TM 1-1520-238-MTF
4-13
Change 5
16. If TGT margin is still out of limits, do not fly the
helicopter. Make appropriate entry in remarks
section of DA form 2408-13.
I. HIT BASELINE CHECK AND ENGINE
PERFORMANCE DATA CHECKS.
CAUTION
If icing conditions exist, do not keep anti-
icing off for longer than is necessary to
do HIT check.
1. Prior to completing maximum power check, a
new HIT baseline is established by the
maintenance test pilot and used if engine
performance is satisfactory on the maximum
power check. During initial HIT check, the
maintenance pilot compensates for the particular
engine characteristic and establishes the TGT
limits to be used in the operational HIT check.
The operational pilot will compare engine
performance to this baseline to check engine
performance.
2. Position helicopter into the wind to minimize hot
gas ingestion.
3. Set ENG INLET ANTI-ICE and HTR switches to
OFF. Set altimeter to 29.92 in. Hg.
4. Set both engines Np/Nr at 100%.
5. Retard engine PWR lever of engine not being
checked until a 0% torque at 92 – 98% Np is
reached.
6. Increase collective pitch to 60% torque and hold
it there for at least 30 seconds.
NOTE
If helicopter is equipped with two FAT gages
and the readings are different, the higher
reading must be used.
