Description

On 5 June 2001, a Fokker F27 Friendship took-off from Jersey Airport, Channel Islands for an empty positioning flight to Bournemouth with three crew members on board. Shortly after takeoff from Runway 27, an uncontained failure occurred to the left engine at an altitude of approximately 670 ft. This resulted in a sudden and complete loss of power from the left engine and a major fire external to the nacelle, but this was extinguished during the Engine Fire Drill as the fuel supply line was closed. The aircraft completed a left hand circuit and landed uneventfully back at the airport.

The Investigation

The investigation of the accident led by UK AAIB concluded that the engine failure was caused by high cycle fatigue (HCF) cracking of the High Pressure Turbine (HPT) disc. Five similar Dart HPT failures had occurred over the previous 29 years, the most recent at London Stansted Airport on 30 March 1998(G-OJEM). During the following necessarily protracted study, testing and analysis by the engine manufacturer, the evidence collected then indicated that a small gap, under running conditions, between the seal arm abutment faces of the HPT and Intermediate Pressure Turbine (IPT) discs could result in high cyclic stresses being present in the HPT seal arm radius at the disc diaphragm, and that these stresses could result in high cycle fatigue (HCF) cracking.