EASA to order checks on A320 angle-of-attack sensors
Airbus A320-family operators are being instructed to check angle-of-attack sensors on their fleets, after discovering that a manufacturing defect could result in the aircraft receiving incorrect data.
11th August 2011
The European Aviation Safety Agency said that the fault, discovered during final assembly line tests, affects particular Thales angle-of-attack probes installed on all A320-family variants.
Incorrect removeal of machining oil during the manufacturing process means that oil residue could be present between the stator and rotor parts of the the angle-of-attack vane position resolvers.
This residue, said EASA, could become viscous at low temperatures, particularly in cruise, and affect the movement of the vane. “Multiple angle-of-attack probes could be simultaneously affected, providing incorrect indications of the angle-of-attack of the aeroplane,” it added.
The problem was found when assembly line tests on two different aircraft revealed incorrect data.
Accurate data is critical because Airbus flight-control logic uses sensor information to prevent the aircraft reaching an attitude at which it could stall.
Erroneous angle-of-attack data, EASA said in a proposed directive on the matter, could result in “delayed or non-activation” of Airbus angle-of-attack protection systems.
EASA is to recommend identification and replacement of the Thales Avionics probes potentially affected within six months.
The AD: http://ad.easa.europa.eu/blob/easa_pad_11_084.pdf/PAD_11-084_1
I wonder if the AF447 crash has had an affect on this.
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August 11, 2011 at 11:34 am