As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNABLE TO SELECT F/D 1 AS MASTER OR ENGAGE CMD A IN FLIGHT.SEEMS TO OPERATE NOORMALLY ON GROUND.F/D 1 WAS SELECTED PRIOR TO TAKEOFF, BUT SWITCHED TO F/D 2 AS MASTER IN AIR. GROUNDED - YES. COULD NOT DUPLICATE MALFUNCTION.ADIRS, FCC'S, FMC'S & CDS LOGGED NO FAULTS.NO A/P DISC, ENG ATTMPT, NOR F/D BOV FAUTLS UNDER FDE.FCC-A BITE CK NORMAL PER BITE GROUP #35.REF B737-900 FIM 22-11 TASKS 856 & 801.