TM 55-1520-240-23-3
4-2.2
PERFORM IN-FLIGHT HEALTH INDICATOR TEST (HIT)
4-2.2
INITIAL SETUP
Applicable Configurations:
Without 74
Tools:
Stopwatch
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:
In-Flight HIT Baseline PTIT Established
(Worksheet) (Task 4-2.3)
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.
Read temperature in FAT C, which is closest to
FAT recorded in step 1.
4.
Use the emergency beep to set N1 percent to
number in N1 percent column next to FAT found
in step 3 on engine being HIT checked while
leaving the other engine online.
5.
Read temperature in in-flight baseline PTIT
column next to N1 percent found in step 4.
6.
Allow indicated PTIT to stablize for a minimum of
30 seconds.
7.
Record indicated PTIT and compare with in-flight
baseline PTIT found in step 5.
8.
Record aircraft hours in aircraft row and
difference between indicated PTIT and in-flight
baseline PTIT found in step 7 in difference from
in-flight baseline PTIT row.
9.
If indicated PTIT is 20-29ºC less than or greater
than in-flight baseline PTIT, make an entry on
DA Form 2408-13
10.
If indicated PTIT is 30ºC or more less than
or greater than in-flight baseline PTIT, do the
following:
a.
Make an entry on DA Form 2408-13.
b.
Upon return to base, ground aircraft until
operational check of PTIT and emergency
power indicating system is performed (TM
55-1520-240-23-T)
11.
Repeat steps 4 thru 10 for number 2 engine.
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