22.28.2 Explain the consideration involved in coping with asymmetric thrust/drag and reduced power.
Unless all of its engines share the same thrust line any multi-engine aircraft which has a failure of one of the engines will have an asymmetric flight problem.
- The line of thrust is offset from the normal axis creating a yawing moment towards failed engine.
- Line of total drag moves toward failed engine which adds to the yawing moment.
- The reduction in of total thrust available is reduced which means overall performance is poorer.
22.28.4 Explain the factors affecting yawing and rolling moments.
Yawing
- Thrust from live engine.
- Distance of the thrust line from the CofG.
- Directional stability.
- Rate of thrust decay.
- Drag of failed engine.
Rolling
- Further effect of yaw.
- Loss of slipstream over wing (loss of lift on side of failed engine).
22.28.6 Define critical engine.
- Engine with the smallest moment arm.
22.28.8 Recall immediate actions and techniques for identifying the failed engine.
- Prevent further yaw with rudder.
- Prevent unwanted roll with aileron.
Apply saying “lazy leg, lazy engine” to identify failed engine.
22.28.8 Explain the three modes of constant-heading asymmetric flight.
-All rudder
Rudder is used to prevent yaw from asymmetric thrust and wings held level.
- All bank
Aileron is used to prevent yaw from asymmetric thrust. Aircraft is banked and constantly side slipped toward live engine.
-Combination of rudder and bank
This is the more normal method of controlling the aircraft. Directing the aircraft in the direction of flight using rudder, and a small amount of bank toward live engine to balance out rudder side force.
22.28.12 Define Vmca and Vmcg.
Vcma – minimum control speed airborne – The minimum control speed following a sudden failure of the critical engine after take-off at which an average pilot will be able to maintain directional control with full rudder and no more than 5degrees bank angle applied. (1.13 x stall speed of same configuration, and is red line on ASI).
Vmcg – minimum control speed ground – The minimum control speed at which after failure of critical engine during take-off run it is possible to maintain directional control with rudder control alone. Speed assumes take off will be continued. It is not applicable to light twin aircraft.
