Yep, SHP could refer to the power turbine out put shaft of a helicopter or any turbine engine, or crankshaft of a recipricating engine. I guess you could use it to measure anything that produced torque. As far as I know the only difference in BHP and SHP is where it is measured. SHP is at the source, BHP is at the wheels. By the way I like your reference to helicopters. I'm an Instructor Pilot for the CH47D Chinook in the Army. My website has some pictures from Desert Storm, if you want to see some serious SHP (7500 SHP).