Synopsis
On 25 February 2019, at 1250 UTC, a Boeing 737-800, registration 9M-MXH, operated by Malaysia Airline Berhad, was performing a scheduled flight from Jakarta (CGK) to Kuala Lumpur (KUL) with 120 passengers and 7 crew members. The aircraft declared an emergency due to a suspected fuel leak in main tank No. 1 and diverted to Sultan Thaha Syaifuddin Airport (WIJJ) in Jambi, Indonesia, landing at 1450. No injuries or aircraft damage were reported.
History of the Flight
At 1308, the aircraft departed Jakarta. While cruising at flight level 380 at 1401, the flight crew conducted a fuel check and noted a fuel imbalance of approximately 20 kgs. The fuel pump for main tank No. 1 was selected off, but the fuel quantity in that tank decreased at a faster rate than in main tank No. 2. The fuel imbalance alert triggered at 1404. The captain assumed control as pilot flying, and the second officer became pilot monitoring. The crew consulted the non-normal checklist for fuel imbalance, which directed them to the fuel leak engine checklist. Although step 6 (checking a 230 kg change in 30 minutes) was not performed, the crew determined a fuel leak existed based on the abnormal fuel decrease rate, the imbalance alert, and the subsequent fuel low alert.
Initially, the crew requested a diversion to Singapore (SIN) and received clearance. However, at 1416, the fuel low alert activated for main tank No. 1. The captain asked air traffic control for the nearest airport and was informed Jambi (DJB) was closest. The crew declared an emergency and diverted to DJB. Approach charts for DJB were unavailable, so the crew obtained necessary information from air traffic control and another aircraft. The aircraft performed one left orbit to intercept the ILS runway 31 and landed safely at 1450, taxiing to bay 6.
Aftermath
After landing, the fuel quantity in main tank No. 1 indicated 630 kgs, but increased to 2380 kgs after engine shutdown. Engineers from Garuda Maintenance Facility (GMF) AeroAsia found no physical signs of a fuel leak. They conducted a fuel quantity system test, which showed no anomalies, and found no water contamination. A magna stick check after refueling showed no discrepancy with the fuel quantity indicator. The aircraft was cleared for departure and flew to Kuala Lumpur at 1858, arriving at 2021 without any abnormal indications.
Findings and Causes
The investigation identified that the flight crew did not refer to the fuel quantity indication on the flight deck to confirm the fuel leak after landing. The fuel quantity indication was unreliable and increased after engine shutdown, leading to a false confirmation of a fuel leak. The crew's decision to divert was based on the fuel imbalance and abnormal decrease rate, but the actual cause was an unreliable fuel quantity indication.
Safety Recommendations
The report includes safety recommendations related to the incident, but specific details are not covered in this summary.