Aviation Investigation Report A98H0003

IFEN – Description

  1. Product 97
  2. Product 99
  3. System Description
  4. Components
    1. Introduction
    2. Line Replaceable Units
      1. Disk Array Unit
      2. Power Supply Unit
    3. Electromagnetic Interference Filter Box
    4. Cabin File Server
    5. Seat Electronics Box
    6. Seat Disconnect Unit
    7. Head-End Distribution Unit
    8. Dual Audio Gameport
    9. In-Seat Video Display
    10. Cluster Controller
    11. Network Switching Unit
    12. Video on Demand
    13. 32-Channel Modulator
    14. 13-Channel Modulator
    15. Management Video Display
    16. Management Terminal Electronics Box
    17. Video Distribution Unit
    18. Printer
  5. General
  6. Network Architecture

Product 97

The IFEN system was installed in the business- and first-class passenger sections of HB-IWF in August and September of 1997, while the aircraft was undergoing a Heavy Maintenance Visit ("D check"). Although the 49 IFEN-equipped business-class seats were installed during this time, the first-class seats were not installed until February 1998 owing to delivery delays.

SR Technics produced EO 513051, "Installation of the IFE[1] System," for the IFEN installation. The EO included the following instructions:

  • Installation of the IFE system will be performed by Hollingsead according to MDL 12003-501.
  • Testing of the IFE system will be performed by Hollingsead according to MDL 12003-501.
  • After installation and test of the IFE system, Hollingsead will provide the FAA Form 337 to SR Technics for the aircraft release.

HI completed FAA Form 337 for HB-IWF on 9 September 1997 for the installation of the IFEN system in accordance with HI MDL 12003-501, as per STC ST00236LA-D, dated 7 August 1997. MDL 12003-501 was applicable to Swissair's MD-11s equipped with 257 passenger seats.

SR Technics' Status List of Engineering Orders identified EO 513051 as being carried out, dated 12 September 1997.

Product 99

In February 1998, as part of Swissair's Product 99 modification, the following work was completed:

  • The first- and business-class seating arrangement was re-configured;
  • The newly acquired IFEN-equipped first-class seats were installed; and
  • The number of economy-class seats was reduced from 196 to 178.

This work was accomplished by SR Technics personnel under SR Technics' EO 511525, "C Configuration Change from Version 1124 to M1130." The seating configuration for both Product 97 and Product 99 was such that each had 12 first-class and 49 business-class seats; however, they differed in the layout of the seating plan. The modifications associated with Product 99 contained several changes, including configuration changes for the PA and cabin telephone systems. HI's involvement in the Product 99 modification was limited to making adjustments to the IFEN system cabling, located on the cabin floor, to accommodate the new seating arrangement. HB-IWF was removed from service for two days, 20 and 21 February 1998, to carry out this and other scheduled work.

SR Technics' Status List of Engineering Orders for HB-IWF identified EO 511525 as being carried out, dated 4 June 1998.

Product 99, as applicable to HB-IWF, included the following SR Technics' EOs:

Table: SR Technics EOs

EO Description Date
511525 New Cabin Configuration Version M1130 4 June 1998
513185 PA Reconfiguration for Product 99 23 February 1998
513184 CTS [Cabin Telephone System] Reconfiguration for Product 99 23 February 1998
513173 Mux [Multiplexer] Reconfiguration Mid Zone P99 23 February 1998
513175 Video Reconfiguration Fwd Zone P99 23 February 1998
513179 LCD on Y/C Centre Bagrack Inst P99 23 February 1998
513170 Mux Reconfiguration Fwd Zone P99 23 February 1998
511509 EA [energy absorbing] Partition Installation/Relocation 23 February 1998
511527 Adapt Interior Finish Change for Version M1130 23 February 1998
511526 First-Class Partition Relocation/Installation 23 February 1998
511602 Centre Bagrack Endcap - LCD Monitor Install 23 February 1998
510363 Gasper Air Panel Assemblies Modification 23 February 1998
510368 Air Conditioning Duct Attachment 23 February 1998
510356 Cabin Version Change - Mod. of O2 Boxes 23 February 1998
510362 Removal of Electrical Wires in Forward Cabin 23 February 1998
513178 Video Re-configuration P99 System Test - 1130 23 February 1998
513174 Mux Programming and Test Version 1130 23 February 1998
217194 Product 97 F-Class Seat Power Installation 23 February 1998
217215 Product 99 Eco + C/Y class Pax Reading Light Relocation 23 February 1998
217096 Product 99 Split of Cabin Ceiling Lights 23 February 1998
514000 Manufacture Cabin Floor Panels for Product 99 23 February 1998

SR Technics EO 511525 did not identify a requirement for the FAA Form 337. Nevertheless, HI provided one for HB-IWF on 21 February 1998 for the installation of HI's Product 99 Cabin Configuration (239 passenger) installation kit in accordance with MDL 12007. The drawings referenced on this form were applicable to the MD-11 installation; however, the MDL was incorrectly identified as 12007. MDL 12007 was applicable to the IFEN installation in Swissair's Boeing B747 aircraft. HI has stated that the installation in HB-IWF was carried out under the applicable MDL; however, a typographical or bookkeeping error was made when completing the FAA Form 337.

HI's Product 99 cabin configuration installation kit, as installed in HB-IWF, was carried out under MDL 12003-501. Although this MDL was previously applicable to the 257-passenger-seat configuration, it had subsequently been revised to reflect Swissair's new interior configuration of 239 passenger seats. On the basis of an economic evaluation, Swissair chose to install the IFEN system in only the first- and business-class seats. HI accomplished this by using the STC approved documentation that was applicable to the 239-seat configuration with the exception of installing the components and cabling required for the economy-class seating.

System Description

The IFEN system, using Windows NT® 4.0, combined computer, video, and audio. It allowed passengers to select, through an ISVD, various functions, including movies, audio, games, news, gambling, and a moving map display. Each ISVD received broadband audio and video signals carried by the Broadcast Distribution Network. Additionally, each ISVD received and transmitted digital data over a LAN that encompassed several displays. The ISVD could also receive and send information to any other component of the IFEN system, by sending messages through the CC.

Power consumption for the IFEN system, as installed in HB-IWF, was 4.4 kVA supplied from the 115 V AC Bus 2 and 0.2 kVA supplied from the 115 V AC ground services bus. The DC loads were less than 20 W.



The major hardware components were mounted above the ceiling in electronic racks (referred to as E-racks). These racks were approximately 100 inches long and comprised seven bays, Bay 1 being the forward-most. E-rack 1 was located in first class, above the right aisle, with its forward support located at FS 647. E-rack 2 was located in economy class, above the left aisle, with its forward support located at FS 1429. HB-IWF was also equipped with the cabling and structural supports to accommodate a third E-rack. These supports were located above the right aisle in economy class, directly opposite E-rack 2.

The relay assembly, located above Galley 8, was the system control unit that encapsulated all of the external interfaces to the aircraft system. These interfaces included the decompression signal, PA system over-ride signal, and 28 V DC power. Additionally, the relay assembly provided control over the 48 V DC power output to the IFEN system. The decompression signal removed PSU power from the IFEN system upon cabin decompression. The PA system over-ride signal was designed to stop all audio and video on the IFEN system whenever the PA was used.

Line Replaceable Units

Disk Array Unit

HB-IWF had one DAU installed in Bay 6 of E-rack 1.

The DAU contained a bank of seven 9 GB HDDs, which stored the digitally encoded movies, assorted video segments, and audio programming. The seven HDDs worked together as a disk array; should one fail, the array automatically uses the additional copies of the information stored on the other disks. The DAU sends the movie and music data using small computer system interface format to the VOD unit upon receiving the request from the UNC (not an acronym), which is incorporated within the VOD unit. The power input requirement was 48 V DC at 4.7 A.

Power Supply Unit

HB-IWF had four PSUs installed. PSU-1 and PSU-2 were located in bays 1 and 2 of E-rack 1. PSU-3 and PSU-4 were located in bays 6 and 7 of E-rack 2. All PSUs were interchangeable.

The PSU received 115 V AC three-phase 400 Hz input from the aircraft AC Bus 2 and, by utilizing a series of capacitors and internal electronics, provided 48 V DC output power used by the IFEN system components.

Electromagnetic Interference Filter Box

HB-IWF had four EMI filter boxes installed, one attached to the top side of each of the PSUs. All EMI filter boxes were interchangeable.

The EMI filter box used inductors, capacitors, and other internal electronics to filter out conducted EMI radiation between the aircraft supply and the PSUs.

Cabin File Server

HB-IWF had one CFS installed, located on a shelf in the middle of Galley 8.

The CFS was the collection point for the credit card data transmitted from each seat. The CFS also controlled the download of movies, through the VOD, for storage on the DAU; it stored flight and casino information; and it controlled the IFEN system's operation by sending a signal to enable the IFEN system. It also connected to the MVD terminal. During flight, the SEBs and CCs communicated their status to the CFS, and the CFS built a statistics file. The CFS included

  • a motherboard with a Pentium 166 MHz processor;
  • a 9 GB HDD partitioned into two logical drives:
    • a 1 GB partition, C:\ operating system,
    • an 8 GB partition, D:\ core software and data storage; and
  • 64 MB of RAM.

The CFS outputs data to a removable disk pack, which was the interface for extracting flight and credit card data and for uploading new data to the IFEN system, and which had a parallel port for output to a printer. The power input requirement was 48 V DC at 3.1 A.

Seat Electronics Box

HB-IWF had 61 SEBs installed, one under each of the first- and business-class passenger seats. All SEBs were interchangeable.

The function of a SEB was to process all information for the passenger interface and display, including video, audio, and display data. Data inputs could be in the form of baseband video and audio through an SDU, plus passenger credit card information, touchscreen data, and game controller data from the passenger seat assembly. The power input requirement was 48 V DC at 0.42 A. The SEB included

  • a custom motherboard with a Pentium 100 MHz processor;
  • a 340 MB HDD;
  • 32 MB of RAM;
  • 16-bit "Soundblaster"; and
  • video graphics array controller.

Seat Disconnect Unit

HB-IWF had 28 SDUs installed, one under each set of first- and business-class seats and one installed behind E-rack 2. All SDUs were interchangeable.

Each SDU contained the tuners and network repeater for each of its associated SEBs. Data inputs were broadband RF from an HDU and "Ethernet 10BaseT, Inter-Integrated Circuit" signals from a CC. The SDU split the Ethernet and RF signals for relay to each of its associated SEBs. The output signals from the SDU were

  • baseband video and audio;
  • 48 V DC to feed the SEB power;
  • Ethernet signals to the SEBs; and
  • 48 V DC broadband RF and Ethernet signals for the next SDU along the chain.

The SDU also housed audio processing equipment. The power input requirement was 48 V DC at 0.25 A.

The SDU installed behind E-rack 2 supported the two MVDs and MTEBs.

Head-End Distribution Unit

HB-IWF had two HDUs installed. Both were mounted on the underside of
E-rack 1, one in each of bays 3 and 4. All HDUs were interchangeable.

The HDU combined the separate video and audio outputs from a modulator, injected a pilot carrier frequency for the SDU automatic gain control, and split the output four ways to provide input to four SDUs. Data input was RF signals from a modulator via an RF splitter. HDU output was RF signals to the associated SDUs, with all channels carrying the video and audio signals. The power input requirement was 48 V DC at 0.007 A.

Dual Audio Gameport

HB-IWF had 61 dual audio gameports installed—one in the armrest of each first- and business-class passenger seat. All dual audio gameports were interchangeable.

Each dual audio gameport had two external connections: a mini-DIN connector for the game controller device (mouse) and a matched set of jacks to mate with the two-pronged headphone jack. Game control and audio were transmitted between the individual SEBs and the gameport, while the gameport communicated with the passenger touchscreen and sent audio signals to the passenger's headphone set. The power input requirement was 5 V DC at 0.5 A.

In-Seat Video Display

HB-IWF had 61 ISVDs installed, one in each armrest compartment between each pair of seats in the first- and business-class passenger sections. All left-hand ISVDs were interchangeable and all right-hand ISVD were interchangeable.

The ISVD was an integrated unit that combined a touchscreen, a magnetic card reader, and a 10.4-inch diagonal LCD. The LCD is a thin-film transistor with a resolution of 640 X 480 dots and "True Colour" capability. There were on-screen buttons to make video and audio selections via the SEB. The power input requirement was 5 V DC at 2 A.

Cluster Controller

HB-IWF had six CCs installed. All were mounted on the underside of
E-rack 1, two each in bays 5, 6, and 7. All CCs were interchangeable.

Each CC managed one SEB cluster network by coordinating all the network administrative tasks. The core software linked each SEB network to the CFS. The power input requirement was 48 V DC at 0.42 A. The CC included

  • a custom motherboard with a Pentium 100 MHz processor;
  • a 340 MB HDD; and
  • 32 MB of RAM.

Network Switching Unit

HB-IWF had one NSU installed, located in Bay 1 of E-rack 2.

The NSU is the hub for the IFEN administrative network. It provides network links for the CFS, CCs, UNC (integral to the VOD), and MTEB. The power input requirement was 48 V DC at 2 A.

Video on Demand

HB-IWF had one VOD, installed in Bay 5 of E-rack 1.

The VOD extracted the movie and music data from the DAU, performed the MPEG decoding, and passed it on to the RF modulators. The VOD could support two DAUs and functioned in an IFT proprietary processing environment. The audio-on-demand was a function incorporated within the VOD, essentially using the VOD capabilities to select and distribute audio. The power input requirement was 48 V DC at 5.3 A. Each VOD included

  • 8 embedded-processor MPEG decompression cards;
  • 8 processors per card; and
  • 64 video streams.

The UNC, which was incorporated within the VOD, was responsible for the coordination of the embedded processors; it handled the interface with the IFEN administrative network and the core software. The UNC included

  • a Pentium 100 MHz processor;
  • a 340 MB HDD; and
  • 32 MB of RAM.

The VOD was also equipped with a removable disk pack, which was the interface for uploading movie data.

32-Channel Modulator

HB-IWF had two 32-channel modulators installed. Both were mounted in
E-rack 1, one in each of bays 3 and 4. All 32-channel modulators were interchangeable.

The modulators converted the baseband video and audio from the VOD to broadband RF and transmitted (distributed) the RF signal through the HDUs to the SDUs for display on the ISVDs at the passenger seats. Two modulators were used per VOD, one for odd-channel modulation and the other for even-channel modulation. There was no resident software in these modulators. The power input requirement was 48 V DC at 3.3 A.

13-Channel Modulator

HB-IWF had one 13-channel (common) modulator, installed in Bay 7 of
E-rack 1.

The common modulator performed the same function as the 32-channel modulator. It converted the baseband video from the VOD to broadband RF and transmitted (distributed) the broadband video to the SDU for display on the ISVDs at the passenger seats. The common modulator was used to distribute video and audio common to the entire aircraft, such as the moving map system and videotape reproducers. There was no resident software in this modulator. The power input requirement was 48 V DC at 1.5 A.

Management Video Display

HB-IWF had two MVDs installed, one in each of galleys 1 and 8. Each MVD was mounted on the bulkhead, facing the rear of the aircraft.

The MVD provided an interface to the IFEN system for cabin crew and maintenance personnel. It connected to the administrative network and served as a point of control for configuring, maintaining, and monitoring the IFEN system. The MVD was an integrated unit that combined a touchscreen, a magnetic card reader, and a 10.4 inch diagonal LCD. The LCD was a thin film transistor with a resolution of 640 X 480 dots and "True Color" capability. There were on-screen buttons to make selections, and data input came from the MTEB. The power input requirement was 5 V DC at 2 A.

Management Terminal Electronics Box

HB-IWF had two MTEBs installed, one in the upper portion of each of galleys 1 and 8.

The MTEB was the primary functional component interface to the IFEN system by the cabin crew and maintenance personnel. The power input requirement was 48 V DC at 0.42 A. The MTEB included

  • a Pentium 100 MHz processor; and
  • a 340 MB HDD.

Video Distribution Unit

HB-IWF had two video distribution units installed—both behind an overhead panel in front of Galley 8, between FS 735 and FS 755. Access to these units was through the flat overhead panel in front of Galley 8.

The video distribution unit permitted video signals to be broadcast simultaneously on the IFEN system and on aircraft video equipment, such as the overhead monitors. The video distribution unit had two separate video inputs, one from the Air Show unit and one from the aircraft video system (e.g., Safety Video). The power input requirement was 28 V DC at 0.15 A.


HB-IWF had a standard commercial full-format printer. This was located on a shelf in Galley 8.

The printer was connected to the CFS and was used to print a variety of reports for passengers and for maintenance. It provided 300 dots per inch at a speed of 120 to 180 lines per minute. The power input requirement was 115 V AC at 400 Hz.


System performance was achieved by clustering sets of passenger interface processors on a local network where the CC handled master system-level network administration and traffic for its collection of processors. The use of specialized digital signal processing software was limited to the areas of in-stream high-rate video signal processing. This was necessary for effective VOD data storage and retrieval. The design concept allowed the effective use of standard operating systems and network protocols in the architecture. The user interface processing capability and the touch screen control and display device simplified passenger use. The IFEN system interfaced with other standard cabin subsystems such as videotape reproducers and moving map systems. Centralized database management and overall system control was accomplished by the CFS on the primary system administrative network.

Network Architecture

The IFEN's fast Ethernet-type WAN was centrally controlled by the CFS. The CFS controlled several CCs and each CC could control up to 32 ISVDs. All the CCs are interconnected with the CFS in the top-level administrative WAN. The hub of the WAN was the NSU. The NSU maximized the data throughput of the WAN by providing an intelligent switching matrix which routed data packets between the CCs, VODs, and the CFS. Since the CFS resided on the administrative network, database updates used a "store and forward" technique from the CC, rather than real-time links to the CC or MVD.

The Swissair IFEN Maintenance Manual, dated 2 September 1997, stated that "the failure of the CFS is not critical to the operation of the WAN, since each CC will continue to operate autonomously without the CFS, and none of the ISVDs will be affected."

Each CC was interconnected with its ISVD in a low-level ethernet-type LAN. Each LAN operated independently of all the other low-level LANs on the aircraft. Consequently, the failure of an individual ISVD would have no effect on the operation of the rest of the ISVDs on the aircraft. Additionally, the failure of an individual CC would only affect that CC's ISVDs.

[1]    IFE is used when describing generic in-flight entertainment systems.

[2]    Date Performed as identified in SR Technics Status List of Engineering Orders for HB-IWF.

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