EMB ERJ 145 ER/LR
Maintenance Airframe; Maintenance Powerplant; Maintenance Avionics
Communication Breakdown; Time Pressure; Troubleshooting
Aircraft Equipment Problem Critical
General Maintenance Action
Company Policy; Human Factors; Manuals; Aircraft; Procedure
May 2012; at XA:00 am at our Air Carrier Hangar at ZZZ airport. I was working an EMB-145 aircraft for a repeat discrepancy of a Parking Brake 'On' light remaining 'On'; after disengaging the brake. I ended up finding wire # W504 had about 2k Ohms resistance with no [voltage indication] connections on either side. I flexed the wire while sending 50v (Volts) through it to Ground; to try to find the short and it spiked and dropped about 12' inches back from the Connector P0528 near some friction tape from an old repair. I removed the friction tape exposing about 6' inches of the harness and found excessive moisture in the harness. The water ran out and formed a small puddle on the ground. I showed the finding to a fellow Mechanic working with me. I determined that the best course of action would be to replace the entire harness rather than just dry the water since I was unable to determine how far the water had wicked into the harness and the possibility of internal corrosion to the wires.The Harness (W504) runs most of the length of the left-hand (L/H) wing and connects to every system along the way; including spoilers; fuel; hydraulics; brakes; et cetera (etc.).  Since the moisture caused a fault in the Parking Brake System; I decided that the options available were to dry the harness and verify the integrity of all of the wires in the harness; or to replace the harness entirely. At this time; my Shift was almost over (XB:45 am); so I made a Write-up of my finding and stated that the harness requires replacement. I returned to work that night and checked to see the status of the EMB-145 aircraft; [only] to find that the harness had not been changed. The harness had been dried and Connector P0528 had been replaced. The only Operational Check performed was on the Brake light to clear the fault without addressing any other wires in the harness.  The event occurred due to urgency of getting the plane out quickly rather than taking the time to either replace the harness of to determine the impact the other affected wires in the harness and the systems tied to them. An occurrence of this event could be avoided if more emphasis was placed on keeping the planes in optimal airworthy condition rather than fixing a discrepancy as quickly as possible. Routine Overnight (RON) maintenance.
Reporter stated he works as an Avionics Mechanic a lot and the electrical harness he was referring to also included six to seven position indication wires involving spoilers; fuel; hydraulics and brake systems. There was a heavy amount of accumulated water in the harness. Reporter stated the event he was referring to; had to do with his Maintenance department drying out one area of the electrical harness instead of replacing the entire water saturated harness. He would not be surprised if phantom faults showed as a result of water that still permeated the harness assembly. He has replaced the same electrical harness in the past for chafed wires in the wheel well.
A Technician reports he found an electrical harness that had become water saturated at a previous wire repair on an EMB-145 aircraft. The water saturation appeared to be one of the causes of a repeat discrepancy for a Parking Brake light that remained 'On' after the Parking Brakes were released.