Matronics Email Lists :: View topic - Prop Strikes and tear downs

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Prop Strikes and tear downs

Matronics Email Lists Forum Index -> Yak-List

View previous topic :: View next topic

Author Message

bhancock(at)worldwidewarb
Guest

Posted: Fri Jul 13, 2007 6:38 am Post subject: Prop Strikes and tear downs

On Jul 12, 2007, at 11:58 PM, Yak-List Digest Server wrote:

 	  Quote: 	
		  

 I heard Carl   

Hays say that if these engines had a prop strike like this - no need   

to worry about the engine and DO NOT tear down to inspect.  Would   

everyone agree? 	




The bag of worms is opened!    



Carl Hays has a lot of experience with these engines and I respect his opinion.  The other side of this is there is AT LEAST 3 known engine failures after prop strikes.   Yes, wood and composite is softer than metal, but just how soft is a baseball bat swung at full speed, or water at 70 mph, or air at 200 mph?  Point here is just because wood core props are "softer" doesn't mean that they are not strong enough to cause internal damage during a sudden stoppage.  



Here is a related example.  We now have a customer with a Lancair IV-P that had a history two nose gear collapses.  After the first one they tore the engine apart only to find that everything was A-OK.....a "waste of money" right?  Well....we get called in on the job after the second prop strike and the owner tells me "we tore it down after the first one and there was nothing wrong....I was at idle, so I'm sure it's OK...just throw another prop on it and I'll go fly it."  Well, he doesn't have a wife or kids, but I still insisted that we at least do a run out on the crank.  Sure enough, it didn't meet spec.  We sent the engine to Firewall Forward (who turned the engine in 5 working days) and both the crank and case were bad.  Had he "just put another prop on it" and went flying, his engine definitely would have failed....  (As an aside, the plane was being used in an upcoming movie called FAST GLASS....we flew in it and maintained all 8 of the airplanes...it was a kick!) 



Incidentally, the nose gear collapses were a result of improper hardware and improper installation by previous "mechanics" ...a story unto itself.



I will never figure out why so many of us pilots put out pocket books before our lives.  If there was even a 1 in 100 chance that you were going to have an engine failure, what do you think your significant other or your kids would tell you to do?



See you at OSH,



Barry



 [quote][b]

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

Ernie

Joined: 11 Jan 2006
Posts: 513

Posted: Tue Jul 17, 2007 7:04 am Post subject: Re: Prop Strikes and tear downs

I'm not sure what kind of engine the Lancair has, but many Continental engines have Nitrited cranks which are stong but as brittle as glass, so yes I would always tear down any flat engine after a prop strike. My old J-58 Bonanza prop suffered a collision with a towbar which was still attached (Dont ask) and when I tore the engine down the crank was cracked.



That said, the overhaul manual for the Husai engine says in so many words.



"If the prop strike wasnt a "Sudden Stoppage", and the damage is located more than 3 feet (more or less, I dont remember the exact dimension), from the center axis of the4 hub (about 6 inches in from the wing tip)  then just replace the prop. I've heard of people doing "Run Out" checks on our round engines. This proves nothing. If the engine was idleing, and you landed on grass or sand, and the prop kept turning, and the blades showed no signs of gross impact (missing metal etc) and the bend occurs beyond the manual specs, then you are probably ok to just replace the prop. Otherwise a teardown is warranted.



Ernie

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

rvfltd(at)televar.com
Guest

Posted: Tue Jul 17, 2007 11:01 am Post subject: Prop Strikes and tear downs

Guys,

Would you put your wife or children in a aircraft that was "probably" 

OK?  For that matter would you fly it your self?  Next time you take a 

buddy flying tell him/her that "ya it had a prop strike, but it's 

probably OK", and watch the reaction.  If they are smart they will run 

like hell.   After owning one of the major aircraft salvage companies in 

the US for nearly 20 years (Aircraft Salvage and Rebuild Inc) and 

salvaging over 1000 aircraft, I think I have seen nearly every type of 

accident, from hand propping to wind damage, from bad external loads to 

cruising full tilt into a cloud full of mountain.  I have seen prop 

flanges break off,  mag gear shafts break, gears loose teeth, lock pins 

and keepers come loose, cylinders come completely off the engine.  I 

have seen "homemade mods" come loose causing all sorts of havoc, exhaust 

with holes which caused engine fires, the list is long but in most 

instances can be traced back to something we could have prevented if we 

had not put our wallets in front of our good judgment. 



Recently as most of you know I had a engine failure where in all three 

of the planetary gears in the nose case failed and all power was lost.  

This accident was felt by all who inspected the engine to be the result 

of a prop strike somewhere in the aircrafts distance past.   True the 

engine installed on this aircraft came from China "used" but it is no 

different than me buying a stateside aircraft that had had a 

undocumented prop strike in it's past.  If you sell your aircraft what 

is your obligation to the guy who buys it?  Did you note the prop strike 

in the logs so he can make an informed decision?  Most owners hesitate 

to do so because they feel that it lessens the resale value of the 

aircraft, but that's a topic for future posts.   Guy's, we have enough 

problems to worry about without having to worry about rather the engine 

has been damaged internally after a prop strike, so believe me when I 

say that you simply rolling the dice, maybe you will and maybe you 

won't, maybe it will run 5 hours maybe it will run 500 hours.   If you 

have had a prop strike I do not believe that you can honestly look me in 

the eye and tell me that you feel good enough about your engine to load 

your love ones up and go flying.  It always amazes me that when we ARE 

fully insured the prop strikes are always worse than when we ARE NOT 

insured.  Yes, some have gotten away with doing nothing but changing the 

prop but folks, it simply is NOT worth the chance, and money in this 

instance should not be part of the equation, if it is maybe you should 

look again at rather or not you can afford to own this type of 

aircraft.  If you cannot afford to install a fresh engine at the minimum 

send the prop struck engine out for tear down and inspection.  Then put 

the engine on a 5 to 10 hour oil change with oil analysis at each 

change, and watch it like your life depends on it, because it just 

might.   



Always Yakin,

Doug



Ernie wrote:



 	  Quote: 	
		  



I'm not sure what kind of engine the Lancair has, but many Continental engines have Nitrited cranks which are stong but as brittle as glass, so yes I would always tear down any flat engine after a prop strike. My old J-58 Bonanza prop suffered a collision with a towbar which was still attached (Dont ask) and when I tore the engine down the crank was cracked.



That said, the overhaul manual for the Husai engine says in so many words.



"If the prop strike wasnt a "Sudden Stoppage", and the damage is located more than 3 feet (more or less, I dont remember the exact dimension), from the center axis of the4 hub (about 6 inches in from the wing tip)  then just replace the prop. I've heard of people doing "Run Out" checks on our round engines. This proves nothing. If the engine was idleing, and you landed on grass or sand, and the prop kept turning, and the blades showed no signs of gross impact (missing metal etc) and the bend occurs beyond the manual specs, then you are probably ok to just replace the prop. Otherwise a teardown is warranted.



Ernie





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=124349#124349

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

f4ffm2(at)adelphia.net
Guest

Posted: Tue Jul 17, 2007 11:56 am Post subject: Prop Strikes and tear downs

Doug is, as always, a voice of reason and experience...saying things  

to which we should pay attention.



I recently happened to be looking directly at a CJ when the pilot had  

a "brain fart" and raised the gear lever.  He didn't raise the gear,  

but he certainly lowered the airplane.  To the point; the airplane  

was parked and the engine was at idle....but when the one blade  

struck the ground, the convulsion that the rest of the airplane went  

through gave graphic evidence of the enormous forces that are working  

inside the engine...even at idle.



Thanks Doug.



Roger_____________________________________________________________

On Jul 17, 2007, at 11:57 AM, Doug Sapp wrote:



 	  Quote: 	
		   



 Guys,

 Would you put your wife or children in a aircraft that was  

 "probably" OK?  For that matter would you fly it your self?  Next  

 time you take a buddy flying tell him/her that "ya it had a prop  

 strike, but it's probably OK", and watch the reaction.  If they are  

 smart they will run like hell.   After owning one of the major  

 aircraft salvage companies in the US for nearly 20 years (Aircraft  

 Salvage and Rebuild Inc) and salvaging over 1000 aircraft, I think  

 I have seen nearly every type of accident, from hand propping to  

 wind damage, from bad external loads to cruising full tilt into a  

 cloud full of mountain.  I have seen prop flanges break off,  mag  

 gear shafts break, gears loose teeth, lock pins and keepers come  

 loose, cylinders come completely off the engine.  I have seen  

 "homemade mods" come loose causing all sorts of havoc, exhaust with  

 holes which caused engine fires, the list is long but in most  

 instances can be traced back to something we could have prevented  

 if we had not put our wallets in front of our good judgment.

 Recently as most of you know I had a engine failure where in all  

 three of the planetary gears in the nose case failed and all power  

 was lost.  This accident was felt by all who inspected the engine  

 to be the result of a prop strike somewhere in the aircrafts  

 distance past.   True the engine installed on this aircraft came  

 from China "used" but it is no different than me buying a stateside  

 aircraft that had had a undocumented prop strike in it's past.  If  

 you sell your aircraft what is your obligation to the guy who buys  

 it?  Did you note the prop strike in the logs so he can make an  

 informed decision?  Most owners hesitate to do so because they feel  

 that it lessens the resale value of the aircraft, but that's a  

 topic for future posts.   Guy's, we have enough problems to worry  

 about without having to worry about rather the engine has been  

 damaged internally after a prop strike, so believe me when I say  

 that you simply rolling the dice, maybe you will and maybe you  

 won't, maybe it will run 5 hours maybe it will run 500 hours.   If  

 you have had a prop strike I do not believe that you can honestly  

 look me in the eye and tell me that you feel good enough about your  

 engine to load your love ones up and go flying.  It always amazes  

 me that when we ARE fully insured the prop strikes are always worse  

 than when we ARE NOT insured.  Yes, some have gotten away with  

 doing nothing but changing the prop but folks, it simply is NOT  

 worth the chance, and money in this instance should not be part of  

 the equation, if it is maybe you should look again at rather or not  

 you can afford to own this type of aircraft.  If you cannot afford  

 to install a fresh engine at the minimum send the prop struck  

 engine out for tear down and inspection.  Then put the engine on a  

 5 to 10 hour oil change with oil analysis at each change, and watch  

 it like your life depends on it, because it just might.

 Always Yakin,

 Doug



 Ernie wrote:



> 

>

> I'm not sure what kind of engine the Lancair has, but many  

> Continental engines have Nitrited cranks which are stong but as  

> brittle as glass, so yes I would always tear down any flat engine  

> after a prop strike. My old J-58 Bonanza prop suffered a collision  

> with a towbar which was still attached (Dont ask) and when I tore  

> the engine down the crank was cracked.

>

> That said, the overhaul manual for the Husai engine says in so  

> many words.

>

> "If the prop strike wasnt a "Sudden Stoppage", and the damage is  

> located more than 3 feet (more or less, I dont remember the exact  

> dimension), from the center axis of the4 hub (about 6 inches in  

> from the wing tip)  then just replace the prop. I've heard of  

> people doing "Run Out" checks on our round engines. This proves  

> nothing. If the engine was idleing, and you landed on grass or  

> sand, and the prop kept turning, and the blades showed no signs of  

> gross impact (missing metal etc) and the bend occurs beyond the  

> manual specs, then you are probably ok to just replace the prop.  

> Otherwise a teardown is warranted.

>

> Ernie

>

>

> Read this topic online here:

>

> http://forums.matronics.com/viewtopic.php?p=124349#124349

>

>

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

Michael Bolton

Joined: 31 May 2007
Posts: 9

Posted: Wed Jul 18, 2007 6:06 am Post subject: Prop Strikes and tear downs

Wow Roger, I thought I was the only one with a brain like that.  I also have 

a Housai engine sitting in the corner of the hangar, anyone intrested? lol

Thanks for all of your help Doug



Michael

---

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

Display posts from previous:

	Matronics Email Lists Forum Index -> Yak-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum