My partner unfortunately had the gear collapse on our Bearhawk in dirt. Throttle was at idle, but ground loop clearly happened and the wing got bent and the prop struck the ground.
I'm a fairly new pilot, only 300 hours, just looking around for some advice. Estimate is getting done as we speak.
My question is this...
Does the engine teardown always occur even when the prop strikes soft surface at idle? If so, does anyone know of good shops in PNW for testing crankshaft, etc.?
Also, the plane was probably only going 30KIAS when ground loop happened, so relatively low force. To the naked eye the fuselage looks absolutely fine. And Bearhawk is steel!!! But does one need to go about any fancy testing to make sure that frame is good to go? The shop seems to think it's good to go, slap new wings on it and take her for a spin. I just have no experience with any of this...seems like someone should write a PDF on what do do when you have a whoopsi.
Thanks for the advice! Looking forward to getting this fixed before the fall flying season.
question about prop strike
Sun Dec 22, 2019 1:18 am
- climbingnerd offline
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Sun Dec 22, 2019 5:51 am
Re: question about prop strike
Interesting question when it comes to the legalities of an experimental. I know of a few prop struck experimentals in Canada where they just put a new prop on, left the prop strike out of the log books though. Don't ask don't tell. Bend a prop with a tug on a certified and your tearing the engine down. I would imagine insurance would be the driving force - probably require you to follow engine manufacturers guidelines for a prop strike inspection no matter if you claim this incident or not. Also comes down to what are you comfortable with? Worth the risk the crank may fail at a later date due to a hairline crack?
Sun Dec 22, 2019 7:04 am
Re: question about prop strike
A long time ago on inexpensive crop dusters, they dialed the crankshaft flange, inspected the oil pump and magnito gears, straightened and tracked the prop, and went back to work.
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Sun Dec 22, 2019 7:10 am
Re: question about prop strike
First, the incident as you describe it qualifies as an “accident”.
Second, I believe the engine inspection after prop strike requirement applies to ANY engine, experimental or certified. But if not, it should.
So here’s the question for you: Do you want to fly behind an engine that may have damaged gears and/or crankshaft, with passengers in that airplane? Over mountainous terrain? If passengers are family?
Get the engine looked at.
As to the fuselage, are you or your partner the builder of record? If so, do you hold a repairman certificate for the plane?
If so, the holder of the repair mans certificate could inspect, install wings and go fly after signing logbooks.
On the other hand, if you don’t hold a repairman certificate for that plane, or an IA certificate, I believe you’re going to have to get a mechanic to inspect and repair. Or at least inspect.
MTV
Second, I believe the engine inspection after prop strike requirement applies to ANY engine, experimental or certified. But if not, it should.
So here’s the question for you: Do you want to fly behind an engine that may have damaged gears and/or crankshaft, with passengers in that airplane? Over mountainous terrain? If passengers are family?
Get the engine looked at.
As to the fuselage, are you or your partner the builder of record? If so, do you hold a repairman certificate for the plane?
If so, the holder of the repair mans certificate could inspect, install wings and go fly after signing logbooks.
On the other hand, if you don’t hold a repairman certificate for that plane, or an IA certificate, I believe you’re going to have to get a mechanic to inspect and repair. Or at least inspect.
MTV
Sun Dec 22, 2019 8:14 am
Re: question about prop strike
There’s still a lot a energy hitting the ground at idle speed no matter what the RPM is.
I would think that a thorough and complete inspection is the best way to go and cheap life insurance and resale value further down the road.
I would think that a thorough and complete inspection is the best way to go and cheap life insurance and resale value further down the road.
Sun Dec 22, 2019 8:45 am
Re: question about prop strike
Actually, we are allowed to dial the crank and if its straight we don't have to carry on any further. I like to dye pen the flanges as well. On a Lycoming they have a service bulletin that requires the rear accessory case come off and a gear/bolt/locking tab be replaced. Also a good idea to have the mags checked. But an idle strike generally won't cause much damage.Mark Y. wrote:Interesting question when it comes to the legalities of an experimental. I know of a few prop struck experimentals in Canada where they just put a new prop on, left the prop strike out of the log books though. Don't ask don't tell. Bend a prop with a tug on a certified and your tearing the engine down. I would imagine insurance would be the driving force - probably require you to follow engine manufacturers guidelines for a prop strike inspection no matter if you claim this incident or not. Also comes down to what are you comfortable with? Worth the risk the crank may fail at a later date due to a hairline crack?
Sun Dec 22, 2019 8:47 am
Re: question about prop strike
climbingnerd wrote:….Does the engine teardown always occur even when the prop strikes soft surface at idle? If so, does anyone know of good shops in PNW for testing crankshaft, etc.? ...
https://www.lycoming.com/content/propel ... -dangerous
https://www.lycoming.com/sites/default/ ... 281%29.pdf
https://www.avweb.com/ownership/the-pro ... dden-stop/
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Sun Dec 22, 2019 9:24 am
Re: question about prop strike
The links provided by Hotrod 180 are pretty convincing, as are the comments by mtv and 58Skylane. Sure, there is a fair chance that no damage has occurred, but, do you want to take that chance ? Personally, I'd be thinking about it on every takeoff, and every time I'm flying over rough terrain.
Premier in Troutdale is located close. LyCon is a highly regarded shop, not too far away in California.
Premier in Troutdale is located close. LyCon is a highly regarded shop, not too far away in California.
Sun Dec 22, 2019 9:27 am
question about prop strike
If it’s a Continental it’s probably cracked at the flange at a minimum. Lycoming might survive it. Either way tear it down. Usually those low power hits with stoppage do more damage than a full power clip.
Airframe and wings, defer to a professional as well. Those repairs typically aren’t too mysterious either.
Airframe and wings, defer to a professional as well. Those repairs typically aren’t too mysterious either.
Sun Dec 22, 2019 11:02 am
Re: question about prop strike
-0-
Last edited by dogpilot on Thu Aug 06, 2020 12:05 am, edited 1 time in total.
Mon Dec 23, 2019 10:08 pm
Re: question about prop strike
Yes what he said just do it.
Mon Dec 23, 2019 10:48 pm
Re: question about prop strike
Dog wrote:Yes what he said just do it.
+1
Fwiw, I know a lot of pilots who have experienced an engine failure WITHOUT the added damage of a prop strike. The NTSB tracks "system malfunction - powerplant" accidents... we call 'em "engine failure". In the Certificated fleet engine failure is the number 2 and sometimes number 1 "root cause" of accidents. Experimental aircraft have a higher number of engine problems - perhaps because owner/builders rationalize away the damage caused by a prop strike. Flying over mtns and experiencing an engine failure is not fun. What about over water? Or at night, or in IMC, or that pretend day VFR some call scud?
I can vouch for Premier at Troutdale as a go to engine shop.
- PapernScissors offline
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Mon Dec 23, 2019 11:13 pm
Re: question about prop strike
I can vouch for Premier at Troutdale as a go to engine shop.
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Tue Dec 24, 2019 2:29 pm
Re: question about prop strike
What gear was on your bearhawk ?
The older gear with the streamline tube for the shock , or the newer gear with the round tube ?
Also where did it fail ?
Thanks Doug
The older gear with the streamline tube for the shock , or the newer gear with the round tube ?
Also where did it fail ?
Thanks Doug
- brown bear offline
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Tue Dec 24, 2019 9:00 pm
Re: question about prop strike
dogpilot wrote:Before the turn of the century, we where a bit more casual about prop strike. Runout checks on the flange, send the prop out and that was pretty much it. Then in the mid-90's more and more Advisory Circulars and Service Notes started to appear on what else to check. The insurance companies also started to get on the wagon of increasing checks, they have a lingering liability.
So at first as all this started to pile on, it was "more FAA BS." Since we tore down 10-20 engines a year in the shop due to an inability of the gear or pilot to keep the prop out of harms way, we inspected more. Well, guess what, we found more. Turned out it wasn't BS. A lot more gizmos got subtle damaged in a sudden stoppage than we thought. There are a lot of gear driven items that have a significant amount of mass whirling about at decent RPM. Stop them suddenly and you get windup. Gears, shafts speeder springs, flyweights, mags, pumps, cams. Heck the list goes on. We found slightly deformed shafts gear teeth, mag drives partial shearing load on cam gear's bolts and such. There is the case cracks from especially dramatic ones, but lots of stuff we had never thought would have been an issue.
So, short answer: have a professional shop do it. A lot more testing and inspection required than you might think. Much is beyond local testing capabilities and NDT equipment. Best to find out what did get deformed than to have your engine let you know down the pike and puke out a few bits and pieces, ceasing to be an engine anymore.
Same thing we found in the overhaul shop I worked in. And as said above....low RPM will surprise you at what gets damaged.
John
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Wed Dec 25, 2019 9:57 am
Re: question about prop strike
As to repairing the airframe damage. A common misconception that needs to be cleared up is that, even if not the "builder", and thus holder of the Repairman Certificate, you (or anyone) are fully authorized to do any work on the airplane. It is an Experimental - Amateur Built aircraft; that's clearly codified in the regs thankfully. Here's EAA's clarification on that: https://www.eaa.org/eaa/aircraft-building/intro-to-aircraft-building/frequently-asked-questions/non-builder-maintenance
//Side Note: Also note the details on the 12-calendar month Condition Inspection requirement (something you thus do annually) that needs to be performed by a holder of the Repairman Certificate, A&P, or FAA Approved Repair Station. Source of the confusion above.
As to the engine, having recently seen a crank failure happen on a friend's plane, tear it down and have proper NDT inspections done on all the bits; later-in-life fatigue failures later in life caused by traumatic events early in life are a fear you don't want to fly around with.
Keep the nose strait ahead, aileron into the wind always, keep the spinning fan spinning, and the rest should work out fine.
//Side Note: Also note the details on the 12-calendar month Condition Inspection requirement (something you thus do annually) that needs to be performed by a holder of the Repairman Certificate, A&P, or FAA Approved Repair Station. Source of the confusion above.
As to the engine, having recently seen a crank failure happen on a friend's plane, tear it down and have proper NDT inspections done on all the bits; later-in-life fatigue failures later in life caused by traumatic events early in life are a fear you don't want to fly around with.
Keep the nose strait ahead, aileron into the wind always, keep the spinning fan spinning, and the rest should work out fine.
Flying Fiddler
Wed Dec 25, 2019 12:01 pm
Re: question about prop strike
Just one more data point. I have a friend that bought a Pitts. The second flight just flying around no aerobatics, the prop flew off. He dead sticked it into a field with no damage. After some investigation he found out that the seller had ground looped the airplane and hit the prop at idle. He claimed it dialed out ok and put a new prop on it. No tear down and no entry in the logs. After being confronted with a fraud investigation and law suit, the seller paid for a brand new engine and prop etc. The new engine and prop cost more than the sale price of the aircraft. 
- RockHopper offline
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Wed Dec 25, 2019 12:39 pm
Re: question about prop strike
[quote="Fiddler"]As to repairing the airframe damage. A common misconception that needs to be cleared up is that, even if not the "builder", and thus holder of the Repairman Certificate, you (or anyone) are fully authorized to do any work on the airplane. It is an Experimental - Amateur Built aircraft; that's clearly codified in the regs thankfully. Here's EAA's clarification on that: https://www.eaa.org/eaa/aircraft-building/intro-to-aircraft-building/frequently-asked-questions/non-builder-maintenance
//Side Note: Also note the details on the 12-calendar month Condition Inspection requirement (something you thus do annually) that needs to be performed by a holder of the Repairman Certificate, A&P, or FAA Approved Repair Station. Source of the confusion above.
/quote]
Yes, I should have clarified that any repairs will have to pass muster at the next condition inspection. And, frankly, anybody can work on a certificated airplane as well.....Just has to be signed off a little sooner.
MTV
//Side Note: Also note the details on the 12-calendar month Condition Inspection requirement (something you thus do annually) that needs to be performed by a holder of the Repairman Certificate, A&P, or FAA Approved Repair Station. Source of the confusion above.
/quote]
Yes, I should have clarified that any repairs will have to pass muster at the next condition inspection. And, frankly, anybody can work on a certificated airplane as well.....Just has to be signed off a little sooner.
MTV
Wed Dec 25, 2019 3:29 pm
Re: question about prop strike
RockHopper wrote:Just one more data point. I have a friend that bought a Pitts. The second flight just flying around no aerobatics, the prop flew off. He dead sticked it into a field with no damage. After some investigation he found out that the seller had ground looped the airplane and hit the prop at idle. He claimed it dialed out ok and put a new prop on it. No tear down and no entry in the logs. After being confronted with a fraud investigation and law suit, the seller paid for a brand new engine and prop etc. The new engine and prop cost more than the sale price of the aircraft.
I expect it's easier (and cheaper to defend) compliance with regs and transparency than the opposite strategy.
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Wed Dec 25, 2019 4:50 pm
Re: question about prop strike
If you weren’t there or at the controls while PIC during the incident then every thing else is void. Would you fly that aircraft comfortably with you kids and wife in it over sub freezing ocean temps crossing the Arms of Alaska, or subject your whole family over non landable and inevitable certain death terrain of Craters of the Moon Idaho? Then I’d certainly want that engine torn down with at least a thorough IRAN.
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