Date: 201212
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: B777-200
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Aircraft component: Cabin Entertainment
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Avionics; Maintenance Airframe
Human factors: Communication Breakdown; Situational Awareness; Training / Qualification
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Other During Maintenance
Result: General Maintenance Action
Contributing factors: Procedure; Aircraft; Human Factors; Chart Or Publication
Primary problem: Aircraft

Narrative: During an IFE switch installation and seat conversion on B777 aircraft; while accomplishing the above listed Service Bulletin (SB) ; wires are added to the P320 panel [in the Main Equipment Center].  I have been involved directly with this SB on several aircraft.  Out of curiosity I wanted to check on how the [P320] panel modification looked after being returned to service and in December 2012; I had the opportunity to inspect Aircraft X; a B777-200; then in C-Check at ZZZ Dock-1.  Upon looking inside the panel I noticed that there appeared to be an interference issue with the main [electrical] bundle that runs up and down the inside of the panel door; near the hinge.  It is my belief that this may cause a potential for arcing or the possibility of fire.  I subsequently notified the Lead Mechanic on the conversion [project] of the potential issue on Aircraft X to insure that the problem will be address on that aircraft.

Callback: Reporter stated their Engineering Department is currently evaluating what protective measures would address the wire bundle chafing he noticed when he opened-up the P320 Ground Service/Handling Power panel in the Main Equipment Center on a B777 aircraft. The P320 door has Circuit Breakers (C/Bs) mounted on the inside of the door; breakers facing forward; through cutouts in door panel. Electrical wires are attached to the aft side of the C/Bs and become a larger bundle as the wires are clamped together and routed to the top of the door near the door hinge. As the wire bundle turns inward; near the door hinge; approximately eight inches of wires are flexing; not clamped before the another clamp secures the bundle. There are four horizontal support rails inside the panel box that run fore and aft; have nut clips on them that are used to clamp and secure the bundles coming off the door. The forward end of the rails are very close to the door hinge and that location is where he found the wire bundle chafing up against the rails when the door is closed.Reporter stated the wire bundle on the inside of the P320 Power panel has increased in size since 1994; especially with the new seat modifications and a Service Bulletin (SB) that adds a power shut-off switch in the Flight deck for the In-flight Entertainment System (IFE) near the Cabin Utility switch panel. The increase wire size contacts the support rails in the box. He would like to see a Fleet campaign where all B777s with IFE Service Bulletin and seat modifications wires that were added to the P320 panel; be checked for chafing due to an interference fit concern for arcing and possible fire.



Synopsis: An Avionics' Technician reports finding an electrical wire bundle chafing inside a P320 Ground Service/ Handling Power panel at the door hinge area; in the Main Equipment Center; on a B777-200 aircraft. Additional wires for an IFE power cut-off switch Service Bulletin (SB) and seat modifications increased the bundle size raising concerns about arcing and possible fire.