Date: 201911
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Climb
Aircraft component: Main Gear
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Workload; Distraction; Troubleshooting
Anomaly: Aircraft Equipment Problem Less Severe
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Departure Airport
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Preflight; taxi and takeoff were all normal. The First Officer was the Pilot Flying and I was the Pilot Monitoring.Just after the completion of the flap retraction in our climb; First Officer called for and I ran the After Take Off Checklist. In verifying the 'Gear......Off; Lights Out' line item of the list I noticed the gear handle in the OFF position but a (GREEN) 'RIGHT GEAR' light illuminated. I completed the remaining items on the After Take Off Checklist and pointed this out to First Officer for his take on it.After some discussion we had decided to run the 'Gear Disagree' QRH Checklist. This made the most sense since the gear handle position very definitely was in disagreement with indicated right main gear position. We; however; did not have any red gear light indications. I gave both the communication and flying tasks to First Officer while I referenced the QRH and worked the Checklist on page 140.3. The checklist has three starting points with reference to the position of the landing gear lever. I began at the 'Landing Gear Lever is Off' entry point and proceeded from there. The procedure advised a maximum speed of 235 kts. and contained a note that 'If a green landing gear indicator light is illuminated on either the center main panel or the overhead panel; the related landing gear is down and locked.' From this I concluded that the right main gear had not retracted and advised First Officer to request our discretion on our speed so as to comply with the checklist restriction and stop our climb at FL200.First Officer continued with the communication and flying tasks and advised ATC of our condition while I used the 'Dispatch Call Me' prompt of the ACARS to get an ARINC frequency to consult with Dispatch and Maintenance Control. After some time we were successful at making voice contact and I explained the condition to Maintenance Control who agreed with our interpretation and also agreed that to 'cycle' the gear in this case was NOT advisable. Between myself; Dispatch and Maintenance Control; we thought the best option was to burn down to below our max landing weight and return to ZZZ. I explained this decision to First Officer and asked him to advise ATC of our intentions. I used the 'TEST' format and explained to the cabin crew that we were returning to Denver. There was; at that time; no need for any special instructions or a cabin preparation but I did explain clearly the nature of the situation and that if anything else further developed as we approached Denver I would have more for them.I made several PA announcements keeping the passengers very well informed of our condition and that we were returning to Denver.When through with all of this; First Officer and I returned to normal two pilot operations with First Officer remaining as the Pilot Flying and me as the Pilot Monitoring. With the need to burn another 2;000 lbs. of fuel to achieve our landing weight we asked ATC for a hold at a fix on our arrival and briefed for our approach at ZZZ. We also discussed some scenarios and what the plan would be if we were presented with any further complications with the gear indications when we configured to land. Through Dispatch and ATC I did [request priority handling] and request ARFF equipment to stay on the conservative side and in case our condition became more complicated as we had discussed. During our configuration to land; First Officer and I watched and listened closely as we extended the gear. No abnormal sounds or indications presented themselves and so we proceeded to a normal landing on Runway XXL where we were met by the ARFF and concluded that their services were not needed. We did however get a Master Caution and an associated 'PSEU' light on the overhead panel just after touchdown which we attributed to the gear disagreement. We taxied without difficulty to the gate. I made an ELB entry regarding our experience and spoke with our local Maintenance Techs who met usat the gate.




Synopsis: B737 Captain reported a gear retraction problem that resulted in a return to the departure airport.