Date: 201707
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: B737-700
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Flap Control (Trailing & Leading Edge)
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Overcame Equipment Problem
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: On approach I called for flaps 5. FO selected flap lever to 5. The aircraft did not slow as normally expected; so I called for landing gear; which the FO selected. The aircraft slowed a bit; but still not as normal; so I called for flaps 10. After 10 was selected and the aircraft was still not slowing properly; I noticed the flap gauge still at zero. (Note: The aircraft had been written up three times in the previous week for the same issue; which we had noted and briefed the before the flight.) We executed a go-around and notified ATC of the need for delay vectors to work the problem. We consulted the QRH; performed the Trailing Edge Flap Disagree Checklist; and executed a flaps 15 landing using alternate extension.Three observations in hindsight:After multiple write ups for the same problem under the same circumstances; a test flight after the second or third instance might have identified the problem better; since the problem did not occur on the ground at all.Enroute; we had noticed the flap gauge showing one TE (Trailing Edge) flap at '0' and the other indicating a little LESS than '0'; about a one-needle-width split (there was no other indication in terms of how the aircraft was handling that there was in fact a flap asymmetry). We figured later on that this indicated - though not factual - asymmetry may have been the cause of the failure of the flaps to move when commanded.As we looked for the proper QRH checklist; we noticed that if one went to the Trailing Edge Flap Asymmetry Checklist (as opposed to the Disagree Checklist); based on the zero/less-than-zero indication on the flap gauge; it could lead a Crew to choose to land with all flaps up; as that checklist cautions not to move the flaps with the ALTERNATE FLAPS switch; as there is no asymmetry protection. In reviewing the logbook; it appears one previous Crew did exactly that and landed with TE flaps up. The other two Crews who had written up the same aircraft each had made different choices; one landed Flaps 40; and one chose flaps 15 (as we did); with all three of us who landed using trailing edge flaps using the alternate extension feature. More explicit guidance might lead to more standardized decision-making in this kind of scenario; though keeping in mind all situations are fairly unique.

Callback: The reporter stated that he saw that the trailing edge flap indicator needles were split about one needle width. The reporter stated he did not see any maintenance action taken addressing the prior times the flaps would not operate in flight. The Reporter also stated the final fix was that they replaced the indicator and test flew the aircraft to ensure the flaps operated okay in flight.



Synopsis: B737 Captain reported a trailing edge flap malfunction while on approach.