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Permalink Reply by Chris Aysen on June 28, 2010 at 9:52am

You can get one that measures inch/lb from an auto parts store. I believe I got mine from NAPA. The torque wrench is a necessary idea. Especially in strategic places such as prop mounting.

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Permalink Reply by Bob Pustell on June 28, 2010 at 10:53am

Yes, you should use a torque wrench, especially on critical fasteners. If you eyeball the torque in a car and get it wrong, you an always coast to the side of the road. Not so in an aircraft.

Torque wrenches should be treated carefully, they are a calibrated precision instrument. If you get any adjustable type torque wrench (as opposed to a beam type) you should reset it to zero after using it. If you leave it set to a torque value for a long time, you can put it out of calibration. Beam types need no calibration due to their construction, but are the most difficult to use accurately. All other types should be recalibrated periodically, maybe every five years or so for a home handyman type, annually for a professional using it frequently. Certified shops must keep their torque wrenches calibrated and current and just keep those calibration records on file. It is important.

You do not NEED to torque every fastener in your airplane, but it would be the theoretical best. Realistically, you should torque anything that is critical. If having that bolt lose clamping force from being undertorqued or having it weakened to where it might snap later from being overtorqued could be a flight hazard, torque it!

By the way, what respectable A&P uses the eighth turn method? I would not use him!

You can get good torque wrenches from internet and mail order houses, Sears, Auto parts stores, many places. Also, keep your eye open at tag sales. If you get a used one, send it in for calibration before you use it, you do not know its history or its accuracy.

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Permalink Reply by Jason Fish on November 26, 2020 at 10:59pm

Any thoughts on the min-max range I should look for in a torque wrench? It seems, according to p32 of the Construction Standards doc, that I'd want one capable of 12 to 260 "lbs (1 to 22 'pounds) which is not an easy wrench to find.

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Permalink Reply by John Austin on November 27, 2020 at 8:12am

I don't have an electronic torque wrench, but I've always wondered ... a lot of electronic instruments are self-calibrating - do the electronic digital torque wrenches self-calibrate?

John

N750A

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Permalink Reply by Darrell Doerhoff on November 27, 2020 at 11:56am

Jason, 

I’ve got 4 torque wrenches. I SELDOM use the 1/2 drive so I didn’t get it out to see the range of it. I hardly use the 1/4”drive, but it’s 10-200 in-lbs.

the two that I use frequently are 3/8 drive. The most used is 25-250 in-lbs. The other one is 100-1000 in-lbs. 

hope this helps. 

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Permalink Reply by Jim and Amelia Isaacs on November 29, 2020 at 7:40am

I use a CDI dial type. Recommend you not skimp and buy the cheapest as propeller torques in particular are critical to safe operation.  Also, research your particular engine and propeller combination and try to find and buy one that covers the entire range needed- Jason makes a good point, it may not be possible but you can cover most needs with one wrench.  

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