Turnbuckles are fitted in the cable assembly for the
purpose of making minor adjustments in cable length
and for adjusting cable tension. One of the terminals
has right-hand threads and the other has left-hand
threads. The barrel has matching right- and left-hand
internal threads. The end of the barrel with the left-hand
threads can usually be identified by a groove or knurl
around that end.
When installing a turnbuckle in a control system, it
is necessary to screw both of the terminals an equal
number of turns into the barrel. It is also essential that
you screw both turnbuckle terminals into the barrel
until not more than three threads are exposed.
After you adjust a turnbuckle properly, it must be
safetied. We will discuss the methods of safetying
turnbuckles later in this chapter.
Taper pins are used in joints that carry shear loads
and where the absence of clearance is essential. See
figure 5-17. The threaded taper pin is used with a taper
pin washer and a shear nut if the taper pin is drilled. Use
a self-locking nut if the taper pin is undrilled. When a
shear nut is used with the threaded taper pin and
washer, the nut is secured with a cotter pin.
FLAT HEAD PINS
The flat head pin is used with tie-rod terminals or
secondary controls, which do not operate continuously.
The flat head pin should be secured with a cotter pin.
The pin is normally installed with the head up. See
figure 5-17, view C. This precaution is taken to
maintain the flat head pin in the installed position in
case of cotter pin failure.
Some of the most commonly used clamps are
shown in figure 5-18. When installing a hose between
two duct sections, the gap between the duct ends should
be one-eighth inch minimum to three-fourths inch
maximum. When you install the clamps on the
connection, the clamp should be one-fourth inch
minimum from the end of the connector. Misalignment
between the ducting ends should not exceed one-eighth
Marman type clamps, commonly used in ducting
systems, should be tightened to the torque value
indicated on the coupling. Use the torque value as
specified on the clamp or in the applicable maintenance
What are five fasteners that are included in
the category of miscellaneous fasteners?
AIRCRAFT ELECTRICAL SYSTEM
An important part of aircraft electrical maintenance
is determining the correct type of electrical hardware
for a given job. You must become familiar with wire
and cable, connectors, terminals, and bonding.
A. PLAIN TAPER PIN INSTALLED
B. THREADED TAPER PIN INSTALLED
C. FLAT HEAD PIN INSTALL
Figure 5-17.Types of aircraft pins.