Date: 201306
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Weather elements / visibility: Thunderstorm; Rain
Light: Night
Aircraft: MD-90 Series (DC-9-90) Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Engine Borescope Plug
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter qualification: Maintenance Powerplant; Maintenance Airframe
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance
When detected: Aircraft In Service At Gate
Result: Aircraft Aircraft Damaged; General Maintenance Action
Contributing factors: Weather; Human Factors; Procedure
Primary problem: Human Factors

Narrative: We had strong storms moving through the area and were in [irregular operations] conditions. I informed my lead that I was very unfamiliar with the borescope job. My lead told me that I would learn it tonight. We got assigned the airplane around XA:00 pm; 2 hours later than normal. We were under a lot of pressure because the airplane had a first flight and had a large work package on the airplane that night. I had removed the first plug when inspection came by and told me that I had removed the wrong plug. I reinstalled that plug and continued on to remove the correct plug. Inspection came back and did their inspection. I reinstalled the borescope plugs and missed installing the plug in question. I didn't have very good lighting because I didn't have my headlight and was using my regular flashlight. I thought that I had installed the plug because earlier I had removed and reinstalled a very similar plug that was located close to this plug. It was about XF:30 am and we were feeling the pressure to finish the airplane and have it ready for first flight so that we didn't get in trouble for causing a first flight delay. A day shift mechanic ran the engines and did not note anything out of the ordinary. The discrepancy was discovered later in the day when the blow open panels on the thrust reverser were found open during a walk around at another station. I am not sure of corrective actions. I am new to the Line Maintenance environment and am still adjusting to the work and the pace. I have been very sick during my previous days off with very strong head and neck pains and had gotten very little sleep. This night and the night before we had a lot of rain and lightning coming through the airport which made it difficult to work. I have been mentally loaded down with a lot of stuff at home. I bought my first home about a month ago; [and] we have six puppies running around. My wife is having a lot of pain and lack of sleep because of ongoing dental work. I did not have good lighting and it was hard to see what I was doing. The issue in my opinion was caused by fatigue; inexperience; lack of lighting; and mental issues that come from my home life. In the future better lighting and a positive way to identify borescope plugs that have been removed such as a compartmentalized parts box to hold the individual plugs and their hardware while they are out of the engine. I will use this method in my future maintenance whether it is a company issued or personal box I keep for these purposes. I will definitely take more time to make sure my task is accomplished safely and correctly and I will do a better job of concentrating on what I am doing.


Second narrative: Our aircraft had a heavy work package; weather conditions were very bad and we started late work due to the late aircraft arrival. Neither of us had completed an engine borescope [on this model] before. While [the other AMT] was doing the borescope; I start doing the rest of our work package. [The other AMT] made a phone call to the borescope team Inspector to make sure which plugs needed to be open but he opened the wrong plug by accident. After the borescope team inspector performed his inspection [the other AMT] missed the wrong plug to install it back. We performed an engine run and leak check; and we didn't find any leak. I trusted his work and signed the inspector block. We both were working hard to put the aircraft back to service on time.


Synopsis: Following an engine borescope inspection; the Maintenance personnel neglected to reinstall a borescope plug.