TM 1-1520-240-MTF
4-43
NOTE
The 20 degrees subtracted from the PTIT for initial
TEAC is not subtracted from subsequent TEACS.
(4) To determine the lower limit baseline
enter figure 5-9 at the prevailing FAT,
proceed vertically to a value 20_C less
than the measured PTIT. The lower limit
baseline is identified as the number of
degrees above the applicable reference
line 1, 2, 3 or 4 on figure 5-9. When the
engine lower limit baseline has been
determined, record the line number and
the number of degrees above the line in
the remarks section of the Historical
Record For Aircraft (Form 2408-15
TEAC overprint).
Example
During the TEAC, PTIT was recorded at 800_C, N1
speed was 103%, FAT was-14_C.
PTIT
=
800_C
Tolerance
=
-20_C
Engine Lower Limit Baseline
=
780_C
The engine lower limit is 5_C above line 3 at all ambi-
ents. Record lower limit in the Historical Record For
Aircraft as shown below.
NOTE
The purpose of the lower limit is to validate the
accuracy of the PTIT temperature measure-
ment system, as mentioned in the trouble-
shooting chart. A PTIT temperature below the
established lower limit, with all other indica-
tions correct, is an indication of temperature
system problems.
