A mechanic reports he inadvertently swapped two wires at a P-6 panel terminal bus; on a B737-800; du...

Narrative:

During the process of complying with engineering order XXX revision X step 10 termination of wires at TB5060G; I inadvertently swapped 2 wires during the installation procedure. Even though continuity was performed per engineering order (eo) XXX; revision X; step 17; this procedure did not reveal the incorrect wiring at TB5060G. As a result; log page #XXX was generated in mar/09 that revealed a problem was created. Performing continuity per engineering authorization revision X; step 17; as written; will not confirm that proper wiring was performed at TB5060G. Callback conversation with reporter revealed the following information: reporter stated the eo directs a retrofit program for future expansion of in-seat power that would allow passengers to connect their computers or other portable devices requiring 115 AC electrical power. Two separate; single type outlets; similar to that used in any home; will be installed under each three-seat row. Each row will also have a bluish colored light that will illuminate; whenever any electrical outlet in a row is in use. Power to these outlets will only be available above 10;000 ft; or when the ground service bus is powered. He was unsure if the power shutoff to these outlets would be through the inflight entertainment system. Reporter stated that part of the eo requires the forward galley to be moved away approximately six inches; to access the outboard side of the P-6 panel to cut and re-crimp a #8 gauge wire to a specific terminal bus. The P-6 panel is actually on the aft side of the circuit breaker panel behind the first officer's seat. Reporter stated a completely separate 'B' check; requiring mechanics to check a different electrical system; had failed; after he had inadvertently swapped the two wires. It was during the troubleshooting procedure for the failed 'B' check item; that mechanics found the swapped wires at the bus. Reporter stated that led him to understand and explain to his supervisor; the electrical continuity check in the eo procedure was inadequate; and would always show continuity; because they were ringing out the system from one bus to another. Reporter stated his supervisor; who had avionics experience; understood immediately and agreed a procedure change was necessary in the eo.

Original NASA ASRS Text

Title: A Mechanic reports he inadvertently swapped two wires at a P-6 panel terminal bus; on a B737-800; during the process of complying with an Engineering Order (EO).

Narrative: During the process of complying with Engineering Order XXX Revision X Step 10 termination of wires at TB5060G; I inadvertently swapped 2 wires during the installation procedure. Even though continuity was performed per Engineering Order (EO) XXX; Revision X; Step 17; this procedure did not reveal the incorrect wiring at TB5060G. As a result; log page #XXX was generated in Mar/09 that revealed a problem was created. Performing continuity per Engineering Authorization Revision X; Step 17; as written; will not confirm that proper wiring was performed at TB5060G. Callback conversation with Reporter revealed the following information: Reporter stated the EO directs a retrofit program for future expansion of in-seat power that would allow passengers to connect their computers or other portable devices requiring 115 AC electrical power. Two separate; single type outlets; similar to that used in any home; will be installed under each three-seat row. Each row will also have a bluish colored light that will illuminate; whenever any electrical outlet in a row is in use. Power to these outlets will only be available above 10;000 FT; or when the Ground Service Bus is powered. He was unsure if the power shutoff to these outlets would be through the Inflight Entertainment System. Reporter stated that part of the EO requires the forward galley to be moved away approximately six inches; to access the outboard side of the P-6 panel to cut and re-crimp a #8 gauge wire to a specific terminal bus. The P-6 panel is actually on the aft side of the circuit breaker panel behind the First Officer's seat. Reporter stated a completely separate 'B' check; requiring mechanics to check a different electrical system; had failed; after he had inadvertently swapped the two wires. It was during the troubleshooting procedure for the failed 'B' check item; that mechanics found the swapped wires at the Bus. Reporter stated that led him to understand and explain to his Supervisor; the electrical continuity check in the EO procedure was inadequate; and would always show continuity; because they were ringing out the system from one Bus to another. Reporter stated his Supervisor; who had Avionics experience; understood immediately and agreed a procedure change was necessary in the EO.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	832472
Time
Date	200902
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	B737-800
Flight Phase	Parked
Component
Aircraft Component	Electrical Distribution Busbar
Person 1
Function	Technician
Qualification	Maintenance Airframe Maintenance Powerplant
Experience	Maintenance Avionics 20 Maintenance Repairman 20
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural FAR Deviation - Procedural Maintenance Deviation - Procedural Published Material / Policy

A mechanic reports he inadvertently swapped two wires at a P-6 panel terminal bus; on a B737-800; during the process of complying with an engineering order (eo).