On 14th June 2022, Qatar Airways Flight QTR-6J, Boeing 777-3DZ(ER) bearing registration A7-BEA, was operating a scheduled passenger flight from Allama Iqbal International Airport (AIIAP), Lahore to Hamad International Airport (HIA), Doha with 197 persons on board. The aircraft was cruising at Flight Level 380 and following the route G214 PG G665 ASVIB within Karachi FIR, with ASVIB as the planned exit point. The aircraft checked ASVIB at 0614 UTC. While still in Pakistani airspace, the flight crew observed a progressive drop in oil pressure on Engine No. 2, which dropped below 10 Pound Square Inch (PSI) and remained low for approximately two minutes. This was accompanied by a rapid decline in oil quantity, indicating a significant oil loss. In response, the crew conducted an in-flight shutdown of Engine No. 2 and declared a “MAYDAY” to initiate a precautionary diversion to Jinnah International Airport (JIAP), Karachi. The aircraft landed safely on a single engine without further incident. A post-landing inspection identified significant oil leakage around the Accessory Gearbox (AGB) area of the engine No.2. Subsequent teardown and laboratory analyses revealed that the oil leak originated from the AGB oil nipple. Investigation determined that thread wear and loss of preload at the oil nipple assembly led to its partial push-out and subsequent oil pressure loss. The failure mechanism traced back to an irregular assembly condition, caused by non-conforming housing thread depth and excess weld rework on the nipple component. These combined factors prevented correct seating and torque preload during installation, ultimately leading to progressive wear, oil loss, and engine shutdown. All corresponding timing are mentioned in Universal Time Coordinated (UTC).
