Torque for oil cooler lines
- Thread starter FORANE
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Mantis Toboggan, MD
D'oh, I don't think that was correct.
Nauga,
who knows rust never seeps
Nauga,
who knows rust never seeps
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To clarify, is this torque for the fitting into the cooler or for a line connected to the cooler? The link below should give you guidance on all torques. However, as a side note, when it comes to NPT fittings up to 1", the old standby technique is finger tight then 2 to 3 turns more to line things up with 4 to 6 threads engaged.
https://www.lycoming.com/sites/default/files/SSP-1776-5 Table of Limits - Complete.pdf
455 Bravo Uniform
Final Approach
Usually -08 is 22.5 - 29 for aluminum and 39 - 45 ft lbs for SS, based on automotive racing applications. Got that off the Summit website. Not sure if aviation or mil spec is different.
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Clip4
Final Approach
10,000 in lb will do it.
Line B-nut torques tend to be airframe/engine specific but as with the NPT fittings there are some guidelines as linked below. Plus there are several similar alternate options. As mentioned above line material comes into play however in some cases an OEM might require torques outside that box for example on turbine engine SS air signal lines. So its best to ensure your aircraft docs dont specify a "unique" torque for that application before using a general torque reference.
https://www.eatonpowersource.com/content/documents/aeroquip/Torque Specifications.pdf
Dan Thomas
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From page 1-41 of the Lycoming document posted by Bell206:
The Pipe Plugs chart is what you'd need. I don't ever remember seeing a torque spec for the oil cooler fittings on a Cessna, for instance.
It's way too easy to overtorque pipe fittings. That NPT means National Pipe Taper. The thread has a taper to it, to wedge the threads tight and make them leak-proof, but the wedging will split things if overtorqued enough. Adding a thread sealant such as teflon goop, or Fuel Lube (EZ-Turn) will make the fitting go in farther for a given torque and will split things far more easily. Had an apprentice split the fuel drain boss on a Marvel Schebler carb that way. 1/8" pipe plug. Expensive mistake.
The Pipe Plugs chart is what you'd need. I don't ever remember seeing a torque spec for the oil cooler fittings on a Cessna, for instance.
It's way too easy to overtorque pipe fittings. That NPT means National Pipe Taper. The thread has a taper to it, to wedge the threads tight and make them leak-proof, but the wedging will split things if overtorqued enough. Adding a thread sealant such as teflon goop, or Fuel Lube (EZ-Turn) will make the fitting go in farther for a given torque and will split things far more easily. Had an apprentice split the fuel drain boss on a Marvel Schebler carb that way. 1/8" pipe plug. Expensive mistake.
Vans offers a reference below but it appears to be the same as Aeroquip. The cooler side doesnt usually stray into this side of the equation. The racing reference mentioned above will work as well and as an FYI I used to buy a lot of AN fittings from the same outlets provided they had the right source docs. Same fittings at less than half the price in some cases.
https://www.vansaircraft.com/faq/torque-specifications-for-hose-end-fittings/
So it looks like 110-121 in lbs would be the spec. But, any adjustment for aluminum vs steel? Any adjustment for wet vs dry threads? Hmmm, seems like the oil cooler manufacturer would or should offer guidance...
Craig
Cleared for Takeoff
There are adjustment for line or nut material, line service, seal type and wet or dry threads. We’ve standard charts as well as flag notes on installation drawings where engineering deviates from the standards.
You develop a feel for how tight fittings need to be after some time and experience. Might be best to get that experience on the ground first?
IMO it is not like a bolt/nut/stud for like a cly head or rod bolt/nut where they can publish a torque when the bolt needs to be stretched to stay in tension.
Of course use pipe dope on the NPT on the adapter fitting that screws into the oil cooler. Then use light oil on the flare threads, not pipe dope. The oil allows you to get it tight and helps when you take it apart.
I have never used a torque wrench when working with AN fittings.
Good luck to you.
IMO it is not like a bolt/nut/stud for like a cly head or rod bolt/nut where they can publish a torque when the bolt needs to be stretched to stay in tension.
Of course use pipe dope on the NPT on the adapter fitting that screws into the oil cooler. Then use light oil on the flare threads, not pipe dope. The oil allows you to get it tight and helps when you take it apart.
I have never used a torque wrench when working with AN fittings.
Good luck to you.
I haven't either, but I'm planning on changing the oil cooler and fuel pump on my lancair. So, I've been doing some research on recommended torque values given the potential cost of getting it wrong...
Not really. You'll find most component venders won't offer such info due to the variables involved with installing their products. Unfortunately, there is not a reference for every mx task on an aircraft even in the TC world. Sometimes you get have to make an educated guess based on general techniques. On the AN fittings side, I usually use the finger-tight + 2 to 3 turns and on the B-nuts I use the flat method when torquing unless the MM specifically states a torque.
Dan Thomas
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Yup. It's real easy to overtorque those, too. So much of this stuff in aviation uses much lower torques than what mechanics in other industries might be used to. The flares on the fitting and tube gets dented or deformed and will not seal properly when overtorqued.
Pinecone
En-Route
Remind me to not have your work on my plane. Or my cars.
Pipe thread is tapered, so if you over tighten the steel fitting into an aluminum part, you WILL crack the aluminum part.
They make aluminum wrenches to prevent over torquing of AN hose fittings. Should tell you something.
Clip4
Final Approach
I guess you need a new torque wrench and a good personal trainer.
Dan Thomas
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If you sick an aluminum fitting into an aluminum part like an oil cooler, without using some anti-seize pipe sealant, the threads will gall terribly when the fitting is removed next time. Ruins the fitting and the cooler or accessory case or whatever.
They make torque wrenches, and specification tables, to prevent overtorquing of all fittings.
From AC 43.13, we get the specs for the tubing nuts. For pipe threads, we need to consult the OEM manuals.
FYI: those aluminum wrenches are mainly to prevent marring of the line nut for aesthetics purposes. Hence the reason speed shops sell them. Steel flare nut wrenches are the norm in aviation for those who prefer to use them on line nuts.
Exactly...
Stewartb
Final Approach
Add Permatex to the oil fitting threads and tighten it snug, Use EZ Turn on the fuel fitting threads and tighten it snug. Test fly a few laps around home base and inspect for leaks.