As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LARGE DISTORTION IN PLENUM EXHAUST PIPE, 12 O'CLOCK POSITION, DID NOT EXCEED MFG LIMIT OF .50 INCH. APU REMOVED FOR REPAIR AND 2,100 HOUR OVERHAUL C/W. SUSPECT CAUSE, HOT AIR LEAK INSIDE OF PLENUM. TEAR DOWN REVEALED CRACK IN TURBINE NOZZLE.