European safety authorities have formally issued an airworthiness directive covering replacement of Thales pitot probes on Airbus A330 and A340 aircraft.
The directive - as previously indicated - requires operators to ensure that at least two Goodrich probes are fitted on the type within four months from 7 September.
It bans outright the installation of Thales 'AA' model probes from 7 January next year, and restricts the fitting of the 'BA' model to just one of the three pitot positions - that of the first officer.
But the directive clarifies that wind-tunnel tests of the 'BA' probe, performed last month, have "not identified any safety issue" regarding its behaviour within the certification specification icing envelope.
Pitot probes on the A330 and A340 have come under scrutiny since the Air France A330 crash on 1 June, following evidence of airspeed discrepancies on the aircraft.
While the European Aviation Safety Agency says the directive is "precautionary", it adds that it amounts to an "interim measure" and further action "cannot be excluded".