Asymmetric Flight

Question 1

22.28.2 Explain the consideration involved in coping with asymmetric thrust/drag and reduced power.

Answer 1

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.

Question 2

22.28.4 Explain the factors affecting yawing and rolling moments.

Answer 2

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).

Question 3

22.28.6 Define critical engine.

Answer 3

• Engine with the smallest moment arm.

Question 4

22.28.8 Recall immediate actions and techniques for identifying the failed engine.

Answer 4

• Prevent further yaw with rudder.
• Prevent unwanted roll with aileron.

Apply saying “lazy leg, lazy engine” to identify failed engine.

Question 5

22.28.8 Explain the three modes of constant-heading asymmetric flight.

Answer 5

-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.

Question 6

22.28.12 Define Vmca and Vmcg.

Answer 6

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.