What happened
On 1 June 2008, a Metro Batavia Airlines flight, operating as 7P-591, arrived at Polonia Airport in Medan from Jakarta. During the final approach, the flight crew observed a red indication for the left main landing gear and an amber ECAM warning. After performing a go-around and holding for approximately 45 minutes, the crew prepared for an emergency landing.
To address the landing gear indication, the crew attempted to cycle the gear and performed a manual extension. During this process, the aircraft touched down on runway 05. The landing was characterized by a heavy braking effect; the aircraft'-s brakes for three main wheels were effectively locked upon contact. The aircraft traveled approximately 1,200 meters down the runway before coming to a stop near taxiway D. While there were no injuries to the 140 people on board, the incident resulted in substantial damage to two main wheels and three tires.
The investigation
The investigation focused on the mechanical state of the landing gear and the crew's response to the abnormal indications. Investigators examined the aircraft's flight data recorder and cockpit voice recorder, as well as the physical wreckage of the landing gear components.
Technical analysis revealed that the left landing gear down-lock cable had broken. Furthermore, the investigation scrutinized the manual landing gear extension procedure performed by the crew. It was determined that the crew's method of cranking the manual extension handle while the gear lever was in the down position caused a hydraulic lock. This action closed the return line to the reservoir, trapping high-pressure fluid in the system. Consequently, the brake pressure reached 4,032 psi, far exceeding the maximum of 1,000 psi specified in the Quick Reference Handbook (QRH).
Findings
- The primary cause of the locked brakes was a hydraulic lock created by the crew's incorrect manual landing gear extension procedure.
- The left landing gear down-lock cable was broken prior to the landing.
- The flight crew lacked sufficient technical knowledge regarding the Airbus A320 landing gear systems and abnormal procedures.
- The crew failed to follow the specific instructions in the flight manual regarding the positioning of the manual extension handle after use.
- The pilots declined an ATC instruction to perform a go-around/flypast due to perceived fuel limitations, despite having sufficient fuel for the diversion to Batam.
- The crew relied too heavily on specific amber light indications rather than utilizing other available aircraft systems to verify gear position.
Safety action
Following the investigation, the NTSC issued recommendations to Batavia Air to review its flight crew training, specifically focusing on technical knowledge of aircraft systems and fuel management. Additionally, a recommendation was made to the Directorate General Civil Aviation to audit the airline's training program oversight.