TM 1-1520-240-MTF
4-42
10. Repeat steps 5 thru 8 for the other engine.
11. Determine Engine Trim.
a. Enter figure 5-8 at the recorded FAT,
proceed vertically to the curves which define
the acceptable range of N1 values, then
horizontally to the topping N1 (percent
scale).
b. Establish the PTIT band of figure 5-9 as
follows:
Upper limit — the upper limit of
the PTIT band is the top most line
as marked on figure 5-9.
Lower limit — from the engine
lower limit baseline.
Establish Engine Baseline Lower Limit
(1) Engine that have previous acceptable
TEAC checks within the upper PTIT
band shall continue to have the band 1
lower limit.
(2) Certain engines have performance
improvements. These engines will be
N1 limited and shall be trimmed to the
acceptable N1 speed band limits. The
thermocouple assemblies shall have a
resistance check performed to assure
serviceability prior to initial TEAC
baseline. Subsequent TEAC checks do
not require resistance checks.
(3) The TEAC performed following Step 2
shall determine the engine lower limit
baseline. A tolerance of 20_C shall be
subtracted from the recorded PTIT.
