EASA has given Airbus A330 operators five years to replace all four wing tank fuel pressure switches with "new ones with a more robust design preventing water accumulation and freezing." (AD 2010-0018
.) At least one operator has reported an in-flight engine spool-down as a result of the problem, EASA noted in both the AD and last October's draft rule
Air France submitted the only comments on the draft AD. The carrier noted that the pressure switches being replaced are installed on the A340 and A320 family as well, while the new switches cannot be installed on A320s. This, notes Air France, leaves open the possibility that the old switches might work their way back into a carrier's A330 spares stock and end up back in the wing tank system. (The same switches are found elsewhere in the A330 fuel system, but only the wing tank switches are affected by the directive.)
Air France suggested that the design of the new switch be reviewed and modified so it is physically different from the old switch, to decrease likelihood that the the old switches are put on an A330 wing tank pump.
EASA said that human factors were considered, and that installing an old switch in "one, two or three" of the affected locations would not create an unsafe condition on the A330. In addition, a physical change would both eliminate the part's "interchangability" on the rest of the the Airbus long-range fleet, and would require "at least" a fuel tank entry on the A330s, which would introduce additional risk.
(NOTE: See .ZIP file contents
for Air France's comments and EASA's responses.)