As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 0224 - SMF - FLIGHT CREW HEARD A LOUD "BANG" AFTER TAKE OFF/CLIMB - E1 LOSING POWER AS INCREASING ALTITUDE TO SMF AND DID AN AIR-RETURN AND DID NOT DECLARE AN EMERGENCY. MAINTENANCE FOUND OUTER BYPASS PANEL BLOWN OPEN AT 11 O`CLOCK. MAINTENANCE REINSTALLED OUTER BYPASS PANEL. OPERATIONALLY AND LEAK CHECKED SATISFACTORY AND ACFT WAS RELEASED TO RETURN FOR SERVICE. (S)