Four incidents within the last two years of operators experiencing separation of engine fan cowls have prompted the US National Transportation Safety Board (NTSB) to issue four safety recommendations to FAA to ensure those components are properly latched before flight.
Three of the four incidents occurred this year, and the fourth happened in 2007. A recurring theme of NTSB's conclusions in the majority of the incidents is improperly fastened cowl latches following engine maintenance.
NTSB is zeroing in on operators of Airbus narrowbodies and Bombardier regional jets. Research conducted by the board shows since 1992 15 engine cowl events involving Airbus aircraft and 33 domestic and foreign instances of engine cowl separation on Bombardier aircraft.
Three of the incidents under NTSB scrutiny involved Airbus A320 family aircraft operated by Spirit Airlines, Frontier Airlines and Northwest Airlines. The fourth cowl separation occurred on a CRJ flown by US Airways.
FAA needs to determine the extent of engine fan cowl separation problems, and if it concludes a widespread issue exists, "require operators of those airplanes to include a dual inspection signoff in their maintenance procedures", says NTSB, to confirm that the cowls are latched after completion of engine maintenance that involves opening the cowl.
The board believes that Airbus operators opting to add duel inspection signoffs to confirm proper latching of the cowls "have had success in preventing future accidents or incidents".
NTSB is recommending FAA require Bombardier and Airbus operators to revise maintenance procedures and inspection documents requiring the dual signoff.
In addition, the board believes is its prudent for FAA to mandate that operators of Airbus narrowbodies and CRJs require their maintenance personnel to inform flight crews if engine fan cowls have been opened prior to a flight.
These incidents have also spurred the need for operators of those aircraft types to supply guidance to both maintenance personnel and flight crews to properly verify fan cowls are latched properly, NTSB notes.