Prop Strike? Action?

Discussion in 'Maintenance Bay' started by Magman, Jun 29, 2022.

  1. EdFred

    EdFred Taxi to Parking

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    Loud is not an indicator of damage. Lots of things can be loud that cause no damage. I can make a sheet of paper sound extremely loud while being 'ripped', and not even tear it.

    And if folks "came running" how did he "get away with it" ?

    Story is starting to have holes.
     
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  2. Rgbeard

    Rgbeard En-Route

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    The Luscombe guy that did the long border-run trip had a minor prop strike, and that yielded to a recollection about a guy whose plane hit an orange cone, and the strike was enough to give damage.

    I'm too preoccupied to look up the references at the moment. That said, it's a prop-strike to me, and is worthy of the appropriate inspection.
     
  3. MauleSkinner

    MauleSkinner Touchdown! Greaser!

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    That’s why I started with “IMO”. You (or anyone else) can handle it how you see fit.
     
  4. Mxfarm

    Mxfarm Line Up and Wait

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    Had a friend hit a deer on runway on rollout after landing, engine @ idle. The insurance was involved as the carcass came around and hit the wing, so they tore the engine down, all was good except for a shaft key that was almost sheared but still in one piece in the accy case. Did the deer cause it? No one knows.
     
  5. Lindberg

    Lindberg Final Approach

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    From the information presented, no course of action can yet be determined because we're missing a key piece of information necessary to determine what action is necessary: Was there a sudden drop in engine RPM? So I'd suggest that the owner actually investigate what happened, beyond relying on a version of the story from the airport bums who heard a noise and found trash.
     
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  6. Dan Thomas

    Dan Thomas Final Approach

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    That's the sort of stuff a sudden RPM drop does. The dowel that keys the crankshaft gear to the crankshaft is the one that the AD is specifically concerned with, along with the retaining bolt:

    upload_2022-6-29_15-12-41.png

    That dowel keeps the gear indexed to the crankshaft. If it shears, it not only puts the camshaft and ignition all out of time, but because of the direction of rotation of the crank, it can loosen that bolt as the cam, magnetos, oil pump, vacuum pump and so on all drag on that gear. All the rotating masses of all those things shock that dowel if the crank is suddenly decelerated or stopped. It's small, big enough to drive everything, but not big enough to take big overloads.

    The gears themselves can suffer cracks in the roots of their teeth. From the Lycoming Direct Drive Overhaul Manual:

    upload_2022-6-29_15-21-38.png

    Lots of rotating mass there, and all of it is driven by that crankshaft gear, with its dowel.
     
  7. GaryM

    GaryM Pattern Altitude

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    The owner may want to hook the CFI up to a polygraph first, as I'd expect the answer to be along the lines of 'it was nothing, not even a blip on the RPM reading'.
     
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  8. RyanShort1

    RyanShort1 En-Route

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    I'm going to 100% disagree. We had a cone left in front of a Cardinal one time in a blind spot. We didn't catch it and neither did the ground crew. Didn't even leave a scratch on the prop. Mechanic almost told us to go fly it, but one of us twisted one of the blades and lo and behold even though there wasn't a speck of visible damage, enough damage was done internally to break one of the pieces that governed the prop rotation. If we'd have taken off, we would have had BIG problems on our hands.

    I'd have that thing looked at very, very carefully.
     
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  9. EdFred

    EdFred Taxi to Parking

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    Was the cone shredded?
     
  10. RyanB

    RyanB Super Administrator Management Council Member PoA Supporter

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    Fine to disagree, as I’ve said more than once now, my opinion was based on my own experience and I haven’t suggested to do any one specific thing in this situation. As always YMMV.
     
  11. RyanShort1

    RyanShort1 En-Route

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    Two or three slices as I recall, still able to stand up... not shredded at all. Still usable. Our prop literally didn't even have a scratch in the paint, and I've got pics somewhere.
     
  12. Clip4

    Clip4 Final Approach

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    I would start with an *** kicking of the idiot CFI.
     
  13. benyflyguy

    benyflyguy En-Route PoA Supporter

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    I could see that doing some damage. Thick rubbery plastic. Can give quite a bit which means it can cause some change in momentum of the blade until
    It tears through.
     
  14. Daleandee

    Daleandee En-Route

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    You and I finally agree on something! :D
     
  15. Lindberg

    Lindberg Final Approach

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    Don't ask; won't know.
     
  16. pigpenracing

    pigpenracing En-Route

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    When I was flying my Pitts S-2C and Model 12 my hangar was on a hill. I would drive the plane up the hill into the hangar, then shut it off and push it in the corner.
    So I taxi in a hangar. LOL!
     
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  17. Dan Thomas

    Dan Thomas Final Approach

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    Another friend did that. Caught the cone with the prop. It bent the prop blade.
     
  18. Albany Tom

    Albany Tom Pattern Altitude

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    I'm kinda wondering if the answer is "call the insurance company". No idea what the answer will be, or who's responsibility it is. But if the pilot knows the airplane hit the cardboard, and doesn't have the engine checked, and something else fails later for any reason, I think that would be difficult to explain. And maybe tough to live with.

    Flying into a hanger doesn't sound like a good idea to me. Storing flat cardboard on the floor, if that's what it was, doesn't either. I don't know how else the prop would've pulled in boxes, but then again I don't know what happens when you fly an airplane into a hanger. Never thought to try that.

    Reading the above, though, I'm thinking there is a market for 4" tall, extra wide, orange traffic cones. Never occurred to me that they could be a serious hazard to aircraft.
     
  19. 3393RP

    3393RP En-Route

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    Cut up a large cardboard box. Is that a "substantial amount" of it?
     
  20. Jim Carpenter

    Jim Carpenter Pre-takeoff checklist

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    FWIW, I think the required Lycoming inspection can be accomplished from the rear of the engine through the accessories case (re: the figures that Dan Thomas posted above), but does not require a complete teardown/crankcase split. (disclaimer: I'm not an A&P)
     
  21. mondtster

    mondtster En-Route

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    The AD mandated inspection on the crank gear and dowel can be, but you would not be able to complete Lycoming's recommended inspection without disassembly.

    https://www.lycoming.com/sites/defa...r Loss of Propeller_Rotor Blade or Ti (1).pdf

    The Lycoming AD requiring the inspection to the crank gear and dowel is the only forced compliance there is on any of the garden variety opposed aircraft engines.
     
  22. EdFred

    EdFred Taxi to Parking

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    I leave flat cardboard on the floor so oil from the "fun meter" doesn't get on the concrete.
     
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  23. midwestpa24

    midwestpa24 En-Route

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    I think everyone can sit here and second guess the situation, and provide all types of anecdotal evidence either way. The truth is no one knows if the engine sustained damage or not.

    From a risk management standpoint, the possibility of damage is probably low. However the severity of the consequences is high if there was damage. Even if the chance of damage is 1%, meaning 99% chance its fine, you have now introduced the chance, even slight, of a catastrophic engine failure in flight. Statistics don't lie that those don't always end well.

    I guess its all in the risk one is willing to accept. Granted, even a newly rebuilt engine comes with some built in maintenance induced risk itself.
     
  24. Daleandee

    Daleandee En-Route

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    It guess that depends on the size of the trash can you are putting it in. Answer: I have no idea ...
     
  25. schmookeeg

    schmookeeg En-Route

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    The CFI is so fired at this point, so I don't think that's an issue. He's shown his craven stripes.

    I presume this CFI does not have sufficient scratch to cover a deductible, much less pay for a teardown out of his threadbare pockets..

    So the owner needs to decide if HE wants to file the claim and get the motor torn down, and if HE wants to be out the deductible.

    If the motor is high-time, it's a betterment opportunity to get a contribution of about 10 grand from insurance to a new overhaul. If the motor is low-time, well... the owner may want to do the same as the CFI and file this whole thing into the trash like it never happened.
     
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  26. Dan Thomas

    Dan Thomas Final Approach

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    Getting the accessory case off is no small job. In some airplanes it can't be done with the engine in the airplane. And in some, the oil sump has to come off as well.

    You can't check the gear, bolt and dowel with the accessory case on.
     
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  27. EdFred

    EdFred Taxi to Parking

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    He's an airline pilot. He makes $500k a year, and has the schedule he wants after only a year of flying!
     
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  28. Daleandee

    Daleandee En-Route

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    ... and he's home every weekend. ;)
     
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  29. Magman

    Magman Line Up and Wait

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    Ironically; there was a similar incident nearby last summer.

    The pilot was taxiing the borrowed Cherokee into the hangar. He noticed the path was obstructed by a tug. He then let the passenger exit in order to move the tug. The pax did not move it quite far enough. As the aircraft moved further into the hangar the prop struck the tug. This was a solid hit so the engine was torn down per prop strike requirements. The cost to restore to flight status was about $35K. This was only partially covered by insurance.

    The Crank was replaced due to corrosion (SB 505 I think) and all 4 cylinders were cracked. None of this was covered by the Insurance Co. The pilot had offered to address the situation via his Insurance. The decision had been reached to submit the claim to the Owners Insurance Co. Subsequently; that premium increased by 50%.

    Folks should realize that rust and wear are never covered by Insurance, Also to research the complete financial consequences prior to to submitting the claim.
     
  30. Jim K

    Jim K En-Route

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    The other confounding factor is that it's about 6mo to get in for an IRAN right now, and cylinders are like a year out. Worst time in history to be doing engine work.
     
  31. donjohnston

    donjohnston Pattern Altitude

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    I did it after almost every flight. :D
     
  32. Lindberg

    Lindberg Final Approach

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    So has anyone figured out what happened in this case?
     
  33. Magman

    Magman Line Up and Wait

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    Ref #72. In this case yes . Hope this answers.

    Non owner pilot recuperating from shoulder surgery and did not want to pull aircraft.

    Prop strike, engine tear down , crank ok per prop strike but n/g for rust ,cylinders cracked. Crank n jugs not covered by insurance so owner pays as well as 50% increase in premium. Owner should have let non- owner Pilot handle via his insurance as offered.
     
  34. Lindberg

    Lindberg Final Approach

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    I meant the situation this thread is about.