Allison. On the Allison GTE, you will use a
There are two solenoids (A and B) installed on the
borescope inspection to determine the condition of the
Allison's customer bleed air valve to control the valve's
liner. The Allison has individual liners or cans. This
position. These solenoids are adjustable and receive the
design will allow you to replace only the cans that are
TIT signal inputs from a relay driver card in the LOCOP.
damaged, not the whole combustion section.
The A solenoid controls the high temperature (valve
closing) operation. The B solenoid controls the low
Garrett. The Garrett has a single combustion
temperature (valve opening) operation. Other than
chamber. If it is damaged, the Garrett's combustion
removal and replacement, the only maintenance you, the
chamber will require complete replacement. The
GSM, may have to perform will be the solenoid
replacement procedure is not difficult and can be
adjustments, and you will most likely be assisted by a
performed at the shipboard maintenance level.
GSE in this task.
Sunstrand. On the Sunstrand GTE, you can use the
500-hour hot-section teardown inspection to check the
Garrett. The Garrett's bleed air (de-icing) valve is
condition of the liner. Like the Garrett, the Sunstrand has
installed on the side of the engine. The Garrett's bleed
a single combustion chamber that will require complete
air valve serves only one function: it supplies hot bleed
replacement if it is damaged. Also like the Garrett, the
air to the turbine air inlet plenum for de-icing. Valve
replacement procedure for the Sunstrand is quite simple
removal and replacement is the only maintenance that
and can be performed at the shipboard maintenance
you will usually have to perform.
level.
Sunstrand. The Sunstrand's bleed air (load
COMBUSTOR DRAIN VALVES. The com-
control) valve operates in a reamer similar to the bleed
bustor drain valves are installed on the Allison and
air valve installed on the Allison. The Sunstrand's bleed
Sunstrand GTEs. For the Allison and the Sunstrand, the
air valve provides bleed air for main engine starting and
tests, inspections, and maintenance of these valves will
anti-icing air. The bleed air is directed to the propeller
involve specific procedures. These procedures are
shrouds, not the engine intakes. The Sunstrand's bleed
covered in the PMS and the applicable manufacturer's
air valve also has automatic controls to maintain the
technical manual.
exhaust gas temperature (EGT) within safe operating
Sunstrand. Every 500 hours of operation, the
limits while it is in use. The removal and replacement
Sunstrand's drain valves must be removed for testing,
of this valve is the only maintenance that you will
inspection, and cleaning.
usually perform.
Allison. The Allison's drain valves, however, are
Combustor
usual] y tested in place. You must consult the appropriate
documentation for each of these GTEs.
The combustor section has a large number of
For either the Allison, Garrett, or Sunstrand, no
serviceable components. Most of these components are
matter what procedure you use or engine you maintain,
designed to be serviceable due to their location on the
it is extremely important for you to be thorough. If you
engine and the extreme conditions to which they are
find a faulty valve in either one of these GTEs, you
subjected during operation. All of the combustor-related
should repair or replace it immediately. Allowing a
components we will discuss in this section are fairly
faulty valve to remain in operation can cause serious
easy to maintain and can provide a long service life if
damage to the engine either through hot starts or a
properly cared for.
post-shutdown fire.
COMBUSTION CHAMBER. Unlike the other
IGNITION SYSTEM. Your maintenance respon-
components, when a combustion chamber is damaged,
sibilities for your GTE's ignition system will be fairly
it must be replaced. This procedure is usually
common, especially concerning the igniters and
accomplished by a SIMA because your ship will likely
lack the required special tools and experienced
Igniters. The igniters on your GTE are cleanable.
personnel.
The frequency with which you should clean your
COMBUSTION LINER. On the Allison, Garrett,
igniters will be based on the hours of engine operation.
and Sunstrand GTEs, you will use a slightly different
Although the cleaning procedure is easy to accomplish,
procedure to determine the condition of the combustion
you must take extra care to make certain the ignition
liner.
system is completely de-energized.
