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parameters recorded after June 2006 on its A330 fleet. As of 18 November
2009 it had identified fourteen events. Only four of them had been detected
and reported by the crews to their airline.
Further, Airbus identified four events that have occurred since 1st June 2009.
BEA is continuing to collect information relative to the management of these
events by the various organisations, that is to say the manufacturer, the
airlines and the authorities concerned.
All of the events attributable, according to Airbus, to a possible obstruction of
at least two Pitot probes by ice, whether previous to or after the accident, are
presented in appendix 7.
1.18.7 History of the Pitot probes on Airbus A330 and management at Air France
The Airbus A330s were initially equipped with Goodrich 0851GR probes.
In August 2001, further to fluctuations and/or losses of speed indication on
A330 reported by certain airlines, the French DGAC published Airworthiness
Directive 2001-354 (B) which imposed the replacement on A330 of the
Goodrich 0851GR probes either with Goodrich type 0851HL or by Thales type
C16195AA probes before 31 December 2003. According to the analysis carried
out at the time, the most likely cause of the problem was the presence of ice
crystals and/or water in the Goodrich 0851GR type Pitot probes within the
upper limits of the original specifications.
In accordance with this Airworthiness Directive, the Thales C16195AA model
was installed on the Air France A340 fleet. As from December 2001, Air France
received its first A330 originally equipped with Thales C16195AA probes.
In September 2007, following measured speed inconsistencies being observed
at the time of heavy precipitations or icing conditions on A320 and some cases
on A330/340, Airbus published Service Bulletin SB A330-34-3206 (Rev. n°00)
which recommended the replacement of C16195AA Pitot probes with the
C16195BA standard. The Service Bulletin indicated that this model performed
better in the case of water ingestion and of icing in severe conditions.
(18)Of these
32 events, twelve
were reported
to Airbus after
1st June 2009.
F-GZCP - 1st June 2009
66
Note: the C16195BA probe was initially developed in 2005 to answer problems relating to
water ingestion observed on the A320 family during strong precipitation at low altitude.
In the absence of problems of this type with its long-range fleet, Air France
chose to replace the C16195AA Pitot probes with C16195BA Pitot probes only
in the case of a failure.
The first event with a temporary loss of speed indication at high altitude
occurred in May 2008 and was followed by several others: one in July 2008,
three in August 2008, one in September 2008 and then another one in October
2008, all on A340.
Air France reported these events to Airbus as early as July 2008, in accordance
with SIL 34-084 published by Airbus “incorrect speed indications - maintenance
actions on the Pitot probes”.
On 24 September 2008, Air France contacted Airbus about the cause of these
events and the solutions to be applied, and asked whether the Thales probe
C16195BA would be able to remedy these problems. Airbus answered that the
origin of the problem was probably a blockage of the probes due to a rapid
accumulation of ice crystals and that the Thales C16195BA probe, developed
to cope with problems of water ingestion at the time of heavy precipitations,
was not likely to improve the performance in the presence of ice crystals.
Airbus stated that there was no solution for totally eliminating the risk of
probe icing, that the three types of probe installed on Airbus satisfy much
stricter criteria than those of the regulatory certification requirements in the
area of icing and recalled the procedure to be applied in the case of incorrect
speed indications.
From October 2008, Air France alerted Thales to the worsening problem of
icing at high altitude. Thales opened an internal technical analysis procedure
on these incidents.
On 12 November 2008, SB A330-34-3206 was revised by Airbus (Rev.n°01).
This Bulletin mentions the improvement that can be provided by the Thales
C16195BA probe in relation to water ingestion and no longer mentions the
improvement that the Thales C16195BA probe can provide in icing conditions.
On 24 November 2008, the problem of speed inconsistencies was raised at the
time of a meeting between the Air France Technical Directorates and Airbus.
Airbus confirmed its analysis.
In February 2009, Thales carried out a comparative study of the behaviour
of the two C16195AA and C16195BA standards in icing conditions that were
more extreme than required by the specifications.
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