Date: 201702
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: IMC
Light: Night
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Transponder
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Time Pressure; Troubleshooting; Workload; Distraction
Second reporter function: Pilot Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
Detector: Person Flight Crew; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action; General Maintenance Action
Contributing factors: Procedure; Human Factors
Primary problem: Human Factors

Narrative: Just after leveling off at FL280 the First Officer reached back to get the last two cans of a six pack of water. As he brought it forward; one can dropped off the plastic holders and hit the center console. The can split open. I grabbed it as fast as possible but it was essentially empty. I grabbed napkins and quickly dried as fast as I could. The First Officer also grabbed napkins to help dry. It seemed that we were able to get most of the water but apparently it reached the ATC control head and number 2 VHF NAV head. ATC asked if we wanted FL320 for a reported better ride. We accepted and started our climb. ATC then said he lost our mode C and could we recycle. We looked down and saw the ATC Fail light. Switched to number 2 and ATC reported our mode C had returned. Continued the flight and descent into ZZZ. During descent into ZZZ; ATC said our transponder code had changed and gave us our number again to correct it. When I went to change it our display showed all 8888. We tried to fix but unable. The First Officer was using LNAV to ZZZZZ Intersection he wondered why it didn't capture to the Localizer. I looked over and now the number 2 NAV head showed FAIL in both active and select windows. The number one head was fine. We transferred control to me and I used the ILS on my side to descend and finish the approach. We landed visually with no further incidents. Called Dispatch and Maintenance Control to advise what had happened and made logbook entries for the two inoperative items.As it was an accident that the can fell; I think that better attention to the possibility of repeat could be prevented with positive control of the cans instead of grabbing the plastic can holders.


Second narrative: Enroute; just prior to reaching final cruising altitude; I was reaching for a water can from behind the center console when one of the two that I had picked up fell out of my hand. The can fell into the center console and split open. The Captain and I picked it up as quickly as we could; but it had already spilled water onto the console. We dried as much as possible; but ATC called us to say our mode C had stopped working. We switched to transponder 2; and this fixed the problem. We continued to monitor the console for further signs of failures; and did not note any. While being vectored to final; ATC called us to say that our transponder was displaying erroneous numbers; and we could see it was displaying all 8's. Finally; on final approach; the First Officer's flight director would not capture the Localizer. This is when we noticed that the VHF NAV 2 radio had failed. We transferred control to the Captain and landed normally. We then called Dispatch and Maintenance to tell them of our problems.


Synopsis: B737NG flight crew reported the First Officer dropping a water can on the center pedestal where is burst open and emptied. A short time later Transponder #1 and #2 NAV tuning head failed which then affected the First Officer's LNAV.