Fatal: walked into prop

Capngrog said:
I'm sure it was just a slip of the key board on your part, but just to clarify: Under normal operations, never approach a running helicopter from the rear. Approach from the front where the pilot can keep you in sight. Of course this bit of sling wing wisdom is often ignored during operations when crew/PAX approach from the sides.

Back to prop arcs. In the Air Force, I was a lowly airframe mechanic working mostly on KC-97s. One night I was out on the flight line taking a break from working on one of the old dogs while the engine guys did a low power run up of engines Nos. 3 and 4. I was standing on the ramp in front of the engines, while my friend, Ken, an engine mechanic, was observing the run up from beneath the right wing. The lighting units were pointing at the front of the airplane as the engines were being run, and the prop arcs were very visible, if somewhat mesmerizing. Due to the taper of the leading edge of the wing, engine No.4 was spaced 2-3 feet aft of No.3 leaving a gap of 2-3 ft between the propeller arcs of Nos.3 and 4. As I watched, Ken walked forward between the propeller arcs, which should have been impossible for my 6'3" friend. It happened so quickly that no one had a chance to react, but the engines were immediately shut down after the fact. Ken never did remember walking between the propeller arcs. It was thought that the lights shining from the front created a high frequency strobe effect with the whirling propeller blades, and this caused Ken to become mesmerized as he approached from the rear. By the way, the 18ft. diameter props were spun by the Pratt & Whitney R-4360, the largest displacement production piston engine ever built.
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Well “front” being 10 & 2 o’clock areas, sure but due to the forward tilt of the transmission, no way I’d approach off the nose between those two positions. In fact, in my current job I’m required (if able) to position the aircraft for a hot load at the 9 o’clock area.

http://www.superior-air.gr/ground-safety/
 
Dana said:
Nosedraggers are harder because the propeller is lower, making it harder to pull it through.
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Side by side seating also means a wider airplane with less prop sticking out, which can take away the option of propping from behind. I always hand-prop the Cub from behind the prop with one foot just in front of the wheel and the throttle within easy reach.
 
Velocity173 said:
Well “front” being 10 & 2 o’clock areas, sure but due to the forward tilt of the transmission, no way I’d approach off the nose between those two positions. In fact, in my current job I’m required (if able) to position the aircraft for a hot load at the 9 o’clock area.

http://www.superior-air.gr/ground-safety/
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It has been over a decade since I was required to place my tender pink body in the proximity of whirling helicopter blades, so my recollection of ground safety is a bit fuzzy. From looking at some information on the ol' Interweb (FAA-11-8083-21B, Chapter 8, et al), it appears that while O.K. to approach a running helicopter from the front, the preferred approach is from the 10 to 8 o'clock (as pointed out by Velocity 173) and from the 2 to 4 o'clock sectors, with the 10 to 8 o'clock (" ... the 9 o'clock area.") preferred. I was mostly working around Bell 206 and 206L helicopters which didn't, as I recall, have any significant forward tilt of the main rotor disk when operating on the ground. The key thing that was always emphasized was, as written by Bell 206 above: " ... never approach a helicopter unless the pilot acknowledges you."
 
Capngrog said:
I was mostly working around Bell 206 and 206L helicopters which didn't, as I recall, have any significant forward tilt of the main rotor disk when operating on the ground.
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FYI: while a B206 is not as low as a S76, with it running and the droop stops disengaged, an L model will part your eyebrows without any blade flex. Sometimes a misadjusted cyclic friction can catch even a good pilot off guard and send the blades low.;)
Capngrog said:
If you don't want to hand prop an airplane, there's always this technique:
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Must be SOP in SA. Helped untangle a couple Air Force Cessnas in Bolivia that didn't have their timing as coordinated. But have heard the stories of rope pulling large round engines during the 40s but they didn't wrap the rope so tight. I'll stick to turbines and keep a Start Pak handy.
 
Bell206 said:
FYI: while a B206 is not as low as a S76, with it running and the droop stops disengaged, an L model will part your eyebrows without any blade flex. Sometimes a misadjusted cyclic friction can catch even a good pilot off guard and send the blades low.;)

Must be SOP in SA. Helped untangle a couple Air Force Cessnas in Bolivia that didn't have their timing as coordinated. But have heard the stories of rope pulling large round engines during the 40s but they didn't wrap the rope so tight. I'll stick to turbines and keep a Start Pak handy.
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S76 is probably similar to a UH-60 in that if a droop stop doesn’t come in, the blade can dip as low as 4 ft off the nose! :( Fortunately, I never had a stuck droop stop in one.
 
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Velocity173 said:
S76 is probably similar to a UH-60 in that if a drop stop doesn’t come in, the blade can dip as low as 4 ft off the nose!
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With everything working correctly the 76 will be at 5 feet with a normal stick position. We developed an inhouse cyclic block to keep the blade tips above 6 feet during ground ops. Been one too many incidents with 76s. I always equated 76s to low wing airplanes when working on them as you had to walk a block out your way to get from one point to another when doing ground run work.
 
luvflyin said:
What different skills are needed to do the job by hand in a 172 or Cherokee vs a small taildragger?
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Different to me in terms of technique. With a cub or something similar, at my height, the prop is such that I know that I can pull down to prop while keeping my momentum going backwards, so if I fall or slip I'm going to fall away from the prop. The little 65-90 hp engine with no accessories attached provides very low resistance, so I can pull it through at speed with barely a fingertip over the trailing edge, if that. The prop on a 172 or Cherokee is more vertical, feels lower even if it isn't, and is going to have more drag because of the higher displacement and attached alternator. Maybe not that big of a deal, and maybe I'm being a chicken, but I don't trust myself to do it. Cub? Have hand propped probably 100+ times.

Reading the above it does seem like I'm being a big baby. But I'm OK with that. If I haven't propped in a while, I will do an actual walk through of the motions beside the plane, before doing it live. To me it's a little like practicing a dance, "pull step step wait", and I'm a terrible dancer.
 
Half Fast said:
The last airplane engine I hand-propped was a Cox 0.49 glow plug engine. My fingers were usually cut up and bruised when I was a kid, and today I have no desire to subject my arms, neck, and head to similar trauma.
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I still have my Cox 0.49 engine . It had The fuel tank under the engine crank case , balsa 172 kit, line controlled . Haven't run it in close to 70 years . Definitely a finger catcher . Usually right at the bottom of finger nail, index finger , right hand.
 
Ed Haywood said:
Whenever we talk about clearance under helo rotors, I get to post one of my favorite pictures. We definitely ducked that day.

View attachment 111865
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Just imagine walking below the tail rotor while it’s spinning. Saw that happen one day in Afghanistan. Was watching an AF MSGT that was waiting to load on the left side of chalk 2 and then took it upon himself to walk around the tail and load on the right side. For some reason (stay close to aircraft) he ran his left hand along the stab as he walked under the tail rotor. His head was inches from the spinning blades. Had on a Kevlar but I’m sure would’ve gotten a massive headache from impact. I always said, no way you can do a proper pax brief when you’re hot loading everywhere you go.
 
Ed Haywood said:
Whenever we talk about clearance under helo rotors, I get to post one of my favorite pictures. We definitely ducked that day.
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Another caution is to never walk uphill when departing a running helicopter that landed on a slope. Unfortunately, this gets a few people every year.
 
donjohnston said:
What's a "droop stop"?
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Pic of a fixed droop stop. You can see two circular tabs. The top one (orange disk) that’s not contacting the blade is a flap restraint stop. The bottom one that the blade is resting on, functions as a droop stop and also a flap restraint. Once the blades are at normal rpm they shouldn’t touch either stop. However, while landing on a large slope and the pilot has too much cyclic into the slope and not enough collective, you can get some droop stop pounding.

In a dynamic stop like mentioned above, it’ll usually be on a spring that puts the stop in place during low rpm. If that spring should fail, there’s nothing to keep the blade from drooping other that the elastomeric bearing mounted to the hub. In that case, the blade will rest at an extremely low position.

2CCD6773-9DE1-4AB1-AE0B-5E8C451E50E8.jpeg
 
Velocity173 said:
Just imagine walking below the tail rotor while it’s spinning. Saw that happen one day in Afghanistan. Was watching an AF MSGT that was waiting to load on the left side of chalk 2 and then took it upon himself to walk around the tail and load on the right side. For some reason (stay close to aircraft) he ran his left hand along the stab as he walked under the tail rotor. His head was inches from the spinning blades. Had on a Kevlar but I’m sure would’ve gotten a massive headache from impact. I always said, no way you can do a proper pax brief when you’re hot loading everywhere you go.
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He was probably used to working with MH-53's. That's exactly how we were taught to move around them.
 
Since I have never personally been up close to a Heli hub, the scale is impossible for me. What is the diameter of the orange bump stop in the above picture?
 
iamtheari said:
I'd never make it to the tail rotor even with a ladder. I'd drop the ladder and fall down laughing at that ridiculous nose.
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Lol, I know. She was ugly and beautiful at the same time.
 
Capngrog said:
If you don't want to hand prop an airplane, there's always this technique:

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Who made the engine? Briggs and Stratton? My dad had a lawnmower when I was a kid that was built before recoil starts were a thing. Real pain in the backside when it decided it didn’t want to mow today!
 
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