What happened
On 15 December 2008, an Airbus A3/19-111, registration G-EZDM, departed from Charles de Gaulle Airport in Paris as a commercial passenger flight. Shortly after takeoff, the crew attempted to retract the landing gear, but the Electronic Centralised Aircraft Monitor (ECAM) indicated that the main landing gear doors had failed to close. While the crew worked to resolve this issue, the aircraft climbed to 1,500 feet, at which point new warnings appeared regarding low fluid levels in the Green hydraulic system and an overheat condition in the Yellow hydraulic system.
As the aircraft continued its climb, the Green hydraulic system experienced a significant loss of fluid. This loss of pressure triggered the Power Transfer Unit (PTU) to automatically engage, attempting to use pressure from the Yellow system to support the Green system. However, because the loss of pressure was due to fluid depletion, the PTU began to overheat. Following established procedures, the crew deactivated the Yellow system engine-driven pump and the PTU, effectively transitioning the aircraft to single-system hydraulic operation. The commander declared a MAYDAY, requested radar vectors, and briefed the cabin crew for a precautionary landing. Despite the low-visibility conditions at the airport, the aircraft completed a safe landing under Category IIIA instrument procedures and was met by fire services at the gate.
The investigation
Investigators examined the aircraft's hydraulic components and identified that a flexible hose for the left main landing gear door close actuator had ruptured. Additionally, the door open hose was found to be worn. Following the replacement of these hoses and a replenishment of the hydraulic fluid, the systems were tested and found to be serviceable. The investigation also revealed that the manufacturer was aware of similar scenarios where a single system failure could escalate into a dual-system issue, as documented in their previous safety communications.
Findings
- The primary cause of the hydraulic fluid loss was a ruptured flexible hose in the left main landing gear door close actuator.
- The secondary overheat condition in the Yellow system was caused by the activation of the Power Transfer Unit (PTU) in the presence of a fluid leak.
- The crew's decision to delay certain system checks until passing 1,500 feet was a deliberate measure to avoid distraction during the critical takeoff phase.