What happened
On December 16, 2023, a British Aerospace Jetstream 32, registration HK4548, was performing a scheduled passenger flight from Medellín to Quibdó, Colombia. During the approach to El Caraño Airport (SKUI), the crew attempted to extend the landing gear, which triggered a total loss of hydraulic pressure.
Faced with the hydraulic failure, the crew decided to perform an emergency landing at the destination rather than returning to Medellín. The crew executed emergency procedures to extend the flaps and landing gear. Upon landing on runway 13, the pilot applied the brakes and subsequently engaged the parking brake. However, the aircraft suffered a loss of directional control via the nose wheel steering and veered off the right side of the runway, coming to a stop in the safety area.
There were no injuries among the 17 occupants (two crew members and 15 passengers), and the aircraft sustained no damage.
The investigation
The investigation conducted by the GRIAA focused on the loss of hydraulic pressure and the subsequent failure of the braking system. Investigators examined the aircraft's maintenance records, which showed that the hydraulic lines were maintained on an "on-condition" basis rather than a fixed time limit.
Technical analysis of the hydraulic system revealed that a flexible hydraulic line in the left main landing gear mechanism had ruptured when the gear was extended. Furthermore, the investigation scrutinized the emergency hydraulic system, specifically why the pressure was insufficient to provide effective braking during the landing roll.
Findings
- The primary cause of the runway excursion was the rupture of a flexible hydraulic line in the left main landing gear mechanism, which led to a total loss of hydraulic pressure.
- The loss of pressure caused a failure of the primary braking system and the nose wheel steering.
- The emergency hydraulic system failed to provide adequate braking because the pressure in the accumulator was likely depleted (purged) when the crew cycled the normal brakes and the parking brake.
- The aircraft was operating under significant limitations, including the inability to use nose wheel steering, flaps beyond 20 degrees, or lift dump systems.