As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
A/C DUCT SPLIT PRESSURE DIFFERENTIAL 20 PSI RIGHT DUCT 17, LT DUCT 37. ACFT GROUNDED. REPLACED PRECOOLER CONTROL VALVE, REF AMM 36-12-02. REPLACED HIGH STAGE REGULATOR REF AMM 36-11-07. REPLACED HIGH STAGE VALVE REF AMM 36-11-06. NO LEAKS NOTED. RAN BOTH ENGINES NO DUCT SPLIT NOTED. ALL WORK PERFORMED ON NR 2 ENGINE.