What happened
On 28 April 2001, a Piper PA-28-180, registration G-AVNP, was conducting a private flight from Wickenby Airfield to Southend Airport. While cruising at 1,500 feet near the Stansted Control Area, the engine experienced a sudden loss of power. Despite the crew's attempts to restore power using the throttle and carburettor heat, the engine failed to recover, necessitating an emergency descent.
The crew identified Nayland Airfield in Essex as a suitable landing site. During the final approach to Runway 32, the aircraft struck a large tree. The impact caused the right wing to detach from the fuselage. The aircraft subsequently struck the ground in a nose-down attitude and rolled onto its right side. The two occupants, both experienced pilots, sustained injuries, with one pilot suffering serious injuries to the hip and leg, while the other sustained minor injuries. A passer-by assisted in extracting the occupants from the wreckage.
The investigation
The AAIB examined the wreckage and the engine components. While investigators found significant wear on the engine's valve operating mechanism, they determined this was a common condition and not the cause of the power loss. The investigation also reviewed the fuel state; although the right tank was ruptured, calculations suggested the aircraft had sufficient fuel remaining to complete the flight.
Meteorological data indicated that the ambient temperature and humidity at the time of the accident fell within the parameters known to promote severe induction system icing in float carburettors. No mechanical or electrical failures were identified as the primary cause of the engine's failure.
Findings
- The engine suffered a sudden loss of power due to induction system icing.
- The aircraft's right wing detached upon impact with a tree during the forced landing.
- The aircraft's right fuel tank was ruptured during the collision.
- The crew followed established procedures, but the icing occurred despite the use of carburettor heat.
Safety action
- A recommendation was made to the CAA to implement both technological and procedural measures to reduce the frequency of accidents involving UK-registered piston-engined aircraft caused by induction system icing.