Aviation Investigation Report A98H0003

IFEN – Wreckage Examination

  1. 8 AWG Wire
    1. Main Power Supply Wire
    2. Jumper Wire
      1. Orange
      2. White
      3. Red
  2. 12 AWG Wire
    1. Identified Wire Exhibiting Heat or Fire Damage
      1. Lower Avionics CB Panel to E-Rack 1 Location
      2. Lower Avionics CB Panel to E-Rack 2 Location
    2. Identified Wire Without Heat or Fire Damage
      1. Lower Avionics CB Panel to E-Rack 1 Location
      2. Lower Avionics CB Panel to E-Rack 2 Location
      3. Left-Hand Mid-equipment Panel to E-Rack 3 Location
    3. Unidentified Wire Exhibiting Heat or Fire Damage
    4. Unidentified Wire Without Heat or Fire Damage
  3. Assessment of Recovered PSU Cable Assemblies Exhibiting Heat or Fire Damage
    1. SDU to Galley 1 MTEB Cable Assembly
    2. IFT/VES 28V CB and Wiring Installation
      1. IFT/VES 28V (1 A CB)
      2. 16 AWG Wire
      3. Relay Assembly and Galley 8 Disconnect
  4. Line Replaceable Units
    1. E-Rack 1 LRUs
    2. E-Rack 2 LRUs
    3. LRUs from Unidentified Locations
    4. LRU Fuse Testing

8 AWG Wire

Main Power Supply Wire

None of the recovered segments of the 8 AWG wire exhibited heat or fire damage.

The following wire segments were recovered:

  • One 18 cm (7-inch) segment of orange wire, attached to terminal strip S3-600
  • One 18 cm (7-inch) segment of cable assembly, attached to terminal strip S3-674
  • Approximately 488 cm (192 inches) of white wire, recovered in varying lengths, location unknown
  • Approximately 457 cm (180 inches) of orange wire, recovered in varying lengths, location unknown
  • Approximately 483 cm (190 inches) of red wire, recovered in varying lengths, location unknown

The average measured length of the 8 AWG main power supply cable assembly from terminal strip S3-600 to the CBs installed in the lower avionics CB panel was 488 cm (192 inches). The average measured length from terminal strip S3-674 to the CBs installed in the left-hand mid-equipment CB panel was 97 cm (38 inches). Based on these measurements, 86.5% of the white wire, 84.3% of the orange wire, and 85.6% of the red wire were recovered.

Jumper Wire

None of the recovered 8 AWG jumper wire segments exhibited heat or fire damage. The following segments of the orange, white, and red jumper wires were recovered:

Orange

  • One segment was identified as the jumper wire between the PSU 3 and PSU 4 CBs on the lower avionics CB panel.
  • Two segments were identified as jumper wires from the lower avionics CB panel, location unknown.
  • Two segments were fracture matched and identified as the jumper wire between the PSU 5 and PSU 6 CBs on the left-hand mid-equipment CB panel.

White

  • Two segments were identified as jumper wires from the lower avionics CB panel, location unknown.
  • One segment was identified as a jumper wire from the left-hand mid-equipment CB panel.

Red

  • Two segments were identified as jumper wires from the lower avionics CB panel, location unknown.
  • One segment was identified as a jumper wire between the PSU 3 and PSU 4 CBs on the lower avionics CB panel or between the PSU 5 and PSU 6 CBs on the left-hand mid-equipment CB panel.
  • One segment was identified as a jumper wire, location unknown.

12 AWG Wire

Identified Wire Exhibiting Heat or Fire Damage

Lower Avionics CB Panel to E-Rack 1 Location

The following recovered segments were identified as power supply cables for PSU 1, PSU 2, PSU 3, and PSU 4:

  • Four segments, each approximately 102 cm (40 inches) long (totalling 406 cm (160 inches) each of the orange, white, and blue wire), were located between approximately STA 383 and STA 427 (these four wire segments were found intertwined). These segments exhibited areas of bare wire and melted copper resulting from electrical arcing.

The average measured length of the power supply cable assembly from the lower avionics CB panel to E-rack 1 was 1 090 cm (429 inches). The overall length of the identified recovered cable assembly is approximately 102 cm (40 inches) or 9.4%.

Lower Avionics CB Panel to E-Rack 2 Location

The following recovered segment was identified as the power supply cable assembly for PSU 3 and PSU 4:

  • One segment of the power supply cable assembly for PSU 3 and PSU 4 measured approximately 762 cm (300 inches). This segment was located between STA 690 and STA 1011 and exhibited heat damage from STA 690 to STA 720 and soot accumulation from STA 690 to STA 790.

Identified Wire Without Heat or Fire Damage

Lower Avionics CB Panel to E-Rack 1 Location

The following recovered segments were identified as the power supply cable assembly for PSU 1 and PSU 2:

  • One segment approximately 20 cm (8 inches) long, attached to an electrical plug, which in turn was attached to the EMI 2 filter box
  • One segment approximately 8 cm (3 inches) long, attached to an electrical plug, and determined to have come from E-rack 1

The average measured length of the power supply cable assembly from the lower avionics CB panel to E-rack 1 was 1 090 cm (429 inches). The overall length of the identified recovered cable assembly was approximately 8 cm (3 inches) or 0.7%. As the wire segment attached to the plug on the EMI filter box was located within E-rack 1, it was not included in the overall recovered length calculation.

Lower Avionics CB Panel to E-Rack 2 Location

The following recovered segments were identified as the power supply cable assembly for PSU 3 and PSU 4:

  • One segment approximately 165 cm (65 inches) long, attached to the plug side of an electrical connector and one segment approximately 140 cm (55 inches) long attached to the receptacle side of the same electrical connector; it was determined that the electrical connector was attached to E-rack 2 at STA 1509
  • One segment approximately 91 cm (36 inches) long, located between STA 1059 and STA 1281 on the right side of the aircraft
  • One segment approximately 163 cm (64 inches) long, located between STA 1059 and STA 1541 on the right side of the aircraft

The average measured length of the power supply cable assembly from the lower avionics CB panel to E-rack 2 was 3 876 cm (1 526 inches). The overall length of the identified recovered cable assembly was approximately 1 181 cm (465 inches) (including heat- or fire-damaged cable) or 30.5%. As the wire segment attached to the receptacle side of the electrical connector was located within E-rack 2, it was not included in the overall recovered length calculation.

Left-Hand Mid-equipment Panel to E-Rack 3 Location

The following recovered segments were identified as the power supply cable assembly for PSU 5 and PSU 6:

  • One segment approximately 356 cm (140 inches) long, located at approximately STA 1059 to STA 1281
  • One segment approximately 178 cm (70 inches) long, located at approximately STA 869 to STA 879
  • One segment approximately 112 cm (44 inches) long, attached to plug P1-7143 and located at E-rack 3
  • One segment approximately 432 cm (170 inches) long, cable-identified but location unknown
  • One segment approximately 406 cm (160 inches) long, cable-identified but location unknown

The average measured length of the power supply cable assembly from the left-hand mid-equipment panel to E-rack 3 was 2 248 cm (885 inches). The overall length of the identified recovered cable assembly was approximately 1 483 cm (584 inches) or 66%.

Unidentified Wire Exhibiting Heat or Fire Damage

The following recovered segments of the power supply cable exhibited heat or fire damage:

  • Approximately 1 438 cm (566 inches) of white wire in varying lengths, location unknown
  • Approximately 1 290 cm (508 inches) of orange wire in varying lengths, location unknown
  • Approximately 1 468 cm (578 inches) of blue wire in varying lengths, location unknown
  • Approximately 198 cm (78 inches) of 12 AWG wire in varying lengths and without insulation, location unknown

Unidentified Wire Without Heat or Fire Damage

The following recovered segments of power supply cable assembly exhibited no heat or fire damage:

  • Approximately 3 223 cm (1 269 inches) of white wire in varying lengths, location unknown
  • Approximately 4 803 cm (1 891 inches) of orange wire in varying lengths, location unknown
  • Approximately 4 034 cm (1 588 inches) of blue wire in varying lengths, location unknown
  • Approximately 43 cm (17 inches) of 12 AWG wire in varying lengths and without insulation, location unknown

Assessment of Recovered PSU Cable Assemblies Exhibiting Heat or Fire Damage

The following total recovered lengths were calculated for each colour of PSU power cable wires:

  • 1 844 cm (1 438 + 406) (726 inches (566 + 160)) of white wire were recovered. This measurement represents approximately 461 cm (1 844/4) (181.5 inches (726/4)) of each PSU power cable.
  • 1 696 cm (1 290 + 406) (668 inches (508 + 160)) of orange wire were recovered. This measurement represents approximately 424 cm (1 696/4) (167 inches (668/4)) of each PSU power cable.
  • 1 875 cm (1 468 + 406) (738 inches (578 + 160)) of blue wire were recovered. This measurement represents approximately 469 cm (1 875/4) (184.5 inches (738/4)) of each PSU power cable.

The overall average length of PSU power cable exhibiting heat or fire damage was approximately 451 cm ((461 + 424 + 469)/3) (177.5 inches ((181 + 167 + 184.5)/3)). If all of the wires exhibiting heat or fire damage were located in the same area, then this average length of PSU power cable would fit between approximately STA 383 and STA 506. This measurement does not include the 198 cm (78 inches) of 12 AWG wire that were recovered without insulation and that could not, therefore, be identified by colour.

SDU to Galley 1 MTEB Cable Assembly

The following recovered segments were identified as originating from the SDU to the Galley 1 MTEB cable assembly:

  • Three segments exhibiting heat or fire damage, measuring approximately 188, 135, and 158 cm (74, 53, and 62 inches), location unknown
  • One segment approximately 1 054 cm (415 inches) long, attached to additional IFEN wiring, exhibiting heat or fire damage to the forward 25 cm (10 inches) of cable, and located from STA 690 to STA 1100

IFT/VES 28V CB and Wiring Installation

IFT/VES 28V (1 A CB)

The 16 AWG jumper wire was recovered with one end attached to a portion of the F2 CB and the other end attached to the terminal of the "IFT/VES 28V" 1 A CB. Neither the wire nor the CB portions exhibited heat or fire damage.

16 AWG Wire

Four segments of tin-coated 16 AWG wire were recovered, each exhibiting an area of melted copper resulting from electrical arcing. Although no wire marking could be distinguished, there was sufficient insulation adhering to these four segments to identify them as portions of wire PN 50013-102, which was installed from the "IFT/VES 28V" 1 A CB to the Galley 8 disconnect. Two segments also had conduit material adhering to them.

These four wire segments were recovered intertwined within the same bundle of wires as the 12 AWG power supply wires that exhibited signs of electrical arcing. PN 50013-102 is the only wire of its type and size within the same area as the 12 AWG wires, located between STA 383 and STA 506.

Relay Assembly and Galley 8 Disconnect

The following recovered components of the relay assembly and Galley 8 disconnect were identified. None exhibited heat or fire damage.

  • Relay assembly PN 80010-101
  • Plug P1-7350, attached to the relay assembly
  • Two segments of the 16 AWG wire and 27 segments of the 20 AWG wire, attached to plug P1-7350 and insulated with ETFE insulation
  • One of the 16 AWG segments from the "IFT/VES 28V" 1 A CB (origin determined based on the pin location of the short length of remaining wire attached to the plug), insulated with M22759/16 type insulation
  • Galley 8 disconnect, including wire segments

Line Replaceable Units

E-Rack 1 LRUs

The following recovered components did not exhibit heat or fire damage:

  • EMI filter box for PSU 2
  • One 32-channel modulator

All of the following recovered components exhibited heat or fire damage:

  • HDU 1 and HDU 2, both exhibiting soot accumulation
  • One 32-channel modulator, exhibiting soot accumulation on its internal ribbon cables
  • Portions of the VOD, some pieces exhibiting soot accumulation
  • Two CCs, both exhibiting soot accumulation
  • Common modulator, exhibiting soot accumulation on the internal ribbon cables and the chassis

E-rack 2 LRUs

The following components were recovered. None exhibited heat or fire damage.

  • PSU 3
  • EMI filter box for PSU 4
  • Portions of the NSU
  • E-rack 2 CB panel

LRUs from Unidentified Locations

The following recovered components did not exhibit heat or fire damage.

  • Chassis from an unidentified PSU
  • EMI filter box

The following recovered component exhibited heat or fire damage:

  • Internal modules for an unidentified PSU, exhibiting soot accumulation

LRU Fuse Testing

All fuses from recovered LRUs were inspected and determined to be in serviceable condition.

Date modified :
2012-07-27