Approved Torque
Aerobat77. The original quesion asked was about the relationship between engine torque and propeller torque. As I am sure you know, the T56 is a constant RPM engine/gearbox/propeller combination. The only indication of engine power available to the crew is torque. For a given atmospheric condition and a given Turbine Inlet Temperature the engine should provide a predetermined torque figure. This can be varied by two things, closing the engine bleed air valves and ram rise as the aircraft accelerates down the runway and becomes airborne. Certainly, in a "hot/high" environment less engine power for a given TIT will be available, thus a lower torque reading results. Conversely, the torque limitation can be reached at a lesser TIT in cold climes. As for all the other theory stated by other posters on this thread, it does not mean anything to the operating crew. The ONLY measure of power available is Torque!!! The T56A-11 was rated at 3750 Equivalent Shaft Horsepower (Shaft Horsepower + jet thrust) The T56A-7 is rated at around 4200 ESHP and the T56A-15 is rated at 4910. It was uncommon in either the C130A (T56A-11) or the C130E (T56A-7) to reach the 19600in/lb limit before reaching the limiting TIT on anything above an ISA day. The C130H (T56A-15) was much more likely to achieve 19600 in/lbs before reaching the limiting TIT, which was higher than on the other engines due to improved turbine design and materials.