What happened
On 16 November 2005, a Jetstream 3202, registration G-BYRA, was performing a passenger flight approaching Inverness Airport, Scotland. During the approach checklist, the flight crew identified an anomaly with the left wheel brake pressure gauge, which was stuck at a reading of 2,000 psi. Fearing that the left wheel brake might be stuck in the 'on' position, the crew executed a go-around to address the potential issue before attempting to land.
During the subsequent flight phase, a passenger noticed purple fluid leaking from the left wing. The crew then observed that the hydraulic pressure indications had dropped to zero, and the hydraulic pumps began to cavitate. To manage the situation, the crew closed the hydraulic Low Pressure cocks. Following the landing gear and flap extension, the crew instructed passengers to assume the brace position. The aircraft touched down gently and managed to maintain its runway heading using propeller reverse pitch and the parking brake, despite the loss of nose wheel steering and main wheel braking systems. The aircraft came to a halt on the runway, and the occupants were evacuated through the left passenger door.
The investigation
Post-flight inspections by maintenance engineers revealed that the left wheel brake pressure gauge had indeed failed at full scale deflection and required replacement. The investigation established that the loss of hydraulic fluid was caused by the failure of a pressure delivery pipe union where it attaches to the left hydraulic pump. While the investigation could not determine if the gauge failure was linked to the pipe union failure, records showed no recent maintenance activity or previously noted defects in that specific area. The failed components were discarded during the repair process, preventing a more detailed analysis of the union failure.
Findings
- The primary cause of the hydraulic fluid loss was the failure of the pressure delivery pipe union connected to the left hydraulic pump.
- The flight crew's decision to go around was prompted by a faulty pressure gauge reading that suggested a potential brake lock.
- There were no injuries to the three crew members or four passengers on board.