TM 1-1510-225-10 5-12 Table 5-1.  Engine Operating Limitations  R GAS GENERATOR RPM N₁ OPERATING CONDITION SHP TORQUE % (1) MAXIMUM OBSERVED ITT ºC RPM % PROP RPM N₂ OIL PRESS PSI (2) OIL TEMP º C (3)  (4) STARTING – – – – – – 1000 (5) – – – – – – – – – – – – -40 (min) LOW IDLE – – – – – – 750  (6) 22,875 61(min)   1180 60 (min) -40 to 99 HIGH IDLE – – – – – – – – – – – – (7) – – – – – – -40 to 99 TAKEOFF and MAX CONT 850 100 800 38,100 101.5 2000 100 to 135 0 to 99 MAX CRUISE 850 100 (8) 800 38,100 101.5 2000 100 to 135 0 to 99 CRUISE CLIMB and REC (NORMAL) CRUISE 850 100 (8) 770 38,100 101.5 2000 100 to 135 0 to 99 MAX REVERSE  (9) 800 – – – 750 – – – 88 1900 100 to 135 0 to 99 TRANSIENT – – – 123 (5) 850 38,500   (10) 102.6   (10) 2200 (5) 200 0 to 104   (11) TABLE NOTES: (1)   Torque limit applies within range of 1600  - 2000 propeller RPM (N₂).  Below 1600 propeller RPM, torque is limited to 49%. (2)   When  gas  generator  speeds  are  above  27,000  RPM  (72%  N₁)  and  oil  temperatures  are  between  60 °C and 71°C, normal oil pressures are: 100 to 135 psi below 21,000 feet; and 85 to 135 psi at 21,000 feet and above. During  extremely  cold  starts,  oil  pressure  may  reach  200  psi.    Oil  pressure  between  60  and  85  psi  is undesirable.  It should be tolerated only for the completion of the flight, and then only at a reduced power setting not exceeding 49% torque.  Oil pressure below 60 psi is unsafe.  It requires that either the engine be shut down, or that a landing be made at the nearest suitable airport, using the minimum power required to sustain flight.  Fluctuations of ± 10 psi are acceptable. (3)   A minimum oil temperature of 55 °C is recommended for fuel heater operation at takeoff power. (4)   Oil temperature limits are  -40 °C and 99 °C.  However, temperatures of up to 104 °C are permitted for a maximum time of 10 minutes. (5)   These values are time limited to 5 seconds. (6)   High ITT at ground idle may be corrected by reducing accessory load or increasing N₁ RPM. (7)   At approximately 70% N₁. (8)   Cruise torque values vary with altitude and temperature. (9)   This operation is time limited to  1 minute. (10)   These values are time limited to 10 seconds. (11)   Values above 99 °C are time limited to 5 minutes.