Hydraulic Failure and Diversion
While on final approach, the airplane encountered a failure of both its 'A' and 'B' hydraulic systems. The captain elected to go around and divert to a nearby military airport, which offered longer runways. The subsequent landing was uneventful.
Investigation Findings
A post-incident investigation revealed that a hole had been chafed through a return line in the 'A' hydraulic system at a bracket located in the left wheel well area. Additionally, it was determined that a return line from the 'A' system and a return line from the 'B' system had been cross connected in the area of the No. 1 pylon. This cross connection allowed fluid from the 'B' system to transfer into the 'A' system and subsequently vent overboard.
System Performance
Prior to the failure, indications, readings, and tests for both hydraulic systems were normal. The dual system failure occurred only after the hole was chafed through the 'A' system line.
Maintenance Record Review
A review of maintenance records could not identify when the hydraulic lines had been reversed.