What happened
On 8 March 2012, a BAE Systems Jetstream 31, registration G-CCPW, was performing a commercial passenger flight from Leeds Bradford International Airport to Isle of Man Airport. During the landing on Runway 26, the aircraft experienced a sudden rightward lean and an unusual noise immediately upon touchdown. As the aircraft's speed decreased, the lean intensified, and the crew realized the right landing gear was malfunctioning.
To prevent the aircraft from leaving the paved surface, the crew applied left aileron and rudder inputs. However, the right main landing gear detached from its trunnions, causing the aircraft to veer right and slide sideways. The aircraft eventually came to a stop on the grass adjacent to the runway, positioned 9 and 0 degrees to the runway heading. During the excursion, the right engine propeller blades struck the runway surface, and the right wingtip and luggage pannier sustained damage. All 12 passengers and 2 crew members evacuated the aircraft without injury.
The investigation
The AAIB investigation examined flight data from the Digital Flight Data Recorder (DFDR) and Terrain Avoidance Warning System (TAWS), as well as audio from the Cockpit Voice Recorder (CVR). The data confirmed that the descent rate at touchdown was 7.7 ft/sec, which was well within the design limits for the aircraft's landing weight. The CVR captured the loud mechanical noise of the propeller blades striking the runway.
Metallurgical analysis focused on the failed right main landing gear yoke pintle. Investigators found a crack measuring approximately 120 mm. Scanning Electron Microscopy revealed that the initial 10 mm of the crack exhibited inter-granular failure, a hallmark of stress corrosion cracking (SCC). The presence of corrosion and cadmium leaching from the steel spigot suggested the crack had been developing for some time.
Findings
- The right main landing gear failed because the forward yoke pintle fractured.
- The failure was initiated by stress corrosion cracking at the top outer edge of the forward yoke pintle.
- The crack grew to a length of 120 mm before the remaining material suffered a ductile overload.
- The landing forces during touchdown were within the aircraft's design specifications, meaning the landing itself was not a heavy landing.
- The crack may have been present during the most recent visual inspection, which had been conducted 11 days prior to the accident.
Safety action
- It is recommended that the European Aviation Safety Agency review the effectiveness of Airworthiness Directive G-003-01-86 in detecting cracks within the yoke pintle housing on Jetstream 31 landing gears.