What Made An Airbus Rudder Snap In Mid-Air?

[Guest Guest]

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 passenger jet

 

David Rose

 

Sunday March 13, 2005

 

The Observer

 

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 family portrait.'

 

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 endorsement.

 

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 aircraft.'

 

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 crews?'

 

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.

 

 

[Guest Guest]

Incidentally, I have my own theories on this, after that A300-600 crash out of New York, and remembering what we used to find on our A checks in New York on our A300-600 which was operating in exactly the same environment as the American A300-600, and a very similar environment to this Air Transat A310. :(

 

I have mentioned my concerns before somewhere else, and they were ridiculed by "experts" in composite technology. :roll:

 

However these incidents convince me even more of the "possible" dangers with water ingress into these composites. :shock:

 

 

[Guest Guest]

Airbus to Recommend Inspections of A300, A310 Planes

 

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.

 

 

[Guest Glenn]

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.

You would think that Airbus could pay for part of the inspections or all of it. Like a recall they do on cars. I had a recall notice from Mitsubishi to have my car inspected because of a fault with something. Just a thought.

 

 

[Guest Guest]

Airbus are still not admitting that there is anything wrong, so they will not be paying for it, especially on such old Aircraft.

 

 

Damaged A310 tail at JFK, but this one hit a hangar. :roll:

 

 

[Guest Sunshy]

A couple of years ago, one of our A300's had a dual yaw damper failure. After fixing the yaw damper, the rudder travel limiter turned out to be damaged as well. I didn't actually see the damage since I was on an outstation at the time, but from what my workmates told me, the A/C could have lost its rudder under slightly different conditions.

 

 

[Guest dolbinau]

Edited out by lame...........................

 

PLEASE be careful what you say, unless you have proof. :shock:

 

I am sure Glenn doesn't want a law suit already. :roll:

 

 

[Guest Glenn]

I can't remember what was said.

 

 

[Guest Guest]

Well I didn't keep a copy of it, however I know that other aviation web sites have been sued over similar comments. :shock:

 

You just cannot make such negative comments about a specific Airline on a public forum, without risking a law suit. :(

 

By all means make general comments, but NOT such specific negative comments about a specific Airline (or person).

 

 

[Guest Glenn]

Thanks for that lame. Last thing I want is to be sued.

 

 

[Guest Guest]

While obviously we want all of the members to post their thoughts and comments, you must remember that this site can be viewed by anyone via the Internet.

 

General comments are okay if you don't name names, and of course you may mention Companies or people in a positive way :D

 

However you cannot post negative comments about ANY Company or person, no matter how true you believe your comments are. :shock:

 

 

[Guest Guest]

Seems some people are coming around to my theory. :roll:

 

Unless they have been reading this site. :shock:

 

-------------------------------------------------------------------

 

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.

 

-------------------------------------------------------------------------------

 

 

[Guest Sunshy]

I'll make sure to keep the law suits in mind when posting stuff. I didn't realize Glenn could be held accountable fo things other people write.

 

Back to the subject; I found a picture of the detached Transat rudder (the missing rudder to be exact) on the web and it looks like it broke off at the hinges. The top hinge appears to have sheared of completely. If my memory serve me well, the hinge structures are made of alloys, not of composites. So I don't think the composites had a major role in this incident. My guess would be that the top hinge failed (due to fatigue, overstressing or an error made when installing the rudder, you name it), and the remaining hinges just weren't able to take up the load over time.

 

Just guessing here, LAME definitely has a point when it comes to the dangers of water entering composites. I've worked on an A320 with one of it's spoiler blown to bits by a lightning strike. Investigation by Airbus revealed that a lousy paintjob allowed water to enter the spoiler. Paintjob combined with poor bonding made it an easy target for the lightning strike.

 

Afterthought: 2 rudders lost in three years should get some alarm bells ringing at Airbus. Asking airlines for a safety inspection does appear to be a bit too easy. Then again, I don't have the data, Airbus does.

 

 

[Guest Guest]

Yes, other similar sites have been sued for comments like the one I deleted, posted by members. :(

 

The party that has been named can also get a court order forcing the site administrator to hand over details of the member involved. :shock:

 

With the water ingress into composites, I am NOT saying that this definitely caused these incidents/accidents ( thus avoiding any law suits ), however in my professional opinion they may have contributed to the incidents. :(

 

 

[Guest Guest]

http://213.30.153.174/GSAC/ad_cns.nsf/0/05703CEEC7AF6D89C1256FC80062091F/$file/UF05_048.pdf

[Guest Guest]

This inspection now includes some early A330s and A340s, which must have similar rudders. :shock:

 

http://213.30.153.174/Gsac/ad_cns.nsf/accueil_FR?OpenPage

 

 

[Guest Guest]

FAA Orders Inspections of Airbus Rudders (AP)

 

By LESLIE MILLER Associated Press Writer

 

Posted: 3/25/2005 2:22 PM

 

WASHINGTON

 

U.S. airlines will be ordered to inspect the rudders of certain Airbus jets following an incident in which most of the rudder fell off an A310 in flight, a spokesman for the Federal Aviation Administration said Friday.

 

The FAA directive, to be issued Monday, affects A310s and A300-600s. American Airlines and FedEx, the only U.S. airlines that fly those models, have a combined 112 of those planes.

 

A plane operated by Canadian-based Air Transat lost nearly all of the rudder _ the vertical moving part at the back of the tail fin _ soon after leaving Cuba for Quebec on March 6. The pilot was able to control the aircraft and returned to Varadero, Cuba. None of the 270 passengers and crew was injured.

 

"No one knows for sure what really happened, but we feel this is a prudent measure," FAA spokesman Les Dorr said of the order. "The basic idea is to get somebody up looking at the rudder to see if there are any problems that can be detected visually or with the tap test."

 

A tap test is a way to inspect parts by tapping a piece of metal or a coin against the surface while listening for dull spots. Bill Waldock, an aviation safety professor at Embry-Riddle Aeronautical University in Arizona, said it's an extremely time-consuming process. "You got a mechanic out there who's going to spend a lot of time tapping."

 

The FAA directive follows a similar order by French civil aviation authorities on March 18. European aircraft maker Airbus SAS also asked airlines to inspect the planes last week out of what it called "an abundance of caution."

 

Airbus spokeswoman MaryAnne Greczyn said the Airbus request speeds up the regular five-year inspection cycle.

 

The Air Transat incident has prompted discussion about the aging characteristics of composites, a relatively new building material which the A300 rudders are made of. Composites are man-made materials made of at least two different kinds of substances; the Airbus rudders are made of carbon fiber and reinforced epoxy.

 

Composites have been used in aircraft manufacture since the 1970s, first as smaller components and then as larger parts. Airbus was the first manufacturer to use composites extensively on large commercial aircraft. Boeing also uses them.

 

An Airbus A300-600, which has the same rudder system as the A310, crashed in New York in November 2001 after its tail fell off and killed 265 people. The National Transportation Safety Board blamed pilot error, inadequate pilot training and overly sensitive rudder controls.

 

Investigators conducted extensive tests on the tail and found no evidence of fatigue, which occurs in aging components and can cause cracking.

 

Dorr said U.S. airlines have to inspect the plans within 550 flight hours or three months.

 

French civil aviation authorities also told airlines to inspect A330s and A340s because the rudders are the same or similar to the A300-600 and A310. The FAA didn't order A330s to be inspected because the planes used in the United States have different rudders. There are no A340s registered in the United States.

 

 

[Guest Guest]

Slowly, more people ae coming around to my theory. :roll:

 

------------------------------------------------------------------------

 

Airbus rudder inquiry

 

If composites are to blame for after-takeoff incident last month, it could shed more light on 2001 Queens crash

 

BY SYLVIA ADCOCK

 

STAFF WRITER

 

April 4, 2005

 

An incident in which the rudder came off an Airbus 310 jetliner similar to the one that crashed in Queens in 2001 is raising new questions among air safety experts about the composite material that made up the rudder and tail of the two planes.

 

The Canadian charter aircraft involved in the March 6 incident landed safely, but the possibilities were horrifying.

 

Twenty-three minutes after takeoff, passengers on the Air Transat flight from Cuba to Quebec City heard a bang in the back of the airplane, and the pilots noticed the plane began to handle differently. They turned the jet around and headed back to Varadero.

 

Only after landing did the crew see what had happened: The rudder, a movable flap on the tail, had torn off in mid-flight. The plane was able to land safely in part because pilots use the rudder only when landing in a crosswind or when one engine is out.

 

Rudders don't just fall off planes for no reason, but so far investigators have little clue why this one did. One may come if they can find the parts that fell off the plane, believed to be floating on the ocean off the coast of Florida. Investigators have tried to predict where the rudder pieces may have drifted, and the U.S. Coast Guard is watching for floating aircraft debris.

 

The investigation is being led by Canadian aviation officials, with assistance from the U.S. National Transportation Safety Board. "Everyone is very interested in this," said Al Dickinson, who runs the aviation safety program at the University of Southern California.

 

In response to the incident, the Federal Aviation Administration last Monday ordered detailed inspections of the rudders of all Airbus 300-600s and Airbus 310s. In the United States, those planes are flown only by American Airlines and FedEx. American acknowledged Friday that its inspections of two Airbus 300-600s found "minor delamination" - separation of some of the layers of the composite material. The two jets were repaired at Kennedy Airport.

 

Airbus spokesman Clay McConnell said the manufacturer asked for the inspections, but retains complete confidence in the material - high-strength carbon fibers placed crosswise with resin and heated - and in maintenance procedures. "It is an unusual event and that is why we are extremely interested in finding out what happened," McConnell said.

 

The Airbus 310 is almost identical to the American Flight 587 Airbus 300-600 that crashed near Rockaway Beach after losing its tail on Nov. 12, 2001, killing 265 people. Although the scenarios are different, both planes lost components made of the high-strength composite material that is increasingly favored by commercial jet manufacturers over traditional metal alloys.

 

The NTSB last fall ruled that the Flight 587 pilot's actions moving the rudder sharply back and forth caused the tail to break off. Safety officials have said the tail would have broken under such stress no matter what it was made of, and it is unlikely any new evidence would change that conclusion.

 

The union that represents pilots has been reluctant to accept that, however, and its safety representatives said last week they may request the National Transportation Safety Board to reopen the Flight 587 case.

 

"We are watching this investigation very closely," said John David, an American pilot who is the deputy safety chairman of the Allied Pilots Association. "It's unheard of to lose a major flight control surface like this," he said, adding, "If it comes out that this was a composite structure that failed spontaneously, we will file for a reconsideration."

 

The case is mystifying because it appears there was no stress on the tail when the rudder came off, air safety experts said. The plane was cruising, and there is no evidence the pilot was using the rudder when it tore off.

 

The rudder's composite material is extremely strong, lighter than metal, and doesn't corrode or rust. Because of that, the material is marketed as extremely low-maintenance - a good thing for cash-strapped airlines.

 

Composites are not new; military jets have been using them for decades. But some experts say the aerospace industry is still learning how they should be maintained and how they age. "It's not as well-sorted-out as it is with metal structures," said Michael Hoke of Arabis, a Reno, Nev.-based firm that offers composites training to the aerospace industry.

 

Mark Shuart, a materials expert at NASA's Langley Research Center who examined the Flight 587 tail for the NTSB, said he and his colleagues are watching the Air Transat investigation closely to see whether the materials are to blame.

 

Copyright 2005 Newsday Inc.

 

 

[Guest Ultralights]

very interesting, i specialised in composite repair white at...... water contamination was the biggest cause of damage that was not linked to impact damage or excessive load.

 

sadly usual techniques for inspecting the damaged area includes tap testing, (dropping a 20c coin onto the surface and listening for the damage) a real hi tech method of finding damage :roll: , then removing the "wet" area applying an appropriate repair.

 

the only time we used ultrsound as a method of NDT was after the completion of repairs, and only then on small components that could be placed on a good sized table.

 

I believe that water contamination resulting in internal delamination over time is the major vice of composite structures, especially now the A300 fleet are starting to show their age!

 

the reason i think this happens is because a small crack can form withing the structure without actually delaminating the layers within, and through capilliary action and aerodynamic pressure, moisture is ingressed into the component.

 

now if only we cound devise a cheap, (low maintainence downtime) method of detecting water within the structure then i will feel more confident in working with Composites in primary structural areas.

 

the second issue responibly is mentioned in the reports, Composite structures can be engineered to take massive loads in 1 or 2 given directions, but are surprisingly week in others, and it only take a relativly small load in the weeker direction to cause complete failure.

 

i remember a while ago, the tail section sheering off a Boeing B52! but that aircraft was undergoing sever turbulence research. the aircraft flew as normal and the crew only knoew of the missing rudder after exiting the aircraft!