Airline equipment manufacturer Honeywell's new Phase 3 Display Units (DUs) reportedly blanked out during a test because of interference from an in-plane wi-fi network.
The DUs blanked out while they were undergoing airline electromagnetic interference (EMI) certification testing for Wireless broadband.
The test failure has prompted aircraft maker Boeing to stop installing in-flight wi-fi connectivity systems on all of its planes including widebody aircraft.
Display blanking durations of as long as six minutes were observed during testing
Boeing is using RTCA DO-307 - which covers Aircraft Design and Certification for Portable Electronic Device (PED) Tolerance - as guidance.
When a manufacturer goes through qual testing in the lab for RTCA DO-307 (as outlined in the FAA's advisory circular AC-20-164), it accounts for both the frequency and energy field value at levels well beyond what a cell phone or Wi-Fi would produce if its near that equipment.
The value covers a range between 100 MHz to 8 GHz. To put that into perspective, Wi-Fi operates at 2.4 GHz or 5 GHz and cell phones operates as low as 460 MHz and as high as 2.17 GHz. So yes, the levels tested far exceed all normal scenarios, but for good reason. Who wants people with malicious intent (oh, say, terrorists) to take RF aim at the cockpit? Uh, nobody, except the terrorists.
If the equipment passes muster, it is considered to be T-PED (tranmissing portable electronic device) tolerant, and that's what Boeing and others are working towards.
This AD is effective [INSERT DATE 35 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER].
We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes, and Model 777 airplanes. This 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. 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.
Clarification of Cause of Unsafe Condition
The cause of the unsafe condition stated in the Discussion section of this AD is a known susceptibility of the Phase 3 DUs to RF transmissions inside and outside of the airplane. This susceptibility has been verified to exist in a range of RF spectrum (mobile satellite communications, cell phones, air surveillance and weather radar, and other systems), and is not limited to WiFi transmissions.
(1) For Model 737 airplanes: Remove all phase 3 common display system (CDS)
(2) For Model 777 airplanes: Remove all phase 3 DUs and replace with phase 1, phase 2, or phase 3A DUs. If any phase 3 DUs are replaced with phase 3A DUs, replace the phase 3 DUs and install the DU database software into the left and right airplane information management system core processor module/graphics generator, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 777-31-0187, dated November 29, 2012.