Requirement for Torque Wrench Calibration

MD11Pilot

MD11Pilot

Line Up and Wait
Joined
Oct 6, 2014
Messages
566
Location
Broken Arrow OK
Display Name
Display name:
MD11Pilot
Digging through my reference materials to answer a question about Torque Wrench Calibration. I cannot find any specific FAR requirement but I have been told that there is. Checked Google and there are articles talking about the need based upon use but it only addresses if a shop needs a certification record. I am not asking as to the need to do this as I agree that it should be but looking for an exact reference. Also, if one can find a calibration testing procedure and kept a record of your findings, would that suffice for the personal use of a wrench on your aircraft?
Thanks in advance.
 
43.13(a) maybe?

The relevant quote is "shall use the tools, equipment, and test apparatus necessary to assure completion of the work in accordance with accepted industry practices"

Just a shot in the dark from my perspective, though. I'm sure there's a pretty deep rabbit hole concerning "accepted industry practices".
 
darrell said:
43.13(a) maybe?

The relevant quote is "shall use the tools, equipment, and test apparatus necessary to assure completion of the work in accordance with accepted industry practices"

Just a shot in the dark from my perspective, though. I'm sure there's a pretty deep rabbit hole concerning "accepted industry practices".
Click to expand...

AC43.13-1B, Chaper 7, here: http://www.faa.gov/documentLibrary/media/Advisory_Circular/Chapter_07.pdf

Scroll down to paragraph 7-40.

Transport Canada requires periodic calibration and uses the Canadian Aviation Regulations to enforce it:


  • 571.02
  • .
  • .
  • (2) A person who performs maintenance or elementary work pursuant to subsection (1) shall ensure that any measuring device or test equipment used
    • (a) meets the specifications of the manufacturer of the aeronautical product with respect to accuracy, taking into account the intended use; and
    • (b) if calibration requirements are published by the manufacturer of the measuring device or test equipment, is calibrated by means traceable to a national standard.
I'm surprised that FAR 43 doesn't have a similar statement. AC43.13 is advisory, not law, right?
 
Again, common sense needs to prevail. "If" you suspect your torque wrench is in need of calibration, of course, have it done.

For 145 CRS and 135/121 operations the GMM or similar document will specify items such as torque wrench calibrations.
 
MD11Pilot said:
Digging through my reference materials to answer a question about Torque Wrench Calibration. I cannot find any specific FAR requirement but I have been told that there is. Checked Google and there are articles talking about the need based upon use but it only addresses if a shop needs a certification record. I am not asking as to the need to do this as I agree that it should be but looking for an exact reference. Also, if one can find a calibration testing procedure and kept a record of your findings, would that suffice for the personal use of a wrench on your aircraft?
Thanks in advance.
Click to expand...

Not sure about the FARs, but as far as calibration the Snap On guy would do them on mine and there was a calibration log in the box. I'd assume that would be sufficient for the record, but...:dunno:
 
Thanks guys. Yes common sense applies but an IA I work with insists it is regs but cannot give a reference.
 
MD11Pilot said:
Thanks guys. Yes common sense applies but an IA I work with insists it is regs but cannot give a reference.
Click to expand...

I think that it's related to the manufacturers recommendations. Snap On suggest every 6 months, and I've never been charged for it.
 
From My Cousin Vinny

Vinny Gambini: Well, did you use the faucet?
Lisa: Yeah.
Vinny Gambini: Then why didn'tcha turn it off?
Lisa: I DID turn it off!
Vinny Gambini: Well, if you turned it off, why am I listening to it?
Lisa: Did it ever occur to you it could be turned off AND drip at the same time?
Vinny Gambini: No. Because if you'd turned it off, it wouldn't drip!
Lisa: Maybe it's broken.
Vinny Gambini: Is that what you're saying? It's broken?
Lisa: Yeah. That's it, it's broken.
Vinny Gambini: You sure?
Lisa: I'm positive.
Vinny Gambini: Maybe you didn't twist it hard enough.
Lisa: I twisted it just right.
Vinny Gambini: How could you be so sure?
Lisa: [sighs] If you will look in the manual, you will see that this particular model faucet requires a range of 10 to 16 foot-pounds of torque. I routinely twist the maximum allowable torquage.
Vinny Gambini: Well, how could you be sure you used 16 foot-pounds of torque?
Lisa: Because I used a Craftsman model 1019 Laboratory Edition Signature Series torque wrench. The kind used by Caltech high energy physicists. And NASA engineers.
Vinny Gambini: Well, in that case, how can you be sure THAT's accurate?
Lisa: Because a split second before the torque wrench was applied to the faucet handle, it had been calibrated by top members of the state AND federal Department of Weights and Measures... to be dead on balls accurate!
[She rips a page out of a magazine and hands it to him]
Lisa: Here's the certificate of validation.
Vinny Gambini: Dead on balls accurate?
Lisa: It's an industry term.
Vinny Gambini: [tosses paper away] I guess the ****ing thing is broken.
Click to expand...
 
Last edited:
MD11Pilot said:
Thanks guys. Yes common sense applies but an IA I work with insists it is regs but cannot give a reference.
Click to expand...



14 CFR 145.109 - Equipment, materials, and data requirements.


(b) A certificated repair station must ensure all test and inspection equipment and tools used to make airworthiness determinations on articles are calibrated to a standard acceptable to the FAA.
Click to expand...
More than likely this is what he is referring to, but again, unless you are a Part 145 Certificate Repair Station, this does not apply.
 
I bought calibrated weights and use that to check calibration of my other tools. Weights won't ever go out of calibration for a long, long time unless someone smashes them up, and it's a great way that I can prove my tools are functioning properly.
 
Calibrating a torque wrench is probably one of the easiest things to do... I have a known weight..... Clamp the wrench by the drive lug in a heavy duty vice, hang the known weight out from that point 12" and observe the reading.. The hardest part is melting out the solder where the adjustment is made..... Easy Pleasy....
 
Calibrating a torque wrench is probably one of the easiest things to do... I have a known weight..... Clamp the wrench by the drive lug in a heavy duty vice, hang the known weight out from that point 12" and observe the reading.. The hardest part is melting out the solder where the adjustment is made..... Easy Pleasy....
Click to expand...

If I understand what you are saying, I don't think it is quite that simple on the click type...when you hang the weight, it is either going to click or not. How do you interpret that?
Beam or electronic, yeah it works. But you have to do more than just one reading at 20#.
 
Let'sgoflying! said:
If I understand what you are saying, I don't think it is quite that simple on the click type...when you hang the weight, it is either going to click or not. How do you interpret that?
Beam or electronic, yeah it works. But you have to do more than just one reading at 20#.
Click to expand...

All I use is the click type.. They are the easiest to calibrate....
 
When you have direction in the publication you are using that requires a calibration of any tool you must comply.

setting the fuel injection on a IO-520 for example requires calibrated gauges.
 
Tom-D said:
When you have direction in the publication you are using that requires a calibration of any tool you must comply.

setting the fuel injection on a IO-520 for example requires calibrated gauges.
Click to expand...

I think the question is 'how often does one need to recalibrate?'
 
Big repair stations likely have thier own lab allowing in house calibration of most tools used. The lab often has a written program and procedures to cover new tools that they have no history of calibrating. Once a history
is established they may extend the intervals.

Even the ground support equipment, such as jacks, are tracked, serviced and proof load tested on manufacturer's schedule to prevent malfunctions.
 
Last edited:
What other tools need calibrating? My hammer seems about the same weight as when I bought it. I guess we need the mtbf for all the handtools!
 
Henning said:
I think the question is 'how often does one need to recalibrate?'
Click to expand...

every time the snap-on trucks comes by.


Mine is a Snap-on and passes every time with no problems
 
Last edited:
Tom-D said:
every time the snap-on trucks comes by.


Mine is a Snap-on and passes every time with no problems
Click to expand...

IIRC the instructions to my Snap On dial unit they recommended every 6 months, so I figure that should be acceptable to "The Administator" since nothing is specified.
 
bending beam type torque wrenches never need calibrating.
 
I have a friend who is an aircraft mechanic and whose advice I trust.

I asked him for a recommendation on a torque wrench, since my old Craftsman DigiTork was out of commission.

He said he waits for the Milwaukee brand torque wrench to be on sale at Harbor Freight - for just under $10 - and just gets a new one every year.

Anyway, I bought two - a 3/8" and a 1/2", and so far so good.

I know, I know, I'm skeptical as well!
 
FastEddieB said:
I have a friend who is an aircraft mechanic and whose advice I trust.

I asked him for a recommendation on a torque wrench, since my old Craftsman DigiTork was out of commission.

He said he waits for the Milwaukee brand torque wrench to be on sale at Harbor Freight - for just under $10 - and just gets a new one every year.

Anyway, I bought two - a 3/8" and a 1/2", and so far so good.

I know, I know, I'm skeptical as well!
Click to expand...

I know a guy that calibrated the wrenches in a big shop. He said that the cheap wrenches (HF in the US as an example, or Princess Auto here in Canada) were so far off when new that it wasn't funny, and that he often could not get any linearity or consistency to the readings. Get it clicking right at one setting and it'll be off at most of the others. And many times, at any given setting, it will click at different actual output torques.

Buy good stuff and have it calibrated unless it comes with a certificate of calibration. It's not even worth using a torque wrench if it's a cheap, inconsistent, uncalibratable tool. Might as well use a hammer.
 
Let me expound on this a bit. I know that many of you are highly qualified aviation professionals as well but I have worked in Part 91, 121 and 145 and have dealt with the FAA (Generic ASIs as well as PMIs) a fair amount. I have also been involved in the writing of Repair Station Manuals. So I believe I have a good idea how they read the FARs.

§ 43.13 Performance rules (general).
(a) Each person performing maintenance, alteration, or preventive maintenance on an aircraft, engine, propeller, or appliance shall use the methods, techniques, and practices prescribed in the current manufacturer's maintenance manual or Instructions for Continued Airworthiness prepared by its manufacturer, or other methods, techniques, and practices acceptable to the Administrator, except as noted in § 43.16. He shall use the tools, equipment, and test apparatus necessary to assure completion of the work in accordance with accepted industry practices. If special equipment or test apparatus is recommended by the manufacturer involved, he must use that equipment or apparatus or its equivalent acceptable to the Administrator.
(b) Each person maintaining or altering, or performing preventive maintenance, shall do that work in such a manner and use materials of such a quality, that the condition of the aircraft, airframe, aircraft engine, propeller, or appliance worked on will be at least equal to its original or properly altered condition (with regard to aerodynamic function, structural strength, resistance to vibration and deterioration, and other qualities affecting airworthiness).
Click to expand...

Paragraph a. If the AMM, ICA, etc. instructs you to torque a bolt to XX Ft-Lbs, how can you be confident that you have done so if the torque wrench has not been calibrated within the timeframe that its manufacturer says to? You cannot. And if the AMM or ICA mention using a calibrated torque wrench, you really had better do so.

Paragraph b. How can you be certain that you have maintained the structural strength, resistance to vibration if a bolt might not be at the proper torque due to a torque wrench that is not calibrated? You cannot.

AC43.13 states:
a. Calibrate the torque wrench at least once a year, or immediately after it has been abused or dropped, to ensure continued accuracy.
Click to expand...

While this is only an Advisory Circular, you'd be hard pressed to explain to an ASI why you did not do so especially in light of what the above quoted FAR says.​

Now as RW mentioned, there is a explicit statement in Part 145 to calibrate so you have zero wiggle room there even if you might believe you have such wiggle room in Part 43/91 ops.​

Now ask yourself this question. Do non 145 shops and independent A&P mechanics often work on some of the same type aircraft that 145 shops do? The answer is yes. So the answers to the calibration question for a Part 145 to me is an excellent standard to use in the non 145 world as well. ​

But if you still doubt that calibration is necessary, ask your FSDO.
 
Again, in PoA style, we are trying to read into regulations (and non regulations) something that doesn't exist.

God forbid we use common sense.
 
Arbitrary calibration intervals like 1 year are pretty standard.

I worked with one airline that ran a metrology lab (calibration lab) certified to ISO 9000 standards. They really knew what they were doing too.

They maintained careful records on each device and when the data showed that a group of devices consistently required no adjustment at cal time, they used that data to justify extension of the calibration period.

If they found a family of units that required adjustment at every calibration, they shortened the interval.

The objective is to make sure the device is always within limits every time it is used.
 
Let'sgoflying! said:
What other tools need calibrating? My hammer seems about the same weight as when I bought it. I guess we need the mtbf for all the handtools!
Click to expand...

Pressure gauges, push/pull scales, inclinometers, volt/ohm meters, ultrasonic machines, cable tensiometers, eddy current machines, hardness testers, weighing scales, micrometers, on and on and on...
 
kontiki said:
Arbitrary calibration intervals like 1 year are pretty standard.

I worked with one airline that ran a metrology lab (calibration lab) certified to ISO 9000 standards. They really knew what they were doing too.

They maintained careful records on each device and when the data showed that a group of devices consistently required no adjustment at cal time, they used that data to justify extension of the calibration period.

If they found a family of units that required adjustment at every calibration, they shortened the interval.

The objective is to make sure the device is always within limits every time it is used.
Click to expand...
Pretty standard for the Navy too.
 
Snap-On is quoted in a Aug 2000 FAA Airworthiness newsletter.

“Periodic recalibration is necessary to maintain accuracy of any torque wrench. Recalibrate every 6 months or more frequently depending on use.”

http://www.faa.gov/about/office_org..._more/maintenance_newsletters/media/aug00.pdf

There's also a April 2010 "Nuts and Bolts" publication posted by FAA Safety which identifies the 43.13 regulation and discusses it in some length.

https://www.faasafety.gov/files/notices/2010/Apr/10-01[1].pdf


The bottom line is, know and follow what the tool manufacturer tells you to do. It's not that difficult. I tracked multiple torque wrench calibrations in the Navy. If the cal shop doesn't put one on it, make your own tag with the shop performing the calibration, date calibrated and date due. Then just check when you're ready to work.
 
Last edited:
bnt83 said:
Pressure gauges, push/pull scales, inclinometers, volt/ohm meters, ultrasonic machines, cable tensiometers, eddy current machines, hardness testers, weighing scales, micrometers, on and on and on...
Click to expand...

Yup. In Canada we do all of that in shops that work on commercial aircraft.
 
bflynn said:
Snap-On is quoted in a Aug 2000 FAA Airworthiness newsletter.

“Periodic recalibration is necessary to maintain accuracy of any torque wrench. Recalibrate every 6 months or more frequently depending on use.”

http://www.faa.gov/about/office_org..._more/maintenance_newsletters/media/aug00.pdf

There's also a April 2010 "Nuts and Bolts" publication posted by FAA Safety which identifies the 43.13 regulation and discusses it in some length.

https://www.faasafety.gov/files/notices/2010/Apr/10-01[1].pdf


The bottom line is, know and follow what the tool manufacturer tells you to do. It's not that difficult. I tracked multiple torque wrench calibrations in the Navy. If the cal shop doesn't put one on it, make your own tag with the shop performing the calibration, date calibrated and date due. Then just check when you're ready to work.
Click to expand...

Well, that Nuts& Bolts article made the same points that I did using the same references but possibly did so in a slightly more eloquent manner. I guess I wasn't so far off. But I'm sure the POA resident experts on all things aviation will still think otherwise. :rofl:
 
Let'sgoflying! said:
What other tools need calibrating? My hammer seems about the same weight as when I bought it. I guess we need the mtbf for all the handtools!
Click to expand...

In addition to the previous lists a lot of mechanical tools like go-no gauges wire/cable crimper dies need to be dimensionally checked. Electrical gear like temperature measurement gear, color and light measurement gear, volt meters, decade boxes, tends to drift as component values drift with age, use, temp etc.

It gets fuzzy with portable automated test equipment. There are two components, the electrical calibration of the electronics and the instructions in the test programs.

If you tell someone to use a calibrated volt meter to make a measurement and give them a pass fail value with tolerances the tech decides fitness based on what he sees.

If you use an automated transponder tester box, the unit can say PASSED, but how do you know the tests performed are the ones required for the level of compliance you require. I refer to XPDRs because aircraft that operate in different continents and altitudes may need to qualify to different rules.

I always thought those testers should be certified because they are used to certify installations on aircraft and so few people in the business really understand it all to the required level of detail. As it stands now vendor claims are what a lot of people rely on.
 
Last edited:
One thing I see getting out of hand is the fees charged by "approved testing / calibrating centers"... They know the FAA requires frequent testing and sign offs and they assume shops will not question their pricing structure... I have personally seen invoices that shows a test for a tool and then looked up the exact same tool... The NEW tool was actually cheaper then the testing price of the old tool..:rolleyes::rolleyes:.....:rolleyes2:...:mad2:
 
N801BH said:
One thing I see getting out of hand is the fees charged by "approved testing / calibrating centers"... They know the FAA requires frequent testing and sign offs and they assume shops will not question their pricing structure... I have personally seen invoices that shows a test for a tool and then looked up the exact same tool... The NEW tool was actually cheaper then the testing price of the old tool..:rolleyes::rolleyes:.....:rolleyes2:...:mad2:
Click to expand...

Never once has the Snap On charged me for a calibration.
 
N801BH said:
Can a Snap On truck provide the needed FAA required cert ?
Click to expand...

:dunno: what "needed FAA required cert" would that be?

As Rotor has pointed out a couple of times - plain old common sense. A calibration certificate does not guarantee that the wrench wasn't dropped off a lift ten minutes after it was issued. If you take your wrench in for it's annual calibration check and it requires adjustment what effect does that have on the last job you signed off using it?

At the airline where company tools are used there is a calibrated test rig where you can verify the accuracy of the wrench you are about to use. Because they are community tools you have no idea what may have happened to it prior to your use. For an independent mechanic who always parks it at null when not in use, knows he hasn't dropped it or stepped on it, hasn't used it as a prybar or a regular wrench to loosen stubborn bolts or as a hammer to coax frozen components off - he can have just as much confidence that his tool is accurate as the guy with a 90 day old sticker who has loaned it to his buddy.
 
Silvaire said:
:dunno: what "needed FAA required cert" would that be?

As Rotor has pointed out a couple of times - plain old common sense. A calibration certificate does not guarantee that the wrench wasn't dropped off a lift ten minutes after it was issued. If you take your wrench in for it's annual calibration check and it requires adjustment what effect does that have on the last job you signed off using it?

At the airline where company tools are used there is a calibrated test rig where you can verify the accuracy of the wrench you are about to use. Because they are community tools you have no idea what may have happened to it prior to your use. For an independent mechanic who always parks it at null when not in use, knows he hasn't dropped it or stepped on it, hasn't used it as a prybar or a regular wrench to loosen stubborn bolts or as a hammer to coax frozen components off - he can have just as much confidence that his tool is accurate as the guy with a 90 day old sticker who has loaned it to his buddy.
Click to expand...

I personally know someone who is a mechanic at Delta Airlines. Each mechanic has their own tool box and tools; I was given a tour. Perhaps other airlines are different?
 
Cap'n Jack said:
I personally know someone who is a mechanic at Delta Airlines. Each mechanic has their own tool box and tools; I was given a tour. Perhaps other airlines are different?
Click to expand...

Can't speak for Delta but at my airline all tools and equipment that require calibration must be controlled. No use of personal torque wrenches, Fluke meters etc. Yes, mechanics have their own screwdrivers and wrenches but even feeler gauges are controlled.
 
Silvaire said:
:dunno: what "needed FAA required cert" would that be?

As Rotor has pointed out a couple of times - plain old common sense. A calibration certificate does not guarantee that the wrench wasn't dropped off a lift ten minutes after it was issued. If you take your wrench in for it's annual calibration check and it requires adjustment what effect does that have on the last job you signed off using it?

At the airline where company tools are used there is a calibrated test rig where you can verify the accuracy of the wrench you are about to use. Because they are community tools you have no idea what may have happened to it prior to your use. For an independent mechanic who always parks it at null when not in use, knows he hasn't dropped it or stepped on it, hasn't used it as a prybar or a regular wrench to loosen stubborn bolts or as a hammer to coax frozen components off - he can have just as much confidence that his tool is accurate as the guy with a 90 day old sticker who has loaned it to his buddy.
Click to expand...


ANY repair station or FBO with a maintenance shop will get an inspection from the FSDO regional office during their audit each year... Just have some tools used in repairing aircraft around without a cert tag and you get a substantial fine... For EACH tool...:eek:..

Rotor and Wing knows this,,,:rolleyes:
 
You must log in or register to reply here.
Back
Top