George’s Point of View
Did the FAA consider grounding the affected planes and avoiding the chance that all “three” could fail and the pilot could lose control of the airplane?
I’m not a pilot but come on, it’s just common sense.
Bravo for taking action, but, is it safe to keep the affected planes in the air?
Regarding the directive and a couple of loose valves:
“The unsafe condition is the possible loss of all three hydraulic systems, which could result in loss of control of the airplane. This AD requires actions that are intended to address the unsafe condition described in the MCAI. ”
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An A330 operator experienced a low level of the Yellow hydraulic circuit due to a loose[ning] of check valve part number (P/N) CAR401. During the inspection on the other two hydraulic systems, the other three CAR401 check valves were also found to be loose with their lock wire broken in two instances.
A340 aeroplanes are also equipped with the same high pressure manifold check valves.
Investigations are on-going to determine the root cause of this event.
Additional cases of CAR401 check valve loosening have been experienced in service on aeroplanes having accumulated more than 1000 flight cycles (FC). The check valve fitted on the Yellow hydraulic system is more affected, probably due to additional system cycles induced by cargo door operation.
The loss of torque due to pressure cycles could contribute to check valve loosening, resulting in a leak and finally the loss of the associated hydraulic system and, in the worst case, of the three hydraulic systems of the aeroplane.
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The unsafe condition is the possible loss of all three hydraulic systems, which could result in loss of control of the airplane. This AD requires actions that are intended to address the unsafe condition described in the MCAI.
