As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DEPARTED AND WAS ISSUED A CLIMB CLEARANCE TO FL190. THROUGH 9000 FEET, OBSERVED THE CABIN CLIMBING TO 4000 FEET AND A LOUD RUSH OF AIR THAT SOUNDED LIKE IT WAS COMING FROM THE WINDSCREEN AREA. NO OTHER CAUTIONS OR WARNING OBSERVED IN THE COCKPIT. REQUESTED A DECENT. EXECUTED THE CHECKLIST AND UTILIZED OXYGEN AS A PRECAUTIONARY MEASURE. DECENDED TO 5000 FEET AND STOWED THE OXYGEN MASKS AND RETURNED TO DEPARTURE WITHOUT INCIDENT. DID NOT DECLARE AN EMERGENCY.