Boeing plans 787 increase

reply to post by ownbestenemy

I am not sure you understand what is exactly being talked about here.

I'll explain: I'm talking about stuff falling off of airplanes like the fuselage panel that fell off the Dreamliner. Like the rudder(s) that fell off the Airbus('s.) And the folly of escalating production before understanding the falling phenomenon.

What made an Airbus rudder snap in mid-air?

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.

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.

reply to post by luxordelphi


Panels fall off. It happens, and it doesn't matter if it's a new airplane or an old airplane.

As for the Airbus rudder, that was an entirely different problem related to manufacturing and delaminating, and could have happened at any time, and in fact most of the aircraft it happened to had been in production for years. They understood them quite well, and still had the problem.

Flight 587 didn't lose the rudder, it lost the entire tail as one piece. I used to have pictures of it from the NTSB.

reply to post by Zaphod58

Well OK the range sounds good, but the engines look like they don't have enough ground clearance. I bet they'll eventually have some scrapes in a strong crosswind landing one day. Is Boeing making all their planes plastic/composites, or just this 787 thing?

reply to post by Mikeultra


The engines have all the clearance they need. Other aircraft have engines that hang lower and have never suffered an engine strike in years of operation and thousands of flights.

Eventually all aircraft will be composite. As was pointed out it's as strong as titanium for a fraction of the weight.

reply to post by Zaphod58

This leads to the vertical fin (the tail), failing. Which leads to it coming off, and the plane losing all controllability. Which is exactly what happened.

Exactly what did happen? The rudder was electronically boosted to bionic rudder proportions and then, empowered, fell? Is that what you're claiming?

Here's my take on the panel falling off story and the rudder rain:

Boeing's Composite Problem

But Boeing is learning how hard composites can be to analyze effectively and build economically for commercial jet structures. The company has had to delay the 787’s introduction because elements of the composite-made wing box–the major structure inside each wing–buckled in stress tests.

The issue with composites isn’t that they aren’t strong; it’s that they are so internally complex. They consist of layers oriented in different directions; those layers, in turn, are made of individual fibers that may vary somewhat in composition. This makes it difficult for engineers to accurately mimic their performance in computer models for premanufacture testing.

“Composite materials are more difficult to analyze than simple homogenous metals,” says John Hansman, director of the International Center for Air Transportation, at MIT. “You generally don’t model every fiber in the structure, so you come up with models that have simplifications.”

reply to post by luxordelphi


Let's try this AGAIN.

In a non fly by wire aircraft you have to push the rudder all the way down to move it to the stops.

In a fly by wire aircraft the speed of the aircraft determines how far you need to push the pedal to get the rudder to deflect. The faster you go the less you have to push the pedal to get more deflection.

Flight 587 was in the wake turbulence of a 747 ahead of them, so there was already stress on the tail beyond normal flight stress. Then a pilot who had been written up several times for excessive rudder use, pushed the rudder pedals to the floor back and forth.

Now you have even more stress, because the rudder is slamming from one stop to the other, pushing the nose back and forth. When the nose goes one way the tail goes the other. The means a lot of stress on a surface not stressed for sideways movement.

That means the bolts failed and the tail came off.

As for composites having anything to do with the panel falling off, bull. Panels have fallen off aircraft since they started putting them on. Fasteners fail, people make mistakes and don't attach them right, etc.

You're looking for a problem that isn't there. This is a known and old problem for all types of planes, composite or not.

Zaphod58
reply to post by luxordelphi

 

All Airbus aircraft have fly by wire.

The A300/310 have conventional hydromechanical flightcontrols like older Boeings, however it didn't have the same kind of rudder travel limiter that Boeings and newer Airbusses have that limits the rudder travel With increasing speed.

Just wondering if you've heard anything about why the fuselage panel fell off in flight and what the fix is going to be for that

It turned out to be a maintenance screw up, panel not properly fastened after inspection.

The fix is simple, put back all the screws next time and it won't fall off.

Zaphod58
reply to post by luxordelphi

 

Because they didn't "just fall off". They never fell off, at any point in testing, be it on the ground, or in flight (obviously).

Again, apparently you're confused. They had a problem with the center wing box that required redesign. And a problem with some fasteners that had to be replaced. At no point in time, EVER, did the wings "fall off".

edit on 10/24/2013 by Zaphod58 because: (no reason given)

Right...they didn't fall off, they buckled which, with advanced carbon composites, is a precursor to falling off like the many Airbus rudders.

The panel that fell off? That could have been from the champagne bottle broken on it at christening. Or maybe the bored assembler tapping out the tune in his headphones. It's the itsy bitsy teeny tiny stress that grows in low pressure.

reply to post by Zaphod58


You know I just recalled that there were reports that more than just the tail/rudder fell off of flight 587. I remember watching helicopter news footage of the recovery of the tail and there was an engine in the shallow water too, away from the crash site on land. What about that?

usread.com...

reply to post by Mikeultra



Engine mounts are designed to hold the engines on the winds during normal flight, which means climbing, descending, flying from point A to point B.

What part of a flat spin do you consider "normal flight"?

Once the tail came of there was nothing to keep the aircraft stable and they went into a spin the engine mounts weren't designed for and they failed.

reply to post by ownbestenemy

You are speaking nonsense and out of your league honestly.

I'm relying on you all to bring the airplane expertise - that's true - BUT, you all are not experts, not anywhere near, on advanced composites and on the hybrid sometime alloy that is in the new Airbus.

The wing box was tweaked, way prior to the certification of airworthiness of the frame so it holds no bearing to your argument. The problem was identified long before it was put into the market.

Gonna have to correct this here and just say that "a" problem was identified and refer you to this link:

Boeing's Composite Problem

I don't have a problem with experimental planes. There are a lot of people who fly them. But they're not assuming that they know what they're all about. A passenger plane is a big item for an experiment and the tendency is to look for a big problem but in the case of advanced composites, the problem can be smaller than microscopic proportions.

Here's another really good article on that:

Why the V-22 is Still Unsafe

reply to post by Zaphod58

Oh, I don't know these things. Thank you, take a look at the last link I put up. there are some high resolution photos of the tail wreckage. You have to click on the photos. I'm not trying to be a pain in the neck, but this new high tech construction just looks cheap to me.

ownbestenemy
reply to post by luxordelphi

 

No fly-by-wire is a direct replacement of old hydraulic systems; not the automation of them.

No the problem was with the training that was given and pilot error. It is clearly documented and confirmed. Pilots were being taught to hit the rudders hard during wake-turbulence and particularly, the First Officer was an offender of utilizing that method. They failed to recognize the limits, capabilities and characteristics of the Airbus 300 in their training and it lead to a fatal accident. Nothing fishy at all.

edit on 24-10-2013 by ownbestenemy because: (no reason given)

Accident Overview

The rudder control system on the A300-600 is conventional for a large transport airplane in that the rudder is actuated hydraulically in response to pilot inputs via foot pedals. The rudder is primarily intended to provide control during engine-out and crosswind situations. In addition to pedal inputs, the rudder can be moved by the rudder trim actuator, the yaw damper actuator, and the yaw autopilot actuator. A command from any of these sources is transmitted through a series of linkages (pushrods, bell cranks, a tension regulator, and cables) through three hydraulically powered servo controls which physically move the rudder.

And there's a safety feature:

A rudder travel limiter provides a variable stop that limits rudder travel as a function of airspeed.

There's more to it than this, of course, but these are the basics. So it could be called some kind of an analog fly by wire, I guess.

And then there's the rudder itself:

The A300-600 vertical stabilizer and rudder are constructed of composite materials, primarily carbon or glass fibers in a polymer resin. These carbon reinforced plastics (CFRP) and glass reinforced plastics (GFRP) are pre-manufactured in sheets, and multiple sheets, or plies, are then stacked in a mold and cured under heat and pressure to form a solid structure. The plies may be specifically oriented to one another to enhance strength characteristics. The stiffness and strength are dependent on the number of plies and the orientation of the fibers in the plies.

reply to post by ownbestenemy


Fly-by-wire does not replace hydraulic systems, it replaces the control cable that feed the input to the actuators. All fly-by-wire systems on Airbus aircraft still employ hydraulic actuators and servo-controllers. Whilst it is true the Boeing have replaced much of their hydraulics with electric actuators, many aircraft manufacturers have not.

Please do not contradict me, I am a systems engineer dealing with ATA27 at Airbus.

reply to post by Zaphod58


The A300 and A310 were not fly by wire, this technology first appeared on the A320.

www.airbus.com...

reply to post by Mikeultra


The flexing of the wings is deliberate, not a sign of weakness, it is a more efficient way of achieving the results given by the upturned wingtips of most other modern airliners.

The most efficient wings are those of birds, the most efficient man made ones those of gliders, they both flex too.

reply to post by Zaphod58


I used to live less than a mile away from the Everett plant where they did these test. Here is a video of the actual failure test on the a wing of the 787.

www.youtube.com...

Even though the failure tests were done inside the plant, you could hear it from where I lived when they final went. Like a sonic boom or a shot gun going off neer by.

reply to post by luxordelphi


And they buckled during a test that was designed to identify a problem. Which was fixed. It's a hell of a lot different than "falling off".

You seem to think that human error never occurs during maintenance of aircraft. That couldn't be farther from the truth. I've seen everything from forgetting to attach nuts and bolts, to leaving tools inside the aircraft. As long as they're worked on by humans, there will be mistakes made like this.

reply to post by TheLoneArcher


I think what he meant to say was hydromechanical systems, not hydraulic systems.

reply to post by waynos


My mistake. That's what I get for staying up too late arguing aircraft.