As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED AFTER TAKEOFF, THAT THE "MAIN AIR VLV 1" LIGHT ILLUMINATED. AFTER RUNNING THE CHECKLIST IT WAS DETERMINED THAT THE NR 1 MAV DID NOT FULLY OPEN AND WOULD NOT CLOSE AND THE NR 1 MAV CB WAS FOUND TRIPPED. TROUBLESHOOTING FOUND THE NR 1 MAV TO BE DEFECTIVE AND WAS REPLACED WITH O/H UNIT.