LM2500 remains very versatile and can also be used for
The number of tests and inspections and the type
many other types of GTEs. As a GSM, your main
of maintenance performed on any of the gearbox
assemblies will vary somewhat, depending on the type
responsibility will be to use this equipment in the most
of unit. Most of the service requirements will pertain
effective way.
to the gearbox accessories rather than the gearbox
itself.
Selection of Equipment
Most of the components attached to the accessory
Now, let's look at figure 7-31 and talk about some
gearbox can be serviced, repaired, or replaced by the
of the major factors that will influence your selection of
ship's personnel. The gearbox itself, on the other hand,
borescoping components.
is normally not serviced by the ship. These units are
normally replaced when damage is suspected. The
PROBES. Your borescope kit will contain three
activity that will perform the removal and replacement
probes. Each probe has a unique configuration with
procedures will depend upon the circumstances, special
special capabilities. The parameters that are varied
tool availability, and experience of the activity's
among each of the three probes to achieve each probe's
personnel. In most cases an IMA or support activity will
special capabilities are the viewing angle, field of vision,
be called upon to perform the job.
and magnifying factor. Let's consider the characteristics
of each of the three probes.
BORESCOPING
Probe No. 1. Probe No. 1 has a 90-degree direction
Some very basic information on borescoping was
of vision, a narrow field of view, and a high
provided to you in the Gas Turbine Systems Technician
magnification factor. Its most important advantage is its
(Electrical) 3/Gas Turbine Systems Technician
high magnification factor. Its main disadvantage is its
(Mechanical) 3, Volume 1, NAVEDTRA 10563. In this
narrow field of view, making it difficult to usc for
section, however, we will go into more detail to
searching for an object. Its short depth of field will also
familiarize you more thoroughly with borescoping
require constant refocusing. You will most likely use
equipment and procedures.
probe No, 1 last. After using probe No. 2, and even probe
No. 3, you will then use probe No. 1 to view a
BoreScope Kit
discrepancy close up.
In most cases, your ship should have its initial
Probe No. 2. Use probe No. 2 (red) for all initial
equipment load out consisting of one set of borescope
inspections. Probe No. 2 is for looking down. In fact, its
equipment. Your ship's borescope set or kit will be
view of 100 from the axis of the probe is designed
provided by either Wolfe or Eder, as these are the only
specifically for looking down. Probe No. 2 also has a
two manufacturers that currently supply the Navy with
wide angle view, making it very useful for searching. Its
this type of equipment.
wide angle view, good depth of field, and an angle of
As for your borescoping responsibilities, it will
view ( 100) that is closest to the horizontal plane (90)
not matter which company manufactured your
all serve to minimize distortion. In fact, you can perform
particular unit. The basic borescoping operation will
an almost complete borescope inspection by using just
always be the same. In the following paragraphs, we
probe No. 2.
will tell you about how you should make the proper
Probe No. 3. Use probe No. 3 only after you have
probe selection, inspect for damage, and determine
used probe No. 2 for your initial inspection. In fact, you
the extent of any damage you discover. We will also
tell you about specific guidelines you should follow
will use probe No. 3 only for retrospect viewing.
when you are documenting the results of your
Because its angle of view is 70 from the axis of the
inspection.
probe, probe No. 3 is used only for looking up. In spite
of its wide view, probe No. 3 tends to be tricky to use.
Remember, the borescoping kit for your ship was
For example, when using probe No. 3 to lookup at (to
originally assembled for the LM2500. Fortunately,
obtain a retrospect view of) the compressor or turbine
many factors were taken into consideration so that the
blade tips. you can accidentally bring the probe into the
borescoping kit would contain a combination of
path of the rotating blades, causing damage to the probe
components that would suit the overall inspection
requirements of the engine. Because of this foresight,
and possibly the engine. Use probe No. 3 with extreme
the borescoping kit that was originally designed for the
caution.
