TM 55-1520-240-23-3
4-2
PERFORM HEALTH INDICATOR TEST (HIT)
4-2
INITIAL SETUP
Applicable Configurations:
Without 74
Tools:
Stopwatch
Materials:
None
Personnel Required:
Inspector
Army Rotary-Wing Aviator (2)
References:
TM 1-1520-240-MTF
TM 55-1520-240-T
Equipment Condition:
Battery Connected (Task 1-39)
HIT Baseline PTIT Established (Worksheet)(Task
4-2.1)
NOTE
A new baseline Health Indicator Test
(HIT) is required following replacement
of a major engine component that
affects airflow/performance (such as a
hot end).
1.
Face aircraft into wind and operate engines until
PTIT and oil temperature have stabilized.
2.
Record free air temperature (FAT).
3.
Set NO. 2 ENGINE CONDITION lever to
GROUND.
NOTE
N2, rotor RPM may be lowered in
cold temperatures to achieve an N1
relative to FAT. Under no conditions
may N2 rotor RPM be lowered below
88 percent.
4.
Maintain 100 percent rotor rpm.
5.
Read temperature in FAT C which is closest to
FAT recorded in step 2 (HIT PTIT LOG).
6.
Set N1 percent to number in N1 percent column
next to FAT found in step 6.
7.
Read temperature in BASELINE PTIT column
next to N1 percent found in step 7.
8.
Allow indicated PTIT to stabilize.
9.
Record indicated PTIT and compare with
BASELINE PTIT found in step 8.
10.
Record aircraft hours in ACFT row and difference
between indicated PTIT and BASELINE PTIT
found in step 10 in difference from BASELINE
PTIT row.
4-12
Change 1
