Dreamliner already having CF problems?

the weakest link in any composite is the resins that are used to bind into a structure. Resins are susceptible to deterioration from all kinds of sources. Then there is the issue of error that creeps into resins, as the formulae are mixed in batches. Composite formation and assembly depends on reactive processes, which has its' own pitfalls of variables to control. The issue of longivity and maintainance is still an unknown on this large scale. Typically alloy airframes have some sort of disassembly available allowing for replacing or refurbishing components and subassemblies. Composite structures do not have that capability. Composite hulls still are combined from sections into a final product, it may be that end of life cycle structures could be cut out in a larger scale and replaced in their entirety vs scrapping an entire hull.

 

I understand where you are coming from, but heck Douglas worked with Sud for 2 years and then terminated the contract ... surely by then they would have known the Caravelle backwards and inside out. In the end Sud were not smart were they.
Pete

 

I don't know what kind of agreement they had with Sud. From what I could see they were helping market the Caravelle in the USA, and the airplane didn't have that much market penetration here, for whatever reason. If the orders had taken off and Sud couldn't produce that many airplanes, the Douglas would have started a production line here.

Maybe there was something that was keeping the plane from being successful and McD figured out they needed a new airplane to provide what the market needed. Also, the French are notoriously difficult to deal with. I can say that from personal experience of three different programs with three different French companies. For whatever reason McD decided it was in their best interest to go it alone.

The DC-9 was launched with no customers. McD took a heck of a risk. If a Caravelle could have been modified to be what the DC-9 was I would have thought that McD would not have taken that risk and would have just modified the Caravelle and built them here. I don't know what the agreements were for co-production, and I don't know the cost structure of the airplane. There were a lot of improvements in manufacturing technology after the Caravelle and it may just have been too expensive to produce. Remember that the 727 was there and Boeing's efficient production capability may have made it relatively less expensive than the Caravelle on a per seat basis. There could be dozens of reasons, I'm just throwing out a few possibilities.

With the success of the DC-9 you have to believe that they did what was best for them and it worked out. Hard to argue with that.

 

I have heard that Delta always refused to buy Airbuses because they felt, when compared to the Boeings, that they were too maintenance-intensive. How that was, I do not know. Now that they have inherited Airbuses from Northwest, I'm curious to find if they still think the same way.

 

The comments to which I refer re Airbus were from contract mechanics who work on everything and who have no preference for Boeing, Airbus, or anything else. Simply observations.

 

Your incorrect about time life limits with Douglas Aircraft. There are none on the DC-8, 9, 10, and 11. The skins are thicker and built like a tank. However, You must abide by the Aging Aircraft Program set up for each operator. Corrosion is the big player which can lead to fatigue and reduced life if not treated properly. The DC-8 was made with a 3 spar wing!

This is why UPS retrofitted their DC-8 fleet and and Fedex did the MD-10 program. They basically zero timed the airframes and got another 25 years out of them.

I know of one DC-10 that has accumulated over 140,000 hours and is still flying for Orbis after we got rid of it. Its N810AX.



cheers

 

It appears that I didn't explain my comment clearly that if the materials are used properly they will give you a long life. If they are pushed to their limits they will give up from the fatigue. The Douglass's were built in a more conservative manner than the 707's and I mentioned the three spar wing, less sweepback, and a stiffer wing. The Boeing's were designed to operate at high Mach numbers and high altitudes and the structures were more exotic than Douglas...strong light alloys, more sweep back, thinner sections. They beat the DC-8 in every category including profit but not longevity. Douglas didn't make one nickel on the DC-8 but it still flies because of its tank-like structure and conservative performance. Typical Douglas, as you said. You are correct to mention corrosion as an element of longevity because it has an outside factor in the initial design of the airplane. I also mentioned the " find and fix" element in the life of any aircraft. The more conservative the design ( DC-3, B-17, DC-8 ) the less fix after the find.

 

An old tussle. When the 707 and DC-8 went into service there were several interesting things that popped up. One that I remember was that the DC-8 couldn't fly non-stop transcontinental with a full fuel load and a full passenger load. Consequently, Douglas initiated a frantic drag and weight reduction program to improve the performance. They changed the shape of the leading edge and eliminated the exposed DC-7 type control horn fairings and a lot of draggy items. They eventually got a good airplane but one thing that I remember with a chuckle, and I think that I have posted this before, was the American Airlines pilot's announcement to the passengers that if they looked down to their left they would see one of the prettiest sights in America, " A DC-8 that left LAX 15 minutes before we did." That was published in Flight Magazine in 1959. Douglass did a lot of good things on the DC-8 that were better than Boeing but the 707 outperformed it as a money maker until it succumbed to a shorter life span...much like a racehorse. It was more difficult to fly than the DC-8 and the younger airline pilots loved it. Douglass did another brilliant thing in the reverse contour of the inboard wing section that diverted the flow under the wing to prevent drag. Every big jet now uses that feature just as they use the basic jet airliner configuration created by Boeing in 1953 with the 367-80.

 

More exotic than Douglas?, Please elaborate? The structure of the DC-8 used advanced bonding and riveting techniques, titanium panelling, roll-tapered light alloy skinning and rip-stop construction. You wont see skin wrinkles either even after 50 years of service!

I dont recall the 707 going mach 1 in it's Flight Test Program? The DC-10 and MD-11 also went mach 1 in their respective Flight Test Programs. Hardly "conservative performance" as you say. How about Sydney to LAX in a DC-8-72 freighter fully loaded at .83 mach? Been there done that.

Douglas did not make a nickel on the DC-8? Fascinating info. What do you base this on? They built 556 and did not make a nickel? Does this include product support, training and field support as well?

There are no time life limits on a Douglas Airframe contrary to a Boeing and Airbus. You can bash Douglas all you want, the fact are the facts.

Cheers

 

Don't know if they 'officially' didn't make a penny on the DC-8, but they were in big trouble financially...

They were trying to meet huge demand for the DC-8 and 9, and A4 - should they expand? How?

Also had big development costs for the DC-10 - maybe cut corners...?

McDonnell picked them up at a fire sale...


But, Douglas built some GREAT airplanes!
The DC-1/2 made United's Boeing 247 look 10 years old on day one, the 2 and 3 are STILL flying.

In the 30's, the DC-2 came in second in an air race from London to Australia. The winner was a built deHavilland Racer... AND, the DC-2 flew it's regular route, carrying passengers and freight, which was 1000 miles longer than the official route flown by the winner.

GREAT airplanes...

 

I guess this is as good a place as any to raise this issue...

I'm currently looking at a carbon-tubbed ex-LMP car. Obviously, the carbon tub's life and durability are of some concern to me. I've been told that inspections are possible and repairs, if necessary, can be effected. I'm just curious what kind of life one should expect out of a stressed carbon component (like a tub) on a race car. A friend who sold his 333SP was telling me that most owners are "staying off the curbing" to slow the damage and breakdown.

Now, I realize that a race car isn't subjected to the same environmental conditions and swings that an airplane is, but what, realistically, should I be thinking in terms of tub-life? Is it, in essence, forever? Or, do I need to be worried about re-tubbing at some point?

Thanks for thoughts,

CW

 

Carbon fiber is very susceptible to UV damage ( the bonding resins not the carbon fibers themselves ). The "sexy" thing is to have all the CF layup on all the parts visable, but that exposes them to the UV. Clear coatings with UV filters can be used to keep the image, but opaque coatings ( paint ) are best. It is easy to accumilate UV damage, definitely when outside, but even inside windows do not stop UV. Keep unprotected CF covered. Physical stress on the tub is going to be hard to measure, too many factors involved. CF structure can take a lot of stress and strain, but can fail easily if point loaded. Our CF failures have been the result of "old school" ignorance, not the CF failing. I think the tub should hold up well for a long, as long as it was not "under spec", the hard part is keeping someone from messing with it. Also CF like alloys needs to be electrically isolated as different metals are attached /come in contact with it, electrolysis will occur damaging the CF as well as the alloy securing anything.

 

CW - I still have the picture in my mind of the Dutch drivers 'old' Ferrari F1 car a few years ago @ Seca.
Comforting to think of all that extra CF surrounding you on an LMP car......

Hope you do it and have fun!

 

Perhaps if I used the word advanced or sophisticated instead of exotic in regards to the materials in the 707 wing it would sound better. The 707 design wasn't conservative in the approach to reach the objective that was foremost; aerodynamic efficiency and light weight. It was using the smaller JT3 and not the JT4 as used on the original DC-8. Frontal area was to be minimized and the most efficient shape dictated. Therefore the wing was very thin and subjected to a lot of flexing and demanded the use of light but strong alloys, the 7000 series. These materials were not as ductile as the 2000 series and caused production difficulties and eventually airframe life limits. BUT it got the job done. High speed low drag airfoils were created and the wing had an L/D of 20 and nobody has achieved that since.The shape, the materials, and the construction pushed the design to the limits so it was not a conservative approach. The DC-8 wing was, as you said, built like a tank. Less sweep, thicker, three spars, and with a less efficient section that was aimed at cheaper construction as much as flight performance. After flying it Douglass had to redo it (fact). It was a conservative approach that eventually paid off for the airplane.(fact)

Ripstop? Boeing developed the ripstop technology after the water tank tests so it had it early on.(fact)

Mach ! The Pan Am 707-121 exceeded Mach 1 by a wide margin although it was in an inadvertent dive. It also made a pullout that reached the yield point in the wing structure and the airplane didn't sustain enough damage to keep it from being put back into service.(fact).

DC-8-72 Series. This airplane isn't anything like its distant relative, the DC-8-10, the airplane of which I was speaking. The 72F is a good airplane and anyone would be a fool to bash it when it is still flying long after the 707 had been put to pasture. After a lengthy development it has better engines, more developed systems , better aerodynamics, and a healthy stretch that was fought against by Douglas management. That brings up the longer DC-8 landing gear that allowed that stretch. Boeing's error was designing the shorter main oleo that prevented the 707 from being stretched. That helped to terminate the program but the reason for it again was to save critical weight in the initial design. Every inch of oleo length adds 65 pounds to the airplane.

Cruise Mach .83 The 707-120 operationally cruised at .82 to .85 55 years ago. From old friends who flew it. The 720B could exceed Mach 1 in level flight if allowed to.

Douglas didn't make a profit on the DC-8(fact).I have the report someplace and I will dig it up if I can. 556 units isn't much production when your break even point keeps running out ahead of you. Boeing also was chasing an elusive break even point but they eventually caught it after almost 2000 units were produced, twice the DC-8 output(fact).

Boeing made a lot mistakes in the original 707: smaller fuselage diameter than the DC-8, short landing gear, etc. but they were sensitive to evolving requirements in the airline industry and offered long range versions, short range models, freighters, combi's,etc. while Douglas dragged its feet on even stretching the fuselage. The DC-8 began to wither on the vine until the higher numbered series evolved.

Douglas did a lot of good things like the main landing gear being supported by a beam instead of a cantilevered torque box, the trailing edge Yehudi allowed more flap area, inboard wing reverse airfoil, and others.

Anyway, I was not "bashing", I was comparing the initial DC-8-10 with the initial 707-120, you're airplane is an entirely different animal.

I failed to mention that Douglas never made a dime on the DC-8 or anything thereafter, thus their being purchased by McDonnell and then Boeing(fact).

Cheers

 

Thank you, Bob...

so sounds like no profit on the DC-9 or DC-10 either...?

 

I bet the DC8-62 was partly reskined when it had its engine and cargo upgrade. MD has had a history of problems on its aircraft when new, but after they get sorted out they last forever it seems. Look at all the DC10 crashes and the MD11 was even worse, turning into an under performing hangar queen when they were new. I never noticed that with the 777's, 767's and 757's we have. Everytime I see a MD80 get deiced when the temp drops below around 40 degrees Farenheit it reminds me of what a great engineering company MD was.

 

I think that the presence of both the DC-10 and L-1011 occupying basically the same market at the same time almost guaranteed that neither one would make money in the long run. In Douglas' case, the only thing that allowed the DC-10 to come close to breaking even was the contract with the USAF for the KC-10 tanker variant.

I hear that after most of the other large airlines had picked either the DC-10 or L-1011, United was the last biggie to chime in. If United had gone with the Lockheed aircraft (and I hear that they almost did), the DC-10 may have died right there!

 

The DC-10 story is one that is much like the Boeing 787 thing with too much critical work sub contracted out that should have been done in-house. Douglas knew that they were in a race with Lockheed and they elected to accelerate development and design time by out-sourcing a bunch of stuff including engineering. They beat Lockheed by 18 months on getting their airplane flown and sold to the first customers and many after that who would have gone with Lockheed. So, Douglas gobbled up the orders and left Lockheed out of the picture. From info gleaned on the L1011 , it was determined that it was a better airplane than the DC-10.

The strut failure on the DC-10 Chicago crash was the result in some of the out-sourced engineering that was just plain bad as was a lot of other things. Thrust loads were jammed into a short link behind the " tombstone fitting" that was doing duty mainly as a torque bulkhead and when the link to the aft wing fitting failed , all the thrust loads turned the bulkhead into a big fortune cookie. There were quite a few other things that should have been more carefully designed but the race was on and...

 

From what I have read the failure of the pylon attachments on the Chicago DC-10 was due to an unapproved maintenance procedure that damaged the pylon attachment points. The Douglas maintenance procedure called for the engine to be removed from the pylon and the the pylon to be removed from the wing in separate steps. Several airlines, including American, came up with a shortcut whereby they removed the engine and pylon as a unit. This greatly reduced the labor involved in the procedure. Douglas maintenance reps were aware of the one step procedure and did not endorse it. But, they had no authority to force American to follow the recommended procedures. The American maintenance crews used a large forklift to support the engine/pylon assembly as it was being disconnected. In the case of the Chicago DC-10, there was a shift change half way through the procedure. The front mount had been disconnected but not the rear. During the maintenance shift change the forklift either shifted or some of the hydraulic pressure bled off causing the engine/pylon assembly to shift and damage the rear mount which had not yet been released. This damage manifested itself when the rear mount failed while the aircraft was accelerating for takeoff causing the engine/pylon assembly to rotate about the front mount and up and over the wing severing hydraulic and control lines as it went.

There may have been redesign of the engine mounts after the crash but the root cause was not the design but the failure of the American maintenance personnel to follow the published procedures.

Kurt O.

 

MD-11s are still crashing today, unfortunately.

 

I am aware of all that you have delineated. The process of removing the nacelle with the engine and strut attached started the problem when the aft mounting bracket was cracked during the process. That U-shaped bracket was aligned in a span wise orientation and not in an alignment with the thrust of the engine. It did nothing to maintain the integrity of the attachment in a thrust-wise direction, it only aligned the thrust centerline of the strut. When it failed the thrust loads were transferred into the remaining tombstone fitting that was also oriented in a span wise position and the thrust simply bent the fitting back, allowing the engine to rotate about the bend line in the fitting and up over the wing. It severed the hydraulics in the wing leading edge and that paralyzed everything else in the left wing. The pilot did everything by the book but without any hydraulics and control of the ailerons, he was defeated. If you can visualize the configuration, the main fitting that attached the strut to the wing was a large bulkhead shaped like a Tombstone that was attached to the front spar by being bolted to a big bracket that attached to the front spar at an angle that accounted for the sweep back. Behind it was a monster link that looked like a giant bicycle chain link attached to the UPPER END of the fitting and several feet later attached to the wing. This was supposed to carry the thrust loads. Running under the wing in the strut was a plate that went back to the aft fitting. On the upper side of the plate was a lug that attached to the U-shaped bracket under the wing .This could not carry any thrust loads but simply held the aft end of strut up to the wing. When this failed, all the thrust went into the tombstone fitting that failed under the heavy thrust loads. One engineer with whom I worked said that it was Barnyard Engineering. Boeing has no less than 4 forged and massive fittings that are arranged in alignment with the engine thrust and tied into wing structure that is also aligned with the thrust loads. The torque bulkheads in the strut do what they were designed to do, carry torque loads while the spars, drag links, and integrated forged lugs carry the thrust loads. In the case of the DC-10 thing, the mechanics only exposed a bad design.

 

The last incident being in 2010 with a Lufthansa cargo flight, if I'm not mistaken.

 

Your absoulely correct. Glad to see someone get their facts straight. Furthermore, the F/O was doing a fine job flying the airplane until the Captain took the airplane away from the F/O, who then released the rudder deflection causing the airplane to roll violently until momemtum and gravity doomed the plane. The Captain's response off added pitch and opposite aileron ultimately caused the left wing to stall prematurely since the slats were retracted on that side.

A huge contributing factor was the improper "transfer of controls"

DAC flew this scenario hundreds of times in the simulator during our investigation and determined the accident could have been avoided had the crew not let the rudder go for those precious seconds.

The FAA fined American Airlines $500,000 for using a faulty maintenance procedure on its DC-10. Continental Airlines was fined $100,000 on a similar charge.

Cheers

 

I would love to hear the F-chat experts tackle this one. Why does the MD-11 have the worst accident record of any airliner built? Let the experts chime in. I wonder how many of you have flown it and the DC-10? If you have? please compare and contrast the flight dynamics of each and the common type rating of the MD-10 and MD-11. Is that a contributing factor?

I am very familiar with ship 449, one of the birds in the Flight Test Program. She was the third one off the assembly line and the first to be powered by P&W engines. She flew nicely at .999 on the PFD while doing flutter tests. She went Mach 1 but the software only registered .999 Onboard telemetry confirmed the mach 1 claim, as well as the T-38 chase plane!

She now flies for FEDEX after flying for WOA as a passenger bird.

Cheers