FLYING QUALITIES OF PILOTED AIRCRAFT - CAFE Foundation

MIL–STD–1797AAPPENDIX A4.6.5 Yaw axis response to other inputs4.6.5.1 Yaw axis response to asymmetric thrust. Asymmetric loss of thrust may be caused by manyfactors including engine failure, inlet unstart, propeller failure or propeller–drive failure. The requirementsapply for the appropriate Flight Phases when any single failure or malperformance of the propulsive system,including inlet, exhaust, engines, propellers, or drives causes loss of thrust on one or more engines orpropellers, considering also the effect of the failure or malperformance on all subsystems powered or drivenby the failed propulsive system. It shall be possible for the pilot to maintain directional control of the aircraftfollowing a loss of thrust from the most critical propulsive source, allowing a realistic time delay of _____seconds, as follows:Takeoff run:Airborne:Waveoff/go–around:Crosswinds:General:During the takeoff run it shall be possible to maintain a straight path on the takeoffsurface without deviations of more than _____ ft. from the path originally intended,following sudden asymmetric loss of thrust. For the continued takeoff, therequirement shall be met when thrust is lost at speeds from the refusal speed (basedon the shortest runway from which the aircraft is designed to operate) to themaximum takeoff speed, with takeoff thrust maintained on the operative engine(s);without depending upon release of the pitch, roll, yaw or throttle controls; and usingonly controls not dependent upon friction against the takeoff surface. For the abortedtakeoff, the requirement shall be met at all speeds below the maximum takeoffspeed; however, additional controls such as nose wheel steering and differentialbraking may be used. Automatic devices that normally operate in the event of athrust failure may be used in either caseAfter lift–off it shall be possible without a change in selected configuration to achievestraight flight following the critical sudden asymmetric loss of thrust at speeds fromVmin (TO) to Vmax(TO), and thereafter to maintain straight flight throughout theclimb–out and to perform 20–degree–banked turns with and against the inoperativepropulsive unit. Automatic devices that normally operate in the event of a thrustfailure may be used, and for straight flight the aircraft may be banked up to 5 degreesaway from the inoperative engineAt any airspeed down to Vmin (L) it shall be possible to achieve and maintain steady,straight flight with waveoff (go–around) thrust on the remaining engines followingsudden asymmetric loss of thrust from the most critical factor. Configurationchanges within the capability of the crew while retaining control of the aircraft, andautomatic devices that normally operate in the event of a propulsion failure, may beusedThe aircraft response requirements for asymmetric thrust in takeoff and landingapply in the crosswinds of 4.6.4 from the adverse directionThe static directional stability shall be such that at all speeds above ____________,with the critical asymmetric loss of thrust while the other engine(s) develop(s) normalrated thrust, the aircraft with yaw control pedals free may be balanced directionally insteady straight flight. The trim settings shall be those required for wings–levelstraight flight prior to the failure.REQUIREMENT RATIONALE (4.6.5.1)The transient and steady–state effects of asymmetric thrust must be limited to amounts which can becompensated by pilot control action.574