B737-800 flight crew reported a right pack failure and loss of pressurization on climb out at 12;500...

Narrative:

During climbout...passing 12;500' the right pack light illuminated. I continued to climb to approximately 14;000' and then immediately descended back to 10;000' MSL and initiated the QRH. As the QRH steps were accomplished and the outflow valve was opened; significant pressure bumps occurred. The cabin pressure never exceeded 10;000'. At about 10;500' MSL and leveling at 10;000'; the cabin altitude warning light illuminated and horn sounded. The cabin altitude warning light qrc was initiated but the cabin altitude was below 10;000' so the mask were not donned. The cabin altitude was climbing so I directed the first officer to close the outflow in accordance the cabin altitude warning QRH. After the cabin pressure was finally stabilized and return [to departure airport] was initiated. The flight attendants reported that a passenger (small child) was experiencing a bleeding nose a possibly bleeding ear. An overweight landing...was accomplished at approximately 149;000 pounds.

Original NASA ASRS Text

Title: B737-800 flight crew reported a Right Pack failure and loss of pressurization on climb out at 12;500 feet with subsequent return to departure airport after regaining control of pressurization.

Narrative: During climbout...passing 12;500' the right pack light illuminated. I continued to climb to approximately 14;000' and then immediately descended back to 10;000' MSL and initiated the QRH. As the QRH steps were accomplished and the outflow valve was opened; significant pressure bumps occurred. The cabin pressure never exceeded 10;000'. At about 10;500' MSL and leveling at 10;000'; the Cabin Altitude Warning light illuminated and horn sounded. The Cabin Altitude Warning light QRC was initiated but the cabin altitude was below 10;000' so the mask were not donned. The cabin altitude was climbing so I directed the First Officer to close the outflow in accordance the Cabin Altitude Warning QRH. After the cabin pressure was finally stabilized and return [to departure airport] was initiated. The Flight Attendants reported that a Passenger (small child) was experiencing a bleeding nose a possibly bleeding ear. An overweight landing...was accomplished at approximately 149;000 pounds.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1477136
Time
Date	201708
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.TRACON
State Reference	US
Aircraft 1
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Air Conditioning and Pressurization Pack
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	First Officer Pilot Not Flying
Experience	Flight Crew Last 90 Days 159
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy Flight Deck / Cabin / Aircraft Event Illness

B737-800 flight crew reported a right pack failure and loss of pressurization on climb out at 12;500 feet with subsequent return to departure airport after regaining control of pressurization.