As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN ENGINES ARE REDUCED TO IDLE TRANSMISSION OIL PRESSURE DROPS BELOW LOW RED AND TRANSMISSION OIL PRESSURE LIGHT ILLUMINATES. ADVANCING EITHER ENGINE TO 70 PERCENT N1 RESTORES PRESSURE TO NORMAL RANGE. WHEN OIL PRESSURE RELIEF VALVE WAS REMOVED IT WAS FOUND TO BE STUCK PARTIALLY OPEN. REPLACED DEFECTIVE OIL PRESSURE RELIEF VALVE.