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  #1  
Old 10-17-2010, 10:42 AM
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skylor skylor is offline
 
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Location: Southern California
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Default Beware of Prop!

In a recent thread, a couple of people talked about getting hit in the head with their propellers when the props unexpectedly swung off of a compression stroke.

This prompts me to remind everyone to be careful around aircraft engines. My philosophy is that engines and propellers should be treated as if they could start at anytime, similar to the way that most people are (or should be) taught to treat firearms as if they are always loaded.

There have been a number of serious accidents over the years involving aircraft engines that started unexpectedly. If we always treat the prop arc with caution as if the engine is running or could start at any time then we'll not only help prevent potential life threatening accidents if an engine starts unexpectedly, but we also might help prevent injuries due to props simply swinging off of compression strokes unexpectedly. In addition, always respecting the prop arc, engine running or not, should reduce accidents of people accidentally moving into a running prop, which unfortunately does happen occasionally.

Skylor

Last edited by skylor : 10-18-2010 at 10:54 PM.
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  #2  
Old 10-17-2010, 04:35 PM
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Mike S Mike S is offline
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Default

Another tidbit I was taught many years ago, if you must move the prop, turn it the opposite direction-----that way, if a mag is hot, the spark will not be at the correct timing to kick the engine over.
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  #3  
Old 10-17-2010, 08:07 PM
Steve Barnes Steve Barnes is offline
 
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Location: Santa Rosa, CA
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Default Impulse Coupling

If your magneto is equipped with an impulse coupling, the impulse coupling does not activate when turned in reverse.

Steve Barnes "The Builders Coach"
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  #4  
Old 10-17-2010, 08:32 PM
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Geico266 Geico266 is offline
 
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Location: Huskerland, USA
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Default

I was working on an 0-235 / RV-3 and had the carb off for over haul, and the exhaust system was off also. I was working on the primer system about 4-5 mins before I grabbed the prop and started to inspect the valves though the exhaust port, when "Click, BANG" I moved the prop enough to set off the magneto! The prop came around and hit my hand hard. I thought it was broken, but I just broke a blood vessel and it swelled up bad. It was several days before I could use my hand again.

I just could not imagine the thing firing, but obviously it did! Gas, spark, ignition! Lesson learned!
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  #5  
Old 10-17-2010, 09:43 PM
Norman CYYJ Norman CYYJ is offline
 
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Location: Victoria B.C.
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Quote:
Originally Posted by Mike S View Post
Another tidbit I was taught many years ago, if you must move the prop, turn it the opposite direction-----that way, if a mag is hot, the spark will not be at the correct timing to kick the engine over.
If you should happen to have a vacuum system turning the engine backwards can destroy the carbon vanes in the vacuum pump.
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  #6  
Old 10-18-2010, 05:11 AM
bignose bignose is offline
 
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Location: Sao Paulo, Brasil
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C L E E E E A R . . .
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  #7  
Old 10-18-2010, 09:43 AM
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jetjok jetjok is offline
 
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Location: Sutter Creek, CA
Posts: 842
Default Another Opportunity for Pain

Years ago, while in A&P school, one of my contemporaries decided that the policy of having two people to do a differential compression check did not apply to him. Needless to say, when he applied the pressure, he quickly found out that his idea of TDC was a few degrees off! Luckily for him, it was an old A-65 and probably had leaky cylinders. He survived with a major gash to the head, a huge knot, and having to clean the blood off the hangar floor upon his return.
This link may seem like it it stating the obvious, but I see many people that are moving propellors like there could be no consequences. In this case, a "life experience" could result in a permanent cancellation of one's ticket to the dance.
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  #8  
Old 10-18-2010, 08:45 PM
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hgerhardt hgerhardt is offline
 
Join Date: Oct 2006
Location: torrance, ca
Posts: 650
Default

Quote:
Originally Posted by Steve Barnes View Post
If your magneto is equipped with an impulse coupling, the impulse coupling does not activate when turned in reverse.

Steve Barnes "The Builders Coach"
If you have dual Lightspeed ignition, the engine will run in reverse just fine for a couple of revs. Don't ask me how I know...
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