Hand prop accident fatal

Aircraft: Piper Cherokee. Injuries: 1 Fatal. Location: San Diego, Calif. Aircraft damage: Destroyed.

What reportedly happened: The passenger reported that he and the pilot were both seated in the airplane when the pilot made three unsuccessful attempts to start the engine. The pilot told the passenger to “get out, I need to jump it.” The passenger got out and was walking away from the aircraft when he heard a noise. When he looked back toward the front of the airplane, he saw the pilot lying on the ground below the propeller. The engine was not running.

Post-accident examination revealed that the magneto switch was in the both position. Investigators determine that it is likely that the pilot moved the propeller, and because the magnetos were in a ready-to-start condition, this resulted in a spark plug firing, which caused the propeller to turn rapidly and strike the pilot.

Probable cause: The pilot’s failure to turn the magneto switch to the off position before moving the propeller to start the engine by hand.

NTSB Identification: WPR12LA085

This January 2012 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.

 

 

Comments

  1. Mack says

    Turning the prop by hand is a normal part of flying a Cherokee.

    First, you must take precautions, of course. You simply must handle the prop as if it is going to start. That means making sure the plane won’t move, and only contacting the prop on it’s front face, so it won’t break your fingers if it kicks back. Your body must be clear of the prop arc, at all times, and you should be prepared to step backward, away from the prop, when the engine starts.

    Turning the prop through by hand, is done slowly, to feel the compression of each cylinder, and sometimes to position the prop where the starter will engage the ring gear in a loose part of the arc, then gain some inertia, for a faster compression stroke.

    On four cylinder Lycomings, the prop will be horizontal for the top dead center firing event. On six cylinder Lycomings, the power events are at thirds of the prop arc, and that makes hand-propping the O-540 extra difficult, and dangerous.

    A four cylinder, though, can be hand-propped easily, if all precautions are taken.
    It requires a competent pilot in the cockpit, or a chocked, tied down aircraft, with a partial throttle.

    Today’s technology, though, should make hand-propping unnecessary. Just check your Cherokee’s start circuit under load, it should be more than nine volts, engaged. If not, replace components that are dropping too much voltage. Today’s starter motors are much more advanced than old Prestolites. They come with low current draw, wider commutators, and even electronics that can detect kickback for immediate shutdown before starter damage occurs.

    If you can afford Slickstart, it’s an electronic mag boost that makes your mags behave like they are doing 900 RPM or more, when your switch is held in the “start” position, and only when in that position.

    My six cylinder Cherokee always starts like a brand new car, whenever I press it’s 40’s style start button!

    I’ll never have to hand- prop it! Even if the battery is dead, those 40 dollar jump starters made for cars, work very well for Cherokees, and store cleanly in the baggage compartment. They have low internal resistance (due to thin separators), and spin the engine fast.

    It’s nearly impossible to start my O-540, by hand propping, but I always treat the prop as if it’s going to start, I stay out of the arc, and move the blade slowly if I’m positioning it.

    A buddy’s four cylinder, I have started, using all precautions, of course!

  2. Gil Jennings says

    This unfortunate accident happened at my airport. The victim was a very bright Geotechnical Engineer who I knew. The engineering community was saddened to hear of this accident… Everyone here surmised that he was trying to hand prop because of a low battery.

  3. Rich says

    I doubt he was trying to hand prop it.
    And I don’t even consider this a hand propping accident.
    IMHO this PROBABLY was the result of repositioning the propeller for what ever reason.

    These things ALWAYS have to be treated as if the mags are hot even if you know the switch is on the off position.
    If you must move the propeller to attach a tow bar for example, turn it backwards a 1/4 turn.
    Never turn it forward!!!! EVER.

    • A36 says

      I was taught that was not correct. Always turn in normal engine driven direction. Turning the prop backwards could damage the airpump and/or other engine accesories.

  4. Ray says

    Tragic accident, my condolences. Hand propping is as safe as shaving with a straight razor. But a moments inattention and you cut your throat.

  5. bjs says

    I don’t know anything about it because I’ve never done it, nor do I intend to, and I know it’s been done since the Wright brothers got the idea of man in flight, but hand propping an engine seems to me akin to playing Russian roullette?

  6. Tom says

    I can remember those days,
    “Switch Off” then 3 hand turns,
    Hand prop to the ready phase,
    “Switch On” and the engine runs.

  7. Greg W says

    Tragic accident likely promoted by a break in routine, much like driving into the towbar. I hand prop on a regular basis, it is very important that your routine be the same and uninterrupted, if it is start over. The first and last thing to touch is the mag switch, first thing off, last thing on. Also for anyone helping someone prop start, the person at the propeller is in charge not the pilot at the controls,they follow you. If the person in the cockpit will not follow your instructions for brakes, prime, throttle,mags, GET AWAY from the airplane and leave them on their own, it is not worth your life.

  8. Thomas Boyle says

    Small edit to the report: the aircraft was undamaged, not destroyed as your headline shows.

    Tragic accident, due to a moment’s inattention. He had evidently turned off the master, not the mags.

Leave a Reply

Your email address will not be published. Required fields are marked *