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Torque values

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Fox5flyer
Guest

Posted: Thu Mar 19, 2009 2:49 pm Post subject: Torque values

I'm preparing to reinstall my prop and I'm ready to  torque the AN5-10 bolts.   The torque values off the  standard chart are for 180-220 inch lbs.  The manual that came with the  prop says 150 inch  lbs.  I'll probably go by the manual, but it makes  me wonder about this big 40 inch lb spread on the chart values.  When faced  with a big spread, which way is the recommended direction to go.  Go with  the lesser, somewhere in between, or the higher number?  Also, I'm using a  crow foot adapter.  Does that make any difference to the values?   Inquiring minds would like to know...

 Deke Morisse

Mikado Michigan

S5/Subaru/CAP  402+ TT

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

- Joseph Joubert

  

 

 

   [quote][b]

vetdrem

Joined: 20 Nov 2007
Posts: 62

Posted: Thu Mar 19, 2009 3:21 pm Post subject: Re: Torque values

the reference chart is to be used when the manufacture has not provided a specific torque spec.  Always use the manufactures recommendations if provided.



A torque wrench is calibrated to be accurate when not using a crowsfoot, handle extension or any other modification to the tool.  If you use a crowsfoot, you can mathematically convert the reading to take the added leverage provided by the crowsfoot into account, but be careful when doing that, mistakes are easy to make, and you could over torque the bolt very easily.



Louie



model 3  912ul

altus, ar

Paul A. Franz, P.E.

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

Posted: Thu Mar 19, 2009 3:46 pm Post subject: Torque values

On Thu, March 19, 2009 2:48 pm, Deke wrote:

 	  Quote: 	
		   I'm preparing to reinstall my prop and I'm ready to torque the AN5-10 bolts.   The

 torque values off the standard chart are for 180-220 inch lbs.  The manual that came

 with the prop says 150 inch  lbs.


	


The specification that accompanies the prop is the one most relevant. These torque

settings are from engineering design. That said, the engineer usually specifies the

torque allowed for the bolt so I would check with the prop manufacturer's engineering

dept to make certain of their intentions.



 	  Quote: 	
		    I'll probably go by the manual, but it makes me

 wonder about this big 40 inch lb spread on the chart values.  When faced with a big

 spread, which way is the recommended direction to go.  Go with the lesser, somewhere

 in between, or the higher number?  Also, I'm using a crow foot adapter.  Does that

 make any difference to the values?  Inquiring minds would like to know...


	


If the crows foot is 90 deg to the wrench handle then it will not make a difference as

long as you carefully push the handle on the center pivot.

-- 

Paul A. Franz

Registration/Aircraft - N14UW/Merlin GT

Engine/Prop - Rotax 914/NSI CAP

Bellevue WA

425.241.1618 Cell



"In Washington, one person's waste is another person's pork. Every

dime spent by the federal government has well-connected advocates

who swear the money is vital to the national interest. ... It's not

that people in government aren't as good or competent as those in

the private sector (though that may be true). The difference lies in

the incentives and feedback they face. Bureaucracies have little

check on what they do, no bottom line, no market prices for their

'output.' What they do have is an incentive to spend all the money

budgeted or risk getting less next year. As Milton Friedman used to

say, no one spends other people's money as carefully as he spends

his own. It is absurd to think the humongous constellation of

federal bureaucracies is going to identify and root out 'waste' in

any significant way. It's just not in the nature of the beast."

-- ABC's "20/20" co-anchor John Stossel

In general, the art of government consists of taking as much money as possible from

one party of the citizens to give to the other.

-- Voltaire (1764)

_________________
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: Fri Mar 20, 2009 5:02 am Post subject: Torque values

Thanks for the response, Paul.  As I said in my original message, I'll be 

using the manufacturer's recommendation.



What I'd really like to know is the answer to my first question.  When there 

is a big spread on a recommended torque value as I said below, what does 

this mean in normal working conditions?  Under what conditions does one use 

the lower, somewhere in the middle, or higher number?

Thanks,

Deke Morisse

Mikado Michigan

S5/Subaru/CAP 402+ TT

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

- Joseph Joubert

---

Lynn Matteson

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

Posted: Fri Mar 20, 2009 5:39 am Post subject: Torque values

My guess...and it's only that...is that for a wood prop, you'd use  

the lower number in dry, less humid conditions, knowing that when it  

got humid, the prop will take on moisture, swell and the tension on  

the bolts would rise.  On the other hand, if you used the higher  

numbers on  a "wet" prop, and conditions dried out, the prop would  

shrink, causing the higher tension on the bolts to decrease.



I recently obtained a new wood prop from Sensenich...built in Florida  

(read humid)...and installed it with 160 in lbs (their recommended  

numbers were 130-160) of torque. I flew it as suggested and after the  

first flight I re-torqued it to that same figure. After about 30  

hours of flying, I noticed that there was a black dust on the  

periphery of the drive flange. I re-checked the torque, and it was  

down to about 85 in-lbs. I re-torqued to 160. What I think happened  

was the prop was manufactured in humid conditions, sent up here to  

Michigan where the winters are dry. The prop dried a bit, torque was  

lost, and the prop began to "slip" on the drive flange, causing the  

black dust....fretted paint from the prop. I've since checked torque  

again, and it was down to 145. There is a sticker on the prop right  

next to the hub which cautions  "wood props need to be checked for  

proper torque frequently in varying humidity conditions" or words to  

that effect. I used to check my prop at oil changes, but now I'll do  

a check between changes, too.



Deke, if you have a metal prop, all the preceding rambling won't  

answer your question, but it should get some of the engineers in the  

audience to warm up their fingers. : )



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 615.2 hrs

Sensenich 62x46

Electroair direct-fire ignition system

Status: flying





On Mar 20, 2009, at 9:01 AM, fox5flyer wrote:



[quote] 

 <fox5flyer(at)idealwifi.net>



 Thanks for the response, Paul.  As I said in my original message,  

 I'll be using the manufacturer's recommendation.



 What I'd really like to know is the answer to my first question.   

 When there is a big spread on a recommended torque value as I said  

 below, what does this mean in normal working conditions?  Under  

 what conditions does one use the lower, somewhere in the middle, or  

 higher number?

 Thanks,

 Deke Morisse

 Mikado Michigan

 S5/Subaru/CAP 402+ TT

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

 progress."

 - Joseph Joubert

 ---

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Paul A. Franz, P.E.

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

Posted: Fri Mar 20, 2009 7:23 am Post subject: Torque values

On Fri, March 20, 2009 5:01 am, Deke Morisse wrote:

 	  Quote: 	
		   



 Thanks for the response, Paul.  As I said in my original message, I'll be

 using the manufacturer's recommendation.


	


You're welcome. You should. However, dbl check with their engineering to be sure of

their intentions.



 	  Quote: 	
		   What I'd really like to know is the answer to my first question.  When there

 is a big spread on a recommended torque value as I said below, what does

 this mean in normal working conditions?  Under what conditions does one use

 the lower, somewhere in the middle, or higher number?


	


As a designer you may have reason to specify a lower torque setting. One comes to mind

is where the bolt goes into or through something that might distort in shape if given

the maximum allowable torque. Another case is where the bolt thread is far stronger

than the material it is anchored in like a steel bolt anchored in an aluminum casting.

The thread depth may not be sufficient to develop the maximum allowable torque in the

bolt.



-- 

Paul A. Franz

Registration/Aircraft - N14UW/Merlin GT

Engine/Prop - Rotax 914/NSI CAP

Bellevue WA

425.241.1618 Cell



"It is natural to man to indulge in the illusions of hope. We are

apt to shut our eyes against a painful truth -- and listen to the

song of that syren, till she transforms us into beasts."

-- Patrick Henry



"The great advances of civilization, whether in architecture or

painting, in science or in literature, in industry or agriculture,

have never come from centralized government."

-- economist Milton Friedman (1912-2006)

_________________
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

Float Flyr

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

Posted: Fri Mar 20, 2009 1:48 pm Post subject: Torque values

Going with the lower torque value will lead to much less stretching of materials including the prop blades.  Speaking of which always go by the manufacturers recommendations.  They may know something about the design of your equipment that you or I  do not know.  

   

   

Noel Loveys  

CDN AME Intern  

PP-Rec, Kitfox III-A  

Areocet 1100 floats  

   

       

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of fox5flyer

 Sent: Thursday, March 19, 2009 8:18 PM

 To: Kitfox List

 Subject: Torque values  

  

  

     

I'm preparing to reinstall my prop and I'm ready to torque the AN5-10 bolts.   The torque values off the standard chart are for 180-220 inch lbs.  The manual that came with the prop says 150 inch  lbs.  I'll probably go by the manual, but it makes me wonder about this big 40 inch lb spread on the chart values.  When faced with a big spread, which way is the recommended direction to go.  Go with the lesser, somewhere in between, or the higher number?  Also, I'm using a crow foot adapter.  Does that make any difference to the values?  Inquiring minds would like to know...  

    

Deke Morisse

 Mikado Michigan

 S5/Subaru/CAP 402+ TT

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

 - Joseph Joubert  

    

   

    



    

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_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Roger Lee

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

Posted: Fri Mar 20, 2009 7:45 pm Post subject: Re: Torque values

If you turn the crows foot 90 degrees from the handle then the torque difference is negligible, but if you keep it in line with the handle here is the proper way to calculate the new value. Open the post below.

Chapter%2007.pdf

Description:

Torque calculations with a crowfoot

Download

Filename:

Chapter%2007.pdf

Filesize:

26.27 KB

Downloaded:

519 Time(s)

_________________
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: Sat Mar 21, 2009 3:34 am Post subject: Torque values

Thanks, Lynn, et al.  I'm surprised how hard it's been to get good hard data 

on these torque values.  AC43.13 has some info--and good stuff too, but it 

doesn't go deep enough and seems to assume we all know about interference 

drag, etc.  I called a local IA who couldn't definitively answer the 

question either, other than to say that he usually just picks a value 

somewhere in the middle of the spread.  He also said he rarely bothers with 

a torque wrench and just goes by feel, depending on what he's doing.  After 

wrenching on airplanes for 30 years, he probably has that "feel", but I 

don't trust mine.  He also said that the torque values are only a guide and 

that "close is good enough" in most cases.  I tend to agree with him for the 

most part, but not with my prop!  I want that puppy exactly like it's 

supposed to be.     So, unless I can find some more information on this 

I'm not going to worry too much about it.

Deke Morisse

Mikado Michigan

S5/Subaru/CAP 402+ TT

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

- Joseph Joubert

---

Lynn Matteson

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

Posted: Sat Mar 21, 2009 8:15 am Post subject: Torque values

Hey, Deke, is it a metal prop? Or does it have a metal hub? The  

numbers on those are a lot less critical (I would think) than if the  

bolts are going to be "crushing" wood. Also, I noticed that you said  

you have AN5-10 bolts....I can't believe the "-10" part. This would  

make the bolts too short to go through almost anything, so I'm  

assuming that's a typo...is it? I'm thinking that if they're that  

short, they're only going through metal, so the range is probably not  

as critical as a wood application.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 616.5 hrs

Sensenich 62x46

Electroair direct-fire ignition system

Status: flying





On Mar 21, 2009, at 7:34 AM, fox5flyer wrote:



 	  Quote: 	
		   

 <fox5flyer(at)idealwifi.net>



 Thanks, Lynn, et al.  I'm surprised how hard it's been to get good  

 hard data on these torque values.  AC43.13 has some info--and good  

 stuff too, but it doesn't go deep enough and seems to assume we all  

 know about interference drag, etc.  I called a local IA who  

 couldn't definitively answer the question either, other than to say  

 that he usually just picks a value somewhere in the middle of the  

 spread.  He also said he rarely bothers with a torque wrench and  

 just goes by feel, depending on what he's doing.  After wrenching  

 on airplanes for 30 years, he probably has that "feel", but I don't  

 trust mine.  He also said that the torque values are only a guide  

 and that "close is good enough" in most cases.  I tend to agree  

 with him for the most part, but not with my prop!  I want that  

 puppy exactly like it's supposed to be.     So, unless I can  

 find some more information on this I'm not going to worry too much  

 about it.

 Deke Morisse

 Mikado Michigan

 S5/Subaru/CAP 402+ TT

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

 progress."

 - Joseph Joubert

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Fox5flyer
Guest

Posted: Sat Mar 21, 2009 4:17 pm Post subject: Torque values

Yup, Lynn, it's a metal cockpit adjustable prop hub by NSI (CAP).   The 

blades are all carbon fiber by Warp Drive.  The bolts go through the crank 

hub and into the prop hub about an inch deep then the bolt heads are all 

safety wired on the engine side of the crank hub.

Deke Morisse

Mikado Michigan

S5/Subaru/CAP 402+ TT

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

- Joseph Joubert

---

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