Wednesday, February 1, 2012

Solo Hand Propping

A recent fatal accident and a dumb incident has folks discussing the dangers of hand propping. There's evidence the fatal in San Diego was not a hand propping accident, but we'll wait for the NTSB to provide a narrative.

Still, any accident should remind us of the dangers inherent in aviation. Since most GA airplanes have starters, hand propping is considered a vestige of the old, reckless days.

There is no FAA requirement to learn hand propping, thus few pilots are exposed to the procedure. It should not be required as many pilots fly successfully for years without ever being exposed to hand propping.

But, as in most thing in aviation, it doesn't hurt to know more.

Who

Some will argue that Federal regulations require two pilots or at least two people. This is incorrect. There is no regulation prohibiting hand propping or requiring two people (or certificated pilots). This confusion arises from airport word-of-mouth and handed down "wisdom." It may also arise from reading The Airplane Flying Handbook has this section in Chapter 2:
HAND PROPPING
Even though most airplanes are equipped with electric starters, it is helpful if a pilot is familiar with the procedures and dangers involved in starting an engine by turning the propeller by hand (hand propping). Due to the associated hazards, this method of starting should be used only when absolutely necessary and when proper precautions have been taken.
An engine should not be hand propped unless two people, both familiar with the airplane and hand propping techniques, are available to perform the procedure. The person pulling the propeller blades through directs all activity and is in charge of the procedure. The other person, thoroughly familiar with the controls, must be seated in the airplane with the brakes set. As an additional precaution, chocks may be placed in front of the main wheels. If this is not feasible, the airplane’s tail may be securely tied. Never allow a person unfamiliar with the controls to occupy the pilot’s seat when hand propping. The procedure should never be attempted alone.
This is excellent advice, but it's not regulation. This is good, otherwise thousands of airplanes would be grounded or thousands of pilots would routinely break the law.

One can argue that it may be less safe to have two people doing the procedure, given the possibility of miscommunication. If you are doing it as a team, the person doing the propping is in charge, end of story. But this post is about solo propping. I'll leave the team method for another post.

What

Only certain airplanes should be hand started. These include the low-compression taildraggers of yesteryear: Cubs, Champs, Chiefs, Taylorcraft, etc. The prop is in the right position, there is no starter, there is (usually) a single impulse mag (which converts slow RPM movement to high RPM winding to produce a spark as it also retards the firing point), and a two bladed-prop (which provides a gap between prop being pushed and the next blade).

WARNING: High compression nosewheel airplanes are not good candidates for hand propping. Sure, ole lefty has done a million of 'em. You're not Lefty. Get a jump or get a preheat or get it fixed.

Now that we've narrowed down the airplanes we will hand start, we must consider the terrain, possess and use chocks and an adequate tiedown.
Terrain
Make sure the airplane is level and the ground in front of the prop is clear of gravel, ice, slick grass -- whatever. More than once I've gotten everything in place to find I was standing on dew-covered grass. Undo the tiedown, remove the chocks, and push it somewhere dry or at least not slick.

Chocks
Put chocks in front of the wheels.  I use a set tied together with nylon rope so I can pull them out from the pilot side.I don't place chocks behind the wheels, since I'm on level ground.

Tiedown
I tie the tail down and attach it to something planted or heavy (I've used the hitch of My F-150 as a tiedown). A dog tie-out is not an adequate tiedown. Even my ancient 65-HP Chief will pull one of those screw-in deals out at takeoff power. The tiedown doesn't need to be tight -- the rope is a safety stop should the chocks not work. Be sure the rope is at least 1200 lbs of break strength (for a small 65-85 HP engine). When travelling I have pushed back to a fence post for a tiedown.

 

When

Only after the airplane is level, chocks are in place, tail is tied down, and the surface is clear and provides good footing do I begin the next phase of the starting procedure. I should emphasize here that fuel is off and mags are off while I'm pushing the airplane into position.

How

Solo starting procedure for the Chief:
WARNING: Always treat the prop as HOT -- that the slightest touch can start it.
  1. Check inside of cockpit: Mags OFF, Fuel OFF, seatbelt out of the way, nothing on the floor.
  2. Walk around strut and stand directly in front of nose within comfortable arm's length (leaning forward is worse than being "too close").
  3. Grab prop near the hub and attempt to move the airplane. It should move back, but stop when it comes forward.
  4. Walk around outside of strut and reach in to turn fuel on, give 4 shots of prime (number of shots may vary).
  5. Check Mags OFF, Fuel ON
  6. Walk around strut and stand directly in front of nose within comfortable arm's length. Check that chocks hold as in step 1.
  7. Step once sideways to left. Reach for prop and without curling fingers around prop rotate prop through six revolutions (this primes the engine and is the procedure called for in the Lycoming O-145-B2 Engine Operator Manual).
  8. Walk around strut, check primer IN, Fuel ON, Mags ON (left is usual impulse coupling), throttle in 1/2".
  9. Walk around strut and stand directly in front of nose within comfortable arm's length. Check that chocks hold as in step 1.
  10. Step once sideways to left. Reach for prop and without curling fingers around prop push prop down and away. This doesn't need to be forced as the impulse coupling are doing the work.
  11. If engine starts, step back, then walk around strut (keeping and eye on the airplane for movement) and reach inside and adjust throttle for smooth idling (800-1000 RPM is recommended Idling speed on startup).
  12. Once engine warms, reduce throttle to low idle (600 RPM) and walk to back and release tail tie down.
  13. Return to cockpit and rev to 800-1000 RPM (low RPM does not provide sufficient oil splash, thus we want to limit the time running at low RPM and resume 800-1000 RPM to keep the oil moving).
  14. Reduce RPM to low idle, lean forward and pull chock rope to release chocks. If they do not release hold onto strut to get better angle. If they cannot be removed then shut down and start all over again with chocks in better position to release (it happens).
This seems like an awfully long and involved procedure. But with practice it's basically automatic and takes all of five minutes. The key is to be consistent, check that the chocks are holding, always tie down, and always treat the prop as hot.

After a while hand propping becomes as normal as every other part of aviating. Just keep the requisite respect and safe procedure to be able to continue!

1 comment:

  1. I'm very pleased to find this post. I'm considering buying an Eaglet home built. The O-145 has zero time SMOH. I'm going out to take some photos this afternoon.

    Roger Ek
    Lee, ME

    ReplyDelete

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