Date: 201204
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Aircraft component: Exterior Pax/Crew Door
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: First Officer
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Attendant
When detected: Aircraft In Service At Gate
Result: General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: We landed and taxied to the gate. The jetway pulled up to L1 and the gate agent knocked on the door. With the parking checklist completed I stepped out to use the rest room and Flight Attendant A appeared to be struggling with moving the levers to get a proper DISARMED indication on the L1 door. The green DISARMED placard was not entirely in the viewing window. The gate agent knocked again as Flight Attendant A was manipulating the levers and I saw the gate agent through the L1 window and shook my head to advise the gate agent not to open the door. When we got the proper DISARMED indication with the L1 door the flight attendant gave the thumbs up to the gate agent and she opened the door. We deplaned and Flight Attendant A mentioned; 'You might want to call Maintenance; I'm having trouble with the door'. Once the jetway was clear of passengers I asked Flight Attendant A to show me again what the problem was with the door. He shut the door and tried to arm it by moving the vent flap and arming handle down simultaneously. He applied normal force and it wouldn't move into the armed position. I stepped in to try and move the handles down and it appeared to be jammed and unable to arm. I called Maintenance and they came on board and Flight Attendant A and Flight Attendant B both demonstrated the use of the door to show the mechanic. Only when the vent flap was cycled separately would the L1 door be able to arm. After cycling the door levers in different configurations the mechanic was able to get the door to arm. It looked like we were going to be able to sign it off when Flight Attendant A checked the door with the mechanic standing by and it did not arm again. Flight Attendant A and Flight Attendant B were both uncomfortable taking passengers on a flight with a door that was not consistently working. I did my best to keep the gate agent informed of our progress to provide the best accommodation to our passengers. The mechanic cycled the handles a few more times and the door was working properly; but whenever Flight Attendant A would try the door; he would open the door; close it; and try to arm it. When he did this the door would not arm. When the mechanic cycled the handles without opening the door the handles would function properly. At this point I was concerned about the door not functioning properly in case we needed to evacuate. I asked the mechanic 'if the door doesn't function properly and then a few minutes later after several attempts it does function properly; do you think that what caused the malfunction initially has been fixed?' He said no and that these doors occasionally are known for having rigging problems and he suspected that might be the case. He decided not to sign off the door for 121 operations with emergency egress in question; but we both agreed operating; as a part 91 ferry; would be acceptable. I have been told that a condition that results in an intermittent CAS message or push button light; including flickering caution/warning lights; are to be considered possibly operating outside design parameters and therefore should be considered as a possible mechanical irregularity. While there is no CAS message or push button light; the DISARMED indication was not aligning properly and the arming lever was not functioning with consistency; which indicates a possible abnormality. The decision to not operate the flight with passengers on board is coincident with the underlying philosophy of the above and the Company policy of safety as a top priority.


Second narrative: I proceeded outside to do the post flight walkaround; and then went into the terminal to the gate podium. I was advised by the Captain and flight attendants that we would be needing maintenance to attend to a problem with the L1 cabin door. I arrived back at the aircraft later; and saw the door problem being demonstrated to the mechanic by the A Flight Attendant. As the L1 door closed; the Flight Attendant attempted to push down the vent flap and slide arming internal door handles; and the handles would not move downward to the armed position no matter how much force was applied. After many unsuccessful attempts; the Flight Attendant opened the cabin door outward; then re-closed it. Sometimes after fully opening the door and closing it again; the door would function properly. Other times; the door would refuse to arm as previously described. After deliberation with maintenance control; the mechanic indicated the he could lubricate the internal door mechanism. He did so; and successfully tested the arming and disarming of the door several more times. The A Flight Attendant once again opened and closed the door and tried to demonstrate arming the door with the internal handles; once again unsuccessfully. Due to the door's inability to correctly function at all times; and the lack of knowledge as to what was causing the defective operation; we felt that the aircraft was not acceptable for FAR 121 revenue service.


Synopsis: EMB170 Captain describes difficulties opening and arming the main cabin door as reported and demonstrated to him by the A Flight Attendant. Maintenance cannot improve the intermittent operation of the door and the aircraft is refused by the crew.