On Dec 2nd 2023, a Pakistan International Airlines Boeing 777-200 operating flight PK-743 from Karachi to Madinah was forced to make an emergency return just minutes after departure when a dramatic engine event lit up the night sky and triggered a fire warning in the cockpit.
The aircraft, registered AP-BMH, had 276 people on board and was climbing out of Karachi’s runway 07R when the right-hand GE90 engine emitted a loud bang, followed by visible sparks and a streak of flames. Almost immediately, the crew received a fire warning for the engine. The climb was halted at about 3,000 feet as pilots shut the engine down, discharged at least one fire extinguishing bottle, and initiated an urgent return to the departure airport.
About 15 minutes after takeoff, the widebody jet landed safely on runway 25L in Karachi, where emergency services were standing by. No injuries were reported, but the incident prompted Pakistan’s aviation authorities to open a formal investigation. While the initial post-flight inspection found no evidence of an actual fire, the seriousness of the event led the airline to cancel the flight and prepare a replacement aircraft for passengers bound for Madinah.
More than two years later, in Jan 2026, Pakistan’s Bureau of Air Safety Investigation and Prevention (BASIP) released its final report, revealing that the incident was not caused by a true engine fire but by a dangerous maintenance-related fault. Investigators concluded that a significant bleed air leak from the 14th stage of the high-pressure compressor had triggered the overheat warning and dramatic visual effects seen by witnesses. The leak was traced to a disconnected high-pressure pneumatic duct on the right engine, caused by improper installation of its securing clamp.
The report painted a troubling picture of maintenance lapses. The clamp had likely been loosened during previous work and never re-torqued or verified, and required leak checks were not performed after engine installation, contrary to the aircraft maintenance manual. Investigators also cited human factors such as night-shift working conditions, poor visibility, limited access due to inadequate platforms, and fatigue, all of which increased the risk of oversight. Communication failures between technicians and ineffective shift handovers further allowed the problem to go unnoticed.
Physical evidence supported the findings. The disconnected duct was found near the 3 o’clock position of the engine, while the clamp itself had fallen to the lower section of the engine area. Heat damage and the deployed pressure relief doors on the thrust reverser confirmed that hot bleed air had escaped, mimicking the symptoms of an engine fire without combustion actually occurring.
Although the aircraft landed safely and no one was injured, the BASIP report underscored how a single overlooked step in maintenance can escalate into a serious in-flight emergency. The incident stands as a stark reminder that in modern aviation, safety depends as much on rigorous procedures and communication on the ground as it does on skillful actions in the cockpit.
