The in-flight entertainment network (IFEN) system in the crashed Swissair flight 111 Boeing MD-11 was installed without consideration for the aircraft's electrical system design concept, an extensive examination by the US Federal Aviation Administration has revealed. Following the study, the FAA has issued an airworthiness directive (AD) designed "to prevent any reactivation or new installation of the [IFEN]".
There is still no evidence, the FAA insists, that the IFEN installation played a part in the accident, on 2 September last year off Nova Scotia, Canada. Prompted, however, by early evidence that a fire in electrical wiring bundles near the flight deck may have been a factor in the accident, the FAA says it began its investigation of the IFEN as one of the electrical components supplied by wiring in that area.
No US-registered MD-11s use the system, and Swissair had deactivated its own immediately the IFEN was implicated as a possible factor. The Transportation Safety Board of Canada confirms that the FAA action is not prompted by any recent new evidence.
The IFEN was made by Interactive Flight Technologies of Phoenix, Arizona, and installed under an FAA supplemental type certificate by Santa Barbara Aerospace, an FAA designated alteration station. Examining the IFEN in other Swissair MD-11s, the FAA found the system was not wired via the cabin non-essential systems busbar, so it would not be isolated when the crew, following the checklist for a smoke/fumes emergency, switched off the "CAB BUS".
Although the IFEN would "eventually be removed via activation of the SMOKE ELEC/AIR rotary switch, the FAA comments, that the crew should be able to assume that the IFEN is isolated with other non-essential cabin equipment. Also, it notes, the only way to switch off the whole IFEN is via the relevant circuit breakers in the flight deck - which the cabin crew cannot do.
Source: Flight International
