Technical data

13773-001
20-70
Page 1
FASTENER AND HARDWARE GENERAL REQUIREMENTS
1. DESCRIPTION
This section contains general requirements for common hardware installation. Covered are selection and
installation of cotter pins, installation of turnbuckle locking clips, rod end inspection requirements, fastener
flushness requirements, self-locking nut installation requirements, and installation and usage requirements
for washers and lockwashers.
2. MAINTENANCE PRACTICES
A. Cotter Pins (See Figure 20-701)
The preferred method to secure a pin or castellated nut is by the use of a cotter pin. Safety wiring is
also an acceptable method to secure pins or castellated nuts.
CAUTION: Cadium-plated cotter pins should not be used in applications bringing them in contact
with fuel, hydraulic fluid, or synthetic lubricants.
(1) Proper Usage of Cotter Pins.
(a) Select cotter pin material in accordance with temperature, atmosphere, and service limita-
tions.
(b) Cotter pins shall be new upon each application.
(c) When nuts are to be secured to a fastener with cotter pins, tighten nut to low side (mini-
mum) of applicable specified or selected torque range unless otherwise specified, and if
necessary, continue tightening until slot aligns with hole. In no case shall the high side
(maximum) torque range be exceeded.
(d) If more than 50% of cotter pin diameter is above nut castellation, a washer should be used
under nut or a shorter fastener should be used. A maximum of two washers may be per-
mitted under a nut.
(e) The largest diameter cotter pin which the hole and slot will accommodate should be used.
In no application shall cotter pin size be less than size called out on the following table.
(f) Install cotter pin with head firmly in slot of nut with axis of eye at right angles to bolt shank.
Bend prongs so that head and upper prong are firmly seated against bolt.
(g) In pin applications, install cotter pin with axis of eye parallel to shank of clevis pin or rod
end. Bend prongs around shank of pin or rod end.
30 Nov 2000