BOLT TIGHTENING
GENERAL
NEVER over tighten a bolt. Tighten ONLY when and as instructed. Particular care is necessary
when tightening bolts which pass through aluminum tubes with no solid internal support. BEFORE
installing bolts, check that the grip-length is correct.
Refer to FAA Advisory Circular AC65-9A, Page 129 for additional information.
Bolts and nuts should be clean and dry before installation. Threads should not be oiled. Bolts and
nuts with damaged threads and/or rough ends should not be used.
Whenever possible, bolts should be installed with the head on TOP or in the FORWARD position.
This positioning tends to prevent the bolt from slipping out if the nut is accidentally lost. There may
be specific instances where the assembly instructions specify a particular bolt orientation. DO NOT
contradict the assembly instructions in such a case.
IMPORTANT: Nylock (locknuts) nuts and lock nuts should NEVER be used more than TWICE as
they become less vibration resistant with each removal.
Castle Nuts should only be tightened to the specified degree of tightness and must always be used
with a Cotter Pin for security. Refer to Figure 1-6 on the previous page for the proper method of
bending Cotter Pins.
NOTE: When Castle Nuts are tightened, the Cotter Pin holes may not line up with the slots in the
nut when the torque setting is reached. Back off to the nearest slot. A Castle Nut must NEVER be
over tightened to permit lining up the safety hole with the next tighter slot.
WARNING: A bolt which is subject to rotation in flight will use a Castle Nut. A Castle Nut
relies on a Cotter Pin to prevent it from backing off. Always ensure Castle Nuts are
secured with a Cotter Pin.
WHENEVER Possible, it is preferred to rotate the nut onto the bolt as opposed to rotating the bolt
onto the nut.
HOLE SIZE Typically a 1/4” bolt will be going into a 1/4” hole. If the fit has interference it is
advisable to slightly clear the hole with the corresponding drill bit. Do not “thread” the bolt into a
drilled hole. Do not HAMMER, BEAT, JAM or any other means of force on a bolt through a hole.
Above applies to all hole sizes.
PART ASSEMBLY Allowing manufacturing tolerances, it is on occasion whereas the bolt will not
easily go thru both parts. If the fit between the two parts has interference, it is advisable to slightly
clear the hole with the corresponding drill bit. Do not “thread” the bolt into the interference. Do
not HAMMER, BEAT, JAM or any other means of force on a bolt through the fittings.
To Next Page
Loading...