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19.? Aerospace manufacturing: past, present and future
Colin G. Drury
This chapter provides an overview of aerospace manufacturing. Aviation hardware, like
most products, has aspects of product and history that make it uniquely challenging, so
these are presented first. The service requirements for aerospace hardware determine to
a large extent the manufacturing requirements. Thus in order to understand how modern
manufacturing issues, such as supply chains, design and outsourcing, affect manufacturing, a current overview is presented before these effects are considered in more detail.
(a) Flying is Hard
The building of heavier-璽han-璦ir flying machines has about a century of history, during
which time the product has been transformed from a single-璼eat wood and fabric biplane
capable of about 50 kph to 3001-璼eat carbon fiber composite airliners capable of cruising at 900 kph over 15,000 km stage lengths. Flying is inherently difficult, and indeed
there were hundreds of years between the desire to fly and its achievement (Gibbs-璖mith
1966). Any aircraft design requires knowledge in the areas of aerodynamics, materials,
structures, power production and increasingly electronics, plus a manufacturing organization capable of design integration and efficient production. Unlike other products,
particularly transportation products, the design requirements are very stringent as the
finished product must actually fly safely in all flight regimes. Aircraft structures must be
light and strong enough to fly with the desired payload, as the total weight of the aircraft
must be supported by the aerodynamic lift generated by the airframe and by the thrust
developed by the engines. The final external form of the product is determined by a deep
knowledge of physics and the desired mission characteristics, rather than by considerations of market aesthetics. Early aircraft manufacturing history abounds with examples
of insufficient strength, for example the shedding of wings or wing covering in World
War I (WWI) fighters (Weyl 1965), or the twisting and flutter in monoplane wings of
the 1930s due to insufficient rigidity (Jarrett 1997a). Even current airliners occasionally
require strengthening after full-璼cale testing to meet structural loads thought to have
been covered in the design phase (e.g. Airbus A-�0, Boeing 787). Finally, aircraft currently cost billions of dollars and there are many years between conception and arrival
in service, e.g. F-�, B-�7. In this respect, a new aircraft is more comparable in scope to
a large building than a more traditional product, such as a computer or an automobile.
(b) Flying is Highly Visible and Highly Regulated
Aircraft (apart from unmanned aerial vehicles or UAVs) carry people and thus any
mishap is a matter of great public concern. Aircraft accidents involve a large amount
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Aerospace manufacturing??�5
of accumulated energy, from kinetic energy of many metric tonnes of machine moving
at over 150 kph to the large mass of chemical energy carried in the tonnes of fuel. Thus
accidents are so spectacular in public consciousness, due to the energy release and
the presence of the traveling public, that safety is the prime consideration in design,
manufacturing and operation. Despite the fact that accidents have decreased by orders
of magnitude over the century of aviation history (Boeing 2012), accidents still cause
detailed investigation and lead to design and operational changes. A recent example
was the crash of the Colgan Air Q-�0 at Buffalo NY in 2009 (National Transportation
Safety Board (NTSB 2010a)). The NTSB cited ?flight crew monitoring failures, pilot
professionalism, fatigue, remedial training, pilot training records, airspeed selection
procedures, stall training? in the crash, of which stall training changes and increased co-�
pilot minimum experience have been finalized by the Federal Aviation Administration
(FAA) to date (2014). Because of this public visibility of aviation, design, manufacturing
and operations are highly regulated industries in every country. In the United States, the
FAA maintains thousands of Federal Air Regulations, covering all aspects of aviation
from design and manufacture to training and maintenance. Companies manufacturing
airliners, for example, must comply with airworthiness standards for all components of
the aircraft, to show that no single component failure can lead to a hull-璴oss accident.
(c) Aircraft are Now Long-璍ived and Expensive
In contrast to the early years of aviation, current aircraft are expected to last for many
years. Until WWII, most aircraft were lost to accidents, or replaced as obsolete, within
a few years. This was partly due to the inherent difficulty of flight, especially in poor
weather conditions, but also due to the rapid development cycle of aircraft. In WWI, aircraft were designed in a matter of weeks and even in WWII there is the famous example
of the P-� that went from order to first flight in 117 days to meet a customer requirement
(Jarrett 1997b). Now both civil and military aircraft are expected to last for decades in
service. Aircraft must often be used for that long to repay their high purchase price, typically around $US80 million for a B-�7 or around $US 300 million for a B-�7. General
aviation aircraft, such as trainers or sport aircraft, can cost around $US100,000, while
military aircraft have ranged up to $US500M for the B-� Civil airliners and general
aviation aircraft can be 25 to 50 years old if maintained correctly, with such compendia
as Jane?s All the World Aircraft still listing airframes designed in the 1960s, such as early
versions of the B-�7 and B-�7 families. Military aircraft can be even longer-璴ived, with
the B-� and Mig-� being 1950s designs still in service, with of course many upgrades to
engines and avionics (National Research Council (NRC) 1997). Note also that in almost
all wars, more aircraft are lost to accidents than to enemy action. This long fleet life is
achieved at the cost of continuous maintenance, again making aircraft a product closer
to a large building than to a consumer artifact.
(d) Aviation is International
The design and manufacture of aircraft have always occurred across countries and
continents, with the USA, France, UK, Germany and Russia having led the industry since the earliest times. Within each country, and now across continents, mergers
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and 璫onsolidations have consistently reduced the number of aircraft manufacturers.
Currently there are only three major airframe manufacturers in the USA: Boeing,
Lockheed-璏artin and Northrop-璆rumman. Obviously these comprise five individual
names of aircraft companies, showing at least the later merger structure. All of these
have large military customers, plus Boeing has a large commercial division: Boeing
Commercial Aircraft. In Europe, the obvious equivalent is the Airbus Group, formed
from companies in France, Germany, the UK, Italy and Spain. Airbus has military
and helicopter product lines in addition to its more famous Airbus airliners. Canada
(with Bombardier Aerospace), China (with Commercial Aircraft Corporation of China,
Comac) and Russia (with United Aircraft Corporation) have had similar consolidation,
so as to be able to meet the large development costs of new large aircraft. The supply
chains are even more international, with major components of aircraft being manufactured, and indeed partially designed, around the globe. As just one example, fuselage
sections for Boeing airliners are made by Mitsubishi in Japan. Smaller manufacturers,
and manufacturers of small aircraft, still abound in most developed countries, ranging
from light plane kits to business jets.
(e) Aviation is a Pioneer of Design Innovation
While not universally true, many new techniques for design and manufacturing started,
or received initial large-璼cale use, in aviation. An obvious example is the use of an integrated design tool such as CATIA, developed by and for Airbus but used successfully
in what was claimed to be the first paperless aircraft, the Boeing B-�7 (Sabbagh 1996).
This technique, also used in other industries such as automotive, allows many business
partners to provide their own design expertise to the overall aircraft design. It has not
been without its problems, but has in general ensured that parts are manufactured using
the same code as their design, with consequently better fit at assembly time. More recent
examples of design innovation are the use of friction-璼tir welding instead of riveting to
join fuselage sections of the Eclipse very light jet and the extensive use of composite
structures in fuselage and wing of the Boeing 787 and Airbus A350.
(f) Space Multiplies the Challenges
Some of the above factors are increased in importance when the product is a spacecraft
rather than an aircraft. Given that even to low earth orbit 1 kg of payload may need 10
kg of rocket and fuel, then payload mass is a huge driver of the feasibility and cost of
space launches. Thus lightness and strength (c.f. Space Shuttle Orbiter failures) are even
more important in spacecraft than in aircraft. We are moving towards privatized, and
potentially cheaper, orbital capability but the cost of payload to orbit was still about
$US4000 to $US15,000 per kg in 2000 (Futron 2002), depending on rocket size and
whether or not the cost was subsidized by government. Launch costs to the much higher
geo-璼tationary orbit are proportionally much greater. When a spacecraft is in orbit,
whether autonomous or manned, the environment is one of the harshest known and
the potential interventions to mitigate unforeseen problems are necessarily limited. This
leads to highly controlled manufacturing, with clean rooms, test cells and comprehensive
procedures all designed to prevent the launch of defective spacecraft.
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Aerospace manufacturing??�7
While a typical aerospace manufacturer probably does not exist, the concept can still be
useful academically as a case study. Here we divide the industry, in a way that it generally labels itself, into those who assemble the complete vehicle and those who design and
build specialist components. As we shall discuss later, the component manufacturers are
playing an increasing role in the complete aircraft design and manufacture process.
(a) Airframes
Manufacturers range from small companies producing general aviation aircraft (e.g.
Opdyke 1999), often providing kits that owners can build for themselves, through
medium-璼ized companies specializing in a niche market (e.g. Beechcraft Corporation for
corporate jets, or Bombardier, making smaller regional airliners) to very large ?airframers? such as Boeing or Airbus which concentrate on large civil and military aircraft.
When companies become very large, they can become prestige symbols for governments� for example, Boeing for the USA, Airbus for the European Union and Comac
for China ? leading to considerable political as well as marketing and manufacturing
pressures. Thus many sales of military aircraft across national borders must offer participation of local manufacturing to gain government backing for the contract.
Flying has traditionally attracted gifted scientists, designers, engineers and pilots, and,
at least in the pioneer days (Opdyke 1999), turned them into de facto manufacturers.
Obvious examples are Glen Curtiss in the USA, A. V. Roe in the UK, Louis Bleriot in
France and Hugo Junkers in Germany, who all founded aircraft design and manufacturing companies bearing their name. Some pioneer designers crossed borders with their
companies, such as Anthony Fokker relocating from Germany to the Netherlands after
WWI (Weyl 1965), or Igor Sikorsky having his company in Russia until the revolution
of 1917 and later in the USA (Cochrane, Hardesty and Lee 1989).
Aerospace companies also have histories that affect their current operations, often a
history of mergers and acquisitions. Excellent histories on many individual manufacturers in publications by Putnam (34 volumes) and Docavia (5 volumes, in French) cover
companies in the UK, USA, Germany, Sweden, Russia (Putnam) and in France and
the USA (Docavia). They range in date from De Havilland aircraft (Jackson 1962),
through the 1980s (Liron 1984) to Junkers aircraft (Kay 2004). These histories cover a
chronological record of the company and its aircraft, but also include photographs of the
manufacturing facilities in different eras. Each of these includes earlier manufacturers
absorbed into the later company; for example, Wegg (1990) details General Dynamics
aircraft including eight absorbed companies from Thomas Morse to Convair. Of course,
subsequent to that publication, the aviation interests of General Dynamics became part
of Lockheed-璏artin in 1993. The history of aviation manufacturing in the former Soviet
Union (subsequently mainly Russia and Ukraine) and China is quite different, with government taking a much stronger hand in all aspects of design, manufacturing and sales.
Manufacturing by smaller companies often has had to diversify in order for them
to stay in business through lean times. A typical example is the Schweizer company, a
maker of high-璸erformance sailplanes in Elmira, New York, which has at various times
manufactured aircraft parts under sub-璫ontract and non-璦viation items such as truck
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bodies and even lathe guards (Schweizer 1991). They also built much of the structure
of the Bell 47J2 helicopter, control surfaces for the Grumman Gulfstream, and even
complete Grumman Ag-瑿at agricultural aircraft and Hughes 300 helicopters, the latter
evolving into their own 330 turbine powered helicopter in 1988. (Note that Schweizer
(1991) is an excellent business as well as aeronautical company history, giving for
example, detailed tables of annual sales and employment.) Even major manufacturers
have weathered hard times by using their aviation skills to produce non-璦viation products. After WWII, Grumman?s orders for naval aircraft dropped rapidly but they used
their aluminum monocoque construction expertise to build light-瓀eight canoes for the
growing consumer market.
(b) Engines
Typically, airframe manufacturers do not produce their own engines, relying on specialist engine manufacturers to produce competitive engines. This has not always been the
case: for example, Curtiss, Bristol and Junkers were all major engine manufacturers as
well as airframers up to WWII. Currently the major engine manufacturers of turbine
engines (turbofans, turbojets and turboprops) are Pratt & Whitney, General Electric and
Rolls Royce, with various subsidiaries producing smaller engines, for example Pratt &
Whitney Canada produces small turbofans and turboprops. Engine supply to both civil
and military aircraft is fiercely competitive, as evidenced by the fights in the US Congress
in the past ten years over an alternative engine to power the F-�. In civil aviation, the
demand is for ever-環igher levels of fuel efficiency because fuel costs are either the largest
single airline operating expense or the second after payroll. Reducing fuel consumption
by a few percent is highly significant, but reduced fuel consumption must be accompanied by reduced emissions and reduced noise levels. Noise levels have decreased from
about 100 decibels (dBA) for an early B-�7 to 78 dBA for a late B-�7 (FAA 2002),
a reduction of over 100 times the sound intensity because a reduction of 3 dBA halves
the sound intensity. Emissions reduction has become increasingly important, with some
countries and regions (e.g. the European Union) introducing a carbon tax on all aircraft,
domestic and foreign, arriving and departing. These beneficial changes have taken place
through extremely careful design and very tight manufacturing tolerances. Often, aircraft engine manufacturers will form consortia to share the very high development costs
of new and progressively developed engines. Examples are CFM International (comprising General Electric and Snecma), MTR (a joint venture between MTU Aero Engines
of Germany, Turbomeca of France and Rolls Royce of the UK) and Engine Alliance (a
joint venture between General Electric and Pratt & Whitney). As engine manufacturers
combine in different ways there is the added challenge of putting firewalls between the
stand-璦lone business and these joint ventures.
(c) Components and Avionics
Most airframers are primarily designers and assemblers of aircraft, or spacecraft, from
components produced by others as much as by themselves. This applies to small manufacturers as it has for most of the 20th century, where standard components (e.g. wheels,
propellers and cockpit instruments, as well as engines) came from more specialized
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Aerospace manufacturing??�9
� anufacturers. This certainly continues today where there are specialist companies prom
ducing components for many different airframers. An example would be Dowty, which
started as a manufacturer of internally sprung wheels (e.g. for the Gloster Gladiator
fighter of the late 1930s) and continued as undercarriage (landing gear in the USA)
specialists. A related example is Dowty-璕otol, which produces propellers for many
turboprop airliners such as those from Bombardier as well as for the Lockheed-璏artin
C-�0J military transport. Dowty bought the Rotol group of propeller manufacturers,
itself formed from propeller divisions of Rolls Royce and Bristol Aircraft.
Aviation electronics, known as avionics, are of increasing importance in aircraft
design. They grew from the simple autopilots developed before WWII into a range of
control, communications and signal detection/processing equipment in civil and military
aircraft as well as spacecraft. Over the past 50 years the primary flight control of the aircraft has changed from rods and cables between cockpit controls and control surfaces,
through power-璦ssisted controls that lower the pilot forces required, to digital controls
that move control surfaces by electric motor or hydraulics in response to electrical input
from the pilot controls. Doing this has reduced both aircraft weight and stick/rudder
forces, but mainly has enabled new control laws to be inserted between pilot controls
and control surfaces. These can be modified by flight regime ? for example, speed, altitude, angle of attack ? to improve control and safety, although there are differences of
opinion over the relative authority of pilot and computer. Engine controls have similarly
evolved from direct mechanical links to Full-瑼uthority Digital Engine Controls, with
similar increases in ease of engine handling and improved safety, for example reduction
of flame-璷ut conditions.
Avionics has transformed the cockpit from individual dial indicators (?steam gauges?
in aviation jargon) into flat-璸anel digital displays integrating many functions (?glass
cockpits?). As with primary flight and engine controls, the insertion of a powerful
computer between pilot and display allows for both increased control capability and
decreased pilot workload. Thus civil aircraft have primary flight displays showing at
least attitude, altitude and heading. More typical displays show navigation (usually via
GPS), terrain maps and airfield information. These displays have become the normal
displays for general aviation, although they may not have increased flight safety (NTSB
2010b) as well as for airliners and the military. Manufacturers of avionics are specialists,
for example Honeywell, Rockwell-瑿ollins or Thales for larger aircraft and Garmin for
general aviation. Airframers specify either off-璽he-璼helf avionics or, for more complex
aircraft, they work with the avionics manufacturer to develop a specific set of displays
integrated into a Flight Management System. In the military, avionics has advanced
to encompass targeting, weapons systems management and digital communications
between inter-璫onnected vehicles, including UAVs.
(d) Maintenance and Repair
As noted above, aircraft last long enough to require considerable maintenance and repair
to ensure what the FAA terms ?continuing airworthiness.? The scale of maintenance is
large enough to warrant its inclusion in manufacturing, as inspection and repair costs
can exceed the initial purchase price of an aircraft. According to the International Air
Transport Association (IATA) the costs for maintenance ranged from $US461 per flight
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hour for regional jets to $US1430 per flight hour for wide-璪ody jets with more than two
engines (IATA 2011), amounting to several millions of dollars per year for each airliner.
The worldwide total of maintenance and repair spending in 2010 was $US42.3 billion
(IATA 2011). All commercial aircraft are designed for maintenance using a design process
termed MSG-�from the Maintenance Safety Group of the FAA. This considers each component (airframe parts, engine parts, avionics, etc.) and determines its failure modes. It
then estimates failure rates over time and the probability of detecting each failure, combining these to provide a set of inspection and repair dates to ensure that no single failure can
result in a hull-璴oss accident. For example, with cracks in airframes (a problem with aging
aircraft fleets), MSG-�determines the crack growth rate for each failure mode and the
inspection reliability for cracks as they become larger. It then specifies a set of inspection
intervals such that there are multiple opportunities for detection of each crack between it
growing to detectable size and it threatening component failure (Drury and Spencer 1997).
Maintenance and repair are carried out by Maintenance and Repair Organizations
(MROs), which may or may not be part of the airline operating the aircraft. MROs
comprise line maintenance performed on the flight line (about 17 percent of MRO
costs), heavy base maintenance conducted at special facilities (about 20 percent), engine
maintenance (about 43 percent) and component maintenance (about 20 percent) (all
estimates from IATA (2011)). For all except line maintenance, the work involves specialized hangars (except in the tropics, where work is often performed outside), specialized
tools for inspection and repair, specialized fixtures for access to large aircraft, and specialized and licensed mechanics, known as Aviation Maintenance Technicians (AMTs)
in the USA. The work is carried out using strict and highly regulated guidelines. For
example, maintenance operations have AMTs following documents called ?task cards,?
signing off on each step that the work was completed, to provide a comprehensive paper
trail paralleling the actual maintenance and repair work (e.g. Patel, Drury and Lofgren,
1994). Heavy engine repair is usually performed in a dedicated engine facility, often operated by the engine manufacturer which sells ?power by the hour? to the airline. Similarly,
component repair is performed in ?back shops? at airlines or other MROs, or often
outsourced to a lower tier of specialists, for example for avionics. In these cases, AMTs
typically replace a component that appears to be defective and send the old component
out to the back shop for diagnosis and repair. Increasingly, maintenance is software
supported with portable or tablet computers being used for presenting the task card to
the AMT and recording the sign-璷ffs (Drury, Patel and Prabhu 2000). In addition, the
software itself can be in need of repair or upgrading, and software changes can be used to
provide functional repairs. This is particularly the case for space vehicles, where physical
repair is exceedingly expensive. The Hubble Space Telescope cost about $US2.5燽illion
to build and launch in 1990, but has had five upgrade missions in the 23 years of operation since then, each costing $US1.7 to $2.4 billion (General Accounting Office (GAO)
2004) for a total cost of over $US10 billion to date. Satellite servicing and repair by
software and reconfiguration is more common than physical repair. For example, the
award-瓀inning QuickSCAT ocean observation satellite launched in 1999 has required
many software changes to reconfigure operational status as batteries fail and antennae
cease to move correctly (NASA 2009). It had a design life of two years but operated as
planned for over ten years and even after 13 years can still be configured from the ground
to provide useful data on ocean winds.
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Aerospace manufacturing??�1
Aerospace manufacturing is a complex industry; even if nothing changed, it would still
face challenges. But the ongoing and coming challenges leave it anything but static.
Although the ultimate speeds of most aircraft classes have not changed much in 50爕ears,
the changes to operating capability and cost/environmental impact have been very large.
For example, each generation of jet airliner improves the safety record and lowers fuel
and maintenance costs (impacting seat km costs) while reducing noise and environmental pollution. However, the continuing expansion of passenger and cargo traffic has kept
overall environmental impact relatively steady. Aircraft design is not the only factor
in the environmental impact of aviation: improved operational procedures also aid in
impact reduction. For example, the move away from radar-璪ased air traffic control to
GPS-璪ased operations allows for what the FAA terms ?Trajectory-瑽ased Operations?
that reduce fuel consumption and environmental costs by providing more direct flight
paths (Joint Planning and Development Office (JPDO) 2011). A specific example is
tests of Required Navigation Performance for landings at Phoenix airport in 2006,
which showed a $US2 million cost saving and a 2500 tonne carbon dioxide reduction
(FAA 2009). These savings are not possible without aircraft design and manufacturing
changes; in this case the addition of appropriate avionics to enable the new procedures.
In this section we will survey some of the challenges to aerospace manufacturing
beyond those relating to sustainability.
(a) Design
Although airframers have traditionally performed their own design work, relying on
outside contractors for engines and components only (see Section 2c above), the trend
is towards more design autonomy within the overall airframer?s specifications. As noted
above (Section 1e), the advent of comprehensive design software has allowed a number
of design innovations of interest in manufacturing. First, it allows second and third
tiers of the supply chain to contribute to the design process in a way that captures their
unique design and manufacturing expertise. Thus outsourcing design of the auxiliary
power unit (APU), which is a small gas turbine engine providing electrical power when
the main engines are not operating, enables APU specialists (e.g. Hamilton Sundstrand
or Honeywell) to design and manufacture their optimal unit within the airframer?s specifications. These will include power output, fuel consumption, weight, space constraints
and operating temperatures, so that the design fits into the overall aircraft package.
Thus not only is the production of components outsourced (see 3b below), but so is
the design expertise. This is a challenge (as well as an opportunity) because it requires
another level of communication within the design team so that integration produces
no surprises in terms of space, weight or function. This is particularly true for multiple
partners in the design who must coordinate with each other as well as the more natural
coordination with the airframer. Initial troubles with Airbus?s A-�0 and Boeing?s B-�7
have hinted at lack of design integration, but there have been no definitive answers so
far. Recent papers have noted problems with distributed design, for example at Boeing,
and Dell (Amaral, Anderson and Parker 2011) and attempted to model optimal partial-�
outsourcing design strategies (Anderson, Feng and Parker 2011).
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Another opportunity comes with the use of integrated software for design: the freedom
from mock-璾ps as the design progresses. With detailed three-璬imensional design in software, fit and tolerances can be predetermined without the need to build a physical mock-�
up for testing. Such mock-璾ps were an integral part of aircraft design stretching back
before WWII, for example the 1946 mock-璾p shown on page 273 of Brown (1970) of the
M.52 prototype supersonic test aircraft by Miles Aircraft that was never built due to government policy changes. They were used to reassure the customer that the aircraft would
be physically accessible to the flight and ground crews, and that such items as cockpit
display layouts fitted customer needs. As Sabbagh (1996) records (pp. 57 et seq.), the
Boeing 777 used CATIA for design and EPIC (Electronic Preassembly In the Computer)
in place of mock-璾ps. This technique allowed, for example, the early detection of a
torque tube that would fit the wing correctly but which had insufficient clearance to
allow assembly. Similarly, the wiring harness could be designed to fit through the structure by software, instead of hand-璦ssembly in the mock-璾p and subsequent recording of
wire lengths and paths. On later aircraft such as the Boeing 787, computer representations of human manikins are used to ensure that AMTs can reach points requiring maintenance and have sufficient clearance to use the correct tools (e.g. McMullin et al. 2008).
New initiatives in design are constantly being tried. The whole Design for X movement
began with Design for Manufacturability (see Boothroyd 1996), and has now embraced
Design for Quality, Reliability, Serviceability and even Design for Inspectability (Drury
1996). More recently Washington (2012) outlines the Defense Advanced Research
Projects Agency?s (DARPA?s) efforts to reduce the design-璽o-璼ervice cycle from decades
(e.g. F-�) to potentially months using a more integrated approach to design. This is
made possible by IT tools that can help handle the complexity inherent in any modern
large-璼cale system. Instead of the design?build?test?redesign cycle the aim is to use valid
subsystem models integrated into a system model to consider design trade-璷ffs in parallel and perform virtual testing of hundreds of potential configurations, again eliminating
the need for mock-璾ps and prototypes.
(b) Outsourcing and Supply Chain Logistics
We have already seen that design can be outsourced (3a above), but outsourcing is far
more extensive in aerospace manufacturing. An obvious starting point is engine and
avionics, which are almost always outsourced, but we are now seeing even major assemblies produced elsewhere and transported to the final airframe assembly plant. From
the outset, Airbus Industrie was designed to involve plants in constituent countries of
the consortium. Thus wings are manufactured in the UK at the former plants of Bristol
Aircraft (Filton) and De Havilland Aircraft (Broughton), while fuselage sections are
sourced in Hamburg, Germany and Saint-璑azaire, France; tail sections in Japan and
Spain. All are assembled in Toulouse (France), Hamburg (Germany) or Tianjin (China).
Engines and avionics come from the suppliers listed earlier. Similarly, Boeing extensively
outsources assemblies with composite fuselage sections from the USA, Japan and Italy;
wings from Japan and tail assemblies either from Italy or Boeing?s own plant. Assembly
is performed in parallel at the main plant (Everett, Washington) and the new plant
(North Charleston, South Carolina) in the United States.
This activity is not new. In each world war, all combatant countries had components
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manufactured by second-璽ier companies, as well as what the UK called ?shadow factories? built to provide parallel sources for each aircraft type. In WWI the wooden-璮ramed
Sopwith Camel could be extensively sub-璫ontracted component by component to local
woodworking shops, while metal fittings were manufactured in quantity by Britain?s reservoir of machine shops. Full-璼cale production was undertaken not only by Sopwith, but
by Boulton & Paul (Norwich) and Fairey Aviation (Hayes), each airframers in their own
right with their own designers (Pudney 1964). Similar outsourcing to meet wartime needs
was just as evident in France and Germany. In WWII, Supermarine Spitfires were built
by the thousands at a shadow factory at Castle Bromwich near Birmingham (Andrews
and Morgan, 1981).
Manufacturing outsourcing presents challenges of supply chain management, particularly regarding quality (e.g. Foster 2007), which can have literally life-璷r-璬eath
consequences in aviation and space vehicles. It also exposes the airframer to the classic
problems of supply chains: bottlenecks and disruptions. These can be manifested in acute
form by the sheer size of some of the components outsourced. Fuselage barrel sections
can be over 6 m in diameter and 12 m long: wing components can be up to 20爉 long, and
all need inter-璫ountry or even intercontinental transportation. Boeing and Airbus have
used ships and outsize aircraft (Airbus A300?600ST Beluga and Boeing 747燚reamlifter)
to transport such huge components, with the aircraft reducing transport time from weeks
to days, for example between Japan and Seattle. There is clear potential for supply disruption by weather or maintenance delays. There is also the potential for outsourced
manufacturing delays, widely publicized for the B-�7, when second-璽ier suppliers do
not have the production expertise or capacity to manage ramp-璾p of production. As
with design outsourcing, manufacturing outsourcing has been blamed (without specific
evidence) for initial problems with the A-�0 and B-�7 (Plumer 2013).
Finally, note that aircraft maintenance is largely outsourced by aircraft operators.
Whereas 25 years ago each airline had extensive ramp and heavy maintenance facilities,
cost pressures have driven them to look for lower overheads and reduced labor costs
through outsourcing. Over 64 percent of aircraft maintenance was outsourced in 2007
(McFadden and Worrells 2012), and this includes line, heavy and component maintenance. As Drury, Guy and Wenner (2010) noted, this introduces added complexity
of interaction between the aircraft operator, the MRO and the regulatory authorities.
However, after three separate studies the authors concluded that the errors tended to
remain potential and that outsourced maintenance did not appear to be any more error
prone than in-環ouse maintenance. In a follow-璾p study on the issue of outsourcing to
non-璄nglish-璼peaking countries (Drury, Ma and Marin 2009), an extensive experimental
data collection on four continents gave quite encouraging results. MROs in Spanish-�
and Chinese-璼peaking countries were able to comprehend work documents, such as task
cards, written in English, even if they did it more slowly than native English speakers.
Training AMTs in technical English and use of well-璬esigned task cards both proved
effective in reducing comprehension errors.
(c) Regulation
As noted above (Section 1b), aviation and space flight are highly regulated activities in
almost all countries of the world. In the USA, the FAA is the regulatory body, while in
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the EU the regulatory authority is the European Aviation Safety Agency, which replaced
the earlier Joint Aviation Authorities. Each of these agencies, and their equivalents in
other jurisdictions, provides detailed regulations that all in aviation must follow in that
country. These range from certification of aircrew, AMTs and air traffic controllers,
through specifics of design and construction of aircraft and components, to the rules
under which aircraft users (e.g. airlines, businesses) must operate. The stated aim of each
regulatory authority is safety for those flying and those on the ground, but at least in the
USA a part of the FAA?s mission is to ensure the ?most efficient aerospace system in the
world.? This means having a dual mission of effectiveness and efficiency, which could
potentially be in conflict; for example, in separation standards for commercial aircraft
where safety demands larger separations while efficiency demands a smaller value. This
is a challenge for regulators, but can also impact design by specifying the equipment
that needs to be installed in each aircraft. For aircraft designers and manufacturers,
these national regulations provide a consistent design and verification framework to
ensure that all manufacturers meet the same minimum standards. Because many regulatory authorities work together, these standards are typically worldwide, although each
reserves the right to its own rules. Thus an airliner may be built in the USA (although
sourced globally) and certified there, but the manufacturers and many regulatory
authorities combine to ensure simultaneous certification in the EU with a minimum of
repeated testing. Some jurisdictions, such as the Civil Aviation Administration of China,
are newer to the task of certifying major indigenous aircraft (e.g. C-�9 or ARJ21) so
delays have been experienced. There is always the possibility of government 璱nterference,
making global certification subject to political pressures.
(d) Materials
Because aerospace continues to move towards higher aircraft performance, it has a
vested interest in new materials. The example given here is of aircraft structures, but
similar examples come from heat-璻esistant materials for turbine engines, fireproof interior materials and new battery technology. Metal structures replaced wooden airframes
throughout WWI, finding almost universal acceptance from the late 1930s onwards.
Light alloy structures demanded careful design where the skin became a load-璪earing
element, in contrast to an underlying wooden or steel structure with fabric as an aerodynamic covering. This monocoque construction is now standard, but the materials
themselves are now changing. Plastics have been used in aircraft structures since WWII,
when thermoset plastics (e.g. Bakelite) were used for covering the radar antennae in an
aircraft nose. In the 1960s more advanced plastics became available, which have seen use
in airframes and other components since the 1980s (GAO 2011). Starting with General
Aviation aircraft, composite structures from glass-璷r carbon-璻einforced plastics initially
provided tail sections for Airbus (A-�0 in 1988) and Boeing (B-�7 in 1995) airliners,
and currently have been used for whole fuselages and wings (B-�7 and A-�0). Such
composites reduce structure weight for the same strength as aircraft-璦luminum alloys
(Kalanchiam and Chinnasamy 2012), plus they are corrosion-�
free and have better
fatigue resistance (Ilcewicz 2010). However, such structures bring their own challenges,
primarily because they fail in different ways from more traditional alloys ? for example,
de-璴amination between layers, disbanding, water infiltration (GAO 2011) ? and new
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techniques for in-璼ervice inspection are required (Drury 2005). These techniques (e.g.
ultra-璼onic non-璬estructive inspection) are not new to the aviation maintenance industry, but need to move to a new level of reliability and productivity to be applicable to
large-璼cale structures.
Future materials changes in metals production (e.g. additive manufacturing and
explosive forming for complex curved parts (Warwick and Norris 2013)) and in composites (e.g. large stitched carbon fiber without an autoclave (Warwick 2013b)) are coming
to airframe manufacturing.
(e) Finance
Design and manufacturing of aircraft are very expensive, and thus a primary challenge
for aviation manufacturing. This is obvious from the asking prices of major military
and commercial aircraft quoted above (Section 1c), but designing, building, certifying, selling and providing customer service for the smallest general aviation aircraft are
certainly not cheap. The start of Airspeed Aircraft in 1930 has been well documented
by N.� S.� Norway, one of its founders, better known as the novelist Neville Shute
(Shute 1954). A small number of aircraft designers, out of work when British airship
manufacturing was abruptly cancelled, decided to form their own aircraft design and
manufacturing company, Airspeed. Norway spent most of one winter soliciting funds for
subscription to a share offering in the new company, but only �00 was raised against
the �,000 minimum thought necessary. The board went ahead, first producing a glider
to break records (to publicize the new company), then receiving a powered aircraft order
from a close friend. The company went on to manufacture some notable light aircraft,
over 8000 Oxford trainers for the Royal Air Force and a number of airliners post-璚WII
before being taken over by a larger aircraft manufacturer. A more current and unusually financed startup corporation, Quest Aviation, was formed in the 1990s to design
and build a rugged, single-璽urboprop bush plane transport for use in the developing
world (Garvey 2013). From the idea to the start of design work in 2002, donations were
received from a large number of charities which saw a need for such an aircraft. By 2004
a prototype was flying, with commercial production starting in 2007 and over 80 of these
Kodiak aircraft have now been delivered. Uniquely, one in ten of these aircraft have been
donated to charities.
The large airframers rely on both commercial and military contracts; thus finance
comes both from governments and the commercial world. Both sources are subject to
large and rapid swings in financial fortunes with changes of government and economic
cycles. Commercial aircraft are particularly vulnerable as they require gestation and
payback periods of many years while their customers are driven by immediate financial pressures. The disputes before the World Trade Organization between Boeing
and Airbus (Disputes DS316 and DS347), each claiming that the other receives illegal
government subsidies, are perhaps the most famous examples of the complexity of the
financing of large commercial aircraft. For spacecraft, the recent financing by NASA
in the USA of commercial vehicles to supply low earth orbit in place of government-�
owned vehicles is seen as a breakthrough worldwide, as governments have dominated
space travel since its inception. US space vehicles have always been built by commercial
enterprises (Boeing, Lockheed-璏artin, etc.) but now the emphasis is on vehicles such as
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the Falcon/Dragon system manufactured by Space Exploration Technologies and flown
by them on commercial contract for International Space Station re-璼upply missions
(Warwick and Ostrove 2013).
While aircraft have been in service for a century and spacecraft for half a century, their
design, manufacture and continued safe operation represent significant challenges to the
enterprises involved. If customers for these vehicles, their operators and passengers, and
the world?s governments were content with stasis, aviation would be relatively simple.
However, despite the fact that aircraft continue in service for many decades, constant
improvement is demanded. Although the nature of that improvement might change,
embracing at different times production rate, passenger safety, operating economics and
environmental concerns, the imperative is still innovation. With such a technically difficult endeavor as flying, the fact that an impressive safety record is now commonplace is
in itself a major achievement. New materials, design and manufacturing methods, ever-�
changing regulations and global production have to be integrated into financially viable
enterprises. With five-瓂ear forecasts for 9287 commercial transports (Warwick 2013a,
p.?100) and 4474 business jets (Warwick, 2013a p.?137), the commercial side of aviation
appears set to experience continued growth. The challenges are not diminishing in the
near future.
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Aerospace manufacturing??�7
Drury, C.G., Patel, S.C. and Prabhu, P.V. (2000), ?Relative Advantage of Portable Computer-�
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308??Handbook of manufacturing industries in the world economy
Wegg, J. (1990), General Dynamics Aircraft and their Predecessors, London, Putnam.
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Collection Docavia ? Editions Lariviere (in French). (The many volumes in this series include at least five on
French aircraft manufacturers which are the best source for French manufacturing history.)
Foster, S.T. (2007), Managing Quality: Integrating the Supply Chain 3rd Edition, NJ, Pearson Education Inc.
(The third edition of a standard text on supply chain quality.)
Huang, G.Q. (ed.) (1996), Design for X: Concurrent Engineering Imperatives, London, Chapman & Hall.
(This older compilation covers the relationship between design and manufacturing, inspection, quality and
Khanna, R. (2012), Entrepreneurial Nation: Why Manufacturing is Still Key to America?s Future, New York,
McGraw-璈ill. (A useful recent book with good data on US manufacturing.)
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record of aviation manufacturers in the UK, USA, Germany and the Soviet Union/Russia.)
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Economics Are Creating an American Comeback, Philadelphia, PA, Knowledge@wharton. (A readable (and
free) download from giving the results of Boston Consulting Group showing the outlines of a
potential revival of American manufacturing.)
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