Date: 201705
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Weather elements / visibility: Rain
Light: Night
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Aircraft component: AC Generator/Alternator
Component problem: Malfunctioning
Reporter organization: Contracted Service
Reporter function: Technician
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Troubleshooting
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Routine Inspection
Result: General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Human Factors

Narrative: I was assigned to work on [a] EMB145. It was my first time installing an engine driven generator and I have the appropriate tech data with me. It was raining when I was removing and replacing the #3 generator. When I got the original generator off the aircraft; I transferred the exhaust ducting to the new generator and installed the o-ring I found in the box onto the new generator after coating with some engine oil from my fingers. Whenever I got back to the engine to reinstall the generator it was very difficult to align into the flexible ducting then align the spline into the engine receptacle. I reached up to the spline to turn it and get it aligned. Once I got it aligned and after some shimmying; the generator slotted into the engine easily. I reattached the exhaust clamp and the flexible ducting clamps and tightening them to secure them. Then we ops checked the generator by starting both engines (which we were doing to get some run-taxi engine run training in) then shutting off all generators except the #3. The ops check passed and we shut everything down except the APU so there would still be power on the plane. After that; I got back out to the engine to finish up the job by safetying the exhaust ducting clamp and safetying the mounting clamp. I did not notice any kind of oil build-up or leakage at this time. There was also no oil on the ladder under the engine. After safetying those clamps and closing up the engine cowling; we got back in the Transit vehicle and drove back to the hangar. I signed off the routine work-order and signed the materials transaction tag; gave the soft copies to Quality control inspector and included the hard copy with the old part. When I was informed of the fault event; I immediately got in touch with my manager; the maintenance representative; and one of the quality control inspectors [to file a] report.I might have knocked the o-ring off when installing the generator or maybe it got caught up in between the spline and the engine receptacle or when I attached the o-ring; it might not have been as secure as I thought it was and came off during installation or transport from the vehicle to the engine.Possibly make the engine leak check longer so that any leakages might have enough time to present themselves. Possibly more rain protective gear or shelter (hangar space) so that the weather isn't distracting or decrementing work.




Synopsis: An EMB-145 Maintenance Technician reported oil leaked from a generator that was recently replaced.