TURBOPROP AIRPLANE CONTROL PROBLEMS ASSOCIATED WITH ENGINE FAILURE CONSIDERATIONS 550193
The turboprop has lagged the turbojet engine by a considerable amount in development timing. The reasons for this include the additive time required to develop satisfactory gear boxes, propellers, and control units. An important consideration in the application of control units to turboprop installations is the minimization of windmilling drag due to engine failure. The implications of this windmilling drag upon each particular airplane’s structural, performance, and control characteristics must be studied before the most desirable means for prevention can be selected. The use of autofeathering (or Emergency Negative Torque Control), decoupling, and low pitch stops can have, in turn, their own implications upon the airplane’s operating characteristics. Consequently, the engine-out integrity of turboprop airplanes depends upon the integration of the proper safety devices into each individual design.