The Federal Aviation Administration plans to require airlines to replace mode control panels (MCP) on Boeing 787s due to a malfunction that could cause the jet’s systems to make uncommanded altitude changes.
The regulator on 14 November released a proposed airworthiness directive to address the issue by requiring operators to complete a fix described in a service bulletin issued by Boeing in April.
“The FAA has received operator reports indicating occurrences of an uncommanded change to the MCP selected altitude,” the agency’s proposed rule says. “The causes of the uncommanded change were determined to be a series of events in the software, the airborne electronic hardware and the electrical circuits in an internal power supply for the encoders in the MCP knob selectors.”
The proposal does not provide details about events that prompted such uncommanded action.
It calls for operators to replace the MCPs, which are manufactured by Honeywell, saying failure to do so could “result in controlled flight into terrain or traffic confliction”.
The proposed rule stands to apply to 165 US-registered 787s, including -8, -9 and -10 variants – essentially the entire US fleet. The FAA estimates replacing the MCPs will cost airlines $405,000 per aircraft but says Honeywell might cover some of that cost under warranties.
The FAA is accepting public feedback about its proposal for 45 days after 17 November.
Boeing and Honeywell did not provide comments to FlightGlobal.
