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Information on A310 that lost it's rudder enroute to Canada from Cuba
I received the following from an acquaintence. Don't know how many
have read it but I found it interesting.
What made an Airbus rudder snap in mid-air?
When Flight 961 literally began to fall apart at 35,000 feet, it
increased fears of a fatal design flaw in the world's most popular
Sunday March 13, 2005
At 35,000 feet above the Caribbean, Air Transat flight 961 was heading
home to Quebec with 270 passengers and crew. At 3.45 pm last Sunday,
the pilot noticed something very unusual. His Airbus A310's rudder - a
structure 28 feet high - had fallen off and tumbled into the sea. In
the world of aviation, the shock waves have yet to subside.
Mercifully, the crew was able to turn the plane around, and by
steering it with their wing and tail flaps managed to land at their
point of departure in Varadero, Cuba, without loss of life. But as
Canadian investigators try to discover what caused this near
catastrophe, the specialist internet bulletin boards used by pilots,
accident investigators and engineers are buzzing.
One former Airbus pilot, who now flies Boeings for a major US airline,
told The Observer : 'This just isn't supposed to happen. No one I know
has ever seen an airliner's rudder disintegrate like that. It raises
worrying questions about the materials and build of the aircraft, and
about its maintenance and inspection regime. We have to ask as things
stand, would evidence of this type of deterioration ever be noticed
before an incident like this in the air?'
He and his colleagues also believe that what happened may shed new
light on a previous disaster. In November 2001, 265 people died when
American Airlines flight 587, an Airbus A300 model which is almost
identical to the A310, crashed shortly after take-off from JFK airport
in New York. According to the official report into the crash, the
immediate cause was the loss of the plane's rudder and tailfin, though
this was blamed on an error by the pilots.
There have been other non-fatal incidents. One came in 2002 when a
FedEx A300 freight pilot complained about strange 'uncommanded inputs'
- rudder movements which the plane was making without his moving his
control pedals. In FedEx's own test on the rudder on the ground,
engineers claimed its 'acuators' - the hydraulic system which causes
the rudder to move - tore a large hole around its hinges, in exactly
the spot where the rudders of both flight 961 and flight 587 parted
company from the rest of the aircraft.
Last night Ted Lopatkiewicz, spokesman for the US National
Transportation Safety Board (NTSB), which conducted the flight 587
investigation, said that the board was 'closely monitoring' the
Canadian inquiry for its possible bearing on the New York crash. 'We
need to know why the rudder separated from the aircraft before knowing
whether maintenance is an issue,' he added.
Airbus - Europe's biggest manufacturing company, to which British
factories contribute major components, including aircraft wings - has
now overtaken Boeing to command the biggest share of the global
airliner market. In sales literature to operators, it described the
A300 series as a 'regional profit machine'.
The firm recently launched its superjumbo, the two-storey A380, which
is due in service next year. Like earlier Airbus models, this relies
heavily on 'composite' synthetic materials which are both lighter -
and, in theory, stronger - than aluminium or steel. Fins, flaps and
rudders are made of a similar composite on the A300 and A310, of which
there are about 800 in service all over the world.
Composites are made of hundreds of layers of carbon fibre sheeting
stuck together with epoxy resin. Each layer is only strong along the
grain of the fibre. Aircraft engineers need to work out from which
directions loads will come, then lay the sheets in a complex,
criss-cross pattern. If they get this wrong, a big or unexpected load
might cause a plane part to fail.
It is vital there are no kinks or folds as the layers are laid, and no
gaps in their resin coating. Holes between the layers can rapidly
cause extensive 'delamination' and a loss of stiffness and strength.
Airbus, together with aviation authorities on both sides of the
Atlantic, insists that any deterioration of a composite part can be
detected by external, visual inspection, a regular feature of Airbus
maintenance programmes, but other experts disagree.
In an article published after the flight 587 crash, Professor James
Williams of the Massachusetts Institute of Technology, one of the
world's leading authorities in this field, said that to rely on visual
inspection was 'a lamentably naive policy. It is analogous to
assessing whether a woman has breast cancer by simply looking at her
Williams and other scientists have stated that composite parts in any
aircraft should be tested frequently by methods such as ultrasound,
allowing engineers to 'see' beneath their surface. His research
suggests that repeated journeys to and from the sub-zero temperatures
found at cruising altitude causes a build-up of condensation inside
composites, and separation of the carbon fibre layers as this moisture
freezes and thaws. According to Williams, 'like a pothole in a roadway
in winter, over time these gaps may grow'.
Commenting on the vanishing rudder on flight 961, he pointed out that
nothing was said about composite inspection in the NTSB's report on
flight 587. This was an 'unfortunate calamity', he said. Although the
flight 961 rupture had yet be analysed, he continued to believe
Airbus's maintenance rules were 'inadequate', despite their official
Barbara Crufts, an Airbus spokeswoman, said visual inspections were
'the normal procedure' and insisted Williams's case was unproven. 'You
quote him as an expert. But there are more experts within the
manufacturers and the certification authorities who agree with these
procedures.' She disclosed that the aircraft used in flight 961 -
which entered service in 1991 - had been inspected five days before
the incident. She said did not know if the rudder had been examined.
Despite these and earlier assurances, some pilots remain sceptical.
The Observer has learnt that after the 587 disaster, more than 20
American Airlines A300 pilots asked to be transferred to Boeings,
although this meant months of retraining and loss of earnings. Some of
those who contributed to pilots' bulletin boards last week expressed
anger at the European manufacturer in vehement terms. One wrote that
having attended an Airbus briefing about 587, he had refused to let
any of his family take an A300 or A310 and had paid extra to take a
circuitous route on holiday purely to avoid them: 'That is how con
vinced I am that there are significant problems associated with these
Another seasoned pilot with both military and civilian experience
said: 'Composite experts across the country advocate state-of-the-art,
non-destructive testing to prevent this type of incident from
happening, yet civil aviation authorities still only require "naked
eye" or other rudimentary inspections. How many more incidents have to
occur for decision-makers to do the right thing by passengers and
He said that while flight 961 had come down safely, to land a plane
without a rudder in a crosswind or turbulence could be impossible. The
rudder was all the more important on a plane such as an A310, because
its wing design meant that it was 'aerodynamically unstable' and
needed the rudder for stability.
Air Transat, a charter operator which flies from Canada to Europe and
the Caribbean, said that after the incident it 'immediately carried
out a thorough visual examination of all its Airbus A310s... and no
anomaly was detected.'
The separation of the rudder may have further implications for the
cause of the 587 crash. In its report, the NTSB said the tail and
rudder failed because they were subjected to stresses 'beyond ultimate
load', imposed because the co-pilot, Sten Molin, overreacted to minor
turbulence and made five violent side-to-side 'rudder reversals'. The
report said the design of the A300 controls was flawed because it
allowed this to happen.
However, the NTSB investigation has been criticised by many insiders.
Ellen Connors, the NTSB chair, told reporters last January that the
report was delayed because of 'inap propriate' and 'intense' lobbying
by Airbus over its contents, adding: 'The potential for contaminating
the investigation exists.' In America, the NTSB staff is small and
manufacturers provide many of the staff employed on air-crash
investigations into their own products.
Dozens of former accident investigators, engineers and pilots,
including some who were involved in the official inquiry but were
disappointed by its conduct, poured their expertise into a parallel
investigation run by Victor Trombettas, who lives near the crash site
and runs a website, usread.com. Drawing on the huge mass of technical
data released after the crash, they question the conclusion that
'aggressive' rudder inputs were the crash's main cause.
'I don't think the NTSB did a quality job,' said Vernon Grose, a
Washington safety consultant who is a former board member. He
supported the conclusion of Trombettas's group - that more than ten
seconds before any rudder movements, the 587 pilots were fighting to
regain control of the aircraft for reasons that remain unknown: a
still-to-be investigated technical failure, or possibly a terrorist
bomb. The crash, he recalled, took place two months after 9/11. Ninety
per cent of the witnesses who saw the plane from the ground said they
saw smoke or fire billowing from it before the tail and rudder fell
off, Grose said.
Against this background, a spokeswoman for the Canadian Transport
Safety Bureau, which is performing the investigation, disclosed that
there is 'no evidence' of any movements by the rudder before its
rupture, while Air Transat confirmed that it had separated when the
plane was at cruising altitude and speed. 'You barely use the rudder
at all in those conditions,' the former A300 pilot said. 'If this
plane lost a rudder with no one doing anything, it has to raise new
questions about the fate of flight 587.'
And the pressure is now on the aviation authorities to review whether
testing by the naked eye is really enough to keep air passengers safe.
Subject: AirBus Rudder
TO - ALL PILOTS
SUBJECT - AIR TRANSAT A310 RUDDER FAILURE
ON 6 MAR, AN AIR TRANSAT AIRBUS A310, FLYING FROM CUBA TO
QUEBEC, APPARENTLY EXPERIENCED RUDDER STRUCTURAL FAILURE AND
RETURNED TO CUBA WHERE IT LANDED SAFELY. FEW DETAILS OF THE
INCIDENT ARE KNOWN AT THIS TIME, HOWEVER THERE APPEARS TO BE
NO DAMAGE TO THE VERTICAL STABILIZER STRUCTURE.
WE ARE MONITORING THIS SITUATION VERY CLOSELY AND ARE IN
CONTACT WITH THE NTSB AND AIRBUS TO GATHER THE FACTS AND
CIRCUMSTANCES REGARDING THIS INCIDENT. WE WILL FORWARD ANY
PERTINENT INFORMATION WHEN IT IS AVAILABLE.
CAPTAIN JIM KAISER - MGR, FLT OPS EFFICIENCY/QUALITY CONTROL
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