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Thread: Prop strike!

  1. #1

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    Prop strike!

    Not me; I was gluing gussets in a 1943 Tcart wing.

    Stearman, W670, wood Sensenich. Hit one of those rubber poles they use to mark parking spots.
    Shattered one blade. Vibration was enough to break both javelins in half. Engine did not suffer a sudden stop.

    My inclination is to do an airframe inspection, put a new prop and javelins on, and keep flying. Looking for other opinions - my radial engine experience is limited.

    On the J3s such an encounter usually results in a small dent in the prop leading edge. We inspect the prop carefully and press on. Even a broken prop (wood) is still a dial indicator and new prop.

    Happy to have your thoughts.

  2. #2
    Hardtailjohn's Avatar
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    If I remember, it's a 2 piece crank kind of like a Wright. I'd dial it and if it has ANY runout, it'd come apart.
    John

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    Charlie Longley's Avatar
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    There’s a reason the old timers carried a spare wooden prop around with them.
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  4. #4
    hotrod180's Avatar
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    Continental W670's are not bulletproof.Click image for larger version. 

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    Cessna Skywagon-- accept no substitute!

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    Steve Pierce's Avatar
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    Quote Originally Posted by hotrod180 View Post
    Continental W670's are not bulletproof.Click image for larger version. 

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    But what is the story? Which bearings? I can break an anvil.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers
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    WhiskeyMike's Avatar
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    [QUOTE=bob turner;789580]Not me; I was gluing gussets in a 1943 Tcart wing.

    Stearman, W670, wood Sensenich. Hit one of those rubber poles they use to mark parking spots.
    Shattered one blade. Vibration was enough to break both javelins in half. Engine did not suffer a sudden stop.


    Roller bearings or original style ball bearings in the crankshaft?It may not have stopped; and Continental may, or may not, have an inspection requirement, but the FAA, your insurance, and the lawyers will have a field day. A radial overhaul shop told me that most rod or crank failures could be traced back to prop strikes even in the distant past. It's is a really nasty sound when a rod breaks - goes round and beats up the cylinder bases so you can't even get the cylinders off the case during teardown. It sounds a little like when you're not quite all the way in gear and let the clutch out - only about a thousand times louder. Then it's a full engine replacement, or maybe the airplane, or worse. Seen it more than once. Got away with field fixes - sometimes, and sometimes not.
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  7. #7
    hotrod180's Avatar
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    Quote Originally Posted by Steve Pierce View Post
    But what is the story? Which bearings? I can break an anvil.
    Dunno the cause, maybe a prop strike in the past (who knows), but the master rod failed (sheared) in that W670.
    No good place to land but the pilot of the Stearman did the best he could. (I was a passenger)
    The old joke about "where you gonna land a biplane when the engine quits? Just look straight ahead" is true--
    it glided like a darn brick.

    Click image for larger version. 

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    Cessna Skywagon-- accept no substitute!
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  8. #8

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    I back up dialing the crank simply to try and tell if the crack slipped.
    Regards, Charlie
    Super Coupe E-AB build in process
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  9. #9
    aktango58's Avatar
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    Quote Originally Posted by hotrod180 View Post
    Dunno the cause, maybe a prop strike in the past (who knows), but the master rod failed (sheared) in that W670.
    No good place to land but the pilot of the Stearman did the best he could. (I was a passenger)
    The old joke about "where you gonna land a biplane when the engine quits? Just look straight ahead" is true--
    it glided like a darn brick.

    Click image for larger version. 

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    Impressive how little damage the airframe appears to have.

    One boss would tell us "When she quits taking care of you, just use her to take care of yourself." He always appreciated our decisions not to risk his birds, and bringing them back in one piece. But if the bird broke in flight he never said a bad word to the pilot making a decision that kept the people safe and alive.

    I have always tried to error on the side of caution. I am not the guy that knows that engine, but I would be talking to the overhaul shops before I flew it again. Guys that see 100 engines a year have a better feel for what the odds are.
    I don't know where you've been me lad, but I see you won first Prize!

  10. #10

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    That's why I ask here. This group has collective experience. I am not a member of the Stearman group; you have to be an owner to talk to them. And all the round engine guys I knew are in rest homes or worse.

  11. #11

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    Quote Originally Posted by bob turner View Post

    Stearman, W670, wood Sensenich. Hit one of those rubber poles they use to mark parking spots.
    Shattered one blade. Vibration was enough to break both javelins in half. Engine did not suffer a sudden stop.

    My inclination is to do an airframe inspection, put a new prop and javelins on, and keep flying. Looking for other opinions - my radial engine experience is limited.

    On the J3s such an encounter usually results in a small dent in the prop leading edge. We inspect the prop carefully and press on. Even a broken prop (wood) is still a dial indicator and new prop.

    Happy to have your thoughts.
    Thinking about it from the standpoint of the next buyer of the plane, I'd say that the best thing is to bite the bullet and have the engine IRAN done and have the mounts checked at the same time.

  12. #12
    Richgj3's Avatar
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    Bob
    I have some experience here. First, I had the gear collapse on a WACO when I taxied too fast on rough grass strip an hit a hole. The 220 was idling and the prop stopped when the first blade touched. The engine was torn down and no problems found. It was a Curtiss Reed prop that was repairable.

    Second was a 220 on a Fleet I owned. Experimental. The Flaglor Hi Tow. No incident anyone would admit to, but an oil change contained halves of ball bearings. When the engine was torn down the counter weights looked like the pictures above. And the rear case was junk.

    Third was on a friend’s UPF-7. The prop bearing on that failed too. Resulted in a partial failure but he got home

    Fourth was a 220 on a Stearman with a wood prop that went on its back very slowly. They didn’t do anything but dial the crank and fix the airframe. Several hours later the crank broke.

    Fifth was a Stearman that was purchased after it hit some trees after the engine quit on take off. Wood prop, no power. The IA who bought it fixed the airframe and dialed the crank. A hundred hours or so later it started running like it was totally out of timing. Some gears internally had jumped. Got back to the airport ok.

    Tear the engine down.

    Rich
    Last edited by Richgj3; 11-22-2020 at 02:34 PM.
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  13. #13
    G44's Avatar
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    Quote Originally Posted by bob turner View Post
    That's why I ask here. This group has collective experience. I am not a member of the Stearman group; you have to be an owner to talk to them. And all the round engine guys I knew are in rest homes or worse.
    No you dont, everyone welcome in the SRA
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  14. #14

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    Thanks. I shall join!

  15. #15
    G44's Avatar
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    Quote Originally Posted by bob turner View Post
    Thanks. I shall join!
    Bob, I sure hope I didn't speak too soon, I will be embarrassed if they changes their policy, actually that would be stupid if they did change their policy. A lot of great contributions come from many who have tons of experience but are not owners.

    Kurt
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  16. #16

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    yesteryearaviation.com Dave is a good guy and he knows how to build a 670. I put one of his engines on a Stearman in may with no issues.

    If it shook enough to break javelins it would be coming off and going to an engine shop if it was my customer.
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  17. #17
    Steve Pierce's Avatar
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    I was an SRA member for many years and not an owner. Great organization.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers
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  18. #18
    skywagon8a's Avatar
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    Not a 220 but an R-680 which had bent the prop in a ground loop. All checked out OK, it was running just fine when it suddenly covered the cowl with copious amounts of oil. Pulled the nose seal and found ALL of the balls in the nose thrust bearing missing. They had been ground up into little flakes and spread throughout the engine.
    N1PA

  19. #19
    phdigger123's Avatar
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    http://www.radialengines.com/contact-us/

    I would call Caleb Curry and get his thoughts. These folks do great work on engines.
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