這是紐約時報7月30日的文章. 我前幾天讀過日本ANA航空發現 有問題 當時因為不打算報導波音787夢想客機近來的問題 所以沒貼文. 今天讀此篇. 改變想法.
波音787夢想客機遭遇維修難題
, 2013年07月30日
Boeing makes the 787’s fuselage out of strands of carbon fiber layered
around a rotating mold by a computer-controlled robot that looks like a
spider.波音在製造由碳纖維構成的787飛機機身。一個蜘蛛外形的機械人，在電腦控制下繞着一個旋轉模具層層疊加碳纖維絲。
波音公司(Boeing)787夢想客機(Dreamliner)輕薄的塑料外殼是個工程學奇蹟，用模具將碳纖維和環氧樹脂塑成巨大的桶型部件，然後放入大熔爐在高達350度的溫度下燒制而成。
然而，儘管這一輕型混合物節省燃油的性能深受航空公司的喜
愛，但最近發生在倫敦希思羅機場一架787客機的火災，首次驗證了修復嚴重損傷的難度和高昂成本。現在正值波音的關鍵時期，公司急於展示，像787這樣的
碳複合材料飛機，即使有重大損傷，也能與老式鋁製機型修復得同樣快、同樣有效。一架飛機每停飛一天，就會讓航空公司損失數萬美元。
- 檢視大圖
Francois Mori/Associated Press位於法國圖盧茲的裝配線在組裝空客A350客機。和波音的787夢想客機一樣，A350擁有複合材料機身。
調查人員認為，起火的原因相當簡單，就是緊急發射器的一根電線扭曲，但造成的損失卻絕不簡單。高溫削弱了機身後部頂端一塊10英尺（約合3米）區域的支撐結構，燒壞了外殼頂部的油漆。這是新的夢想客機迄今為止所受到最嚴重的損傷。
航空專家表示，波音將把受損部分切割下來，然後用膠水，或
者很可能是螺栓，把一塊由多層複合材料板構成的大補丁，固定到這架使用不到一年的鋥亮的新飛機上。聖迭戈航空顧問漢斯·W·韋伯(Hans W.
Weber)說，「這有點像《歌劇魅影》(Phantom of the Opera)，裡面那傢伙戴着面具，掩蓋他半邊臉沒了的事實。」
波音還需要安裝新的複合材料支架，其中一些可能將由強度更
高的鈦製成，目的是固定住補丁，並鞏固飛機的結構強度。假如破損更嚴重，波音還可以把容納機身後部大部分結構的23英尺長的桶狀外殼整體取下，簡單地換上
新外殼。不過複合材料專家懷疑，此次這樣做的可能性不大。擁有這架飛機的是埃塞俄比亞航空公司(Ethiopian Airlines)。
波音表示，正準備把各種維修方案提交給該航空公司，不會公開對此進行討論。波音的工程師正通過計算機模型分析花費，以及其他一些需要權衡的因素，比如支架增加的重量將在多大程度上削弱波音宣稱的787省油量。
波音高管表示，隨着逐步增加其他機型上複合材料部件的應用，公司多年來一直在開發相關的維修技術，而且許多技術與鋁製機型採用的維修方法類似。
波音首席執行官小W·詹姆斯·邁克納尼(W. James McNerney Jr.)上周稱，「我們感覺很踏實，我們知道如何應對這一問題，以及可能出現的多數其他結構問題。」
然而，一些分析人士似乎沒那麼有信心。2011年底以來，
波音公司交付了70架夢想客機。分析人士認為，埃塞俄比亞航空公司飛機起火提出了一些未知問題，可能導致維修工作比其他已交付飛機的維修複雜得多。波音透
露，公司曾在少數幾架787上進行過規模較小的複合材料修復，這些飛機的破損源於雷擊，或是被機場服務車或機修工具撞擊。
波音希望在接下來的數十年里賣出數千架這樣的飛機，鑒於這
種創新型噴氣機對波音的未來至關重要，紐約州華盛頓港航空顧問羅伯特·曼(Robert
Mann)說，「此刻，他們會不惜採取任何措施，來顯示飛機是可以修復的。我們會知道，波音公司需要多長時間來修復飛機，不過老實說，我們也許永遠不會知
道維修的成本。」
複合材料給航空機械師帶來了新的挑戰，他們需要新的維修工具和技巧。和鋁製飛機不同，碳結構不會產生明顯的凹陷，需要特殊的超聲波探測器來辨別受損部位，而目前正缺少受過相關培訓的機械師。
為了應對這些擔憂，波音已經發明了新的維修工具包，以修復常見的損傷，比如行李車撞上飛機時產生的損傷。
為了減少複雜維修的需要，並縮短維修時間，波音已經設計了一些備件，能夠用螺栓固定到特定部位，這些都是其他機型上易於受損的部位。其中包括機鼻附近的損傷，由於駕駛員在跑道上拖着機尾滑行導致的損傷，以及客艙門或貨艙門附近由服務車碰撞導致的損傷。
華盛頓大學(University of
Washington)運輸飛機結構先進材料卓越中心(Center of Excellence for Advanced Materials in
Transport Aircraft Structures)主任、機械工程學教授馬克·塔特爾(Mark
Tuttle)說，「現在已經有完善的維修技術，用來維修複合材料的結構，不過，公平地說，這些得到認可的技術只適用於修復較小的部位。」
對於細微的剮蹭，機械師能夠用環氧樹脂和便攜式鼓風機產生的熱量，把新的複合材料層粘合到破損部位。其他破損可能需要鑄模、特殊的切割工具、真空封接或小型熔爐和螺栓，才能把新複合材料層固定就位。
當損傷更嚴重時，最大的問題就來了，比如埃塞俄比亞航空公司這架飛機的損傷。專家說，在這種情況下，鑒於受損範圍較大，受損部位位於機尾正前方的關鍵區域，在那裡垂直尾翼連入機身，波音必須拿出一個定製的維修方案。
空客(Airbus)在製造A350客機時採用了有點不一樣的方式。它沒用採用波音青睞的桶型構造，而是使用40英尺乘60英尺的複合材料板打造機身的各個部位。空客認為，這種工藝使維修更加容易。
不過，隨着技術的改進，以及航空公司優化其能力，拆卸並替換機身特定部位受損部件，最終，機身是採取桶狀構造還是以複合材料板打造，也許並沒有太大區別。
不過此刻，所有人都會把注意力放在這架埃塞俄比亞客機上，關注波音如何處理這一次維修。
航空顧問韋伯說，「對於航空業和航空公司而言，這是一次極其重大的考驗。」
翻譯：黃錚、張薇New Challenges For the Fixers Of Boeing’s 787
and July 30, 2013
The thin plastic skin on Boeing’s 787 Dreamliner is
an engineering marvel, a mix of carbon fibers and epoxy molded into
large barrel-shaped sections that are then baked at up to 350 degrees in
giant ovens.
But while airlines love how
this lightweight concoction saves fuel, the recent fire on a 787 at
Heathrow Airport in London provides the first test of how difficult and
costly it will be to repair serious damage. It’s happening at a pivotal
moment for Boeing, which is eager to show that even significant damage
to a carbon-composite plane like the 787 can be repaired as quickly and
effectively as in the old aluminum models. Each day a jet remains
grounded costs an airline tens of thousands of dollars.
Francois Mori/Associated Press
An Airbus A350 on the assembly line in Toulouse, France. Like Boeing’s 787 Dreamliner, the A350 has a composite fuselage.
Investigators believe that
the cause of the fire, a pinched wire on an emergency transmitter, was
fairly mundane. But the damage was anything but. The high temperatures
weakened the supports in a 10-foot stretch at the top of the rear
fuselage and seared the paint on the top of the skin, causing the most
extensive damage yet to one of the new Dreamliners.
Aviation experts say Boeing
will cut out the damaged areas and glue or, probably, bolt a large
patch, made of overlapping panels of composite materials, onto the shiny
new plane, which is less than a year old. “That’s a little like
‘Phantom of the Opera,’ where the guy had this mask to cover the fact
that half his face was missing,” said Hans W. Weber, an aviation
consultant in San Diego.
Boeing will also need to
install new composite supports, and possibly some made of stronger
titanium, to hold that mask in place and shore up the structural
integrity of the plane, owned by Ethiopian Airlines. If
the damage were more extreme, the plane maker could remove the entire
23-foot-long barrel containing most of the jet’s rear fuselage and snap
in another one, though composite experts doubt that it will do so in
this case.
Boeing said it was
presenting the repair options to the airline and would not discuss them
publicly. Its engineers are running computer models to analyze the costs
and other trade-offs, like how much the added weight from the bracing
might reduce the plane’s heralded fuel savings.
Boeing executives say they
have been developing the repair techniques for years, as they gradually
increased the use of composite parts in other planes. And many of them
are similar to the methods used with aluminum.
“We feel comfortable that
we know how to address this issue and most other structural issues as
they arise,” Boeing’s chief executive, W. James McNerney Jr., said last
week.
But some analysts seemed
more skeptical, saying the fire on the Ethiopian jet raised a wild card
that could make the repairs much more complicated than others on the 70
Dreamliners delivered since late 2011. Boeing said it had made smaller
composite repairs on a few 787s that had been hit by lightning or bumped
by airport service vehicles or mechanics’ tools.
Given how crucial the
innovative jets are to Boeing’s future — it expects to sell thousands of
them in the coming decades — “they will do anything at this point to
show that that airplane is repairable,” said Robert Mann, an aviation
consultant in Port Washington, N.Y. “We’ll know how long it takes them
to fix it, but realistically, we may never know what it costs.”
The composite materials
have created new challenges for airline mechanics, who need new
maintenance tools and skills. Unlike aluminum, carbon structures do not
dent visibly and require special ultrasound probes to identify damaged
areas, and there is a shortage of mechanics with the right training.
To address these concerns,
Boeing has devised repair kits to fix common types of damage, like when
luggage carts bang against a plane.
To reduce the need for
complicated fixes, and cut repair time, Boeing has engineered spare
parts that can be bolted onto areas that have been prone to damage on
other planes. Those include damage around the plane’s nose, from pilots
dragging the tail on the runway, or collisions with service vehicles
near passenger and cargo doors.
“There are well-established
repair techniques that have been developing to repair composite
structures but it is fair to say that these recognized techniques are
for smaller areas,” said Mark Tuttle, a professor of mechanical
engineering and the director of the Center for Advanced Materials in
Transport Aircraft Structures at the University of Washington.
For minor scrapes,
mechanics can make simple repairs by bonding new layers of composite
over the damaged areas with epoxy and heat from portable blowers. Other
damage might require casting molds, special cutting tools, vacuum seals
or small-scale ovens as well as bolts to hold the new composite layers
in place.
The biggest problems come
with more substantial damage, like on the Ethiopian Airlines jet. In
this case, experts said, Boeing has to come up with a custom repair
given the extent of the damage and its location at a critical area right
in front of the tail, where the vertical stabilizer is attached to the
fuselage.
Airbus has taken a somewhat
different approach in building its A350 jets. Instead of the
barrel-shaped architecture favored by Boeing, Airbus is using 40-foot to
60-foot composite panels for each section of the fuselage. Airbus
contends that the process will make for easier repairs.
But as techniques improve,
and airlines perfect the ability to cut out and replace damaged pieces
within a section of the fuselage, it may not make much difference in the
end whether the fuselage is made out of barrels or panels.
For now, though, all eyes will be on the Ethiopian jet and how the repair is handled.
“This is a very important test for the industry and the airlines,” said Mr. Weber, the aviation consultant.
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