Air Transat loses A310 rudder inflight
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Zeke
When I first read the words in the Airbus statement that you quoted "... the crew reported that a loud bang was heard. The pilot took manual control and returned to land safely at Varadero. ....", I rather assumed that Airbus was implying that the bang was the rudder departing. However, the words "loud bang" rather rang a bell in my head because I seemed to remember the same words in a previous PPRuNe thread being used where the rudder did NOT depart the aircraft. Searching back I found the following. It describes one of four incidents under the heading, "Survey Of 4 Yaw Incidents BEFORE AA Flight 587.":
---- Start quote -------
6/27/00. Airbus A300B4- 605R, Reg. N14065. As the aircraft was approaching FL220, at a reported airspeed of 325 KIAS, the aircraft experienced an abrupt disturbance which was perceived by the flight crew to be a disturbance in yaw with no attendant lateral motion evident in the resulting manoeuvre. They believed that the yawing motion had been caused by an uncommanded rudder input. The disturbance was accompanied by a loud bang which was noted by both the flight crew and some of the cabin attendants. They all reported the noise as being coincident with the disturbance. At the time of the event the aircraft was configured as follows: flaps and slats 'IN', landing gear 'UP', auto pilot 'OFF', pitch trim (systems 1 and 2) 'ON' and yaw damper (systems 1 and 2) 'ON'. The aircraft was clear of cloud and there were no other aircraft reported in the vicinity. Following the disturbance the aircraft appeared to behave normally. However, the commander decided to return to London (Heathrow) rather than commence a transatlantic flight following a suspected uncommanded flight control input. An uneventful, overweight landing on Runway 09L was completed at 1624 hrs. Ref. AAIB Bulletin No: 2/2001, ref EW/C2000/6/10. No cause attributed.
--- End of quote ----
This sounds to me like a loud bang caused by a rudder hard-over WITHOUT the rudder departing.
The quote above came from an early PPRuNE thread on Flight 587, but I have not been able to find the original.
Cheers,
When I first read the words in the Airbus statement that you quoted "... the crew reported that a loud bang was heard. The pilot took manual control and returned to land safely at Varadero. ....", I rather assumed that Airbus was implying that the bang was the rudder departing. However, the words "loud bang" rather rang a bell in my head because I seemed to remember the same words in a previous PPRuNe thread being used where the rudder did NOT depart the aircraft. Searching back I found the following. It describes one of four incidents under the heading, "Survey Of 4 Yaw Incidents BEFORE AA Flight 587.":
---- Start quote -------
6/27/00. Airbus A300B4- 605R, Reg. N14065. As the aircraft was approaching FL220, at a reported airspeed of 325 KIAS, the aircraft experienced an abrupt disturbance which was perceived by the flight crew to be a disturbance in yaw with no attendant lateral motion evident in the resulting manoeuvre. They believed that the yawing motion had been caused by an uncommanded rudder input. The disturbance was accompanied by a loud bang which was noted by both the flight crew and some of the cabin attendants. They all reported the noise as being coincident with the disturbance. At the time of the event the aircraft was configured as follows: flaps and slats 'IN', landing gear 'UP', auto pilot 'OFF', pitch trim (systems 1 and 2) 'ON' and yaw damper (systems 1 and 2) 'ON'. The aircraft was clear of cloud and there were no other aircraft reported in the vicinity. Following the disturbance the aircraft appeared to behave normally. However, the commander decided to return to London (Heathrow) rather than commence a transatlantic flight following a suspected uncommanded flight control input. An uneventful, overweight landing on Runway 09L was completed at 1624 hrs. Ref. AAIB Bulletin No: 2/2001, ref EW/C2000/6/10. No cause attributed.
--- End of quote ----
This sounds to me like a loud bang caused by a rudder hard-over WITHOUT the rudder departing.
The quote above came from an early PPRuNE thread on Flight 587, but I have not been able to find the original.
Cheers,
Last edited by PickyPerkins; 14th Mar 2005 at 04:15.
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PickyPerkins,
Thank you, keep up the good work, AAIB report below.
Sorry I cannot find the original myself. 
Thank you, keep up the good work, AAIB report below.
AAIB Bulletin No: 2/2001
Ref: EW/C2000/6/10 - Category: 1.1
Aircraft Type and Registration:
Airbus A300B4- 605R, N14065
No & Type of Engines: 2 CF6-80C2A5 turbofan engines
Year of Manufacture: 1989
Date & Time (UTC): 27 June 2000 at 1547 hrs
Location: 10 nm North East of Filton, Gloucestershire, UK
Type of Flight: Public Transport
Persons on Board: Crew - 13 - Passengers - 191
Injuries: Crew - None - Passengers - None
Nature of Damage: None
Commander's Licence: Airline Transport Pilot's Licence
Commander's Age: 52 years
Commander's Flying Experience: 10,500 hours (of which 3,426 were on type)
Last 90 days -178 hours
Last 28 days - 62 hours
Information Source: AAIB Field Investigation
History of the flight
The aircraft was planned to operate a scheduled flight from London (Heathrow) to New York (J F Kennedy). The aircraft mass at take off was 377,738 lb with the centre of gravity (CG) calculated to be at 32×5% of mean aerodynamic chord; this represents an aircraft operating close to its maximum mass at an aft CG. The serviceable aircraft had a flight deck complement of three pilots, of whom the first officer (FO) was the handling pilot. The aircraft took off at 1534 hrs from Runway 09R and was cleared to follow the Compton Five Juliet standard instrument departure prior to routing to the west.
During the departure and climb the FO flew the aircraft manually. As the aircraft was approaching FL220, at a reported airspeed of 325 KIAS, the aircraft experienced an abrupt disturbance which was perceived by the flight crew to be a disturbance in yaw with no attendant lateral motion evident in the resulting manoeuvre. They believed that the yawing motion had been caused by an uncommanded rudder input. The disturbance was accompanied by a loud bang which was noted by both the flight crew and some of the cabin attendants. They all reported the noise as being coincident with the disturbance. At the time of the event the aircraft was configured as follows: flaps and slats 'IN', landing gear 'UP', auto pilot 'OFF', pitch trim (systems 1 and 2) 'ON' and yaw damper (systems 1 and 2) 'ON'. The aircraft was clear of cloud and there were no other aircraft reported in the vicinity.
Following the disturbance the aircraft appeared to behave normally. However, the commander decided to return to London (Heathrow) rather than commence a transatlantic flight following a suspected an uncommanded flight control input. An uneventful, overweight landing on Runway 09L was completed at 1624 hrs.
Flight recorders
The 30 minute, tape based, CVR had overwritten the recording of the event. However, the solid state FDR was successfully replayed at the AAIB and the data were available for analysis.
Following the departure from Runway 09R at London (Heathrow) the aircraft turned towards the west and climbed. Thirteen minutes later, with the aircraft being flown manually and climbing through FL220 at 327 kt, the values of normal and lateral acceleration, which were recorded from the accelerometer mounted at the aircraft's centre of gravity, showed a small disturbance. There were no observable changes in the recorded values of heading or rudder deflection but the aircraft rolled from wings level to 2.4° left wing down. All engine parameters remained constant.
Within one second of the onset of the disturbance roll, right aileron was applied and the discrete parameters for right roll spoiler panels 4 to 7 indicated deployment for one second. (It should be noted that the roll spoiler panels only have to extend by approximately 2° for the FDR discrete parameters to indicate deployment.) The aircraft rolled to 1.4° right wing down before roll left aileron was applied with simultaneous deployment of left roll spoilers 3 to 7 being recorded. The recorded value of rudder position showed a momentary deflection of 0.3° left from its normal position, indicative of yaw damper operation. The nose up pitch attitude increased by 1° to 3.5° during this time. The roll to the left continued to 4.2° left wing down before corrective roll right aileron was applied and right spoiler panels 6 and 7 indicated deployment. Rudder deflection of 0.3° right from normal position was recorded and a small amount of down elevator was applied to reduce the nose up pitch attitude back to 2.5°. All of the control surface deflections recorded after the initial disturbance were consistent with the control inputs demanded by the crew. The complete event lasted no more than seven seconds,
The aircraft continued to climb on its heading of 284°M at a reduced speed of 310 kt. It levelled off at FL280 and the autopilot was engaged before a left turn back towards London (Heathrow) was initiated. After landing ground spoiler deflection on all 14 panels was recorded as the aircraft slowed during the rollout.
Engineering investigation
Over the following three days the aircraft was examined for damage and any failure or defect that could have been implicated in the in-flight disturbance. The aircraft completed a test flight before re-entering service.
An external examination showed that nothing had detached from the aircraft and there was no evidence of anything having struck the aircraft. Detailed inspections of the ailerons, spoilers and rudder and their attachments found no damage. One spoiler actuator rod end was found to have excess play and its liner was replaced. A BITE (Built in Test Equipment) fault was reported from one of the two Electrical Flying Control Units (EFCU). This concerned the '5 ft' warning from the Flight Warning Computer involved in the arming of the ground spoilers. This was found to have cleared on further inspection and did not re-occur. Given the behaviour of the spoilers during the incident this was not considered to be relevant. Functional checks of the primary and secondary flying controls and BITE tests of the associated computers revealed no anomalies.
Special equipment was installed to mimic the in-flight conditions to the aircraft flight control systems. The control systems were operated and the electrical looms serving the flying control computers were shaken and manipulated in an attempt to reveal any break in a conductor or connector fault. The looms were examined for any indication of possible screening defects. Mobile telephones and a laptop computer were operated close to the avionics racks but this is acknowledged as not being a systematic or scientific test of the vulnerability of the aircraft's systems to such effects. Current avionics installations do not necessarily provide protection against radio frequency emissions from mobile telephones. Close attention was paid to the rudder system and the yaw damper but no defects were found. No movement of the rudder was seen when it was operated from a single hydraulic supply or when switched between systems and there was no sign that the input mechanism on any of the three actuators was stiff in operation (which could cause the input spring strut to collapse).
The loud bang reported by the crew could have been directly associated with the cause of the upset or could have been a secondary result of the movement of the aircraft. In trying to identify the source of the noise, which was heard on the flight-deck and in the cabin, the freight and baggage holds were examined for any sign that a load had been unsecured or had moved. The ground crew who unloaded the freight reported that there was no sign that any freight had moved. The equipment areas alongside the holds were opened and examined for anything, such as the disconnection of an air conditioning duct, which could have caused such a noise but none was found.
No anomalies in the operation of the aircraft were found on the test flight during which it was manoeuvred vigorously whilst being operated in the same manner as on the incident flight.
Air traffic control
The London Area and Terminal Control Centre was controlling the aircraft during its standard routing from London (Heathrow) prior to the flight across the North Atlantic. As it approached the Bristol area, climbing through FL220, it was directly behind a Boeing 777 (B 777) that had passed through exactly the same airspace (as derived from radar data) some 4 minutes and 18 seconds earlier. When it passed through this point the B 777 had been at FL229 and was at an estimated mass of 243 tonnes. No other aircraft had recently passed this location, close to this level, either along the same track or across it.
Meteorological conditions
The disturbance experienced by the aircraft could be attributed to a localised severe turbulence event. Assistance was requested from the Meteorological Office at Bracknell for an analysis of the atmospheric conditions in the area of the disturbance encountered by the A-300 aircraft. The synoptic situation at 1200 hrs on 27 June 2000 indicated that an area of high pressure was centered to the north of Scotland with a substantial ridge of high pressure extending over all of the United Kingdom. Radio sonde ascents indicated a subsidence inversion associated with the ridge of high pressure. Above this inversion the air was dry and relatively stable until at very high altitude where some cirrus cloud may have been encountered. A comparison of the visible and infra red satellite photographs confirmed that any low cloud was well broken and there was some cirrus at high level. However, satellite photographs taken at 1424 hrs indicated that in the area of interest there was little or no high cloud. The local wind at altitude was estimated to be a light westerly between 10 to 20 kt, wind data from the inertial navigation system recorded on the FDR was 280°/08 kt at the time of the disturbance.
In order to define what may have caused the localised turbulence the following meteorological phenomena were considered:
Clear Air Turbulence. Clear air turbulence is often associated with large horizontal wind shears in the vicinity of jet streams. In this instance the nearest jet stream was over the North Sea and the horizontal wind gradients in the area in which the disturbance was encountered were very small.
Breaking Gravity Waves. Clear air turbulence can also be associated with breaking gravity waves. Gravity waves can be generated by surface topography or convection and then require suitable stability conditions to allow the waves to break. In this case the surface winds were extremely light and the atmosphere very stable, it is therefore considered to be unlikely that gravity waves will have been generated. Furthermore, there was no evidence from the satellite photographs of the presence of gravity waves.
Convective Turbulence. Turbulence can also be associated with strong updrafts in convective conditions. The atmosphere was stable in this instance and there was no evidence of any convective activity.
Turbulence at Cloud Tops. On occasion moderate turbulence can be encountered at the top of layer clouds. This is normally widespread and not localised. There was no evidence of any such clouds that may have affected the aircraft in this manner.
Wake Vortex Encounter. In the prevailing conditions of stability and light winds the wake vortices from heavy aircraft can be relatively long lived. Furthermore, the vortices would be expected to slowly sink and decrease in altitude. It is therefore considered that the most likely meteorological reason for any localised turbulence would be an encounter with a wake vortex generated by another aircraft.
Ref: EW/C2000/6/10 - Category: 1.1
Aircraft Type and Registration:
Airbus A300B4- 605R, N14065
No & Type of Engines: 2 CF6-80C2A5 turbofan engines
Year of Manufacture: 1989
Date & Time (UTC): 27 June 2000 at 1547 hrs
Location: 10 nm North East of Filton, Gloucestershire, UK
Type of Flight: Public Transport
Persons on Board: Crew - 13 - Passengers - 191
Injuries: Crew - None - Passengers - None
Nature of Damage: None
Commander's Licence: Airline Transport Pilot's Licence
Commander's Age: 52 years
Commander's Flying Experience: 10,500 hours (of which 3,426 were on type)
Last 90 days -178 hours
Last 28 days - 62 hours
Information Source: AAIB Field Investigation
History of the flight
The aircraft was planned to operate a scheduled flight from London (Heathrow) to New York (J F Kennedy). The aircraft mass at take off was 377,738 lb with the centre of gravity (CG) calculated to be at 32×5% of mean aerodynamic chord; this represents an aircraft operating close to its maximum mass at an aft CG. The serviceable aircraft had a flight deck complement of three pilots, of whom the first officer (FO) was the handling pilot. The aircraft took off at 1534 hrs from Runway 09R and was cleared to follow the Compton Five Juliet standard instrument departure prior to routing to the west.
During the departure and climb the FO flew the aircraft manually. As the aircraft was approaching FL220, at a reported airspeed of 325 KIAS, the aircraft experienced an abrupt disturbance which was perceived by the flight crew to be a disturbance in yaw with no attendant lateral motion evident in the resulting manoeuvre. They believed that the yawing motion had been caused by an uncommanded rudder input. The disturbance was accompanied by a loud bang which was noted by both the flight crew and some of the cabin attendants. They all reported the noise as being coincident with the disturbance. At the time of the event the aircraft was configured as follows: flaps and slats 'IN', landing gear 'UP', auto pilot 'OFF', pitch trim (systems 1 and 2) 'ON' and yaw damper (systems 1 and 2) 'ON'. The aircraft was clear of cloud and there were no other aircraft reported in the vicinity.
Following the disturbance the aircraft appeared to behave normally. However, the commander decided to return to London (Heathrow) rather than commence a transatlantic flight following a suspected an uncommanded flight control input. An uneventful, overweight landing on Runway 09L was completed at 1624 hrs.
Flight recorders
The 30 minute, tape based, CVR had overwritten the recording of the event. However, the solid state FDR was successfully replayed at the AAIB and the data were available for analysis.
Following the departure from Runway 09R at London (Heathrow) the aircraft turned towards the west and climbed. Thirteen minutes later, with the aircraft being flown manually and climbing through FL220 at 327 kt, the values of normal and lateral acceleration, which were recorded from the accelerometer mounted at the aircraft's centre of gravity, showed a small disturbance. There were no observable changes in the recorded values of heading or rudder deflection but the aircraft rolled from wings level to 2.4° left wing down. All engine parameters remained constant.
Within one second of the onset of the disturbance roll, right aileron was applied and the discrete parameters for right roll spoiler panels 4 to 7 indicated deployment for one second. (It should be noted that the roll spoiler panels only have to extend by approximately 2° for the FDR discrete parameters to indicate deployment.) The aircraft rolled to 1.4° right wing down before roll left aileron was applied with simultaneous deployment of left roll spoilers 3 to 7 being recorded. The recorded value of rudder position showed a momentary deflection of 0.3° left from its normal position, indicative of yaw damper operation. The nose up pitch attitude increased by 1° to 3.5° during this time. The roll to the left continued to 4.2° left wing down before corrective roll right aileron was applied and right spoiler panels 6 and 7 indicated deployment. Rudder deflection of 0.3° right from normal position was recorded and a small amount of down elevator was applied to reduce the nose up pitch attitude back to 2.5°. All of the control surface deflections recorded after the initial disturbance were consistent with the control inputs demanded by the crew. The complete event lasted no more than seven seconds,
The aircraft continued to climb on its heading of 284°M at a reduced speed of 310 kt. It levelled off at FL280 and the autopilot was engaged before a left turn back towards London (Heathrow) was initiated. After landing ground spoiler deflection on all 14 panels was recorded as the aircraft slowed during the rollout.
Engineering investigation
Over the following three days the aircraft was examined for damage and any failure or defect that could have been implicated in the in-flight disturbance. The aircraft completed a test flight before re-entering service.
An external examination showed that nothing had detached from the aircraft and there was no evidence of anything having struck the aircraft. Detailed inspections of the ailerons, spoilers and rudder and their attachments found no damage. One spoiler actuator rod end was found to have excess play and its liner was replaced. A BITE (Built in Test Equipment) fault was reported from one of the two Electrical Flying Control Units (EFCU). This concerned the '5 ft' warning from the Flight Warning Computer involved in the arming of the ground spoilers. This was found to have cleared on further inspection and did not re-occur. Given the behaviour of the spoilers during the incident this was not considered to be relevant. Functional checks of the primary and secondary flying controls and BITE tests of the associated computers revealed no anomalies.
Special equipment was installed to mimic the in-flight conditions to the aircraft flight control systems. The control systems were operated and the electrical looms serving the flying control computers were shaken and manipulated in an attempt to reveal any break in a conductor or connector fault. The looms were examined for any indication of possible screening defects. Mobile telephones and a laptop computer were operated close to the avionics racks but this is acknowledged as not being a systematic or scientific test of the vulnerability of the aircraft's systems to such effects. Current avionics installations do not necessarily provide protection against radio frequency emissions from mobile telephones. Close attention was paid to the rudder system and the yaw damper but no defects were found. No movement of the rudder was seen when it was operated from a single hydraulic supply or when switched between systems and there was no sign that the input mechanism on any of the three actuators was stiff in operation (which could cause the input spring strut to collapse).
The loud bang reported by the crew could have been directly associated with the cause of the upset or could have been a secondary result of the movement of the aircraft. In trying to identify the source of the noise, which was heard on the flight-deck and in the cabin, the freight and baggage holds were examined for any sign that a load had been unsecured or had moved. The ground crew who unloaded the freight reported that there was no sign that any freight had moved. The equipment areas alongside the holds were opened and examined for anything, such as the disconnection of an air conditioning duct, which could have caused such a noise but none was found.
No anomalies in the operation of the aircraft were found on the test flight during which it was manoeuvred vigorously whilst being operated in the same manner as on the incident flight.
Air traffic control
The London Area and Terminal Control Centre was controlling the aircraft during its standard routing from London (Heathrow) prior to the flight across the North Atlantic. As it approached the Bristol area, climbing through FL220, it was directly behind a Boeing 777 (B 777) that had passed through exactly the same airspace (as derived from radar data) some 4 minutes and 18 seconds earlier. When it passed through this point the B 777 had been at FL229 and was at an estimated mass of 243 tonnes. No other aircraft had recently passed this location, close to this level, either along the same track or across it.
Meteorological conditions
The disturbance experienced by the aircraft could be attributed to a localised severe turbulence event. Assistance was requested from the Meteorological Office at Bracknell for an analysis of the atmospheric conditions in the area of the disturbance encountered by the A-300 aircraft. The synoptic situation at 1200 hrs on 27 June 2000 indicated that an area of high pressure was centered to the north of Scotland with a substantial ridge of high pressure extending over all of the United Kingdom. Radio sonde ascents indicated a subsidence inversion associated with the ridge of high pressure. Above this inversion the air was dry and relatively stable until at very high altitude where some cirrus cloud may have been encountered. A comparison of the visible and infra red satellite photographs confirmed that any low cloud was well broken and there was some cirrus at high level. However, satellite photographs taken at 1424 hrs indicated that in the area of interest there was little or no high cloud. The local wind at altitude was estimated to be a light westerly between 10 to 20 kt, wind data from the inertial navigation system recorded on the FDR was 280°/08 kt at the time of the disturbance.
In order to define what may have caused the localised turbulence the following meteorological phenomena were considered:
Clear Air Turbulence. Clear air turbulence is often associated with large horizontal wind shears in the vicinity of jet streams. In this instance the nearest jet stream was over the North Sea and the horizontal wind gradients in the area in which the disturbance was encountered were very small.
Breaking Gravity Waves. Clear air turbulence can also be associated with breaking gravity waves. Gravity waves can be generated by surface topography or convection and then require suitable stability conditions to allow the waves to break. In this case the surface winds were extremely light and the atmosphere very stable, it is therefore considered to be unlikely that gravity waves will have been generated. Furthermore, there was no evidence from the satellite photographs of the presence of gravity waves.
Convective Turbulence. Turbulence can also be associated with strong updrafts in convective conditions. The atmosphere was stable in this instance and there was no evidence of any convective activity.
Turbulence at Cloud Tops. On occasion moderate turbulence can be encountered at the top of layer clouds. This is normally widespread and not localised. There was no evidence of any such clouds that may have affected the aircraft in this manner.
Wake Vortex Encounter. In the prevailing conditions of stability and light winds the wake vortices from heavy aircraft can be relatively long lived. Furthermore, the vortices would be expected to slowly sink and decrease in altitude. It is therefore considered that the most likely meteorological reason for any localised turbulence would be an encounter with a wake vortex generated by another aircraft.
Wake vortex encounters
All aircraft in flight leave behind them wake vortices with characteristics that are a function of the generated lift and are thus dependent upon: gross weight, wing planform, airspeed, configuration and attitude. These characteristics are then altered by interaction between the vortices and the ambient atmosphere. Studies suggest that, at medium level and in still air, the shed vortices tend to drift slowly downwards at a rate of approximately 400 feet per minute and level off, usually not more than 1,000 feet below the flight path of the aircraft. However, their behaviour is not predictable, particularly in the aspects of their trajectory and decay.
In general wake vortex encounters tend to occur close to airports where the density of operations is high and where aircraft are manoeuvring after take off or prior to landing on prescribed tracks at relatively slow speeds. Suitable separation minima are applied in these areas with the aim of reducing the probability of a vortex wake encounter to an acceptably low level, and to minimise the magnitude of the upset when an encounter does occur.
Wake vortex encounters during the climb or cruise are relatively rare since the airspeed is high and it is less likely that aircraft will be directly behind each other. Furthermore, with a standard vertical separation of 2,000 feet it is unlikely that the vortex will descend far enough to disturb the following aircraft. Finally, vortices require specific atmospheric conditions to enable them to persist. However, the use of modern navigation aids increases the likelihood that aircraft will follow specific tracks more accurately and thus the possibility of flying directly behind another aircraft is increased. Also, the introduction of Reduced Vertical Separation Minima can reduce the vertical separation to 1,000 feet. It is therefore possible that wake vortex encounters during the cruise may become more prevalent.
The Boeing Commercial Airplane Group have conducted extensive wake turbulence research during which a B 737 was purposely flown through the wake of a B 727 in order to study the behaviour of the aircraft during a wake vortex encounter. During this research a sound was sometimes associated with the wake encounter when the aircraft centreline intercepted the descending wake. It was estimated that the sound (described by the flight test crew as a \'thump\') can occur when the fuselage of the aircraft touches the centre of the vortex where the pressure is at its lowest. Research is continuing into a system that could disrupt the vortices generated by the wing. This might be achieved by moving some of the flight control surfaces in order to interrupt the flow over the wings but without diminishing the wing\'s lifting ability. At present this research is concentrating on the approach profile where the problem of wake turbulence is currently at its most intrusive.
Discussion
The aircraft was established in the climb, in seemingly quiescent air, with no aircraft apparently in the vicinity when it encountered a sudden disturbance, which the flight crew perceived as a yaw excursion. The value of the lateral acceleration, recorded from the accelerometer mounted at the aircraft\'s centre of gravity, showed a small disturbance but it is probable that the flight crew, being seated in the cockpit, perceived a higher level of lateral acceleration, which they interpreted as uncommanded rudder input. Extensive engineering investigation did not find any reason for the disturbance to have occurred and no anomalies in the operation of the aircraft were found during the test flight. Furthermore, there was nothing from the engineering investigation that could explain the loud noise reported by both the flight crew and the cabin attendants. A number of meteorological phenomena were considered. It is most probable that the reason for any localised turbulence was an encounter with the wake vortex generated by a B 777 aircraft which had passed through the same airspace some four minutes and 18 seconds earlier. Research into wake vortex encounters indicates that a loud noise can be associated with entry into the core of the vortex if the geometry is appropriate.
All aircraft in flight leave behind them wake vortices with characteristics that are a function of the generated lift and are thus dependent upon: gross weight, wing planform, airspeed, configuration and attitude. These characteristics are then altered by interaction between the vortices and the ambient atmosphere. Studies suggest that, at medium level and in still air, the shed vortices tend to drift slowly downwards at a rate of approximately 400 feet per minute and level off, usually not more than 1,000 feet below the flight path of the aircraft. However, their behaviour is not predictable, particularly in the aspects of their trajectory and decay.
In general wake vortex encounters tend to occur close to airports where the density of operations is high and where aircraft are manoeuvring after take off or prior to landing on prescribed tracks at relatively slow speeds. Suitable separation minima are applied in these areas with the aim of reducing the probability of a vortex wake encounter to an acceptably low level, and to minimise the magnitude of the upset when an encounter does occur.
Wake vortex encounters during the climb or cruise are relatively rare since the airspeed is high and it is less likely that aircraft will be directly behind each other. Furthermore, with a standard vertical separation of 2,000 feet it is unlikely that the vortex will descend far enough to disturb the following aircraft. Finally, vortices require specific atmospheric conditions to enable them to persist. However, the use of modern navigation aids increases the likelihood that aircraft will follow specific tracks more accurately and thus the possibility of flying directly behind another aircraft is increased. Also, the introduction of Reduced Vertical Separation Minima can reduce the vertical separation to 1,000 feet. It is therefore possible that wake vortex encounters during the cruise may become more prevalent.
The Boeing Commercial Airplane Group have conducted extensive wake turbulence research during which a B 737 was purposely flown through the wake of a B 727 in order to study the behaviour of the aircraft during a wake vortex encounter. During this research a sound was sometimes associated with the wake encounter when the aircraft centreline intercepted the descending wake. It was estimated that the sound (described by the flight test crew as a \'thump\') can occur when the fuselage of the aircraft touches the centre of the vortex where the pressure is at its lowest. Research is continuing into a system that could disrupt the vortices generated by the wing. This might be achieved by moving some of the flight control surfaces in order to interrupt the flow over the wings but without diminishing the wing\'s lifting ability. At present this research is concentrating on the approach profile where the problem of wake turbulence is currently at its most intrusive.
Discussion
The aircraft was established in the climb, in seemingly quiescent air, with no aircraft apparently in the vicinity when it encountered a sudden disturbance, which the flight crew perceived as a yaw excursion. The value of the lateral acceleration, recorded from the accelerometer mounted at the aircraft\'s centre of gravity, showed a small disturbance but it is probable that the flight crew, being seated in the cockpit, perceived a higher level of lateral acceleration, which they interpreted as uncommanded rudder input. Extensive engineering investigation did not find any reason for the disturbance to have occurred and no anomalies in the operation of the aircraft were found during the test flight. Furthermore, there was nothing from the engineering investigation that could explain the loud noise reported by both the flight crew and the cabin attendants. A number of meteorological phenomena were considered. It is most probable that the reason for any localised turbulence was an encounter with the wake vortex generated by a B 777 aircraft which had passed through the same airspace some four minutes and 18 seconds earlier. Research into wake vortex encounters indicates that a loud noise can be associated with entry into the core of the vortex if the geometry is appropriate.
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@Squibs
No, you are not the only one...
@Wino
I know that aircraft by some extend, have also flown with various guys in the left and right seat. In contrast to A320/340 I've never experienced a situation with the lightest touch of PIO on that ship.
Regards
No, you are not the only one...
@Wino
I know that aircraft by some extend, have also flown with various guys in the left and right seat. In contrast to A320/340 I've never experienced a situation with the lightest touch of PIO on that ship.
Regards
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“… Research into wake vortex encounters indicates that a loud noise can be associated with entry into the core of the vortex if the geometry is appropriate. ….”
Surely there is a difference between a “loud noise” and a “loud bang”? Does anyone really believe that wake turbulence could cause a loud bang 258 seconds after its formation?
The excerpt below is from the cockpit voice recorder transcript of American Airlines Flight 587. As Wino says, it includes a reference to a “loud bang”. However, it is not the first unusual sound heard, and max power was called for before the “loud bang”.
0915:28.5 HOT-2 [sound similar to yawn] thank you.
0915:36.4 DEP American five eighty seven heavy, turn left, proceed direct WAVEY.
0915:37.3 HOT-1 [sound of brief squeak and a rattle]
0915:41.0 RDO-1 uh, we'll turn direct WAVEY, American five eighty seven heavy.
0915:44.4 HOT-2 left turn direct WAVEY….
0915:44.7 HOT-1 little wake turbulence, huh?
0915:45.6 HOT-2 …yeah.
0915:47.3 HOT-2 [sound similar to five sets of stabilizer trim switch clicks]
0915:48.2 HOT-2 two fifty thank you.
0915:51.8 CAM [sound of a thump]
0915:52.3 CAM [sound of click]
0915:52.9 CAM [sound of two thumps]
0915:54.2 HOT-2 max power. [spoken in strained voice]
0915:55.0 HOT-1 you all right?
0915:55.3 HOT-2 yea, I'm fine.
0915:56.3 HOT-1 hang onto it. hang onto it.
0915:56.6 CAM [sound of snap]
0915:57.5 HOT-2 let's go for power please.
0915:57.7 CAM [sound of loud thump]
0915:58.5 CAM [sound of loud bang]
0916:00.0 HOT-2 [sound similar to human grunt]
0916:00.2 CAM [roaring noise starts and increases in amplitude]
0916:01.0 HOT-2 holy #.
0916:01.0 CAM [sound similar to single ECAM chime]
0916:02.0 CAM [sound similar to single ECAM chime]
0916:04.4 CAM [sound similar to stall warning repetitive chime for 1.9 seconds]
HOT Crewmember hot microphone voice or sound source
RDO Radio transmission from accident aircraft
CAM Cockpit area microphone voice or sound source
# Expletive
Cheers,
Surely there is a difference between a “loud noise” and a “loud bang”? Does anyone really believe that wake turbulence could cause a loud bang 258 seconds after its formation?
The excerpt below is from the cockpit voice recorder transcript of American Airlines Flight 587. As Wino says, it includes a reference to a “loud bang”. However, it is not the first unusual sound heard, and max power was called for before the “loud bang”.
0915:28.5 HOT-2 [sound similar to yawn] thank you.
0915:36.4 DEP American five eighty seven heavy, turn left, proceed direct WAVEY.
0915:37.3 HOT-1 [sound of brief squeak and a rattle]
0915:41.0 RDO-1 uh, we'll turn direct WAVEY, American five eighty seven heavy.
0915:44.4 HOT-2 left turn direct WAVEY….
0915:44.7 HOT-1 little wake turbulence, huh?
0915:45.6 HOT-2 …yeah.
0915:47.3 HOT-2 [sound similar to five sets of stabilizer trim switch clicks]
0915:48.2 HOT-2 two fifty thank you.
0915:51.8 CAM [sound of a thump]
0915:52.3 CAM [sound of click]
0915:52.9 CAM [sound of two thumps]
0915:54.2 HOT-2 max power. [spoken in strained voice]
0915:55.0 HOT-1 you all right?
0915:55.3 HOT-2 yea, I'm fine.
0915:56.3 HOT-1 hang onto it. hang onto it.
0915:56.6 CAM [sound of snap]
0915:57.5 HOT-2 let's go for power please.
0915:57.7 CAM [sound of loud thump]
0915:58.5 CAM [sound of loud bang]
0916:00.0 HOT-2 [sound similar to human grunt]
0916:00.2 CAM [roaring noise starts and increases in amplitude]
0916:01.0 HOT-2 holy #.
0916:01.0 CAM [sound similar to single ECAM chime]
0916:02.0 CAM [sound similar to single ECAM chime]
0916:04.4 CAM [sound similar to stall warning repetitive chime for 1.9 seconds]
HOT Crewmember hot microphone voice or sound source
RDO Radio transmission from accident aircraft
CAM Cockpit area microphone voice or sound source
# Expletive
Cheers,
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"...a replacement rudder is being fitted..."
Good grief - I hope they do a thorough inspection of the fin structure and aft fuselage, and particularly the engine mounting lugs, before it's flown again. There is surely no rush....
Zeke, I have read with interest your postings on this topic and hope I have learned from your technical briefs posted here. I retain an open mind into this rudder failure until the facts are known.
My concern is Airbus' past history of dubious investigations....
I was at CX when we had all manner of problems with the intro of the 330, to the extent that we had to ground them voluntarily because Airbus would not admit a problem with the gearbox scavenge system design. Other problems at the time plagueing the aircraft were well known ( including the wreck of the demo example during an engine-out climb involving the test pilot and a dodgy altitude capture, mismatched ADC's on another involving conflicting warnings during the cruise, the radar-reflective paint coating used on the radome by mistake, etc ). Then there's the A-320's early history and Airbus investigations.... Let's not forget that the 340 currently has upper-wing crack problems, less than 10 years into service.
These are aircraft designed in the age of C.A.D - not slide rules such as the 747 and 737.
There simply seems to me no excuse for these problems. How many serious technical probs have there been with the introduction and structures of the most recent new designs from Boeing, ie aircraft designed post-formation of Airbus Industrie? 757? 767? 777?
Very few.
Why is that, Zeke? You've worked on both.
When you speak to pilots around the world about Airbus products, they are very, very polarized: they either love 'em or absolutely hate 'em. Odd....
Every pilot I've met who flies the new Boeings absolutely loves them. No complaints.
Why is that?
Airbus' behaviour, rightly or wrongly, always seems to reek of extreme protectionism of future orders foremost, rather than honest factual reporting. This may not be true, but it's the way it comes across. It's bad PR, and it probably could be avoided.
Good grief - I hope they do a thorough inspection of the fin structure and aft fuselage, and particularly the engine mounting lugs, before it's flown again. There is surely no rush....
Zeke, I have read with interest your postings on this topic and hope I have learned from your technical briefs posted here. I retain an open mind into this rudder failure until the facts are known.
My concern is Airbus' past history of dubious investigations....
I was at CX when we had all manner of problems with the intro of the 330, to the extent that we had to ground them voluntarily because Airbus would not admit a problem with the gearbox scavenge system design. Other problems at the time plagueing the aircraft were well known ( including the wreck of the demo example during an engine-out climb involving the test pilot and a dodgy altitude capture, mismatched ADC's on another involving conflicting warnings during the cruise, the radar-reflective paint coating used on the radome by mistake, etc ). Then there's the A-320's early history and Airbus investigations.... Let's not forget that the 340 currently has upper-wing crack problems, less than 10 years into service.
These are aircraft designed in the age of C.A.D - not slide rules such as the 747 and 737.
There simply seems to me no excuse for these problems. How many serious technical probs have there been with the introduction and structures of the most recent new designs from Boeing, ie aircraft designed post-formation of Airbus Industrie? 757? 767? 777?
Very few.
Why is that, Zeke? You've worked on both.
When you speak to pilots around the world about Airbus products, they are very, very polarized: they either love 'em or absolutely hate 'em. Odd....
Every pilot I've met who flies the new Boeings absolutely loves them. No complaints.
Why is that?
Airbus' behaviour, rightly or wrongly, always seems to reek of extreme protectionism of future orders foremost, rather than honest factual reporting. This may not be true, but it's the way it comes across. It's bad PR, and it probably could be avoided.
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Airbus to Recommend Inspections of A300, A310 Planes (Update1)
March 14 (Bloomberg) -- Airbus SAS, the world's biggest planemaker, will tell airlines to inspect the rudders of 400 aircraft worldwide after most of a tail part fell off during a flight earlier this month, a company spokesman said.
Airbus will take the action for A310 and A300-600 planes ``out of an abundance of caution'' after most of the rudder came off an Air Transat plane at cruising altitude, the spokesman, Clay McConnell, said in an interview. The plane, an A310 carrying 261 passengers and nine crew from Cuba to Quebec City, was forced to return to Cuba about 30 minutes after takeoff.
Airbus will tell airlines to conduct inspections, usually done every five years, within a few weeks, McConnell said. The carrier is recommending visual inspections and a so-called ``tap'' audio analysis to determine whether there are internal flaws in the carbon-fiber rudder, he said. A310 and A300-600 planes have identical rudders, he said.
``We don't know yet what happened'' with the Air Transat plane, McConnell said. ``We feel that this event is so unusual it really does require that we do something to be sure that there's not a problem out there.''
McConnell said Airbus will make the recommendation in a bulletin to operators, probably on Wednesday. French regulators will probably require the inspections, and other aviation regulators around the world, including the U.S. Federal Aviation Administration, are expected to follow suit, McConnell said.
Examinations
Canadian aviation investigators are still examining the Air Transat incident and haven't determined why most of the rudder came off. The rudder is a movable part of the plane's vertical tail fin used to push the aircraft's nose left and right during cross-wind landings and engine outages.
Air Transat inspected all 10 of the A310s it operates on the day of the incident. They were released back into service within hours, said spokeswoman Rachel Andrews. Air Transat, Canada's largest charter carrier, is a unit of Transat A.T. Inc.
U.S. operators of the A310 and A300-600 planes include FedEx Corp., AMR Corp.'s American Airlines and United Parcel Service Inc. McConnell said he didn't know how much the inspections would cost or whether the evaluations could be done as part of routine maintenance. Airlines will pay the cost of the inspections, he said.
Canadian investigators examined the Air Transat aircraft last week in Cuba and so far have found no problems with the hydraulics that operate the rudder, said Marc Fernandez, senior investigator with the Transportation Safety Board of Canada. The rudder that detached hasn't been found, he said.
Structure
``Structure-wise we don't have much left of the rudder there, so what we've decided to do is remove the whole tail of the aircraft,'' Fernandez said. Airbus investigators will return to Cuba Thursday to remove the tail section for further analysis, he said.
The U.S. National Transportation Safety Board last October ruled that an American Airlines pilot caused a fatal November 2001 crash of an A300-600 in New York with ``unnecessary and excessive'' rudder movements that resulted in the plane's vertical tail fin snapping off.
The sensitivity of the A300-600 jet's rudder control system contributed to the accident that killed 265 people, as did pilot training by American, the board said. Flight 587 crashed less than two minutes after leaving John F. Kennedy International Airport on Nov. 12, two months after the Sept. 11 terrorist attacks.
The tail fin remained on the plane in the Air Transat incident, which is unrelated to the New York accident, Fernandez said.
March 14 (Bloomberg) -- Airbus SAS, the world's biggest planemaker, will tell airlines to inspect the rudders of 400 aircraft worldwide after most of a tail part fell off during a flight earlier this month, a company spokesman said.
Airbus will take the action for A310 and A300-600 planes ``out of an abundance of caution'' after most of the rudder came off an Air Transat plane at cruising altitude, the spokesman, Clay McConnell, said in an interview. The plane, an A310 carrying 261 passengers and nine crew from Cuba to Quebec City, was forced to return to Cuba about 30 minutes after takeoff.
Airbus will tell airlines to conduct inspections, usually done every five years, within a few weeks, McConnell said. The carrier is recommending visual inspections and a so-called ``tap'' audio analysis to determine whether there are internal flaws in the carbon-fiber rudder, he said. A310 and A300-600 planes have identical rudders, he said.
``We don't know yet what happened'' with the Air Transat plane, McConnell said. ``We feel that this event is so unusual it really does require that we do something to be sure that there's not a problem out there.''
McConnell said Airbus will make the recommendation in a bulletin to operators, probably on Wednesday. French regulators will probably require the inspections, and other aviation regulators around the world, including the U.S. Federal Aviation Administration, are expected to follow suit, McConnell said.
Examinations
Canadian aviation investigators are still examining the Air Transat incident and haven't determined why most of the rudder came off. The rudder is a movable part of the plane's vertical tail fin used to push the aircraft's nose left and right during cross-wind landings and engine outages.
Air Transat inspected all 10 of the A310s it operates on the day of the incident. They were released back into service within hours, said spokeswoman Rachel Andrews. Air Transat, Canada's largest charter carrier, is a unit of Transat A.T. Inc.
U.S. operators of the A310 and A300-600 planes include FedEx Corp., AMR Corp.'s American Airlines and United Parcel Service Inc. McConnell said he didn't know how much the inspections would cost or whether the evaluations could be done as part of routine maintenance. Airlines will pay the cost of the inspections, he said.
Canadian investigators examined the Air Transat aircraft last week in Cuba and so far have found no problems with the hydraulics that operate the rudder, said Marc Fernandez, senior investigator with the Transportation Safety Board of Canada. The rudder that detached hasn't been found, he said.
Structure
``Structure-wise we don't have much left of the rudder there, so what we've decided to do is remove the whole tail of the aircraft,'' Fernandez said. Airbus investigators will return to Cuba Thursday to remove the tail section for further analysis, he said.
The U.S. National Transportation Safety Board last October ruled that an American Airlines pilot caused a fatal November 2001 crash of an A300-600 in New York with ``unnecessary and excessive'' rudder movements that resulted in the plane's vertical tail fin snapping off.
The sensitivity of the A300-600 jet's rudder control system contributed to the accident that killed 265 people, as did pilot training by American, the board said. Flight 587 crashed less than two minutes after leaving John F. Kennedy International Airport on Nov. 12, two months after the Sept. 11 terrorist attacks.
The tail fin remained on the plane in the Air Transat incident, which is unrelated to the New York accident, Fernandez said.
Zeke-that is reasonable.
This topic is quite interesting. I jumpseated once on a FEDEX A-300 and was impressed with the c0ckp1t and instrument/overhead panel design, and would have enjoyed the opportunity to fly it. Never mind the desire to have more job security working for a package/freight carrier.
Is the carbon material used in the rudder the same as that in the vertical stabilizer?
It must be a nightmare to inspect the tails with x-rays or anything else, and spot tiny cracks in composite materials.
Are the structural members all made of aluminum? How about in the 319/320?
This topic is quite interesting. I jumpseated once on a FEDEX A-300 and was impressed with the c0ckp1t and instrument/overhead panel design, and would have enjoyed the opportunity to fly it. Never mind the desire to have more job security working for a package/freight carrier.
Is the carbon material used in the rudder the same as that in the vertical stabilizer?
It must be a nightmare to inspect the tails with x-rays or anything else, and spot tiny cracks in composite materials.
Are the structural members all made of aluminum? How about in the 319/320?
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Just check out the photos. The aft rudder surface or whats left of it is obviously some kind of composite. The forward section looks like aluminium (check the yank using the correct spelling!) but one will have to crack in 2 and have its photo posted for me to tell ya.
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I find it hard to believe the forces that are involved in these incidents, IF there is nothing else wrong, particularly the American A300.
To rip off a rudder, or much worse a whole tail, from a servicable Aircraft, they must be huge.
This is an identical Airbus A310, that was towed at speed into a hangar roof at JFK, and the hangar roof won.
Despite all this damage, the tail was still firmly attached.
To rip off a rudder, or much worse a whole tail, from a servicable Aircraft, they must be huge.
This is an identical Airbus A310, that was towed at speed into a hangar roof at JFK, and the hangar roof won.
Despite all this damage, the tail was still firmly attached.
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PickyPerkins,
I would hear several loud bangs each flight, most of the time it’s associated with cabin crew moving about carts etc. I have heard bangs also when going into turbulance, again this was found to come from the galley.
RRAAMJET,
Airbus does not do the public investigations, or the reports, they maybe an "expert" used for assistance, however they do not publish reports. Information from all reports I have shown here are from various government bodies.
They dont make engines either, something another manufacturer has been saying about the number of failures its had, including one on a demo flight for a customer.
In most cases Airbus do not even do the FDR,QAR,CVR analysis, they might get a copy of it, but don’t do analysis like in AA587 which the NTSB did.
I am not aware of any aircraft entering service that has not had it problems, including the ones you mentioned are good aircraft. Cracks in aircraft structures are not an airbus only problem.
The A330 crash during flight test in my view was due to people being a little to inattentive flying around single engine. From memory the aircraft did everything it was supposed to do.
As for aerospace engineers, like pilots they are industrial prostitutes working on contract going from A to B back to A back to B depending on who has the work on at the time. The software used at A and B these days for designing stuff (CATIA) is the same, it’s originally a French product. Most of the computers its runs on are American. If you trash one product your really trashing both, at the end of the day the same people design them, and the source from the same or similar sub system providers (i.e engines, wheels, brakes, tyres, avionics, FMC's, pumps, electronics etc)
By the way, I have never heard a pilot yet that cannot complain about something. Just ask them how much they think they are worth.
Ignition Override,
I would think they are, the fibers are essentially the same, what tends to vary if the epoxy matrix, and the process of curing the part, i.e., the temperature, pressure, and time required in the autoclave.
"Are the structural members all made of aluminum" if you mean the spar in the tail etc, no not metal, try and keep composite with composite, biggest problem with composites is how to join them to metal, or use of fasteners.
"spot tiny cracks in composite materials." Tiny cracks are not anything to worry about, you have tiny cracks in wodden aircraft, they are the first true composite material. You could say we are going around the full circle, from kittyhawk where it was mainly a composite aircraft to the 787 which will have a composite fuselage.
When you buy the rolls of the material, it already has broken fibers in it, where composites has its advantage over metal is that the expoxy matrix will transfer the load from the broken fibre to surrounding fibers retaining structural integerity, cracks dont propergate in composites like they do in metal, no grains in the metal for the cracks to develop.
planemad2,
Your jumping the gun a little, no has said that the rudder came off due to excessive force. Many ways to weaken a structure without people knowing about it, like lightning.
I would hear several loud bangs each flight, most of the time it’s associated with cabin crew moving about carts etc. I have heard bangs also when going into turbulance, again this was found to come from the galley.
RRAAMJET,
Airbus does not do the public investigations, or the reports, they maybe an "expert" used for assistance, however they do not publish reports. Information from all reports I have shown here are from various government bodies.
They dont make engines either, something another manufacturer has been saying about the number of failures its had, including one on a demo flight for a customer.
In most cases Airbus do not even do the FDR,QAR,CVR analysis, they might get a copy of it, but don’t do analysis like in AA587 which the NTSB did.
I am not aware of any aircraft entering service that has not had it problems, including the ones you mentioned are good aircraft. Cracks in aircraft structures are not an airbus only problem.
The A330 crash during flight test in my view was due to people being a little to inattentive flying around single engine. From memory the aircraft did everything it was supposed to do.
As for aerospace engineers, like pilots they are industrial prostitutes working on contract going from A to B back to A back to B depending on who has the work on at the time. The software used at A and B these days for designing stuff (CATIA) is the same, it’s originally a French product. Most of the computers its runs on are American. If you trash one product your really trashing both, at the end of the day the same people design them, and the source from the same or similar sub system providers (i.e engines, wheels, brakes, tyres, avionics, FMC's, pumps, electronics etc)
By the way, I have never heard a pilot yet that cannot complain about something. Just ask them how much they think they are worth.
Ignition Override,
I would think they are, the fibers are essentially the same, what tends to vary if the epoxy matrix, and the process of curing the part, i.e., the temperature, pressure, and time required in the autoclave.
"Are the structural members all made of aluminum" if you mean the spar in the tail etc, no not metal, try and keep composite with composite, biggest problem with composites is how to join them to metal, or use of fasteners.
"spot tiny cracks in composite materials." Tiny cracks are not anything to worry about, you have tiny cracks in wodden aircraft, they are the first true composite material. You could say we are going around the full circle, from kittyhawk where it was mainly a composite aircraft to the 787 which will have a composite fuselage.
When you buy the rolls of the material, it already has broken fibers in it, where composites has its advantage over metal is that the expoxy matrix will transfer the load from the broken fibre to surrounding fibers retaining structural integerity, cracks dont propergate in composites like they do in metal, no grains in the metal for the cracks to develop.
planemad2,
Your jumping the gun a little, no has said that the rudder came off due to excessive force. Many ways to weaken a structure without people knowing about it, like lightning.
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I didn't say it did, and certainly DON'T believe it was the cause of EITHER of these accidents/incidents.
From my experience, I believe the MAIN cause is that these composite components on both Aircraft were weakened by water/ice ingress over a long period of time into these components.
From my experience, I believe the MAIN cause is that these composite components on both Aircraft were weakened by water/ice ingress over a long period of time into these components.
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planemad2,
Sorry if I mis understood what you said, I cannot say at this stage if that was the cause.
This photo gives you an idea of what severe turbulence can do to the vertical stabilizer with delamination not being a factor.
Sorry if I mis understood what you said, I cannot say at this stage if that was the cause.
This photo gives you an idea of what severe turbulence can do to the vertical stabilizer with delamination not being a factor.
In flight with extensive tail damage - B-52H-170-BW S/N 61-0023 From a famous series of photographs taken after severe turbulence sheared off most of the vertical stabilizer. The aircraft had been specially instrumented for air turbulence research after some operational B-52s were lost. The tail was lost after a severe and sustained burst (+5 seconds) of clear air turbulence violently buffeted the aircraft. The Boeing test crew (Pilot - Chuck Fisher & Copilot - Dick Curry) nursed to aircraft to Blytheville AFB, Arkansas and landed safely. Also note the (inert) AGM-28 Hound Dog missiles still attached to the wing pylons. The dotted line shows the normal outline of the vertical stabilizer and rudder.
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Someone asked about different types of carbon. Slightly OT but..
Yes there are different grades of Carbon. Carbon fiber doesn't stretch much but within limits it's possible to adjust it elasticity (Modulus) when it's made. You can also weave cloths with mixtures of Carbon, Kevlar and other materials to make hybrids with very specific properties.
Photo
There are more exotic materials around (eg Boron fiber) but Carbon is reasonably cheap these days.
For more info see a Guide to composites
Later Edit: I forgot to add that....
In the event of two similar crashes, the use of the same type of Carbon would not constitute a really significant link (any more than the use of the same type of aluminium would).
Yes there are different grades of Carbon. Carbon fiber doesn't stretch much but within limits it's possible to adjust it elasticity (Modulus) when it's made. You can also weave cloths with mixtures of Carbon, Kevlar and other materials to make hybrids with very specific properties.
Photo
There are more exotic materials around (eg Boron fiber) but Carbon is reasonably cheap these days.
For more info see a Guide to composites
Later Edit: I forgot to add that....
In the event of two similar crashes, the use of the same type of Carbon would not constitute a really significant link (any more than the use of the same type of aluminium would).
Last edited by cwatters; 15th Mar 2005 at 18:13.
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Zeke
Seems like we need some calibration on "loud bangs" here.
The ultimate sideways load for failure of the tail fin for American Airlines Flight 587 was, I believe, about 37.5 tons. The sound of the fin failing under this load seems to have been described on the CVR as either the "sound of snap" or as a "loud bang". At the same time we have pilots such as yourself describing the sound of carts moving about in the galley as "loud bangs".
Surely these sounds must have been of a different order of magnitude?
Cheers,
Seems like we need some calibration on "loud bangs" here.
The ultimate sideways load for failure of the tail fin for American Airlines Flight 587 was, I believe, about 37.5 tons. The sound of the fin failing under this load seems to have been described on the CVR as either the "sound of snap" or as a "loud bang". At the same time we have pilots such as yourself describing the sound of carts moving about in the galley as "loud bangs".
Surely these sounds must have been of a different order of magnitude?
Cheers,
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PickyPerkins,
If it were to fail, it is outside the aircraft, the length of the aircraft away from the cockpit, with the aircraft moving away from the noise in relative motion, and a cockpit door that is closed, and well insulated. Think about how quiet it is in an aircraft with the engine noise just outside. Can you hear the APU running whilst on the ground with a cockpit door open ?
The term "loud noise/bang" I would suggest could only be something relatively close to be heard in a closed cockpit.
If it were to fail, it is outside the aircraft, the length of the aircraft away from the cockpit, with the aircraft moving away from the noise in relative motion, and a cockpit door that is closed, and well insulated. Think about how quiet it is in an aircraft with the engine noise just outside. Can you hear the APU running whilst on the ground with a cockpit door open ?
The term "loud noise/bang" I would suggest could only be something relatively close to be heard in a closed cockpit.
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Zeke
I was assuming that the sound would be transmitted through the structure if the aircraft, but maybe it does not work that way. The whole fuselarge must have twisted when the fin snapped off, presumably followed by a torsional oscillation. I agree about not hearing the APU, but one does hear the flap extension mechanism operating and the gear being lowered. The loudest bang I ever heard in an aircraft was a tyre blowing after retraction, seemingly right under my feet.
Cheers,
I was assuming that the sound would be transmitted through the structure if the aircraft, but maybe it does not work that way. The whole fuselarge must have twisted when the fin snapped off, presumably followed by a torsional oscillation. I agree about not hearing the APU, but one does hear the flap extension mechanism operating and the gear being lowered. The loudest bang I ever heard in an aircraft was a tyre blowing after retraction, seemingly right under my feet.
Cheers,
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Seems some people are coming around to my theory.
Unless they have been reading this site.
-------------------------------------------------------------------
The Airbus rudder: Compromised composites?
Pittsbburg Tribune-Review
Friday, March 18, 2005
The rudder of an Airbus A310 fell off at 35,000 feet on a March 6 flight from Cuba to Quebec. The crew maintained control and returned to the island.
A former Airbus pilot, who now flies Boeings, told The Observer of Britain that rudders just didn't fall apart like that -- until now.
The fates were kinder to the 270 people on board this month's flight than the 265 who died in November 2001 when a nearly identical Airbus A300 crashed after takeoff in New York.
Pilot error was blamed for the loss of the rudder and tail fin. It is disputed whether pilot "overcorrections" occurred before or after the plane started falling apart.
European manufacturer Airbus has overtaken Boeing as the top jetliner-maker. Its A380 superjumbo will be carrying passengers next year.
A key to the Airbus success has been use of carbon composite materials -- used on the A300, A310 and A380 -- valued for their lightness and strength.
Fins, flaps and rudders on some A300s and all A310s are made of these composites. Some say only ultrasound instead of the typical visual inspections can detect possible structural failures because of water condensation between layers.
Airbus says it will ask for (ask for?) airline inspections (of what kind we don't know) in light of the March 6 debacle, but it stands behind the crafts' safety.
One hopes no more planes drop parts before Airbus starts acting more responsibly.
-------------------------------------------------------------------------------
Unless they have been reading this site.
-------------------------------------------------------------------
The Airbus rudder: Compromised composites?
Pittsbburg Tribune-Review
Friday, March 18, 2005
The rudder of an Airbus A310 fell off at 35,000 feet on a March 6 flight from Cuba to Quebec. The crew maintained control and returned to the island.
A former Airbus pilot, who now flies Boeings, told The Observer of Britain that rudders just didn't fall apart like that -- until now.
The fates were kinder to the 270 people on board this month's flight than the 265 who died in November 2001 when a nearly identical Airbus A300 crashed after takeoff in New York.
Pilot error was blamed for the loss of the rudder and tail fin. It is disputed whether pilot "overcorrections" occurred before or after the plane started falling apart.
European manufacturer Airbus has overtaken Boeing as the top jetliner-maker. Its A380 superjumbo will be carrying passengers next year.
A key to the Airbus success has been use of carbon composite materials -- used on the A300, A310 and A380 -- valued for their lightness and strength.
Fins, flaps and rudders on some A300s and all A310s are made of these composites. Some say only ultrasound instead of the typical visual inspections can detect possible structural failures because of water condensation between layers.
Airbus says it will ask for (ask for?) airline inspections (of what kind we don't know) in light of the March 6 debacle, but it stands behind the crafts' safety.
One hopes no more planes drop parts before Airbus starts acting more responsibly.
-------------------------------------------------------------------------------