Asymmetric Thrust Mechanics

081-08-02Pablo Asensio Martínez2026-04-011 min

The Moments

When an engine fails, Thrust is lost on one side.

  1. Yaw Moment: Towards the dead engine. ($Thrust \times Arm$).
  2. Roll Moment: Towards the dead engine. (Loss of induced flow over the wing + fuselage masking).

Establishing Control (Vmca)

To maintain heading, the rudder must generate a side force to create an opposing Yaw Moment.

  • Rudder Effectiveness: Proportional to $V^2$. At low speeds, rudder authority decreases.
  • Vmca: The speed below which full rudder is insufficient.

Importance of Bank

Banking usually 5° towards the Live Engine assists the rudder.

  • It creates a side component of Lift that helps oppose the turn.
  • Significantly lowers $V_{MCA}$ (makes the plane safer/controllable at lower speeds) compared to wings-level.
  • Zero Sideslip: Requires a small bank towards the live engine.
Written and reviewed by

Pablo Asensio · 2026-04-01

Aeronautical engineer. Passed the thirteen EASA ATPL(A) theoretical knowledge exams studying from these very notes. Writes and reviews each topic against the Part-FCL Learning Objectives.

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