ATA 29

Hydraulic Line Integrity
We have learned that there have been events where hydraulic lines are cracking. On a recent incident, the left main hydraulic annunciator came on about 30 minutes after takeoff, followed by the right hydraulic annunciator. The crew returned to home base, blew the landing gear down, and landing uneventfully. It was found that the pressure line into the lift dump valve was cracked near a B-nut. The hydraulic pumps ran dry for an indeterminate time. As you go about your routine area inspections, please pay attention for hydraulic fluid staining and fluidleaks. As the fleet continues to mature, we want to ensure we are aware of areas that may become fleet symptoms. Advisory Circular 43-4A identifies problem areas for corrosion, and one of them is around B-nuts and line marking tapes. Corrosion will weaken the line sufficiently to cause failure. If you have recently experienced a similar situation, please let us know via e-mail to westwind@worthingtonav.com