Date: 201911
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight phase: Parked
Aircraft component: Horizontal Stabilizer Control
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Powerplant; Maintenance Airframe
Human factors: Time Pressure; Confusion
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Aircraft In Service At Gate
Result: General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Procedure; Manuals; Aircraft
Primary problem: Procedure

Narrative: I was assigned to Aircraft X and one of my tasks was to perform a wire inspection of the CA and FO's yoke wires to look for safety wire not pigtailed and causing chafing to the wire insulation. This also has an inspector buy back block on the job card as well. The first step is to remove the yoke boots from the Capt. and FO's yoke to look for the safety wire and chaffed wires. The CA side passed; but the FO's side had a non-pigtailed safety wire on the yoke adjust bolt and 4 chafed wires. The inspector also agreed with this and wrote down the 4 wire ident codes from the wire insulation. After receiving the 4 codes; I promptly went to the aircraft wire manual under the wire list to make sure that none of these wires were 'fly-by-wire' wires which would be labeled with a Y. All 4 of the wires listed were not Y labeled; which meant that you could repair the wire with a splice at the damaged area. Unfortunately; none of the wires were accessible easily; so me and another mechanic had to remove the J side of the cannon plug to be able to access the wires for the repair. After removing the 2 nuts and screws; the j side of the cannon plug came out. After looking at the wires again; I discovered a 5th wire with chafing damage. Not realizing that this was a Y labeled wire; I wrote down the ident code and repaired the wire. Also; 'fly-by-wire' wires are usually banded with yellow bands and labeled 'fly-by-wire.' At this time; there was no label around the wire which led me to believe that this wire was repairable. This was not the case. This was a non-repairable wire that I had just repaired with a splice and signed off as serviceable. It was brought to my attention 19 days later by one of the [union] representatives that my repair was not done correctly and was corrected by someone else.How could I prevent this from happening again? As soon as I found the 5th wire and took down the ident code; I should have immediately gone to the wire list to research the wire code. I failed to do this because I didn't see yellow bands or anything labeled as 'fly-by-wire' while in the cockpit. Even though this was taking a great deal of time to do the repair; I should have done better research on the 5th wire. I can honestly say that I will always do better research from now on. I will never let this happen again.




Synopsis: Technician reported finding 5 chaffed wires in the First Officer's control column and made an unauthorized splice repair to one wire.