Date: 201809
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class B ZZZ
Aircraft component: Flap Control (Trailing & Leading Edge)
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Second reporter function: Pilot Flying; Captain
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Weight And Balance
When detected: In-flight
Result: Flight Crew Returned To Departure Airport
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: During climb phase after a normal departure from ZZZ; at approximately FL210-FL220; I noticed the LE Flaps Transit light illuminate amber and immediately notified the Captain. As the Pilot Flying; the Captain immediately instructed for me to request a descent down to FL200 and a reduction in speed to 230 knots with ATC. The Captain remained Pilot Flying while I proceeded to run through the respective QRH for LE Flaps Transit. Upon guidance from QRH; Captain disengaged the autopilot and noticed a slight turning tendency; reaffirming that we could possibly have a #1 LE Krueger flap extended. The A Flight Attendant was then contacted and asked to inspect visually. The Flight Attendant returned and stated that she noticed something was possibly sticking out and it didn't feel right in her judgment. At that point; after assessing our risks; and in order to mitigate any further risk; we both agreed and elected a return to ZZZ due to proximity and facilities available. We coordinated with ATC; Dispatch; and Operations and headed towards ZZZ. We noted that we would be over our maximum structural landing weight and further elected to burn fuel within the vicinity of the ZZZ airport area before making an uneventful landing; while conforming with the remainder of the LE Flaps Transit QRH procedures. We taxied back to the gate after running our brake cool procedures and the flight concluded normally.


Second narrative: Climbing through FL 220 with the autopilot on; we received a LE Flaps Transit light. We checked overhead and saw a #1 Kruger flap showing full extension. We coordinated with ATC; leveled off; and descended to FL 200. While in the descent; I disengaged the autopilot and noticed a slight roll toward the #1 side. I trimmed it out; and leveled off; while the F/O (First Officer) got out the QRH. I asked the A F/A (Flight Attendant) to take a look; and she said it appeared 'something was hanging down and there was a funny sound over the wing.'I was not experiencing controllability issues; and so re-engaged the autopilot; and did not declare an emergency. We ran the QRH; talked about mitigating our risk; and decided to return receiving clearance to ZZZ. Being overweight; we had to hold for approximately one hour to burn down fuel. I appraised the Passengers; Dispatch; and ZZZ Operations of the situation. The remainder of the flight was uneventful.


Synopsis: B737 flight crew reported a flap indication problem along with controllability issues at FL210 and decided to return to departure airport.