The FAA today adopted an airworthiness directive requiring the replacement of Honeywell phase 3 display units (DUs) on 1,326 U.S.-registered Boeing 737 and 777 airliners. The AD, which takes effect November 5, is based on concerns that the data such as airspeed, altitude, pitch and roll, attitude and heading could disappear from the displays due to interference from wireless devices. It requires the phase 3 DUs to be replaced with phase 1, 2 or 3A units, as well as the installation of new DU database software.

Operators will have 60 months to comply with the AD, after the FAA declined a request by the Airlines for America (A4A) group to extend this to 72 months.

The FAA estimates that the total cost for each 737 will be $10,370 and $10,455 for the 777. Overall cost estimates for all U.S. operators impacted by the AD is estimated at approximately $13.8 million. The AD covers all 777s and the -600, -700, -700C, -800, -900 and -900ER versions of the 737.

As of press time, neither Boeing nor Honeywell had issued statements on the new AD. Previously, Honeywell has pointed out that there have been no in-flight incidents in which the displays have failed due to Wi-Fi interference. Honeywell, along with some individual airlines and A4A, has urged the FAA to reduce the scope and delay the time frame for the required actions.