Uzbekistan Airways Boeing 787 Returns to Seoul After Windshield Crack (UK78701)

Incident Overview and Initial Delay On March 21, 2022, a Boeing 787 operated by Uzbekistan Airways, registration Uk78701, was preparing to depart Seoul Incheon International Airport (ICN) for Tashkent on flight NU-512. During taxiing to runway 15R, the crew received an “ENG REVERSER L” message on the Engine Indication and Crew Alerting System (EICAS), along with status messages related to several left-engine systems. The crew requested to return to the stand, where ground engineers investigated the issue. The fault was traced to a failure of the left engine data concentrator (MEDC) channel A. After performing required deactivation procedures and a test engine start, the aircraft was released for flight with Minimum Equipment List (MEL) items deferred. ## In-Flight Windshield Damage The aircraft departed from runway 33L at 11:00 UTC under night conditions. After reaching cruising altitude FL401, the crew heard a loud bang. The left forward flight-compartment window cracked, followed by sparking. The crew decided to return to the departure airport. After preparing the aircraft and burning fuel, they made a safe landing at Seoul. ## Investigation and Findings The operator’s investigation committee reviewed crew and engineer statements, the technical logbook, and maintenance records. The technical logbook recorded: “At FL-401 left forward window cracked. NNC performed.” A physical inspection of the removed left forward window found no visible signs of mechanical impact or foreign object damage. The committee assessed the risk associated with the left flight-compartment window as “extremely rare” in probability and “hazardous” in severity, with a risk index of 16, deemed acceptable with further risk-reduction measures. ## Aircraft and Maintenance Details The aircraft, serial number 38363, was manufactured by Boeing in 2016 and had accumulated 15,524.48 flight hours and 3,531 cycles. The left forward window, part number 190800-15, serial number 1819, had been installed at the factory and had not been replaced during service. Following the incident, the window was replaced, and the aircraft was returned to service without restrictions after passing operational tests.