TM 55-1520-240-23-3
4-2.3
ESTABLISH IN-FLIGHT (HIT) BASELINE
4-2.3
INITIAL SETUP
Applicable Configurations:
Without 74
Tools:
None
Materials:
None
Personnel Required:
Army Rotary Wing Aviator (2)
Army Aircrew Member
References:
TM 55-1520-240-MTF
TM 55-1520-240-T
Equipment Condition:
None
NOTE
The In-flight (HIT) check may be used
on the return flight of the last flight
of the day. This will count for the
next days (HIT) check. If any engine
maintenance has been performed
since the last return flight, a ground
(HIT) check must be performed prior
to flight. If an in-flight (HIT) was not
completed on the previous flight, a
ground or in-flight (HIT) check must
be performed. This in-flight (HIT)
check may be deferred to the last
flight of the day.
1.
With aircraft in cruise flight at 110-120 knots,
record free air temperature (FAT).
2.
Maintain 100 percent rotor RPM.
3.
Enter line 1 at FAT nearest free air temperature.
4.
Use the emergency beep to set N1 percent to
value indicated in line 2 on engine being (HTIT).
5.
Allow indicated PTIT to stabilize for a minimum
of 30 seconds.
6.
Read PTIT from indicator.
7.
Apply — PTIT A correction factor in line 3 to
indicated PTIT and record result in open space
in line 4.
8.
Apply — PTIT B correction factors in line 5 to
PTIT in line 4 and record result in line 8 for
corresponding columns.
9.
Enter baseline information in the respective
columns of the (HIT) PTIT log (Task 4-2.2).
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