The US FAA is warning opening and closing of cockpit side windows could lead to electrical arcing, smoke and fire problems in the cockpits of next generation Boeing 737 aircraft.
A proposed airworthiness directive (AD) issued by the agency on 26 January would require operators of 687 US-registered 737s to perform inspections of orientation of coil cord connectors of both "number 2" side windows in the cockpit within four years, adjusting or replacing the assemblies if problems are found.
The proposed directive occurs after one report of arcing and smoke on a left number 2 window, which was traced to "mechanical damage of the heat-coil assembly at the 90-degree connector back shell," says the FAA.
Investigators determined that damage was related to the opening and closing of the windows, an action pilots and mechanics often perform at the gate.
"This condition, if not corrected, could lead to injuries to or incapacitation of the flight crew," says the FAA. The agency estimates that corrections could cost as much as $2,100 per aircraft, though Boeing may cover some of the costs under warranty.
Boeing issued a service bulletin on 7 July to address the problem.