EMB ERJ 135 ER/LR
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Flight Crew Returned To Departure Airport; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft; Procedure
Based on the final cockpit scan as directed by AOM1 (Aircraft Operating Manual); me and the Captain checked the circuit breakers were in closed or out and collared; after takeoff we had a LG/LEVER DISAGREE we [requested priority handling] and followed the procedures back to ZZZ. I meet the maintenance guys at the bridge and I heard from them taking to the Flight Attendant that they were working on the same problem we had (landing gear not retracting).I understand that the reason behind the LG/LEVEL DISAGREE was a circuit breaker was pulled out and collared based of AOM1 when I checked the circuit breaker in the cockpit safety scan I ensures that all breakers are IN (closed) or OUT(collared). I will take my time to check each collared circuit breaker before flying the aircraft.
EMB-135 First Officer reported overlooking a circuit breaker that was pulled and collared by Maintenance and caused an Air Turnback when the landing gear would not retract.