Displays Units on Boeings Went Blank Under Interference from In-plane WI-FI network.
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.
FAA
AIRWORTHINESS DIRETIVE – AD
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.
We are 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.
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.
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. We are
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.
(1)
For Model 737 airplanes: Remove all phase 3 common display system (CDS)
DUs
and replace with phase 1, phase 2, or phase 3A CDS DUs. If any phase 3 CDS DUs are
replaced with phase 3A CDS DUs, replace the phase 3 CDS DUs and install new database
software into the display electronics units, in accordance with the Accomplishment
Instructions of Boeing Special Attention Service Bulletin 737-31-1471,dated
November 29, 2012.
(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.
