As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DUCT PRESSURE DIFFERENTIAL INDICATED BY LEFT DUCT AT 10 PSI, RIGHT DUCT AT 45 PSI READ PASSING LEVEL 330 IN CLIMB. AT LEVEL 380 LEFT =10 PSI ,RIGHT=36 PSI N1'S AT 87.5%. GROUNDED - YES. ACCOMPLISHED T/C NG-36WC-0001 PRECOOLER CONTROL VALVE FAILS, REPLACED PCV REF AMM 36-12-02-000-801 OPS/LEAK CK GOOD. CROSSOVER TEST FAILED. REPLACED PRSOV REF AMM 36-11-04-000-801/-400-801. NO DEFECTS NOTED. ACCOMPLISHED ENGINE BLEED AIR CROSSOVER TEST PER AMM 36-11-00-710-801, OPS CK PASSED.