As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DIVERTED DUE TO APU FIRE INDICATION IN FLIGHT AT 12000' AND 300 KIAS. COMPLIED WITH QRH PROCEDURE & APU FIRE INDICATION EXTINGUISHED. AIRCRAFT LANDED WITHOUT INCIDENT. FOUND SURGE VALVE STUB SHAFT CLOCKED 180* OUT CORRECTED IAW BD-100 AMM CHAPT, 49-16-05. R&R EXTINGUISHER BOTTLE WITH OVERHAULED AND NEW CARTRIDGE.