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ah ok...allora mi tocca dire che avevo già risposto a questa tesi, pagine fa, proprio in risposta a Devil...evidentemente gli è sfuggito...lo riposto quotando me stesso...
Originally posted by Ayrton
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detto questo, spero lo capiate, direttamente da Air France:
"Paris, 06 June 2009 - 23:09 local time
Following the many questions which have appeared in the media on the issue of the Pitot probes in its fleet (the Pitot probe is an instrument which measures the air speed of the aircraft), Air France wishes to make the following clarifications:
1) Malfunctions in the Pitot probes on the A 320 led the manufacturer to issue a recommendation in September 2007 to change the probes. This recommendation also applies to long-haul aircraft using the same probes and on which a very few incidents of a similar nature had occurred.
It should be noted that a recommendation from the manufacturer gives the operator total freedom to apply the corresponding guidelines fully, partially or not at all. Should flight safety be concerned, the manufacturer, together with the authorities, issues a mandatory service bulletin followed by an airworthiness directive (AD).
The recommendation to change the probes was implemented by Air France on its A320 fleet where this type of incident involving water ingress had been observed. It was not implemented on the A340/330s as no such incidents had been noted.
2) Starting in May 2008 Air France experienced incidents involving a loss of airspeed data in flight, in cruise phase on A340s and A330s. These incidents were analysed with Airbus as resulting from pitot probe icing for a few minutes, after which the phenomenon disappeared. Discussions subsequently took place with the manufacturer. Air France asked for a solution which would reduce or eliminate the occurrence of these incidents. In response to these requests, the manufacturer indicated that the probe model recommended for the A320 was not designed to prevent such incidents which took place at cruise levels, and reiterated the operational procedures well-known to the crews.
In the first quarter of 2009 laboratory tests suggested, however, that the new probe could represent a valuable improvement to reduce the incidence of high altitude airspeed discrepancy resulting from pitot probe icing, and an in service evaluation in real flight conditions was proposed by Airbus. Without waiting for the in service evaluation, Air France decided to replace all its probes and the programme was launched on 27 April 2009.
Without making any assumptions as to a possible link with the causes of the accident, Air France speeded up this programme and reminded its pilots of the current instructions issued by the manufacturer to cope with the loss of airspeed data."
altri eventi simili :
# 1 August 2005 - Malaysia Airlines Flight 124, a Boeing 777-2H6ER departed Perth, Western Australia for Kuala Lumpur. Climbing through 38,000 feet a faulty accelerometer caused the aircraft's ADIRU and autopilot to command changes of altitude. The flight crew overrode the system and manually returned to land the aircraft at Perth. The subsequent ATSB investigation led the US FAA to issue emergency airworthiness directive 2005-18-51 on the fly-by-wire software.[12]
# 6 August 2008 - The FAA issued airworthiness directive 2008-17-12 expanding on the requirements of the earlier AD 2003-26-03 which had been determined to be an insufficient remedy. In some cases it called for replacement of ADIRUs with newer models, but allowed 46 months from October 2008 to implement the directive.[13]
# 7 October 2008 - Qantas Airlines Flight 72, an Airbus A330 departed Singapore for Perth. Some time into the flight, while cruising at 37,000ft, a failure in the No.1 ADIRU led to the autopilot automatically disengaging followed by two sudden uncommanded pitch down manoeuvres, according to the Australian Transport Safety Bureau (ATSB). The accident injured up to 74 passengers and crew, ranging from minor to serious injuries. The aircraft was able to make an emergency landing without further injuries. The aircraft was equipped with a Northrop Grumman made ADIRS, which investigators sent to the manufacturer for further testing.[14][15]
# 15 January 2009 - The EASA issues Emergency Airworthiness Directive No 2009-0012-E to address the above A330 and A340 Northrop-Grumman ADIRU problem of incorrectly responding to a defective inertial reference.
An Air France Airbus A340-300, registration F-GLZL performing flight AF-279 from Tokyo Narita (Japan) to Paris Charles de Gaulle (France), was enroute at FL310, when the airplane went through a line of thunderstorms. The captain's air speed indication suddenly dropped to 140 knots, the systems issued an alert regarding disagreeing speeds (NAV IAS DISCREPANCY), the navigation display showed a tail wind component of 250 knots. The captain released control of the airplane to the first officer and tried to switch his display from ADIRU1 to ADIRU3. 2 minutes later autopilot and autothrust disconnected and the fly by wire changed into alternate law. The crew noticed icing conditions (static air temperature [SAT] -29 degrees Centigrade) and switched anti ice including pitot heating systems from automatic to on. The speed indications became normal again and agreed again, the autoflight systems were reengaged and ATC informed of severe icing. ATC reported, that two flights had just passed the location without problems. When the crew attempted to reset and reengage ADIRU 1 two times, the system again brought the message "NAV IAS DISCREPANCY" on both attempts, although the speed data appeared consistent. The crew suspected polluted pitot tubes.
Maintenance found, that the drainage holes of all three pitot tubes had been clogged, rendering it very likely that weather combined with the clogged drainage holes caused the incident. Maintenance had reported more clogged drainage holes on A330 and A340 aircraft in the past to Airbus Industries. Airbus Industries was aware of the problems, changes had already been introduced to the pitot tubes on the A320 family, where similiar problems had occured. A modification of the A330/A340 pitot tubes was already planned by AI.
Second incident: An Air France Airbus A340-300, registration F-GLZN performing a flight from Paris Charles de Gaulle (France) to New York JFK,NY (USA), encountered brief turbulence while enroute. The autoflight systems dropped offline, "NAV IAS DISCREPANCY", "NAV PRED W/S DET FAULT" and stall alerts were repeatedly issued during the following two minutes. The airplane continued to JFK without further incident. A review of the policy of retrofitting pitot tubes was recommended and authorities informed. "
"Paris, 06 June 2009 - 23:09 local time
Following the many questions which have appeared in the media on the issue of the Pitot probes in its fleet (the Pitot probe is an instrument which measures the air speed of the aircraft), Air France wishes to make the following clarifications:
1) Malfunctions in the Pitot probes on the A 320 led the manufacturer to issue a recommendation in September 2007 to change the probes. This recommendation also applies to long-haul aircraft using the same probes and on which a very few incidents of a similar nature had occurred.
It should be noted that a recommendation from the manufacturer gives the operator total freedom to apply the corresponding guidelines fully, partially or not at all. Should flight safety be concerned, the manufacturer, together with the authorities, issues a mandatory service bulletin followed by an airworthiness directive (AD).
The recommendation to change the probes was implemented by Air France on its A320 fleet where this type of incident involving water ingress had been observed. It was not implemented on the A340/330s as no such incidents had been noted.
2) Starting in May 2008 Air France experienced incidents involving a loss of airspeed data in flight, in cruise phase on A340s and A330s. These incidents were analysed with Airbus as resulting from pitot probe icing for a few minutes, after which the phenomenon disappeared. Discussions subsequently took place with the manufacturer. Air France asked for a solution which would reduce or eliminate the occurrence of these incidents. In response to these requests, the manufacturer indicated that the probe model recommended for the A320 was not designed to prevent such incidents which took place at cruise levels, and reiterated the operational procedures well-known to the crews.
In the first quarter of 2009 laboratory tests suggested, however, that the new probe could represent a valuable improvement to reduce the incidence of high altitude airspeed discrepancy resulting from pitot probe icing, and an in service evaluation in real flight conditions was proposed by Airbus. Without waiting for the in service evaluation, Air France decided to replace all its probes and the programme was launched on 27 April 2009.
Without making any assumptions as to a possible link with the causes of the accident, Air France speeded up this programme and reminded its pilots of the current instructions issued by the manufacturer to cope with the loss of airspeed data."
altri eventi simili :
# 1 August 2005 - Malaysia Airlines Flight 124, a Boeing 777-2H6ER departed Perth, Western Australia for Kuala Lumpur. Climbing through 38,000 feet a faulty accelerometer caused the aircraft's ADIRU and autopilot to command changes of altitude. The flight crew overrode the system and manually returned to land the aircraft at Perth. The subsequent ATSB investigation led the US FAA to issue emergency airworthiness directive 2005-18-51 on the fly-by-wire software.[12]
# 6 August 2008 - The FAA issued airworthiness directive 2008-17-12 expanding on the requirements of the earlier AD 2003-26-03 which had been determined to be an insufficient remedy. In some cases it called for replacement of ADIRUs with newer models, but allowed 46 months from October 2008 to implement the directive.[13]
# 7 October 2008 - Qantas Airlines Flight 72, an Airbus A330 departed Singapore for Perth. Some time into the flight, while cruising at 37,000ft, a failure in the No.1 ADIRU led to the autopilot automatically disengaging followed by two sudden uncommanded pitch down manoeuvres, according to the Australian Transport Safety Bureau (ATSB). The accident injured up to 74 passengers and crew, ranging from minor to serious injuries. The aircraft was able to make an emergency landing without further injuries. The aircraft was equipped with a Northrop Grumman made ADIRS, which investigators sent to the manufacturer for further testing.[14][15]
# 15 January 2009 - The EASA issues Emergency Airworthiness Directive No 2009-0012-E to address the above A330 and A340 Northrop-Grumman ADIRU problem of incorrectly responding to a defective inertial reference.
An Air France Airbus A340-300, registration F-GLZL performing flight AF-279 from Tokyo Narita (Japan) to Paris Charles de Gaulle (France), was enroute at FL310, when the airplane went through a line of thunderstorms. The captain's air speed indication suddenly dropped to 140 knots, the systems issued an alert regarding disagreeing speeds (NAV IAS DISCREPANCY), the navigation display showed a tail wind component of 250 knots. The captain released control of the airplane to the first officer and tried to switch his display from ADIRU1 to ADIRU3. 2 minutes later autopilot and autothrust disconnected and the fly by wire changed into alternate law. The crew noticed icing conditions (static air temperature [SAT] -29 degrees Centigrade) and switched anti ice including pitot heating systems from automatic to on. The speed indications became normal again and agreed again, the autoflight systems were reengaged and ATC informed of severe icing. ATC reported, that two flights had just passed the location without problems. When the crew attempted to reset and reengage ADIRU 1 two times, the system again brought the message "NAV IAS DISCREPANCY" on both attempts, although the speed data appeared consistent. The crew suspected polluted pitot tubes.
Maintenance found, that the drainage holes of all three pitot tubes had been clogged, rendering it very likely that weather combined with the clogged drainage holes caused the incident. Maintenance had reported more clogged drainage holes on A330 and A340 aircraft in the past to Airbus Industries. Airbus Industries was aware of the problems, changes had already been introduced to the pitot tubes on the A320 family, where similiar problems had occured. A modification of the A330/A340 pitot tubes was already planned by AI.
Second incident: An Air France Airbus A340-300, registration F-GLZN performing a flight from Paris Charles de Gaulle (France) to New York JFK,NY (USA), encountered brief turbulence while enroute. The autoflight systems dropped offline, "NAV IAS DISCREPANCY", "NAV PRED W/S DET FAULT" and stall alerts were repeatedly issued during the following two minutes. The airplane continued to JFK without further incident. A review of the policy of retrofitting pitot tubes was recommended and authorities informed. "
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