Helicopter power plant control

An engine control system for a helicopter having plural gas-coupled turbine engines geared to a common lifting rotor system with collective pitch control, the engine control system comprising, in combination, means including a condition control for setting the power level of each engine;

• a fuel control for each engine including a condition servomotor and a collective pitch servomotor;
• means for additively coupling said condition servomotor and said collective pitch servomotors to produce a fuel supply level to each engine;
• means coupled to the condition control for transmitting a power level request electrical control signal decreasing with increasing power level request from the condition control to the condition servomotor;
• and means coupled to the collective pitch control for transmitting an electrical control signal decreasing with increasing collective pitch request from the collective pitch control to the collective pitch servomotor;
• the servomotors operating in such sense that fuel supply is increased in response to decreasing power level request signals calling for increased power and fuel supply is also increased in response to decreasing collective pitch signals indicative of increased collective pitch, with the result that a failure of transmission of either signal simulates a maximum power request with relation to that signal.

An engine control system for a helicopter having plural gas-coupled gas turbine engines geared to a common lifting rotor system with collective pitch control, the engine control system comprising, in combination, means including a condition control for setting the power level of each engine;

• a fuel control for each engine including a condition servomotor and a collective pitch servomotor;
• means for additively coupling said condition servomotor and said collective pitch servomotors to produce a fuel supply level to each engine;
• means coupled to the condition control for transmitting a power level request electrical control signal decreasing with increasing power level request from the condition control to the condition servomotor;
• means coupled to the collective pitch control for transmitting an electrical control signal decreasing with increasing collective pitch request from the collective pitch control to the collective pitch servomotor;
• the servomotors operating in such sense that fuel supply is increased in response to decreasing power level request signals calling for increased power and fuel supply is also increased in response to decreasing collective pitch signals indicative of increased collective pitch, with the result that a failure of transmission of either signal simulates a maximum power request with relation to that signal;
• means responsive to speed of the rotor effective to vary the engine power level settings of all the engines;
• and means responsive to power output of several engines effective to adjust the power level settings to equalize the power outputs in normal operation.