Honeywell Phase 3 Display Units (DUs) have shown themselves susceptible to "blanking" during airline electro magnetic interference (EMI) certification testing of wireless broadband systems (Wi-Fi) on various Boeing 737NG airplanes, prompting Boeing to cease linefit installs of in-flight connectivity systems across its portfolio, including widebody aircraft.

Multiple sources tell ATI and Flightgloal that the blanking occurred during EMI testing for Aircell's Gogo in-flight Internet supplemental type certificate on 737NG aircraft. Aircell has declined comment, saying "this topic is not Aircell specific and, as such, we do not have any comment on the matter".

Boeing says it has deferred the activation of wireless systems that interface with passenger devices that could potentially interfere with the DU 3 displays. "Boeing has not delivered any installations that would have this issue. Honeywell has assured us that they are working to address the problem and we are satisfied that they are taking the necessary steps to do so," says Bret Jensen with BCA Engineering Communications.

A source with knowledge of the situation tells ATI and Flightglobal that Boeing has "gone through and scrubbed the avionics numbers to make sure that there are no anomalies and that the avionics will not be affected by personal electronic devices (PEDs). It has been discovered that there is stuff out there that doesn't meet those requirements yet, and we may uncover more as we go down that path".

The source adds: "There are three specific part numbers associated with the [Honeywell] display that could be installed. Those are the ones [found to be] susceptible to transmissions."

Fallout from the event is already occurring. Multiple sources tell ATI and Flightglobal that one of the conditions for STC is that 737NG operators place placards in the flight deck saying that Wi-Fi devices are to be powered off.

Another condition, say sources, is that 737NG operators are not to have DU 3 displays installed with the presence of in-flight connectivity systems, be they Wi-Fi or cellular-based.

On a Boeing Business Jet fitted with in-flight connectivity, for instance, there is a note in the log book that says Phase 3 DUs are not to be installed, but that "version 4 is fine and version 2 is fine", says a source.

Panasonic partner AeroMobile's eXPhone in-flight mobile connectivity solution, which was made linefit offerable on certain Boeing types, is not being installed until the Honeywell issue has been addressed. As such, customers of eXPhone are not receiving aircraft with eXPhone as planned. Customers of eXPhone include Emirates, Turkish Airlines and V Australia.

"We're continuing to work closely with Boeing and our partners at Panasonic to bring eXPhone to full line-fit offerability across the entire Boeing fleet," says AeroMobile.

Boeing, meanwhile, says: "Current testing by Boeing and Honeywell has determined that blanking may occur when a DU is subjected to testing procedures specified by the FAA requirements (AC-20-164) during installations of Wi-Fi systems on the airplane. Based on testing that has been conducted, Boeing and Honeywell have concluded that actual EMI levels experienced during normal operation of typical passenger Wi-Fi systems would not cause any blanking of the Phase 3 DU. This issue does not exist with the Phase 1 or 2 DU's."

Honeywell says that, during recent ground testing "at elevated power levels", the company observed a momentary blanking on the 'flat panel' liquid crystal displays that it developed and pioneered for Boeing.

"The screens reappeared well within Boeing's specified recovery time frame. The screens have not blanked in flight and are not a safety of flight issue. Honeywell is working to ensure the problem is addressed and fixed and that our technology will continue to exceed specifications," says Honeywell.

The firm stresses that there have been "no blanking incidents of in-service aircraft with the Wi-Fi system installed".

A spokesman for the FAA says: "The FAA is aware of some issues involving interference between Honeywell flight displays and in-flight WiFi that surfaced during STC testing. The FAA is currently working with both manufacturers to examine the technical data and test results. After a thorough review, the FAA will consider if further safety action is necessary."

Sources say a Service Bulletin from Boeing is expected.

Source: Air Transport Intelligence news