As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) APPROXIMATELY 1 MINUTE AFTER TAKEOFF, A POP WAS HEARD. AIRCRAFT LANDED BACK AT STAGING AREA. INVESTIGATION REVEALED GAS GENERATOR VENT LINE HAD COME UNDONE AT THE 'B' NUT. NUT WAS RE-INSTALLED AND TORQUED. GROUND RUN SUCCESSFULLY. AIRCRAFT RETURNED TO SERVICE.