TM 1-1500-204-23-6
Figure 2-33. High Tensile Washer
Figure 2-34. High Tensile Countersunk Washer
Figure 2-35. Preload Indicating Washers
(4)
Preload indicating washers. The preload indicating washer consists of two plain washers, one inner
preload washer, and one outer preload washer. The plain washers mash the inner preload ring into the outer preload ring;
when this has occurred the nut or bolt is properly tightened.
(a)
Installation . Install the preload indicating washers in the following order:
1
Install plain washer
2
Install Inner preload washer.
3
Install outer preload washer.
4
Install plain washer.
NOTE
An aircraft inspector or supervisor may be required to be present during tightening of the preload indicating washers to
verify that the preload washer has been properly tightened.
(b)
Tightening. To tighten preload indicating washers, use the following procedures:
1
Place a ratchet handle wrench with socket on the nut.
2
Place a scribe in one of the preload indicating outer ring holes.
3
Move the preload ring with the scribe and tighten the nut. As soon as you can no longer move
the preload washer with the scribe, stop tightening the nut The proper load (or torque) has been reached.
4
The tightening procedure is the same whether the preload washer is used on a stud or with a bolt
2-5
Screws. Screws are the most common type of threaded fasteners used on aircraft. They are similar to other
types of threaded fasteners, such as bolts, but differ mainly by using a lower material strength, a looser thread fit, and
shanks threaded along their entire length. However, several types of structural screws are available that differ from
structural bolts only in the type of head, the material is equivalent and there is a definite grip.
2-37
