As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APPROXIMATELY A 4 FT FLAME SHOT OUT OF THE APU EXHAUST UPON START UP. REMOVED FROM SERVICE. C\W OPS TEST OF APU IAW AMM TASK 49-00-00-710-801. OPS TEST GOOD. OBSERVED APU DURING START UP. NO UNUSUAL FLAME OR SMOKE NOTED . NO FAULTS IN CDS. RETURNED TO SERVICE.