Overspeed Condition (Aircraft Systems)

An overspeed condition occurs when an engine, propeller, or entire aircraft exceeds its maximum certified speed or allowable rotational limits. This can result in structural damage, aerodynamic instability, or total loss of control.

1. Engine Overspeed

Definition

Engine overspeed occurs when an engine rotates beyond its maximum certified speed.

Causes

• In jet aircraft, axial compressors may exceed allowable RPM.
• In propeller-driven aircraft, the propeller shaft RPM can exceed limits.
• Engines without proper regulation can overspeed when loaded improperly or not at all.

Consequences

• Potential engine failure or permanent damage.
• May lead to loss of control.

Overspeed Protection

• Aircraft often include governors and overspeed devices.
• Turbine systems monitor RPM and may shut down an engine if limits are exceeded.

2. Aircraft Overspeed

Definition

Aircraft overspeed occurs when the aircraft exceeds its maximum certified speed (Vne).

Causes

• Uncontrolled acceleration or descent.
• Sudden wind changes.
• Pilot error.

Consequences

• Structural damage.
• Loss of aerodynamic stability.
• Total loss of control.

Overspeed Warning Systems

• Aircraft have overspeed warnings to alert pilots when approaching or exceeding Vne.
• Systems include visual and audio cues.
• Some autopilot systems initiate corrective actions (e.g., pitch-up) during overspeed.

Recovery Procedures

• Pilots are trained in overspeed recovery techniques.
• Recovery may include:
  • Reducing power
  • Increasing pitch attitude
  • Deploying speed brakes
  • Extending landing gear