EMB ERJ 145 ER/LR
Maintenance Airframe; Maintenance Powerplant
Situational Awareness; Time Pressure; Distraction
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
MEL; Human Factors; Aircraft
September 2013. I was on an EMB-145LR aircraft troubleshooting an APU deferral and a seat Non-Essential Function (NEF) [deferral]. For the APU; the original discrepancy was the APU would not start. I closed and un-tagged the Circuit Breakers labeled 'APU CONTROL' located on the overhead Circuit Breaker Panel and on the small panel behind the captain's seat. I attempted to start the APU; but to no avail. I proceeded to [also] look at a passenger seat to determine what parts we needed to order to fix it. I completely forgot to pull the 'APU CONTROL' breakers again. I exited the aircraft and called Maintenance Control to tell them about the seat NEF. They asked me to look at the part number on the seat. I went back out to the aircraft to write down the Part Number. By this time they had started boarding the aircraft. I quickly got the part number off of the seat and returned to the office to call Maintenance Control back and give it to them. After I got off the phone; a coworker asked me if I re-opened those circuit breakers for the APU. Realizing I forgot to do that; I ran back out to the aircraft. They were finished boarding at this point. I entered the cockpit and told the crew I forgot to pull the circuit breakers. I then pulled and collared the 'APU CONTROL' breaker on the upper control panel and what I thought was the 'APU CONTROL' Breaker behind the captain's seat. I was in a rush and didn't read the legend well enough. I actually pulled the 'APU START' Breaker instead. I told the crew I pulled the correct breakers (thinking that I had); but I later found out I had not. MEL 49-00-00 clearly states which breakers to pull to defer an APU. I was in too much of a rush and didn't verify which breakers I had pulled and collared. This is very uncharacteristic of me as I usually double check everything I do. The bottom line is I was in a hurry and failed to verify the correct circuit breaker was pulled. I take full responsibility for my actions. In the future; I will be sure not to let myself rush through things like this. Something this simple can be prevented by not letting myself get in too much of a rush to verify my work. [Maintenance] procedure not followed.
A Line Aircraft Maintenance Technician (AMT) was informed he had pulled the 'APU Start' Circuit Breaker (C/B) instead of re-tagging and re-opening (pulling) the 'APU Control' Circuit Breakers on an EMB-145LR aircraft. Technician noted he was rushing and distracted with a passenger seat Non-Essential Function (NEF) deferral.