn't like the 74 over 80
 
bnt83 said:
I do that about 40 PSI, set it, step out of the way and turn it up to 80. Take the reading then spray with soapy water looking for cracks, check the oil filler, exhaust and induction manifold for noise/air flow. Then onto the next.
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As it should be done, never get in the prop arc when the cylinder is pressurize to 80.
think about this: You are on the left side of the 0-200, #4 cylinder is pressurized to 80PSI and you are holding up on the blade just a degree or two off center, to stop it from rotating,,,,,,, then some walks by on the right side and pushes down on the other blade.
Remember the crank, piston assembly will rotate off TDC in either direction just as easy either way.
just put it at TDC and stay out of the arc.
 
Norman said:
Tom, Ya gotta remember "We Didn't Light The Fire".

You did! :mad2:
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You changing the subject again? If you are going to eve's drop pay attention.
 
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