Tecnam P2002 JF - Torque Data; Chapter 20; Maintenance Practices; General

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20-10
TORQUE DATA – MAINTENANCE PRACTICES
20-10 TORQUE DATA
MAINTENANCE PRACTICES
General
This paragraph gives the standard practices for torque loading nut and bolt combinations.
The importance of correct torque application cannot be overemphasized.
Undertorque can result in unnecessary wear of nuts and bolts, as well as the parts they secure.
Overtorque can cause failure of a bolt or nut from overstressing the threaded areas. Uneven or
additional loads that are applied to the assembly may result in wear or premature failure.
The following are a few simple, but important procedures, that should be followed to ensure
that correct torque is applied.
Be sure that the torque applied is for the size of the bolt shank, not for the wrench size.
Calibrate the torque wrench at least once a year, or immediately after it has
been abused or dropped, to ensure continued accuracy.
Be sure the bolt and nut threads are clean and dry, unless otherwise specified
Run the nut down to near contact with the washer or bearing surface and check
the friction drag torque required to turn the nut. Whenever possible, apply the
torque to the nut and not the bolt. This will reduce rotation of the bolt in the
hole and reduce wear.
Add the friction drag torque to the desired torque. This is referred to as “final
torque,” which should register on the indicator or setting for a snap-over type
torque wrench.
Apply a smooth even pull when applying torque pressure. If chattering or a
jerking motion occurs during final torque, back off the nut and retorque.
When torque is applied to bolt heads or cap screws, apply the recommended
torque plus friction drag torque.
Whenever possible, apply the torque to the nut and not the bolt. This will reduce
rotation of the bolt in the hole and reduce wear.
If special adapters are used which will change the effective length of the torque
wrench, the final torque indication or wrench setting must be adjusted accordingly.
Determine the torque wrench indication or setting with adapter installed as shown in figure
below.