As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN PERFORMING THE REVERSE FLOW PROTECTION CHECK THE LT NR 1 ENG APPEARED TO HAVE A COMPRESSOR STALL & WENT SUB-IDLE & STAYED THERE WITH BOTH ENG BLEED VLVS OPEN. THE ISOLATION VLV OPEN & BOTH THROTTLES INITIALLY AT IDLE THE DUCT PRESS WAS NORMAL AROUND 15 PIS INCOMPLETE. R & R NR 1 ENG REVERSE FLOW CHECK CONTROLLER. OPERATIONS CHECKED GOOD ON ENG RUN IAW AMM 36-11-18 & JRH 2-5-1.