proper torque for H maintenance ?
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I'm sure hand tight would be suffice,
Hex Cap Screws Torque Specifications - Engineer's Handbook
Hex Cap Screws Torque Specifications - Engineer's Handbook
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If you find any that are loose just snug them up a bit. The plastic threads can be stripped out easily.
PatR
Premium Pilot
That table starts with fastener sizes much larger than what we use and is not valid for other reasons.
Normally the torque values would be in the area of 3-6in.lb., but when dealing with dissimilar materials that goes out the window. Published torque specs are not valid when using metal screws that are secured in softer materials. Plastic deformation has to be factored in. Plastic threads will deform long before similar metal material will and we must remember that screws become tight because threads and screw shanks stretch. Works the same way when using metal bolts and screws to secure wood propellers. The torque values used for a metal to metal assemblies crush the wooden hub of the propeller, making an accurate and successful torque impossible to achieve from that point on.
Normally the torque values would be in the area of 3-6in.lb., but when dealing with dissimilar materials that goes out the window. Published torque specs are not valid when using metal screws that are secured in softer materials. Plastic deformation has to be factored in. Plastic threads will deform long before similar metal material will and we must remember that screws become tight because threads and screw shanks stretch. Works the same way when using metal bolts and screws to secure wood propellers. The torque values used for a metal to metal assemblies crush the wooden hub of the propeller, making an accurate and successful torque impossible to achieve from that point on.
PatR
Premium Pilot
Had to go head to head with some pretty arrogant engineers on this subject when they were experiencing a lot of propellers exploding on the test stand. They kept blaming defects in propeller material and design. Using the engine manufacturer as their information source they told me the prop bolt torque could not be disputed. The manufacturer was dead wrong and later amended bolt torque specs
A little trickery finally provided proof of argument. After they left one afternoon I reduced bolt torque from over 100in.lb. to 60in.lb. for the next week of testing. That was the only prop that stayed together for more than a couple hours. In fact, it remained intact until it was removed a week later to test a different propeller, which also survived because it was installed with the lower torque value. There's nothing like watching and hearing 28" wood, all carbon, and carbon over wood propellers explode at thousands of RPM. There are times the "school of hard knocks" will prevail
A little trickery finally provided proof of argument. After they left one afternoon I reduced bolt torque from over 100in.lb. to 60in.lb. for the next week of testing. That was the only prop that stayed together for more than a couple hours. In fact, it remained intact until it was removed a week later to test a different propeller, which also survived because it was installed with the lower torque value. There's nothing like watching and hearing 28" wood, all carbon, and carbon over wood propellers explode at thousands of RPM. There are times the "school of hard knocks" will prevail
i still would like to know the proper torque for such screws as the ones
hold on the engines they are metal to metal vibrations can cause them to loosen .
yes i can use locktight and hand tight . but it still is not to spec .
guess ill call yuneec .
thanks though
hold on the engines they are metal to metal vibrations can cause them to loosen .
yes i can use locktight and hand tight . but it still is not to spec .
guess ill call yuneec .
thanks though
PatR
Premium Pilot
Yuneec has not published a torque specification sheet, or any other maintenance regimen that I'm aware of.
The specs for an m3 cap head screw is 2.48n.m., or 21in.lb. For m2.5 the value is 1.43n.m., or 12 in.lb. Personally, I don't use max torque values with Chinese made fasteners, ever. Too much work digging the shafts out later. Use medium blue Loctite.
https://www.holo-krome.com/uploads/7/2/7/5/72754089/hk_torquedatachart.pdf
The specs for an m3 cap head screw is 2.48n.m., or 21in.lb. For m2.5 the value is 1.43n.m., or 12 in.lb. Personally, I don't use max torque values with Chinese made fasteners, ever. Too much work digging the shafts out later. Use medium blue Loctite.
https://www.holo-krome.com/uploads/7/2/7/5/72754089/hk_torquedatachart.pdf
