Incident Summary
On April 5, 2010, at about 0629 eastern daylight time, a JetBlue Airways Airbus A320-232, registration N535JB, operated as a scheduled passenger flight from Newark Liberty International Airport (EWR) to Fort Lauderdale, Florida. During takeoff, the left engine fan cowl assembly separated from the aircraft. The flightcrew was unaware of the separation until passengers alerted them. The crew informed air traffic control and returned to EWR for an uneventful landing. After parking and deplaning, additional damage was noted on the left engine pylon, leading edge flaps, left main landing gear, and horizontal stabilator. The separated fan cowls were recovered from airport property. There were no injuries among the 6 crew members and 134 passengers.
Examination Findings
Examination of the recovered fan cowls revealed that the latch assemblies and keeper housing assemblies were intact, with no evidence of malfunction, distortion, or damage. The cowling structure showed no failure; some delamination was observed but was determined not to be contributory. The latch hardware exhibited no mechanical damage consistent with being secured and locked at the time of separation.
Maintenance Procedures
According to JetBlue maintenance records, a scheduled inspection of the left engine had been performed prior to the flight, requiring the opening and closing of the fan cowls. The maintenance sign-off sheet indicated that a mechanic had latched and locked the fan cowls, and a second mechanic had verified the task. Both the action and inspection signature blocks were signed as part of JetBlue's Required Inspection Item (RII) procedures. The RII program requires a second mechanic or inspector to visually inspect the latches to confirm locked position.
False Latch Condition
To indicate latch status, each latch is weighted and painted (typically red or orange) on the inside and sides; when properly locked, the latch handle is flush with the cowling and the paint is not visible. If unlocked, the handle swings down exposing the painted surfaces. Examination of an exemplar JetBlue Airbus A320 fan cowl revealed the possibility of a false latch condition. Mechanics reported that they sometimes push the latch assembly up against the keeper housing to stow it while working, avoiding head injuries. In this position, the latch is neither latched nor locked but can appear flush, hiding the painted indicator. Tests by NTSB and JetBlue investigators on several A320s demonstrated that the latch assembly can become stuck in the keeper housing, giving a false impression of proper latching.