partial assembly of the parts, and will be
accomplished during assembly of the components.
JET ENGINE TEST CELLS
For a jet aircraft engine to operate properly, it
must be adjusted properly. The checks for proper
adjustment can best be made during controlled
operation of the engine. The various types of test
facilities, or test cells, are designed for service testing
of the jet engine according to procedures and manuals
published by the Naval Air Systems Command
(NAVAIRSYSCOM). Most engine test cells are used
at the intermediate-or depot-level maintenance
facilities.
Operators of these test facilities are required by
OPNAVINST 4790.2 (series) to be certified by
completion of at least one of the following three basic
methods of operator training:
Figure 10-17.-Measuring the turbine wheel to
1. Completion of formal training at a Naval Aviation
exhaust cone clearance.
Depot (NADEP) school, based on the specific model of
test facility.
2. Completion of on-site training provided by a Naval
the latest technical instructions for that particular
Air Engineering Service Unit (NAESU) engineer.
engine.
3. Completion of on-the-job training (OJT) under the
direct supervision of a senior petty officer or civilian
MAIN ENGINE BEARINGS INSPECTION
technician who is a certified test
Because of the high rpm, main engine bearings
are critical sections of an engine. The number of main
engine bearings may differ from one model engine to
another. With the engine disassembled and in the
vertical position, all bearings and housings can be
inspected and replaced as necessary.
ACCESSORIES DRIVE SECTION AND MATING
GEAR INSPECTIONS
The accessories drive section contains the
various gearboxes for driving the accessories. These
gearboxes should be inspected for cracks and worn
areas, and the splines should be checked for proper fit
and clearances. When you remove or replace
gearboxes, the splined drive shafts must be carefully
removed or installed to prevent spline damage.
Most mating gears require backlash as well as
end clearance checks. You should carefully inspect
the gear and spline teeth for irregular or excessive
wear, galling, and flaking. Usually, runout
Figure 10-18.-Afterburner duct and nozzle
measurements are not required if there is no evidence
assembly.
of gear teeth spalling. These checks may require
10-19