Testing Shows Some Units Can Be Affected By Onboard WiFi Systems

The FAA has posted an Airworthiness Directive (AD 2014-20-06) dated October 1 for all Boeing 737-600, -700, -700C, -800, -900, and -900ER series airplanes, and Model 777 airplanes. The AD was prompted by testing reports on certain Honeywell phase 3 display units (DUs). These DUs exhibited susceptibility to radio frequency emissions in WiFi frequency bands at radiated power levels below the levels that the displays are required to tolerate for certification of WiFi system installations.

According to the AD summary, the phase 3 DUs provide primary flight information including airspeed, altitude, pitch and roll attitude, heading, and navigation information to the flightcrew. This AD requires replacing the existing phase 3 DUs with phase 1, phase 2, or phase 3A DUs, and for certain replacement DUs, installing new DU database software. The FAA is issuing this AD to prevent loss of flight-critical information displayed to the flightcrew during a critical phase of flight, such as an approach or takeoff, which could result in loss of airplane control at an altitude insufficient for recovery, or controlled flight into terrain.

The AD affects 1,149 737 airplanes and 177 triple-sevens.

The FAA estimates that the overall cost of the AD to U.S. operators of 737 airplanes will be $11.9 million. The cost to U.S. 777 operators will be $1.85 million.

 FMI: AD