Date: 201705
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Dusk
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Main Gear
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate; Pre-flight
Result: General Maintenance Action
Contributing factors: Human Factors; Aircraft; Procedure
Primary problem: Procedure

Narrative: I arrived at the gate at XA:15 at my appropriate show time. Captain and myself boarded and began our preflight duties.During the walk around; I noticed that the left main landing gear shimmy damper sight gauge did not have an indicator band inside the max/min lines inside the sight glass. I informed the Captain; who came out with me to look at both landing gear sight glasses in order to confirm that the left did not look acceptable. Maintenance arrived promptly after arriving; and I showed them the sight gauge and how there was no indicator band. After getting the glass cleaned up; the consensus was that the damper was either over serviced or not serviced at all. These mechanics were polite professional and a pleasure to work with.They began to work on servicing it and completing it; when the Supervisor arrived and informed me at XB:00 that the damper was serviceable and good to go.I informed the Maintenance Supervisor that I did not agree and did not feel safe with it in that position; and requested that he show me in the book where it needs to be (referring to the maintenance manual regarding the indicator gauge and where it needs to go). I was polite; tactful; and professional in my approach to the mechanic. He began to look for the serviceability limits inside the manual; and pointed to the diagrams and showing me that it was good to go. I again informed him that according to the book; there is no indicator band even showing on the gauge itself.I spoke with the Captain again and informed him of what my personal thoughts were; and that the damper was over serviced; out of limits; and needed to be fixed; and that the book was supporting my position. Captain went down to talk to the Supervisor and point blank asked him what would happen if we took the airplane in its current condition; to which he responded with 'I don't know'. The Captain said to the mechanic that the airplane was not going anywhere until it was fixed.Five minutes later they had drained some fluid out of the damper; and the indicator band was right where it needed to go. The book was signed off correctly; and no further delay was incurred. This completes my report.1. If there is any sort of disagreement between the pilots and mechanics; who becomes the deciding factor if it's right or not? Our preflight guide; IOE training; and other references say one thing; but the mechanics say another; who is the deciding factor on if it's a safe operation? There seems to be some ambiguity to it; and maybe needs some clarification. Particularly; where there are some areas of operation that are gray; such as intake fan blade blending/repair; as well as these dampers; maybe have a spot or explanation that will be clear and concise so there is no doubt.2. Where my issue is that the Supervisor was insisting that the airplane was safe to fly and airworthy; when there were a few other mechanics as well as myself (I was a mechanic in the military for almost 7 years); that all said something did not look right. The fact that there was pressure to fly and just take it and that it's serviceable; did not sit well with me. All of our guidance said that it was not serviced correctly; and therefore needed maintenance action. How can we go about eliminating the conflict from happening again? I felt bad having to challenge the mechanic and ask to see the book on the limit indicators; but had I not done so; we might have taken a particularly unsafe airplane airborne.




Synopsis: Embraer EMB-175 First Officer reported a discrepancy on the main landing gear that maintenance felt was airworthy. Eventually the issue was addressed and the flight departed.