As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON GROUND, CABIN DOOR WAS PROPERLY CLOSED AND LATCHED. DOOR LIGHT OUT. AFTER TAKEOFF AND DURING CLIMB, HEARD A RUSH OF AIR. DOOR LIGHT WAS ON. DOOR SEEMED TO BE LATCHED. RETURNED TO AIRPORT FOR VISUAL INSPECTION. INITIALLY NO DEFECTS NOTED. IN-DEPTH INSPECTION FOUND LATCH SPRING ON LOWER DOOR REAR LATCH PIN STRETCHED. REPLACED THE STRETCHED SPRING, PN 53827-00. OPS CHECK GOOD.