Hand propping an aircraft engine, at least some engines, is a routine task, but it’s woefully unforgiving of carelessness and lack of technique and caution. In this video, AVweb’s Paul Bertorelli examines what can go wrong and all too often it ends up with an airplane wrecked and occasionally someone hurt. Sense of humor recommended.

27 COMMENTS

  1. Hi Paul:

    As usual, very good…and humorous.

    Looks like you need an MS25171-1S electrical boot on the P-lead terminal. Not likely on your J3 with limited wiring and plumbing in the engine compartment but movement inflight of a hose or wire can touch the P-lead post causing momentary ground out and shut down of the mag and consequent rough running. Hard to duplicate on the ground.

  2. Well said. I’ve hand propped only once. Did it for an O-320 in a Tri-Pacer I owned at the time 40 years ago because of a weak battery. I didn’t want to take the time to charge the battery nor did I do all of the stuff you recommended like a tail tie-down or have anyone in the cockpit. Used common ordinary chocks but I did make sure to barely crack the throttle open. It was a cold December day and I propped from the front with a leg kick making sure to step back from the prop as I yanked it through and did wrap my fingers around the prop only because the compression seemed to demand it. Worked out okay with the engine eventually starting at idle after 6 or 8 pulls but I was on edge the whole time I was doing it.

  3. Good video. I’m a leg swinger. Have been since I was taught to prop (Champs) in ’58. Makes me feel like I’m, with every pull, stepping away from the action. Without the leg swing, I feel like I’m leaning into the action. Hot mags. I was taught, in ’58, to assume that an aircraft engine is always hot, as the principle of mags was explained to me. I was taught to assume that every time I touched a prop. I’ve always done so. (I’ve seen so many times persons, while assuming the mags are off, pull props carelessly with out regard to the totally rare possibility that it could be hot.) Finally happened to me a few years ago at my local airport. Friend of mine asked me to prop his J3 for him. Happy to. He was in the cockpit and said, “switch is off, brakes set, throttle closed, pull it through six times to prime it”. That’s exactly what I do with my A65 in my Chief. So, using good technique, with leg swing, I began to pull. Pulled once, pulled twice, pulled three times and the damn thing started right in front of my face. I was so surprised and shocked, I swear me being in denial that it shouldn’t have started yet , I almost threw my hands out to stop it. I didn’t though. My friend was at that moment busy yelling, “the mags are off! the mags are off! I swear the mags are off!” Yep, investigation showed loose P led. Took years for it to happen to me. So always assume a prop is hot if you dare move it for any reason.

    • Hey, cut a brother some slack! IMHO, Paul Bertorelli could very well be an imaginist in aviation with an emphasis on accurate depiction. His extensive and well-cultured cynicism and cojones allow him to produce tempting, and provocative images of the affairs in Aeronautica. He Da Man!!

  4. If Paul Bertorelli wrote it I’m going to read it. His video and articles are always right on and explain the safety aspects for the topic of discussion as clear as new Piper Cub glass. Paul, have you written any books?

  5. Paul, I have to admit to not having to “prop” an airplane in my career. R-2800s and jets don’t tend to lend themselves to that procedure well. That said, I did grow up on a medium sized farm in Western NY. My Dad had a 1932 Case tractor with a 4 cyl engine he used for plowing, etc. Like your Cub, no electrical system so hand cranking was “it”. The crank was always there thinking about how it could “get you”. Once I was old enough, thus big and strong enough to actually pull the handle and move the engine, Dad was very thorough in teaching me how to do it. He showed be a single way to accomplish the task and was very blunt in saying that using any other technique was asking for at least a broken arm. He did stress, with extreme force I might add, to ALWAYS double check that the transmission was in neutral and the hand brake was set. His point was clear: if I didn’t do all this stuff, I was going to get either a broken arm or run over by a several thousand pound tractor. Events I successfully avoided I might add.
    Clearly, that tractor had no prop to worry about but the points you allude to in the video are good ones that apply to all machinery. Those points are that “it” is a machine and is automatically dangerous at some level. And, that machine is always capable of injuring or killing any human that comes near it. So, the lesson to take away from you video is a good one: learn how to safely and correctly operate (in this case start), your “machine, be it a plane, a tractor, a power screwdriver, whatever.
    Good work on using enough humor in your video to make your points clear and memorable.

  6. How I wish the guy who destroyed my sweet 172R had seen this video before hand-propping his Champ a few years ago here in San Diego. I had just installed an engine monitor, ADS-B in/out, and an AOA HUD. The plane already had a GPS and a capable autopilot with altitude hold. In a flash, the runaway Champ not-so-gently nuzzled into the intersection of the right wing and fuselage. A minute or so earlier, the usual weekend group of skydivers from the nearby skydiving school had walked past my right wing and turned left on their way to the 206 that would take them aloft. Champ destroyed, my 172 totaled, two other aircraft damaged, six humans almost turned into sliced meat.

  7. The Insider articles are almost alway my first read on Avweb Flash. Never had to hand prop a plane. One nice feature on the PA32 is a socket for jumper cables. I only had to use it once but was glad to have it. I was at a non towered airport and hadn’t had my plane long. Shortly thereafter I replaced the battery. Not being a long time pilot or having been based at a public airport, I didn’t get the Bonanza reference.

  8. Some planes are not meant to be hand propped, a PA32 being one of them. Sure, anything can be done. But those are the events where both the pilot and the propper are not familiar, the engine usually opens at a high power setting, and it does a runaway. Also, tri gear planes are at a very bad angle for hand propping, usually have high horsepower/compression. On the rare occasion I prop a C150 or even a C172, I try to get folks to hold the tail down for a better angle of the dangle.

  9. The cameos are a nice touch.
    As a guitar player, hand propping is totally out of the question.
    Said hello to you in the Walmart produce section at OSH this year. Aviation groupie through and through.
    Always enjoy how your mind works, Paul.
    Thanks.

  10. It’s complicated!

    Hand Propping: A Legal Primer (AOPA)

    https://pilot-protection-services.aopa.org/news/2015/march/25/hand-propping

    More: The FAA recommends a two-man hand prop procedure. FAA-H-8083-3B, Page 2-13

    “It is critical that the procedure never be attempted alone. Hand propping should only be attempted when two properly trained people, both familiar and experienced with the airplane and hand propping techniques, are available to perform the procedure. The first person is responsible …”

    https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook/media/04_afh_ch2.pdf

  11. Oh no! No one mentioned that hoary old chestnut “A Farewell to Arms”, of Hemingway Starter fame. I guess it’s been used so many times, the funny side has been lost.
    Excellent video Paul. Nothing like belt ‘n braces to ensure a happy day!

  12. I have been hand propping airplanes since I learned to fly a J-3 Cub when I was 15 years old. I now teach in that very same airplane today, some 40 years later. I worked as a line boy for many years and hand propped an range of aircraft. I was always taught to treat the engine as hot at all times. This Cub was used to tow gliders so it has a release hook on the tail, even now. I was originally taught exactly as you presented in your video, and followed that process for a very long time. As I gained more confidence and became complacent, I have routinely started this Cub by myself, from behind the prop without chocks or tie down….I have been lucky. After watching your video and recently there was a runaway incident at a nearby airport, I have decided to get back to basics and always tie the tail down and chock the wheels. This came in handy last week when I was going to fly with a student for a flight review. She followed the checklist to a tee…As I pulled the engine through for the second blade….it started! Mag switch in the off position and running like a clock at idle. This was a non-event, but given the right circumstances it could have been much worse. Thank you for pointing out the obvious, even for those of us who have been doing this for years.