Date: 202103
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Dawn
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Exterior Pax/Crew Door
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural FAR
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate
Result: Flight Crew Overcame Equipment Problem; Flight Crew Returned To Gate; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Procedure; Aircraft; MEL
Primary problem: Procedure

Narrative: Prior to performing the engine start checklist; we noticed the main cabin door was not indicating closed. We asked the Flight Attendant to try to reopen and close the door and after multiple attempts it would not show closed so we called Maintenance. To my surprise; they offered to defer it under MEL52-3-1 without sending Maintenance to the aircraft. In my experience; mechanics have always gone over to the aircraft whenever there are issues relating to the main cabin door so I found this a little odd. We reviewed the MEL and Maintenance Control asked about nuisance messages which did not exist at the time; so we put the MEL in the logbook but shortly after I realized that we did not have any nuisance messages because we did not have engine 1 running which would prompt a Master Warning MAIN DOOR OPEN. We went back to Maintenance Control and discussed how the maintenance action required to remove the micro switches was required because once we start engine 1 the system logic will generate a MAIN CABIN DOOR EICAS warning. They argued that was not a 'nuisance' because it was only going to triple chime once and not continuously and I had to reiterate multiple times that a Master Warning EICAS being displayed is inappropriate and a distraction/nuisance. I was passed over to the Maintenance Supervisor; and another Maintenance Control person who all seemed generally confused with what I was talking about. I suspect they misunderstood the system logic or which door we were deferring because they said they issue this MEL '2-3 times a week' which I highly doubt. Eventually; we told them they need to send a mechanic out because we had already made a PA that the aircraft would need to be inspected by Maintenance. A mechanic came out and removed the micro switches faster than it took to stay on that circular conversation with Maintenance Control. Shortly after applying the MEL and pushing back; we started engine 1 and MAIN DOOR OPEN EICAS warning presented. This was extremely confusing because that message should not appear when the micro switches are removed; similar to when they perform that same procedure on the bag door micro switches. Additionally; when a message is going to be displayed after an MEL is applied it usually includes that information as a note on the MEL; like with MEL 21-13. I called a friend in Flight Technical for some clarification on why that message appeared and he agreed it should not be present and it was possible the maintenance action was not done appropriately because an Embraer manual shows the need to remove 4 micro switches but the AMM Task only has the Mechanic remove 2. I called Maintenance Control again and explained the situation; and the supervisor was adamant the AMM Task was completed correctly and only required the removal of 2 micro switches and reiterated multiple times that the message should be displayed because the micro switches were removed. At this point; we had been racing against a DOT 3 hour limit clock and an FAR 117 max duty time limit; so we elected to take the aircraft because the supervisor confirmed all maintenance actions required of this MEL had been completed; we verified compliance with the MEL; and we knew why that message was presented.Either there is a discrepancy with the AMM that doesn't tell them to remove all of the required micro switches or the MEL should include a note that says the Master Warning displayed. Accepted aircraft after confirmation from Maintenance Control Supervisor that there was no other option to make the EICAS Master Warning extinguish. First of all; is this an MEL we really want our planes flying multiple days with? The aircraft flew an entire day the following day; so this MEL was not applied to get the aircraft to a maintenance hub. If we had an RTO (rejected takeoff); how would I know which door is really opened and closed? That's literally why we have the door pages up during takeoff. Next; the company needs to investigate the inconsistency withthis MEL not saying the EICAS warning should be present or the improper maintenance action that caused it to appear.




Synopsis: Captain reported confusion over MEL procedures and aircraft condition during preflight; but elected to take the aircraft.