FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 7. Aircraft Hardware, Control Cables, and Turnbuckles | 6. Pins | 7-104. Spring Pins
9/8/98
SECTION 6. PINS
AC 43.13-1B
7-101. TAPER PINS. Plain (AN385) and
threaded (AN386) taper pins are used in joints
which carry shear loads and where the absence
of play is essential. The plain taper pin is usu-
ally drilled and secured with wire. The
threaded taper pin is used with a taper-pin
washer (AN975) and shear nut (safetied with a
cotter pin) or self-locking nut (if undrilled).
Typical pin types are shown in table 7-15.
7-102. FLATHEAD PINS (AN392
THROUGH AN406). Commonly called a
clevis pin, this pin is used in conjunction with
tie-rod terminals and in secondary controls
which are not subject to continuous operation.
The pin is normally installed with the head up,
or forward, to prevent loss should the cotter
pin fail or work out.
7-103. COTTER PINS (AN380). Cotter
pins are used for securing bolts, screws, nuts,
and pins. Use AN381 or MS24665 cotter pins
in locations where nonmagnetic material or re-
sistance to corrosion is desired. Cotter pins
should not be reused.
7-104. SPRING PINS. The spring pin is
designed for use in double-shear applications.
The pins are manufactured with the diameter
greater than the holes in which they are to be
used. Spring pins are stronger than mild car-
bon steel straight pins, taper pins, or grooved
pins of the equivalent size. The spring pin is
compressed as it is driven into the hole, and
exerts continuous spring pressure against the
sides of the hole to prevent loosening by vi-
bration. Spring pins require no other means of
securing, and can be used inside one another to
increase shear strength.
vibration or repeated load conditions (espe-
cially in soft materials, such as aluminum al-
loys and magnesium). They should not be
used in an aircraft component or system where
the loss or failure of the pin might endanger
safe flight.
b. The joints where spring pins are used
for fastening shall be designed like riveted and
bolted joints. Spring pins should not be mixed
with other structural fasteners in the same
joint. These pins, for primary structural appli-
cations, should be used only where there will
be no rotation or relative movement of the
joint. Spring pins may be reused if a careful
inspection reveals no deformation of the pin or
hole.
c. Be careful to observe that the hole has
not enlarged or deformed preventing proper
functioning of the spring pin. Where hole
misalignment results in the pin gap closing or
necessitates excess inserting force, the spring
pin will not be used. The spring pin should
not be used as a substitute for a cotter pin.
When a spring pin is used in a clevis joint, it is
recommended that the pin be held by the outer
members of the unit for maximum efficiency
and reduced maintenance.
7-105. QUICK-RELEASE PINS. These
pins are used in some applications where rapid
removal and replacement of equipment is nec-
essary. When equipment is secured with these
pins, no binding of the spindle should be pres-
ent. Spindle binding could cause the locking
balls to remain in the open position which
could result in the pin falling out under vibra-
tion.
a. Be careful when using these pins,
since spring-pin performance depends entirely
on the fit and the durability of the fit under
7-1067-121. [RESERVED.]
Par 7-101
Page 7-17 (and 7-18)