B777-200
Maintenance Airframe; Maintenance Powerplant; Maintenance Avionics
Maintenance Avionics 12; Maintenance Technician 3
Communication Breakdown; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Human Factors
Upon opening P-110 Power Panel to install new wiring; found six relay bases installed incorrectly.  Because of improper installation of the bases; four of the installed relays were contacting panel structure or the adjacent relay.  Relay bases affected: DK23022; DK23025; DK23040; DK23041; DK23042 and DK23043.
Reporter stated he has 15 years experience; much of the time in avionics doing special wiring modifications on various aircraft for an air carrier. He was installing new wiring for Wi-Fi and passenger seatback touch screens on some of their B777 aircraft when he saw the improper relay installations in the Left P-110 Power Management Panel in the lower Main Equipment Center (MEC). Reporter stated all the relays have a common base; are installed with three screws and involve the In-flight Entertainment System (IFEs). When properly installed; there is approximately 1/4' of an inch clearance between the relays. But since the bases of the six relays were torqued at an angle and installed on the opposite side of their mounting flange; the tops of the relays were contacting the adjacent relays and chafing against the inside of the P-110 Power Panel. He suspects the six relays have been flying around in that condition for three years; possibly since the last Service Bulletin (SB) modifications involving the Cabin IFE System that brought some of their B777 up to a base standard to allow future expansion of cabin IFE equipment. The six relays were replaced and installed correctly.
An Aircraft Avionics Technician reports finding six relay bases installed incorrectly; contacting structure and adjacent relays inside the Left P-110 Power Panel located in the lower Main Equipment Center (MEC) on a B777-200 aircraft.