HEADQUARTERS OH-58A, Technical Manual

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TM 55-1520-228-10
Change 1
4
5-7
SECTION III. POWER LIMITS
5-11. ENGINE LIMITATIONS.
Refer to Figure 5-1
A
, Figure 5-2. If N2 limit is exceed-
ed, entry on DA Form 2408-13-1 must include duration
and torque indicated.
5-12. FUEL OPERATION LIMITS.
a. JP-4. No restrictions are imposed when JP-4 fuel
is used.
b. JP-5, JP-8, Jet A and Jet A-1. Operations with
these fuels are restricted to ambient temperatures of
-32
_
C (-25
_
F) and above. If fuel other than JP-4 is
used, a deceleration check must be performed prior to
first flight of the day. If autorotations are to be performed,
a deceleration check will be done prior to each flight.
Refer to paragraph 8-18.
NOTE
Engine starting difficulties may be en-
countered if any fuel other than JP-4 is
used at ambient temperatures below
+5
_
C (+39
_
F).
c. Emergency Fuel Aviation Gasoline
(MIL-G-
5572) without Tricreasyl Phosphate (TCP).
(1) The helicopter shall not be flown when
emergency fuel has been used for a total accumulated
time of 6 hours. Entry in remarks section of DA Form
2408-13-1 is required for each time emergency fuel is
used.
(2) Practice autorotation is prohibited using
emergency fuel.
5-13. DELETED.
5-14. ENGINE STARTING LIMITATIONS.
During starting if N1 does not reach 58 percent in a total
time of 45 seconds (or 60 seconds below 10
_
C FAT),
close throttle and press starter switch until TOT is below
200
_
C. If engine fails to start on third attempt, abort start
and make an entry on DA Form 2408-13-1.
5-15. HEALTH INDICATOR TEST (HIT).
HIT is the method by which the aviator in day-to-day
flying monitors aircraft engine condition. This is accom-
plished by the aviator selecting N1 speed (%) predicted
upon the existing FAT. The TOT must then be compared
to predicted value (Baseline TOT) within a certain toler-
ance. TOT variation from baseline values are logged by
the aviator. This log is part of aircraft records and is an
aid
to
maintenance personnel in monitoring performance
trends and troubleshooting the engine. When the differ-
ent between recorded and baseline TOT is
$
20
_
C or
greater, an entry on DA Form 2408-13-1 will be made to
notify maintenance. Limits for grounding are
$
40
_
C.
5-16. HOVERING LIMITATIONS.
Refer to paragraph 5-24.