As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU INOP. PERFORMED BITE PROCEDURE OF APU ECU IAW AMM 49-61-05, NO FAULTS FOUND AND APU OPERATES NORMALLY. MCC REQUESTS REPLACEMENT OF GCU. REMOVED AND REPLACED APU GCU IAW AMM 24-22-02. PERFORMED OPS CHECK OF APU GCU AND BITE CHECK. NO FAULTS FOUND, OPS CHECK GOOD.