IFEN Continued Airworthiness
HI developed and issued the Maintenance Instructions for Continued Airworthiness of Interactive Flight Technologies Inc. Interactive Passenger Entertainment System on Swissair MD11 to comply with FAR 25.1529, Instructions for Continued Airworthiness. This document was released on 20 March 1997 and referenced numerous HI drawings and documents. The maintenance instructions contained the following information:
IFT issued 38 SBs, the majority of which were primarily for system software upgrades, movie and content updates, and for product improvement modifications to IFEN components. Some of the product improvements, each addressed by a separate SB, included the replacement of a single blow fuse with a self-resetting circuit protection switch in the cluster controllers, VOD, seat electronics boxes, and management terminal electronics boxes. None of the IFT SBs were considered directly pertinent to the investigation.
HI issued 15 SBs for technical changes or improvements to the IFEN system. One SB, applicable by fuselage number to the occurrence aircraft, was considered to be of interest because it involved the installation of additional wiring within the area that was fire damaged in the occurrence aircraft. During the TSB investigators' inspections of Swissair's fleet of MD-11 aircraft, it was observed that the PA wire was installed in various conduits above Galley 2, even though the SB documentation specified the conduit to be used. SB 23-12003-11, Communications-IFT System, PA Key Line Modification, was issued on 2 June 1997 and was applicable by fuselage number to HB-IWF (the occurrence aircraft). HI recommended that this modification, which provided PA audio through the IFEN system, be accomplished during the earliest practical maintenance period. SR Technics could not locate a document referring to this SB, nor was this SB identified in the SR Technics Status List of Engineering Orders. However, HI had performed this modification, at SR Technics facilities, under HI Work Order 67793. An FAA Form 337 was completed by HI on 18 March 1998.
Detail-Specification for Interactive IFE, Section 5, dated 22.7.96 Rev 1, outlined the PA system requirements. These requirements included the need for the PA signal to override all audio channels of the IFEN system and stop all video, audio, and other functions for the selected PA zone(s). The original IFEN system-to-aircraft integration design did not meet this condition; therefore, HI issued SB 23-12003-11.
Swissair IFEN MM Rev B, issued on 2 September 1997, provided the following information pertaining to the PA system, even though the design was not capable of performing the actions as described:
When the PA system is operated from one of the flight crew [or flight] attendant positions all IFEN activities are paused, and the messages are broadcast simultaneously over the PA and through the IFEN system headphones.
Drawing 50013-103 A/C Systems to G8 Disconnect and Drawing 50024-101 Relay to G8 Disconnect were to be modified to accomplish this SB.
The SB, with supporting documents, provided the following wire installation information:
The TSB identified the following discrepancies:
All maintenance activities related to the IFEN system were documented in a database. Between the first installation and system deactivation on 28 October 1998, 17 052 discrepancies were recorded for all Swissair aircraft equipped with the IFEN system.
The collected data included aircraft registration information, "trouble" information, "action" information, "date A/C in," and "date A/C out." "Trouble" referred to the recorded discrepancy and "action" referred to the maintenance activity that was carried out to address this discrepancy. For the purpose of evaluation, the TSB defined four data categories and grouped similar entries into the appropriate category.
A comparison between HB-IWF and a sampling of the other MD-11 aircraft with the same IFEN system configuration is provided below.
Table: MD-11 IFEN System Configurations
One incident was reported of an in-flight trip of a PSU CB. This incident occurred on HB-IWL on 30 August 1998. The PSU 2 CB, F9, located in the lower avionics CB panel, tripped and was reset in-flight but tripped again. When maintenance personnel reset the CB, it immediately tripped and a noise was heard in PSU 2. This PSU was subsequently removed and forwarded to IFT for corrective action. The repair estimation report identified the following:
No detailed examination of the unidentified metallic residue was performed and the reason for the failure was not identified.
The FAA released Policy Statement ANM-01-04 on 2 July 2001 to advise applicants for type certificates, amended type certificates, supplemental type certificates, or type design changes on how existing rules, currently contained in 14 CFR, Part 21, are to be interpreted. This notification did not establish any new rules but provided comprehensive guidance on the required elements of a design package and the actions required for compliance. The FAA stated that the policy was necessary to correct deficiencies associated with the submission of design data and instructions for continued airworthiness involving airplane system wiring for type design, amended design, and supplemental design changes. The notification advised applicants of the range and quality of type design data that the FAA expects applicants to submit as part of the certification project.
The FAA did not intend to establish a binding norm with the general policy stated in this document, nor would the FAA apply or rely upon this document as a regulation. However, the FAA expected that those tasked with the responsibility of aircraft certification should generally attempt to follow the policy, when appropriate.
It is and has been the FAA's policy to require that type design data packages submitted for multiple approvals include the following elements: a drawing package that completely defines the configuration, material, and production process necessary to produce each part in accordance with the certification basis of the product; any specification referenced by the required drawings; and drawings that completely define the location, installation, and routing, as appropriate, of all equipment in accordance with the certification basis of the product.
The FAA's Notice of Final Policy, dated 28 January 2002, incorporates changes based on comments received from four sources who responded to the FAA's request for the public to present their views on this policy statement. These changes are identified as footnotes within the applicable section.
The following statements are extracted from the FAA Policy.
The FAA review of a number of recent certification projects identified various problems, many of which were evident in the IFE system certification documentation, including the following:
 "A/C" means aircraft.
 "Reset" is defined as "causing a device to return to a former state." Therefore, when a tripped CB is pushed in, it is "reset." "Reboot" is defined as "to boot up a system again." Therefore, when a CB is deliberately pulled and then pushed in (i.e., cycled), it is done to "reboot" the system. Swissair and SR Technics personnel use the terms "reboot" and "reset" interchangeably when they are referring to rebooting the IFEN system software. None of the "reboot" entries identified above are for a "reset" of a tripped CB.
 "C-Class" refers to business class.
 "F-Class" refers to first class.
 ANM-01-04 states: "Multiple approvals are approvals for modifications that may be installed on any airplane of a specific type."
 ANM-01-04 states: "Type design data packages should meet the intent of 14 CFR part 21.31 (a)."
 ANM-01-04 states: "It is important that the routing of the wiring follow the intent of the criteria established by the FAA in the certification basis as reflected in the original or subsequently approved type design approval holder's design."
 ANM-01-04 states: "The FAA expects applicants to provide engineering drawings instead of merely statements such as 'install in accordance with industry standard practices,' or 'install in accordance with AC 43.13-1A.'"