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Never, Never Stick Your Finger in
the Propeller
Before I took the job as AMA Insider safety columnist, I remember lamenting
to my beautiful wife that it might be hard to make the column interesting. I
remember saying, “Just how many times can you tell someone not to put his
finger in the propeller?” On a warm Friday afternoon in late August, I found
that the answer. After 30 years of flying airplanes, I had my first
encounter with a spinning propeller.
I was with a bunch of flying buddies at our preferred float-flying spot,
enjoying the late summer morning. It was the first flight of the day on my
.30 four-stroke powered Newbie float plane. As the flight progressed, I
could see the motor was not developing full power, so I made an early
landing and taxied back to do some engine adjustment.
With another flier holding the airplane, I was adjusting the high-end needle
setting when my hand somehow wandered into the full-throttle propeller. In
an instant, the motor stopped and the blood began to run. The cuts were
quite serious and we immediately went into damage-control mode. We had a
first aid kit along, but it was a small one. We applied pressure and
bandaged the wound with the only high strength tape available, a roll of
black electrical tape. With the blood flow temporarily stopped, I made my
way to the emergency room for a two-hour stay and about 14 stitches from a
very competent and friendly emergency room doctor. This little lady looked,
to me, to be about 14, but she did a great job sewing up four separate
propeller strikes on my right hand. She mentioned that I was her very first
prop-strike victim and I replied that it was also a first for me.
Fortunately, there was no permanent damage except to my pride. I managed to
hit the blade with the flat of my hand rather than the fingers. That stopped
the propeller and reduced the number of strikes somewhat. It is now almost
two months later and I have just the scars to remind me of my errant ways.
Who do I have to blame? No one but myself—it was a preventable accident. In
hindsight, I lost what the military calls “situational awareness.” I was so
focused on the job at hand (no pun intended), which was tuning the engine
that I totally ignored the close proximity to the spinning propeller. I know
better. On that day, evidently, I did not know better and all it takes is
one lapse in concentration. That is the lesson I leave with you and why I am
sharing my experience.
A second observation. This little four-stroke is my smallest motor. Maybe
that is why I was not as conscientious as I might have been. As you can see,
small propellers do just as much damage as big ones.
A third observation; and one that my flying group has now corrected. Our
first aid equipment was inadequate. We have since purchased a much better
equipped first aid kit and put it in the storage locker in our retrieval
boat. That kit now matches the one we have at our field. By the way, it
still includes the roll of electrical tape. I can vouch for how well it
worked at compressing the bandage over the wound.
A fourth observation. I have my flying buddies to thank for the help and
assistance. It is important to surround yourself with fellows who are safety
conscious and who can be trusted in an emergency.
And last: Never, never stick your finger in the propeller.
Arming Switches on Electric Airplanes
This past summer, I learned of a couple of instances where an electric
airplane started before the pilot was ready. In one instance, the pilot
turned on the transmitter but had it improperly set to another airplane
program. Evidently, the programmed airplane had the throttle reversed and
when the airplane battery pack was plugged in the motor engaged. Most good
ESCs are supposed to prevent this by making you put the throttle to its
lowest setting before arming. I’m not sure what happened here.
In the second instance, the airplane was on the bench and the transmitter
had yet to be programmed. The throttle stick was in the mid-range. Once
again, when the battery was plugged in, the motor engaged. An arming switch
is a good way to prevent any accidental motor start on an electric airplane.
They are most feasible on larger motors, but many electric gurus say they
can be fitted to an airplane of almost any size.
Another good reason for the arming switch is to be able to plug in the
battery and then prepare the airplane for flight. Many times there are
cowlings or hatches that have to be secured or other preflight preparations
to complete. Why do that with the battery and motor armed? A number of
commercial arming switches are out there. They are not very expensive and
are easy to use. Your local hobby shop can surely provide you with one.
If you want to tackle the project in your shop, just peruse the online
forums and you will find lots of pictures and schematics. Here’s one in the
RCGroups forum:
www.rcgroups.com/forums/showthread.php?t=1335070 .
And here’s an even better idea. These two clubs have posted pertinent
information and how-tos on their websites for their members and others to
use. I think that is a great idea. It would be a simple matter to create a
link on your site to these documents or write one of your own.
Here’s a great reference from the East Bay RC Club in Livermore, California:
www.eastbayrc.org/TimTips/TimsTips_ArmingSwitch.htm .
And another from the White Hills Eagles club in Shelton, Connecticut:
www.whitehillseaglesrc.org/membercontent%5Ctransmittercutoff%5Celectricflightthrottlesafety.pdf.
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