The US National Transportation Safety Board (NTSB) has issued new safety recommendations for passenger service units (PSUs) and crew seats in the Next Generation Boeing 737 family aircraft.
PSUs are installed directly below the overhead stowage bins, and each unit is aligned with each passenger seat unit. Each unit houses additional oxygen generators, oxygen masks and ventilation air vents. The NTSB wants changes in how these units are mounted to overhead bins to ensure that the 5.7kg (12.5lb) units do not fall on passengers during survivable crashes.
The NTSB has made these recommendations after reviewing evidence from a number of accidents that occurred over the last four years, including:
- The Aires Airlines 737-700 crash at San Andres Island, Colombia – 16 August 2010
- The runway excursion by an American Airlines 737-800 in Kingston, Jamaica – 22 December 2009
- The Turkish Airlines 737-800 crash in Amsterdam – 25 February 2009
- The runway excursion by a Continental Airlines 737-500 in Denver – 20 December 2008
Investigations on the crashed aircrafts’ cabins revealed that the PSUs tore loose during the crash and fell into the seats, likely causing head injuries to passengers, or fell into the aisle, potentially restricting access to emergency escape routes. The crash investigation reports also revealed that the crew seat belt restraints failed in two cases, likely causing back injuries to the flight crewmembers.
The NTSB stated that, in view of this evidence, the cabin overhead units and crew seat belt restraints were designed or tested to inadequate levels for an actual crash, and need to be improved.
Consequently, NTSB has asked the FAA to provide safety devices that would "capture" the PSUs if they break lose. The NTSB has also asked for airlines to retrofit the crew seat belt restraints with stronger brackets.