History of the Flight
On 16 November 2005, a Jetstream 3202, registration G-BYRA, was on approach to Inverness Airport, Scotland, when the flight crew noticed the left wheel brake pressure gauge indicating full scale deflection, 2,000 psi. Concerned that the left wheel brake might be locked on, the crew performed a go-around. They closed the hydraulic Low Pressure cocks to reduce system pressure, but the gauge continued to read 2,000 psi. The circuit breaker for the indicator was pulled and reset, with no effect. Hydraulic power was restored, and the crew briefed the cabin crew on the possibility of landing with the left brake locked.
During preparations for landing, a passenger reported purple fluid leaking from the left wing. The crew selected landing gear DOWN and flaps to FULL, after which hydraulic system pressure dropped to zero and the hydraulic pumps cavitated. After confirming the landing gear was down and locked, the crew instructed passengers to assume the brace position. The aircraft touched down gently and, despite the lack of nose wheel steering, tracked the runway heading and was brought to a halt using propeller reverse pitch and the parking brake. After shutdown, the fire service reported fluid leaking from the left engine; all occupants were evacuated through the left passenger door without injury.
Hydraulic System Description
The Jetstream 3202 hydraulic system has two modes of supply: NORMAL and EMERGENCY, both supplied from a common reservoir fitted with a divider plate. The NORMAL system is pressurised by two engine-driven pumps and operates all hydraulic services. The EMERGENCY system allows hydraulic operation of the landing gear and flaps via a hand pump adjacent to the pilots' seats.
Examination and Findings
An inspection by the operator's maintenance organisation revealed that the left wheel brake pressure gauge had failed at full scale deflection and was replaced. The loss of hydraulic fluid was attributed to the failure of the pressure delivery pipe union attaching the pipe to the left hydraulic pump. A detailed inspection of the failed pipe and union was not possible, as they had been discarded during rectification. It was not established whether the failure of the indicator was connected with the subsequent failure of the pipe union. The aircraft's records confirmed no recent maintenance activity on this system and no defects observed during routine inspections of the relevant area.