TM 55-1510-215-10
The lower limit of 1725 to 1775 RPM is controlled by the
5-9A. Autopilot Limitations.
primary governor. The upper limit of 2332 RPM is
maintained by the power turbine governor (should the
a. During autopilot operation, one pilot must be
primary and overspeed governors fail). During reverse
seated at the controls with seat belt fastened.
pitch operation, the power turbine governor prevents
b. Autopilot and yaw damper must be disengaged
propeller speed from exceeding 2040 RPM. Refer to
during takeoff or landing.
c. The system is approved for
Category
1
5-9. Starter Limitations.
operation only (approach mode selected).
d. Do not operate autopilot with flaps extended
The starters in this aircraft are limited to an operating
beyond the approach position.
period of 40 seconds on, then 60 seconds OFF, for two
starter operations.
After two starter operations the
e. Maximum altitude for autopilot operation is
starter shall be operated for 40 seconds on, then 30
25,000 feet.
minutes OFF.
Section III. POWER LIMITS
of 850C is time-limited to two seconds duration when
5-10. Engine Limitations.
accelerating engine.
Operation of the T74-CP-700 engines is monitored
b. During engine starting the temperatures and
by instruments with the operating limits marked on the
time limits listed in the Engine Operating Limitations
face of the dial. Table 5-1 shows all operating conditions
Chart shall be observed (Table 5-1). When these limits
and limits for the engine.
are exceeded, the incident shall be entered as an engine
a. Engine operation using only the engine driven
discrepancy on DA Form 2408-13. It is particularly
primary (high pressure) fuel pump without auxiliary fuel
important to record the amount and duration of
pump or engine-driven boost pump fuel pressure is
overtemperature.
limited to 10 accumulative hours.
All time in this
c. Whenever the prescribed engine overspeed limit
category shall be entered on DA Form 2408-13 for the
or engine RPM operating limit is exceeded the incident
attention of maintenance personnel.
must be reported as an engine discrepancy on DA Form
b. Use of aviation gasoline is time-limited to 150
2408-13.
It is particularly important to record the
hours of operation during any Time-Between-Overhaul
maximum percent of RPM registered by the tachometer,
(TBO) period. It may be used in any quantity with
and the duration of overspeed.
primary or alternate fuel.
5-12. Power Definitions For Engine Operation.
NOTE
The following definitions describe the engine power
Aviation gasoline (AVGAS) contains
ratings listed in the Engine Operating Limitations Chart,
a form of lead which has an
accumulative adverse effect on gas
a. Takeoff Power. The maximum power available
turbine engines. The lowest octane
from an engine for takeoff, limited to periods of five
AVGAS available (less lead content)
minutes duration.
should be used. If any AVGAS is
used the total operating time must be
b. Maximum Power.
The maximum power
entered on DA Form 2408-13.
available from an engine for use during an emergency
operation.
5-11. Overtemperature and Overspeed Limitations.
c. Normal Rated Climb Power. The maximum
power available from an engine for continuous normal
a. Whenever the limiting temperatur es listed in the
climb operations.
Engine Operating Limitations Chart are exceeded and
cannot be controlled by retarding the power levers and
d. Normal Rated Power. The maximum power
the engine shall be shut down or a landing shall be
available from an engine for continuous operation in
made as soon as possible. It should be noted that
cruise (with lower ITT limit than normal rated climb
maximum observed interstage turbine temperature (ITT)
power).
Change 5 5-5
