B737 flight crew reported severe turbulence on approach causing momentary loss of control and flap overspeed.
Synopsis
B737 flight crew reported severe turbulence on approach causing momentary loss of control and flap overspeed.
Narrative
Weather throughout [the state] was terrible; heavy rain and moderate turbulence. Numerous aircraft were holding due to weather conditions at ZZZ. We received clearance for ILS XXL and proceeded inbound. Around ZZZZZ intersection we hit turbulence strong enough to kick off the autopilot. Windshear was +/- 30 knots and we could not maintain a stabilized descent so a go-around was conducted at 2300 ft AGL. We considered returning for a second attempt but the weather was worsening so we elected to divert to ZZZ1. The remainder of the flight was uneventful and we landed in ZZZ1 with 7000 FOB (fuel on board). During the approach into ZZZ I felt that we successfully dealt with the wind shear and turbulence; however several days later I received a call from the company stating that a flap overspeed had occurred. Our configuration at the time of the exceedance was gear down with flaps 15; and the data recorded an overspeed of 14 knots. Im not entirely surprised that I failed to notice the overspeed; as the turbulence was strong enough to prevent a consistent focus on the flight instruments. Since I was not aware of the overspeed no entry was made in the maintenance logbook.
Second reporter narrative
Upon approach into ZZZ; we were in IMC conditions with moderate to heavy rain. Aircraft in front of us were safely making a landing. We configured earlier than usual due to weather conditions and ATC restriction. Airspeed was drastically fluctuating but no wind shear activation. Just below 2500 AGL; the aircraft jerked left; kicked off the auto pilot. I attempted to stabilize the aircraft but could not; executed a max thrust go-around to help climb out of the conditions. The entire time; I was fighting moderate to severe turbulence hand flying the aircraft knowing auto pilot would not be able to fly the aircraft. The Captain was heavily task saturated as PM; and I turned on the autopilot as soon as i safely could. ATC offered another attempt into ZZZ but was then providing heavy to extreme rain with severe turbulence to the ground. Having already discussed a diversion plan amongst ourselves and Dispatch; we executed it and diverted to ZZZ1. Upon safely landing in ZZZ1 uneventful; we discussed the events back in ZZZ. With everything going on in ZZZ on approach and the drastic changes in airspeed; we mentioned about the possibility of an overspeed condition but we didn't recall any. We determined everything we did were the proper and safe things to do.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.