# General Aviation folk, I need your help again ~ **URL:** \ **Category:** In My Humble Opinion\ **Created:** [February 19, 2016, 12:30pm UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545 "2016-02-19T12:30:57Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![Morgenstern](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@Morgenstern](https://boards.straightdope.com/u/Morgenstern)\ **Post date:** [March 13, 2016, 4:45pm UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/41 "2016-03-13T16:45:27Z")
> [@saje](#): > > I think he’s more PO’d about the damage to the nearly new prop than he is about the damage to his head! > > [The prop](http://i1030.photobucket.com/albums/y368/sswj61/eeca1486-7edd-4406-b2e2-a79f3332b409_zpsqoozsfba.jpg) > > Certifiable, he is. > > When we went to the hangar the first thing he did was to turn the mags on to see if the strobes were going. and they were. He can’t believe that he ignored those and kept doing whatever he was doing, but there doesn’t seem to be any other explanation. 😕 > > . If you go to the next picture, you see a tiny bit of blood on the lower edge of the lower white stripe on the propeller. That might indicate he was struck by it, but I’m thinking a strike would have resulted in a lot more blood on the prop. Did he clean it before the pictures? If he didn’t, it really looks more like his injury was caused by something other than the prop hitting him. Like the prop hitting something that hit him. ETA. That could be just the remains of a bug though. I don’t really know. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 13, 2016, 5:05pm UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/42 "2016-03-13T17:05:44Z")
> [@saje](#): > > I think he’s more PO’d about the damage to the nearly new prop than he is about the damage to his head! > > [The prop](http://i1030.photobucket.com/albums/y368/sswj61/eeca1486-7edd-4406-b2e2-a79f3332b409_zpsqoozsfba.jpg) > > Certifiable, he is. > > When we went to the hangar the first thing he did was to turn the mags on to see if the strobes were going. and they were. He can’t believe that he ignored those and kept doing whatever he was doing, but there doesn’t seem to be any other explanation. 😕 > > . Um… not to be rude because I have a similar plane… But the mags are not connected to the strobe. That’s a separate switch. The mag switch is key operated. It sounds to me like he flipped the master switch on which is located under the left seat. That turns the electrical buss on. If he left the stobes on then they would be powered. The mags are self powered and are independent of the electrical system. They are always “live” unless grounded by the switch in the off position. That’s to ensure they work even if there is a power failure and a switch failure. If the mag switch was turned off and the engine fired then it’s not grounding properly which means the grounding wire broke or the connection corroded. This is why you always treat the engine as if the mags are on. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 13, 2016, 5:17pm UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/43 "2016-03-13T17:17:08Z")
Looking at the picture I see an arc of black on the leading edge of the prop that would correspond to striking a round object. Was he wearing a hat at the time? The is more likely the mark I would expect. There wouldn’t be any blood on it because the wound wouldn’t have time to bleed at the point of impact unless it sliced through it. The mark on the prop is shiny on both sides of it as if contact was made from an object. If it was a bug it would continue along the plane of the arc and not curve and there wouldn’t be a shiny path on either side of the trajectory. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [March 13, 2016, 5:20pm UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/44 "2016-03-13T17:20:39Z")
> [@saje](#): > > I think he’s more PO’d about the damage to the nearly new prop than he is about the damage to his head! > > [The prop](http://i1030.photobucket.com/albums/y368/sswj61/eeca1486-7edd-4406-b2e2-a79f3332b409_zpsqoozsfba.jpg) > > Certifiable, he is. Mrs. L.A. says, ‘Well the head will heal…’ ---
**Author:** ![saje](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saje/32/3631_2.png) [@saje](https://boards.straightdope.com/u/saje)\ **Post date:** [March 13, 2016, 6:09pm UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/45 "2016-03-13T18:09:16Z")
Nope, watched him do it. Turned the key, strobe came on. I know nothing though so I’m only going by what I saw. The prop my have been sprayed off when the fire rescue crew hosed the blood out of the hangar, I don’t really know. And he often wears a baseball cap, but I don’t really know. I didn’t get one back with his shredded & bloody clothes, and I didn’t see one in the hangar so…? Still, it’s kind of an impressive mark - (shudder) ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [March 13, 2016, 6:43pm UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/46 "2016-03-13T18:43:15Z")
Real good that the part that hit him was so close to the hub. If it had been the tip… He is very lucky. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 13, 2016, 8:14pm UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/47 "2016-03-13T20:14:46Z")
> [@saje](#): > > Nope, watched him do it. Turned the key, strobe came on. I know nothing though so I’m only going by what I saw. I’m only bringing this up because this is a serious issue. The strobes have no relation to the mag switch. Strobes are on an electrical circuit. The mags are self powered with no connection to the plane’s electrical system. No voltage goes to them. Please understand I’m not trying to argue a point. I’m trying to convey that it’s possible your plane’s magneto switch is bad and it’s always live which is a very dangerous situation which can lead to unplanned starts. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 13, 2016, 8:43pm UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/48 "2016-03-13T20:43:46Z")
> [@GusNSpot](#): > > Real good that the part that hit him was so close to the hub. If it had been the tip… > He is very lucky. Just walking into the tip when it’s not running is really dangerous. I always rotate it straight up after shut down and assume the mags are on. ---
**Author:** ![I\_Love\_Me\_Vol.I](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/i_love_me_vol.i/32/521_2.png) [@I\_Love\_Me\_Vol.I](https://boards.straightdope.com/u/I_Love_Me_Vol.I)\ **Post date:** [March 14, 2016, 3:51am UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/49 "2016-03-14T03:51:58Z")
You relate quite a story! > [@saje](#): > > They said the **magneto** s were on in the plane and so yes, he did indeed take a prop strike to his head. Probably knocked him senseless for a bit given the size of the blood patch, and then he came to and sort of realized he needed to do something but couldn’t figure out how. When the guys talked to him he did remember his name and mine, but couldn’t remember my number or the code for his phone. > > There is no way I can express how grateful I am to these guys who went back to look instead of driving on and laughing about the weird dude. Neither one knew him from Adam… > > This happened on Friday afternoon. He spent 4 hrs in surgery to remove a plum sized blood clot from his brain and to piece together the bits of his skull. He’s now got a 9" incision that appears to be healing nicely, and a skull put together with plates and **titanium** mesh. I always wondered where Paul McCartney got the idea for the song [“Magneto and Titanium Man”](https://www.youtube.com/watch?v=sTBukDar6vE). ;):D:) Sorry, I shouldn’t make light of a serious situation but I thought it wasn’t too totally out of bounds. I hope your husband is feeling better now and recovering nicely. ETA: Really, I hope you don’t take my lame post poorly. It’s just that I’ve never seen ‘magneto’ and ‘titanium’ in the same group of paragraphs before and I couldn’t help myself. ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [March 14, 2016, 4:39am UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/50 "2016-03-14T04:39:38Z")
> [@Magiver](#): > > Just walking into the tip when it’s not running is really dangerous. I always rotate it straight up after shut down and assume the mags are on. More than 2 blades makes that a hard thing to do. he he he My mantra, “If the mags are off the engine and laying on a bench, the MAGS ARE ON” (hot) The vertical prop is a good idea, just getting it there takes a deliberate well thought out act done the same way EVERY time to prevent disaster. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 14, 2016, 9:31am UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/51 "2016-03-14T09:31:04Z")
> [@GusNSpot](#): > > More than 2 blades makes that a hard thing to do. he he he > > My mantra, “If the mags are off the engine and laying on a bench, the MAGS ARE ON” (hot) > > The vertical prop is a good idea, just getting it there takes a deliberate well thought out act done the same way EVERY time to prevent disaster. The last time I went flying with a buddy I was still in the plane after shut down when I hear the impulse coupler snap over. He got out and had moved the prop to connect the tow bar. I look up to see the key still turned to “both” and got that “eeeeeeiiiiiiiii” feeling up my spine. Fortunately he treats the engine as if it’s live but it still gave me the willies. ---
**Author:** ![saje](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saje/32/3631_2.png) [@saje](https://boards.straightdope.com/u/saje)\ **Post date:** [March 14, 2016, 9:57am UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/52 "2016-03-14T09:57:43Z")
> [@I\_Love\_Me\_Vol.I](#): > > You relate quite a story!I always wondered where Paul McCartney got the idea for the song [“Magneto and Titanium Man”](https://www.youtube.com/watch?v=sTBukDar6vE). ;):D:) > > Sorry, I shouldn’t make light of a serious situation but I thought it wasn’t too totally out of bounds. I hope your husband is feeling better now and recovering nicely. > > ETA: Really, I hope you don’t take my lame post poorly. It’s just that I’ve never seen ‘magneto’ and ‘titanium’ in the same group of paragraphs before and I couldn’t help myself. I don’t at all - I’m really hard to offend 🙂 ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [March 14, 2016, 5:01pm UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/53 "2016-03-14T17:01:37Z")
> [@Magiver](#): > > The last time I went flying with a buddy I was still in the plane after shut down when I hear the impulse coupler snap over. He got out and had moved the prop to connect the tow bar. I look up to see the key still turned to “both” and got that “eeeeeeiiiiiiiii” feeling up my spine. Fortunately he treats the engine as if it’s live but it still gave me the willies. :eek: I am not sure I could refrain from getting on a soapbox. :smack: But I have never ‘peed’ on an electric fence either. :rolleyes: I have no problem with learning from others on most things. 🆒 ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [March 15, 2016, 2:30pm UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/54 "2016-03-15T14:30:41Z")
> [@Magiver](#): > > The last time I went flying with a buddy I was still in the plane after shut down when I hear the impulse coupler snap over. He got out and had moved the prop to connect the tow bar. I look up to see the key still turned to “both” and got that “eeeeeeiiiiiiiii” feeling up my spine. Fortunately he treats the engine as if it’s live but it still gave me the willies. If you heard the impulse coupling he rotated the engine forwards. IOW, he did two things wrong. And he didn’t treat the engine as live; he treated it with abject ignorance for the risk to his own life. He was just a tiny whiff of fuel fumes away from joining at best the OP’s husband and at worst the choir eternal. ---
**Author:** ![BrotherCadfael](https://avatars.discourse-cdn.com/v4/letter/b/977dab/32.png) [@BrotherCadfael](https://boards.straightdope.com/u/BrotherCadfael)\ **Post date:** [March 15, 2016, 2:53pm UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/55 "2016-03-15T14:53:39Z")
> [@Magiver](#): > > Just as an FYI, this scenario plays out ALL THE TIME in aviation. At some point every single pilot will make this mistake. My dad had a prop kick back once, but he was lucky enough to escape with only a broken arm. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 16, 2016, 12:42am UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/56 "2016-03-16T00:42:30Z")
> [@LSLGuy](#): > > If you heard the impulse coupling he rotated the engine forwards. IOW, he did two things wrong. And he didn’t treat the engine as live; he treated it with abject ignorance for the risk to his own life. > > He was just a tiny whiff of fuel fumes away from joining at best the OP’s husband and at worst the choir eternal. How do you figure? The prop was rotated in the direction the engine turns and as if it was being propped. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [March 16, 2016, 2:17am UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/57 "2016-03-16T02:17:08Z")
And that’s the error. ALWAYS rotate the engine backwards. That prevents the impulse coupling from firing. Rotating the engine forwards is how you start it. Which is the opposite of your goal when handling the prop for ALL other purposes. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 16, 2016, 3:31am UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/58 "2016-03-16T03:31:49Z")
> [@LSLGuy](#): > > And that’s the error. ALWAYS rotate the engine backwards. That prevents the impulse coupling from firing. Rotating the engine forwards is how you start it. Which is the opposite of your goal when handling the prop for ALL other purposes. That’s hard on dry vacuum pumps. Not sure about valves. ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [March 16, 2016, 4:58am UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/59 "2016-03-16T04:58:22Z")
> [@Magiver](#): > > That’s hard on dry vacuum pumps. Not sure about valves. Does not hurt valves. Aircraft engine cams are not wild enough for slow turns backwards to damage them. A full 180° backward rotation will do so little damage to the dry vacuum pump, if any, that it is a non starter when compared to the danger of the impulse coupling kicking an inadvertently hot mag through a spark point. Your Flight Hours May Vary :D:o:p ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 16, 2016, 10:20pm UTC](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545/60 "2016-03-16T22:20:25Z")
> [@GusNSpot](#): > > Does not hurt valves. Aircraft engine cams are not wild enough for slow turns backwards to damage them. That’s not true of all aircraft engines but probably true with the Lycoming. You don’t want to do that to Rotax engines as it can draw air into the oiling system. > [@GusNSpot](#): > > A full 180° backward rotation will do so little damage to the dry vacuum pump, if any, that it is a non starter when compared to the danger of the impulse coupling kicking an inadvertently hot mag through a spark point. > > Your > Flight > Hours > May > Vary > :D:o:p I don’t know if you’ve ever rebuilt a [dry vacuum moto](http://www.sdsefi.com/8061.jpg)r but the graphite vanes are set up to move in one direction only and are fragile. You’re right that it’s dangerous to move the prop and that’s why I brought up the warning about mag switches not grounding properly on shutoff. But I move the prop as if I’m starting it. You’d be surprised at how many people can’t look at a prop and tell which way it’s supposed to turn. [Previous page](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545.md?page=2) [Next page](https://boards.straightdope.com/t/general-aviation-folk-i-need-your-help-again/746545.md?page=4)