3-1. General. In the maintenance of Army aircraft, the
fabrication of many parts may be required. During this
process, accurate measurements must be made before
and during the fabrication procedure. A partly finished or
a finished part must also be checked for accuracy. This
inspection includes comparing the dimensions of the
workplace with the required dimensions shown on a
drawing or sketch. These measurements are made using
a variety of measuring tools. The accuracy of the
measurements will depend upon the types of tools used
and the ability of the aircraft repairer to use them
3-2. Levels. Levels are tools designed to prove whether
a plane or surface is in the true vertical or true horizontal.
All levels consist of a liquid-filled glass tube or tubes
supported in a frame.
a. Types. There are many types of levels used in
aircraft maintenance. Some of these are described
(1) Master precision level.
precision level, shown in figure 3-1, has a ground and
graduated main vial. The top and bottom of the level are
milled and ground to make sure both surfaces are
absolutely parallel. This level is used to determine the
true horizontal with the main vial. The true vertical is
determined by using the two smaller vials.
Figure 3-1. Master Precision Level
The machinist's level,
shown in figure 3-2, has an extra large vial. This
increases its accuracy and sensitivity. Some of these
levels have grooved bottoms which fit over pipes and
shafts. They are used in machine shops for leveling work
Striding level. The striding level is a
machinist's level which is mounted on a raised base. This
level, shown in figure 3-3, is used to span existing
cabling, piping, or similar obstructions. It is extremely
useful in a machine shop for checking the true horizontal
of the flatway on a lathe.
Figure 3-2. Machinist's Level
Figure 3-3. Striding Level