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Brambo

Well Known Member
I?m working on the fuel and vent lines in the forward cabin and have run across something interesting. The torque values given in the Aircraft Handbook show 40-65 for -4 and 75-125 for -6 aluminum flared fittings. I am experimenting with the Mechanics? Toolbox program and it shows torque values of -4 (100-140) and -6 (150-195). That?s a big difference, does anyone know why this would be?

Bill Rambo
RV-7A
 
Use your numbers

My A&P General Handbook (FAA doc EA-AC 65-9A) gives the same as the lower ones you got for Aluminum tubing -

-4 40 - 65 inch-lbs.
-6 75 -125 inch-lbs.

I'd use these numbers....

gil in Tucson
 
Brambo said:
I?m working on the fuel and vent lines in the forward cabin and have run across something interesting. The torque values given in the Aircraft Handbook show 40-65 for -4 and 75-125 for -6 aluminum flared fittings. I am experimenting with the Mechanics? Toolbox program and it shows torque values of -4 (100-140) and -6 (150-195). That?s a big difference, does anyone know why this would be?

Bill Rambo
RV-7A
Click to expand...

I use AC 43.13. That's the bible in my opinion. Wrench torque for tightening AN-818 nuts on aluminium tube (inch pounds).
-4 min 50 max 65
-6 min 110 max 130
 
Crow's foot?

Since you normally can't get a socket on these, do you use a Crow's foot on the torque wrench?

I seem to remember seeing posts that the German method was OK - "good'n tight", but don't over do it.
 
Rick_A said:
Since you normally can't get a socket on these, do you use a Crow's foot on the torque wrench?

I seem to remember seeing posts that the German method was OK - "good'n tight", but don't over do it.
Click to expand...

I used a crows foot on a torque wrench. I would say it would be very difficult for an inexperienced person to ensure that they were within the min and max torques for these fittings without some form of calibration. And these are very crucial fittings.

Bob
 
Crows Foot

I'm just about ready to install my lines also.....where can you purchase a Crows foot in order to torque thoses nuts properly?

Thanks

Henry T.
N918HB
9A
 
Harbor Freight has 'em for half of what they cost at Sears.

In the absence of either, I think somewhere I saw instructions about tightening to snug, and then a certain number of flats past that? Somebody fill in the blanks for me here.
 
Buy a full set; you'll find other uses. ($40 at Sears 2 years ago, Plus lifetime replacement warrantee.)

Jekyll
 
Beam wrenches

Jekyll said:
Buy a full set; you'll find other uses. ($40 at Sears 2 years ago, Plus lifetime replacement warrantee.)

Jekyll
Click to expand...
Still $40... and if you use a beam type torque wrench, you can keep the 90 degrees correct, and not have to apply any mathematics for torque correction... :)

Details here....

http://www.trialsnuts.com/TORQUED.pdf

gil in Tucson
 
az_gila said:
Still $40... and if you use a beam type torque wrench, you can keep the 90 degrees correct, and not have to apply any mathematics for torque correction... :)

Details here....

http://www.trialsnuts.com/TORQUED.pdf

gil in Tucson
Click to expand...

Easy to do with a ratcheting wrench - you just need to clock the adapter to the 90 each time. Granted, it is simple with a beam type but, I don't want to give the impression that one must buy a different wrench if they already own a ratcheting wrench.

Gil is absolutely right, make sure that adapter is on the 90 or, make the measurements and do the math.

Jekyll
 
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