Figure 8-15. Simplex Fuel Nozzle
a. General Procedures. The following procedures
shall be adhered to during turbine engine maintenance.
(1) Mark location of all attaching support brackets,
clamps, and clips prior to removing lines, tubes, or
conduit to facilitate reassembly with a felt tip marker
Use ink conforming to Federal Specification TT-1-544.
(2) Use new O-rings, packing rings, cotter pins,
lockpins, gaskets, and washers.
(3) Apply lubricating grease, MIL-G-4343, on all O-
rings prior to installation.
(4) Apply thread compound, MIL-A-13881, to all
threaded parts attached to the hot section.
(5) When gears are replaced, examine for pattern
wear and backlash.
b. Health Indication Test. The Health Indication Test
(HIT) is the method by which the aviator In day-to-day
flying monitors the aircraft engine condition. This is
accomplished by the aviator selecting an N1 speed (%)
predicated upon the existing Free Air Temperature
(FAT). The interstate Turbine Temperature (ITT) must
then relate to a predicated value (Baseline ITT) within a
certain tolerance. ITT variation from baseline values
are logged by the aviator in accordance with the
applicable maintenance manual This log, part of the
engine records, is available to the maintenance officer
as an aid In monitoring performance trends and in
recorded ITT and the baseline ITT is 20 °C (68
greater the aviator will make an entry on DA Form 2408-
13 to notify the maintenance officer. A difference of
30C (86°F) or greater is cause for grounding the aircraft
until troubleshooting determines the cause of the
excessive ITT. New ITT baseline values for HIT should
be established after performing a baseline engine
performance check. A new engine performance check
should be made when an engine Is changed, when the
fuel control unit is adjusted or replaced, or when repairs
are made to the engine hot section.
c. Hot Start Inspection. A hot start occurs when
exhaust gas temperature exceeds normal starting
A hot start may be expected when a
greater-than-normal starting fuel flow
Is observed just as the power lever is
moved Into the IDLE position.
d. Turbine Engine Analysis Check (TEAC). A normal
Turbine Engine Analysis Check (TEAC) is performed for
comparison of normal TEAC data with baseline data.
degradation has occurred and to what degree. In
addition, TEAC data can be an aid in determining the
cause of the performance loss (Refer to TEAC
troubleshooting). A normal TEAC shall be performed
whenever installed engine performance degradation Is
suspected or as part of a general test flight (if
e. Foreign Object Damage Inspection. Most damage
incurred by the engine is the result of ingestion of
foreign objects Although screens are provided in the
lower aft cowling section and around the engine
compressor inlet case to prevent entry of larger objects,
sand and grit will enter and cause compressor damage.
The resultant damage will be in the form of nicks or
scratches on the compressor blades. Such a nick or
scratch can cause fatigue failure hours later, with
disastrous effects to the entire engine.
When maintenance is performed on
the engine, every effort shall be
made to retrieve any object (wire,
rivets, nuts, screws, etc.) dropped
through the compressor inlet screen
or into the cowling, even if engine
disassembly Is required. Damage to
the engine may otherwise result.