TM 1-1520-238-10
5-8
Change 9
Section III.
POWER LIMITS
5.6 ENGINE START AND STARTER LIMITATIONS.
The pneumatic starter is capable of making the number of
consecutive start cycles listed below, when exposed to the
environmental conditions specified, with an interval of at
least 60 seconds between the completion of one cycle
and the beginning of the next cycle. A starting cycle is the
interval from start initiation and acceleration of the output
drive shaft, from zero rpm, to starter dropout. The 60-sec-
ond delay between start attempts applies when the first at-
tempt is aborted for any reason and it applies regardless
of the duration of the first attempt. If motoring is required
for an emergency, the 60-second delay does not apply.
a. Refer to Figure 5–1 for limitations.
b. At ambient temperatures of 16 C (61 F) and be-
low, two consecutive start cycles may be made, followed
by a 3-minute rest period, followed by two additional con-
secutive start cycles. A 30-minute rest period is then re-
quired before any additional start cycles.
c. At temperatures above 16 C (61 F), two consecu-
tive start cycles may be made. A 30-minute rest period is
then required before any additional start cycles.
d. Dual engine starts are prohibited.
5.7 ENGINE OVERSPEED CHECK LIMITATIONS.
Engine overspeed check in flight is prohibited. Only main-
tenance test flight pilots are authorized to perform an
overspeed check.
5.8 APU OPERATIONAL LIMITS.
CAUTION
Avoid prolonged operation at 94% – 96%
Nr with the APU running. The APU clutch
will oscillate from engaged to disen-
gaged. This creates high loads on the
clutch and shall be avoided.
a. APU operation is prohibited during normal flight.
After a fault or aborted start, wait 30 seconds after the
compressor has stopped before attempting another start.
After two consecutive start attempts, wait 20 minutes be-
fore third start is attempted. No more than three start at-
tempts are permitted in one hour.
CAUTION
Do not operate the APU for more than
five minutes when the main transmission
oil temperature is between 120 C and
130 C (248 F – 266 F). Shut down the
APU to prevent damaging accessory
gearbox components.
b. During prolonged ground operations greater than
30 minutes the on-command test 19–TRAN shall be peri-
odically executed and the XMSN 1 and XMSN 2 tempera-
tures observed. If the temperature exceeds 130 C (266
F), the APU shall be secured and the transmission fluid
allowed to cool for 30 minutes prior to resuming APU
ground operations; or transmission fluid may be cooled by
operating an engine with rotor turning. There is no re-
quirement to remove transmission side panels during ex-
tended APU ground operations. However, the transmis-
sion fluid will not get as hot under high ambient
temperature conditions if the side panels are removed.
