As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AN ACRID SMELL OF FUMES WERE NOTED IN THE COCKPIT AT THE START OF THE APU. FLIGHT ATTENDENTS ALSO REPORTED A "LOUD POP " (NOISE) IN THE REAR OF THE AIRCRAFT. C/W NO GO ODI PREVENTION PROGRAM. INSPECTED APU WITH NTF. FOUND CLAMP LOOSE AND DUCT SEPARATED RT TRIM AIR VALVE. SECURED .(5057198).