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When installing a wheel on the A380, the nut is permitted to be torqued an extra X degrees if the holes do not align.

Any idea why its in degrees instead of X torque or percentage of torque value?

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  • $\begingroup$ For bolts, or threaded fittings in general, the torque varies widely with the lubrication. Perhaps that's the reason behind using repeatable references, such as that angle... $\endgroup$ – xxavier Apr 11 '17 at 7:31
  • $\begingroup$ I'd be interested in a reference to where you question comes from. What is meant by "if the holes do not align"? Which nut? There's only one that holds the wheel on??? I'm not doubting you, I'd just like to get more info. $\endgroup$ – FreeMan Apr 11 '17 at 11:40
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    $\begingroup$ I'm guessing the OP may be referring to the holes used for lock wire. $\endgroup$ – Steve Apr 11 '17 at 13:17
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    $\begingroup$ Presumably the designers of the nut would know precisely how much torque an extra X degrees would apply. When you're trying to align holes, knowing the number of degrees you can turn the nut will be much more useful than knowing how many more N-m you can apply. $\endgroup$ – Greg Hewgill Apr 11 '17 at 20:44
  • $\begingroup$ its a hole which fits a bolt. akin to a castellated nut and pin. $\endgroup$ – timo Apr 13 '17 at 15:50
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The reason is simple, the measurement from the point correct torque is achieved to the location of the hole for the bolt is in degrees, not ft-lbs (the number of degrees is absolute, whereas the force needed to get the alignment can vary). The torque specification has a built-in tolerance for additional torque needed for alignment. If you have to go more than X degrees to align it means you'll be applying excessive torque.

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