Engine Operating Limitations -- Continued
An engine oil temperature of 74°C to 80°C is recommended.
Oil temperature limits are -40°C to 105°C. However, temperatures of up to 110°C are permitted for a
maximum time of 10 minutes.
These values are time limited to 5 seconds.
High TGT at ground idle may be corrected by reducing accessory load and/or increasing N 1 RPM.
At approximately 72% N 1 .
Cruise torque values shall be set per Chapter 7. Operating engines during cruise at higher torque values
than those listed in chapter 7 will reduce engine life.
These values are time limited to 20 seconds.
Torque limited to 94% when operating at 1500 RPM (N2). Torque limited to 83% when operating at
1700 RPM (N2).
Oil Pressures below 90 PSI are undesirable. Under emergency conditions, a lower oil pressure limit of
60-PSI is permissible at reduced power, not to exceed 54% torque.
Avoid selecting LOW IDLE during NORMAL operations, excluding ENGINE START/SHUT-
DOWN/FEATHER procedures. LOW IDLE position may produce a PROP RPM below 1000 and shall be
avoided to the maximum extent possible.
Use of aviation gasoline is time-limited to 150 hours of operation during any Time-Between-Overhaul
(TBO) period. It may be used in any quantity with primary or alternate fuel.
5-14. OVER TEMPERATURE AND OVERSPEED LIMITATIONS.
a. Whenever limiting temperatures, listed in the Engine Operating Limitations chart (Table 5-1), are exceeded,
and cannot be controlled by retarding the power levers, the engine will be shut down and a landing made as soon
b. During engine starting the temperatures and time limits listed in the Engine Operating Limitations chart (Table
5-1) must be observed. When these limits are exceeded, the incident will be entered as an engine discrepancy in
the appropriate maintenance forms. It is particularly important to record the value and duration of over temperature.
c. Whenever the prescribed engine overspeed limit or engine RPM operating limit is exceeded, the incident
must be reported as an engine discrepancy in the appropriate maintenance forms. It is particularly important to
record the maximum percent of RPM registered by the tachometer, and the duration of overspeed.
d. Continued engine operation above 810° C will reduce engine life.
5-15. POWER DEFINITIONS FOR ENGINE OPERATIONS.
The following deinitions describe the engine power ratings.