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jlno7(at)aim.com
Guest

Posted: Mon May 04, 2009 7:25 am Post subject: prop questions

I have a 87 Kitfox 1 with 2 modifications with a three blase wooden 

prop.  At the ehd on one of the blades is a hairline crack about 2.5 cm 

long.  I polyurethaned and sanded it.  Is that sufficient or do I need 

to replace it?  Can you replace one blade or do you need to replace all 

three?



Jerry Novak

N299JK

Pulaski, WI

matronics(at)bob.brennan.
Guest

Posted: Mon May 04, 2009 7:51 am Post subject: prop questions

Hi Jerry,



A crack in a wood propellor blade is reason to replace it yes. You

undoubtably have a GSC prop and they will replace a single blade for you but

they need the other two blades to match and balance it. I would recommend

contacting them first and then sending all three blades. They will make sure

the other two are ok and might even replace the defective blade at a reduced

cost.



Verify that you have a GSC prop and go to

http://www.ultralightprops.com/index.html



Bob Brennan - N717GB

ELSA Repairman, inspection rated

1991 UK Model 2 ELSA Kitfox taildragger

Rotax 582 with 3 blade GSC prop

Wrightsville Pa  



--

Fox5flyer
Guest

Posted: Mon May 04, 2009 8:06 am Post subject: prop questions

If it is a GSC prop I would email or write them and await their 

recommendation.  Same goes for pretty much any of the other vendors.  GSC is 

generally very good at supporting their products.  A closeup photo helps.

Deke Morisse

Mikado Michigan

S5/Subaru/CAP 406+ TT

"The aim of an argument or discussion should not be victory, but progress."

- Joseph Joubert



---

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Mon May 04, 2009 1:12 pm Post subject: Re: prop questions

Your GSc is likely expired if it is that old. 

I would bet if original 3 blade it will be the square root ends and not adjustable. 



I have GSC  66 " of a 532  3 blade with only 10 hours on it since new last year.   I would sell for 450 $ 



I have a GSC inflight adjustable  70 " with Warp blades and nickel leading edges .  1500 $ 



Here is what happens to  them when they fail  

http://www.cfisher.com/gsc



I sell all brands of props new and some used. What engine and gearbox ratio you have ? 

Dave

dave(at)cfisher.com

_________________
Realtime Kitfox movies to separate the internet chatter from the truth
http://www.youtube.com/user/kitfoxflyer
Hundreds of Kitfox Movies
Most viewed Kitfox on youtube
Most popular on youtube
Highest rated on youtube

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Mon May 04, 2009 6:41 pm Post subject: prop questions

Does the crack go all the way through the blade or is it a surface crack?

Pics?



Noel



--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Mon May 04, 2009 6:46 pm Post subject: Re: prop questions

Hi Jerry,



You could not have fixed the prop deep inside the grain. It will grow whether you see it or not from vibration. Toss the blade or prop and start new. If it comes apart in flight some day it may not be pretty. If the prop is from 1987 it is past its life anyway and you got your money's worth.

Better safe than sorry.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

Fox5flyer
Guest

Posted: Tue May 05, 2009 4:09 am Post subject: prop questions

I fail to see what a small crack in the tip of a (as yet type unknown) prop 

blade has to do with a blade letting go at the hub. Again, my advice is he 

should go to the manufacturer where the real experts can advise him and 

leave the scare tactics and sales pitch to the politicians.

Deke Morisse

Mikado Michigan

S5/Subaru/CAP 406+ TT

"The aim of an argument or discussion should not be victory, but progress."

- Joseph Joubert

 	  Quote: 	
		  

 Here is what happens to  them when they fail

 http://www.cfisher.com/gsc

matronics(at)bob.brennan.
Guest

Posted: Tue May 05, 2009 4:54 am Post subject: prop questions

Sorry to respectfully disagree here Deke but having recently had such issues

drilled into me so that I could get my Repairman's ticket I feel I need to.



Any grain crack or evidence of delamination in a wooden structure in an

aircraft application is reason to ground the aircraft until it is replaced,

especially in a prop. Nicks and dings to a certain size, with no evidence of

damage to grain or lamination, can be sanded and re-coated. In class we had

to evaluate actual rejected wooden parts to try and find the defect, some

were really hard to find.



Any grain crack or delamination in a prop blade can quickly propagate to the

hub with catastrophic results. No inspector would let an airplane fly with

that kind of defect, not even to get home.



I was the orignal reply to Jerry's question - recommending he send the

blades back to the manufacturer for inspection and replacement as necessary

and I stick by that, but as an inspector I would stamp that aircraft as

non-airworthy. It's not scare tactics, it is an FAA requirement.



Bob Brennan - N717GB

ELSA Repairman, inspection rated

1991 UK Model 2 ELSA Kitfox taildragger

Rotax 582 with 3 blade GSC prop

Wrightsville Pa  



--

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Tue May 05, 2009 6:12 am Post subject: Re: prop questions

Deke, Get the chip off your shoulder eh !! 



this is a safety issue, A GSC prop from 1987 is 22 years old man. Might work fine,  but it way past TBO . 



When you call it scare tactics ?  What the heck that mean that you a moderator and will not let others speak the truth and facts?  



I SELL PROPS,  I promote safety as well. Prop departure is scary, I have first hand experience in flight  do you ? 



When was your last prop failure> ?   



Dave   < -- Facts  from  3  decades of aviation not from the armchair . 



 	  Fox5flyer wrote: 	
		  I fail to see what a small crack in the tip of a (as yet type unknown) prop 

blade has to do with a blade letting go at the hub. Again, my advice is he 

should go to the manufacturer where the real experts can advise him and 

leave the scare tactics and sales pitch to the politicians.

Deke Morisse

Mikado Michigan

S5/Subaru/CAP 406+ TT

"The aim of an argument or discussion should not be victory, but progress."

- Joseph Joubert

 	  Quote: 	
		  

 Here is what happens to  them when they fail

 http://www.cfisher.com/gsc

Paul A. Franz, P.E.

Joined: 02 Dec 2008
Posts: 280
Location: Bellevue WA

Posted: Tue May 05, 2009 10:48 am Post subject: prop questions

On Tue, May 5, 2009 5:06 am, fox5flyer wrote:

 	  Quote: 	
		  

 I fail to see what a small crack in the tip of a (as yet type unknown) prop

 blade has to do with a blade letting go at the hub. Again, my advice is he

 should go to the manufacturer where the real experts can advise him and

 leave the scare tactics and sales pitch to the politicians.


	


Whoa! You sure got a couple violent responses to this posting! Who'd have known? I

agree with your assessment for the most part though.



Comments were made suggesting this prop was beyond TBO. Hmmm, I'm not convinced there

is a TBO per se, for wood props and hubs. TBO on props usually applies to ones with a

pitch control mechanism. Maybe that "5 years, 5 hundred hours" condition that's stated

for GSC is applicable.



Unless there is something you'd judge would cause that prop to have its tip crack

grow, I agree that it's probably OK to fly on. But if the crack is due to a tip

strike, that might mean the base has been weakened. If the crack is due to picking up

gravel and damaging the finish, it is likely repairable. Several techniques can be

used to force epoxy into the crack. Just like you can seal cracks in a windshield, you

can force epoxy into a crack. My guess is that there has to be a pretty tight finish

intact all around the injection point for it to work though.



If you were the factory and your advice could subject you to liability, how would that

temper your response?  I might be inclined to utter in a knee jerk reaction - 'we

better get out of this business before the lawyers bankrupt us'. Some one else might

react with a less fearful approach. Maybe, lets have a look before we tell them we

can't stand behind any repairs made to this old propeller. Yet another might be, let's

carefully inspect the bases and evaluate whether or not we can repair the cracks at a

lesser cost than replacing one or all of the blades.



If the subject prop is a GSC, getting them in the loop seems to me will get you on the

right track and you'll be relieved at knowing just what you're supposed to do.

-- 

Paul A. Franz, P.E.

PAF Consulting Engineers

Office 425.440.9505

Cell 425.241.1618



"The ideal tyranny is that which is ignorantly self-administered by its

victims. The most perfect slaves are, therefore, those who blissfully

and unawaredly enslave themselves. A truth's initial commotion is

directly proportional to how deeply the lie was believed. It wasn't the

world being round that agitated people, but that the world wasn't flat.

When a well-packaged web of lies has been sold gradually to the masses

over generations, the truth will seem utterly preposterous and its

speaker a raving lunatic."



-- author Dresden James

_________________
Paul A. Franz, P.E.
Registration/Aircraft - N14UW/Merlin GT
Engine/Prop - Rotax 914/NSI CAP
Bellevue WA
425.241.1618 Cell
425.440.9505 Office

Fox5flyer
Guest

Posted: Tue May 05, 2009 12:34 pm Post subject: Re: prop questions

Bob, thanks for the respectful  response.  If you go back and read both of my emails I think you'll see that we were saying the same thing.  I was recommending that Jerry go direct to the manufacturer for their opinion on the best course of action.  I did not recommend that he fly the airplane, nor would I ever do that.  More than likely GSC (if it was a GSC) would ask him to send in his blades for inspection and may either recommend a new blade or all three.  I said this because it is very easy to give personal advice to someone over the internet when you don't have to live with the result.

Deke

(The armchair pilot with 1500+ hours mostly TD)

Oh, yeah.  I flew two hours this morning down to Midland MI and back.  Had lunch with a cutie and had smooth air both directions.  Doesn't get much better.



 	  matronics(at)bob.brennan. wrote: 	
		  Sorry to respectfully disagree here Deke but having recently had such issues

drilled into me so that I could get my Repairman's ticket I feel I need to.



Any grain crack or evidence of delamination in a wooden structure in an

aircraft application is reason to ground the aircraft until it is replaced,

especially in a prop. Nicks and dings to a certain size, with no evidence of

damage to grain or lamination, can be sanded and re-coated. In class we had

to evaluate actual rejected wooden parts to try and find the defect, some

were really hard to find.



Any grain crack or delamination in a prop blade can quickly propagate to the

hub with catastrophic results. No inspector would let an airplane fly with

that kind of defect, not even to get home.



I was the orignal reply to Jerry's question - recommending he send the

blades back to the manufacturer for inspection and replacement as necessary

and I stick by that, but as an inspector I would stamp that aircraft as

non-airworthy. It's not scare tactics, it is an FAA requirement.



Bob Brennan - N717GB

ELSA Repairman, inspection rated

1991 UK Model 2 ELSA Kitfox taildragger

Rotax 582 with 3 blade GSC prop

Wrightsville Pa  



--

matronics(at)bob.brennan.
Guest

Posted: Tue May 05, 2009 1:11 pm Post subject: prop questions

Deke,



I absolutely agree with you on returning the blades to the manufacturer and

yes we were saying the same thing, I just wanted to add a bit of gravity to

the advice. I know we are experimental pilots and can do as we please, but

as a certified inspector I would reject a wood prop blade with a crack for

use without question, other than hung on a wall with a clock in it.



I will also respectfully disagree with Paul Franz (sorry Paul!) who agrees

with us "for the most part". Wood has grain and laminates, that once

separated can easily split along that separation. Using epoxy on the split

is like using epoxy on a small crack in a piece of glass. Despite the epoxy

the strength has been compromised and pressure on the surface could easily

propagate the crack or split, epoxy will not stop it. As I said earlier -

epoxy is a good fix for dings and dents and nicks in wood, but unacceptable

as a repair to a grain or laminate split.



Wooden propeller inspection requirements and repair procedures can be found

in detail in FAA document AC 43.13-1B - "Aircraft Inspection, Repair &

Alterations. Acceptable methods, techniques & practices".



And Paul if there are any aircraft part manufacturers out there that behave

like you described in your "If you were the factory and your advice could

subject you to liability..." response I would steer well clear of them, but

I don't personally know of any wood propeller manufacturer that in any way

fits your description so I don't think we should be trying to scare list

posters away from working with the manufacturers.



Bob Brennan - N717GB

ELSA Repairman, inspection rated

1991 UK Model 2 ELSA Kitfox taildragger

Rotax 582 with 3 blade GSC prop

Wrightsville Pa  



--

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Tue May 05, 2009 2:11 pm Post subject: prop questions

Better to be out flying than to sit at the computer making the  

accusations fly, eh, Deke? Too bad I didn't know about your flight to  

Midland....I and two other planes flew up to Mt. Pleasant for  

lunch....hell, that's only 25 miles apart. Coming back was a bit  

bumpy though.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 644.7 hrs

Sensenich 62x46 Wood prop

Electroair direct-fire ignition system

Status: flying

do not archive



On May 5, 2009, at 4:34 PM, Fox5flyer wrote:



 	  Quote: 	
		   

 <fox5flyer(at)idealwifi.net>



 Bob, thanks for the respectful  response.  If you go back and read  

 both of my emails I think you'll see that we were saying the same  

 thing.  I was recommending that Jerry go direct to the manufacturer  

 for their opinion on the best course of action.  I did not  

 recommend that he fly the airplane, nor would I ever do that.  More  

 than likely GSC (if it was a GSC) would ask him to send in his  

 blades for inspection and may either recommend a new blade or all  

 three.  I said this because it is very easy to give personal advice  

 to someone over the internet when you don't have to live with the  

 result.

 Deke

 (The armchair pilot with 1500+ hours mostly TD)

 Oh, yeah.  I flew two hours this morning down to Midland MI and  

 back.  Had lunch with a cutie and had smooth air both directions.   

 Doesn't get much better.





 matronics(at)bob.brennan. wrote:

> Sorry to respectfully disagree here Deke but having recently had  

> such issues

> drilled into me so that I could get my Repairman's ticket I feel I  

> need to.

>

> Any grain crack or evidence of delamination in a wooden structure  

> in an

> aircraft application is reason to ground the aircraft until it is  

> replaced,

> especially in a prop. Nicks and dings to a certain size, with no  

> evidence of

> damage to grain or lamination, can be sanded and re-coated. In  

> class we had

> to evaluate actual rejected wooden parts to try and find the  

> defect, some

> were really hard to find.

>

> Any grain crack or delamination in a prop blade can quickly  

> propagate to the

> hub with catastrophic results. No inspector would let an airplane  

> fly with

> that kind of defect, not even to get home.

>

> I was the orignal reply to Jerry's question - recommending he send  

> the

> blades back to the manufacturer for inspection and replacement as  

> necessary

> and I stick by that, but as an inspector I would stamp that  

> aircraft as

> non-airworthy. It's not scare tactics, it is an FAA requirement.

>

> Bob Brennan - N717GB

> ELSA Repairman, inspection rated

> 1991 UK Model 2 ELSA Kitfox taildragger

> Rotax 582 with 3 blade GSC prop

> Wrightsville Pa

>

> --



 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 42820#242820

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Fox5flyer
Guest

Posted: Tue May 05, 2009 4:13 pm Post subject: prop questions

Lynn, my friend.  Even if I'd known that your lameness was nearby I probably 

wouldn't have met up with you anyway.  I had something much better going on!

When I took off from Midland about 1500 it was a little bit choppy, but 

after climbing out to 3500 it smoothed right out and stayed that way until I 

got home.  Even had a small tailwind.

Life is good!

Deke

do not archive

Subject: Re: Re: prop questions

 	  Quote: 	
		   



 Better to be out flying than to sit at the computer making the 

 accusations fly, eh, Deke? Too bad I didn't know about your flight to 

 Midland....I and two other planes flew up to Mt. Pleasant for 

 lunch....hell, that's only 25 miles apart. Coming back was a bit  bumpy 

 though.



 Lynn Matteson

 Kitfox IV Speedster, taildragger

 Jabiru 2200, #2062, 644.7 hrs

 Sensenich 62x46 Wood prop

 Electroair direct-fire ignition system

 Status: flying

 do not archive



 On May 5, 2009, at 4:34 PM, Fox5flyer wrote:



> 

>

> Bob, thanks for the respectful  response.  If you go back and read  both 

> of my emails I think you'll see that we were saying the same  thing.  I 

> was recommending that Jerry go direct to the manufacturer  for their 

> opinion on the best course of action.  I did not  recommend that he fly 

> the airplane, nor would I ever do that.  More  than likely GSC (if it was 

> a GSC) would ask him to send in his  blades for inspection and may either 

> recommend a new blade or all  three.  I said this because it is very easy 

> to give personal advice  to someone over the internet when you don't have 

> to live with the  result.

> Deke

> (The armchair pilot with 1500+ hours mostly TD)

> Oh, yeah.  I flew two hours this morning down to Midland MI and  back. 

> Had lunch with a cutie and had smooth air both directions.   Doesn't get 

> much better.

>

>

> matronics(at)bob.brennan. wrote:

>> Sorry to respectfully disagree here Deke but having recently had  such 

>> issues

>> drilled into me so that I could get my Repairman's ticket I feel I  need 

>> to.

>>

>> Any grain crack or evidence of delamination in a wooden structure  in an

>> aircraft application is reason to ground the aircraft until it is 

>> replaced,

>> especially in a prop. Nicks and dings to a certain size, with no 

>> evidence of

>> damage to grain or lamination, can be sanded and re-coated. In  class we 

>> had

>> to evaluate actual rejected wooden parts to try and find the  defect, 

>> some

>> were really hard to find.

>>

>> Any grain crack or delamination in a prop blade can quickly  propagate 

>> to the

>> hub with catastrophic results. No inspector would let an airplane  fly 

>> with

>> that kind of defect, not even to get home.

>>

>> I was the orignal reply to Jerry's question - recommending he send  the

>> blades back to the manufacturer for inspection and replacement as 

>> necessary

>> and I stick by that, but as an inspector I would stamp that  aircraft as

>> non-airworthy. It's not scare tactics, it is an FAA requirement.

>>

>> Bob Brennan - N717GB

>> ELSA Repairman, inspection rated

>> 1991 UK Model 2 ELSA Kitfox taildragger

>> Rotax 582 with 3 blade GSC prop

>> Wrightsville Pa

>>

>> --

>

> Read this topic online here:

>

> http://forums.matronics.com/viewtopic.php?p 42820#242820

>

>

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue May 05, 2009 4:50 pm Post subject: prop questions

It all depends on the crack...  but I second your opinion that the only ones

to consult on it are the manufacturers of the blades.



Cheers



Noel

Getting closer to getting the 912 in the air



--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue May 05, 2009 4:53 pm Post subject: prop questions

Perhaps it's the scary tone that Deke doesn't like...  but as you say, it is

scary!  Like most on the list I would not fly with it until it has been

passed by the manufacturer.  Now ask me if I think the manufacturer would

pass it...  not a chance.



Noel



--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue May 05, 2009 5:02 pm Post subject: prop questions

Per se???  I don't know about pre-se but I sure know about what is written

on the manufacturers home page.  Sure there is no way the manufacturer can

make you take the prop off your plane but how smart would it be to fly it

knowing the guy who designed and built it thinks it has not been safe for

many years and you can see potential catastrophic damage to it.



I'm not trying to scare the heebie geebies out of any one just to say it as

it is.  If you think the blades can be restored send them back to GSC for

evaluation and rebuilding.  If not enjoy a nice fire.



Noel



--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

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