Propeller pitch control failure leads to forced landing of Piston Provost

Casualties unknown • Shoreham Airfield, West Sussex, GB

A Hunting Percival P56 T Provost Mk 51 experienced a sudden loss of propeller pitch control during a test flight, resulting in a heavy landing and gear collapse at Shoreham Airfield.

What happened

On 16 September 2010, a Hunting Percival P56 T Provost Mk 51, registration G-BLIW, departed from the grass runway at Shoreham Airfield for a test flight following a rebuild. The aircraft, powered by an Alvis Leonides 126 radial engine, was being prepared for its initial flight after maintenance work by its owner.

During a left-hand climbing turn at 2,300 feet, the pilot attempted to adjust the engine RPM by moving the propeller lever. This action triggered a sudden drop in RPM and intense vibrations. Subsequent attempts to increase power failed to significantly improve thrust or stabilize the engine, as the vibration intensified whenever power was increased.

Recognizing the emergency, the pilot declared a PAN-PAN urgency call and initiated a descent to the south of the airfield to attempt a landing on Runway 25. While on final approach at 90 knots, the aircraft's airspeed began to decay. Realizing an overshoot of the runway was imminent, the pilot executed a turn to avoid a raised bank at the runway end, aiming for a field within the airfield boundary. During this maneuver, the right wing dropped, leading to a heavy touchdown that caused the main landing gear to collapse. The aircraft came to rest approximately 250 meters southwest of the Runway 07 threshold. There were no injuries to the pilot.

The investigation

The investigation focused on the mechanical failure of the propeller pitch mechanism. Post-landing inspections revealed that the propeller was in the full coarse position, despite the pilot having set the lever to full fine pitch. The investigation established that the loss of propeller pitch control was the primary factor in the aircraft's inability to maintain sufficient airspeed for a controlled landing.

Findings

  • The propeller failed to respond to lever inputs, remaining in a coarse pitch setting.
  • The lack of a headwind and the reduced drag typically provided by a fine pitch setting contributed to the decaying airspeed.
  • The aircraft sustained significant damage to the wings, landing gear, tailwheel, cowlings, air box, oil cooler, and propeller.

Probable cause

The primary cause of the accident was the failure of the propeller pitch control mechanism, which left the propeller in a coarse pitch position, preventing the pilot from maintaining adequate airspeed during the approach.

Frequently asked questions

What happened in the 2010-09-16 Hunting Percival P56 T Provost Mk 51 accident near Shoreham Airfield, West Sussex, GB?

A Hunting Percival P56 T Provost Mk 51 experienced a sudden loss of propeller pitch control during a test flight, resulting in a heavy landing and gear collapse at Shoreham Airfield.

What aircraft was involved and where did it happen?

The accident on 2010-09-16 involved a Hunting Percival P56 T Provost Mk 51, registration G-BLIW, at Shoreham Airfield, West Sussex, GB.

What was the probable cause of the accident?

The primary cause of the accident was the failure of the propeller pitch control mechanism, which left the propeller in a coarse pitch position, preventing the pilot from maintaining adequate airspeed during the approach.

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