24 JOM • March 2000

Featured OverviewAdvanced Materials

Editor’s Note: A hypertext-enhanced version of this article isavailable on the web at www.tms.org/pubs/journals/JOM/0003/Martin-0003.html.

Emerging metallic materials, processing,and manufacturing technologies offer animportant opportunity to meet current air-craft-airframe and jet-engine affordabilitygoals, due to their inherent low materialcosts and excellent producibility character-istics. But to successfully meet systems goalswithin this new affordability-driven scenario,a consolidation of industry and military-agency development resources and technol-ogy-implementation activities is necessaryto positively impact the military-aircraftproduction and sustainment infrastructure.To address this need, a consortium of aircraftand engine manufacturers and key material-and component-supplier companies has beenformed to identify critical affordable metaltechnologies, develop a strategic roadmap foraccelerated development and insertion of thesetechnologies, and oversee execution of devel-opment activities by integrated industryteams. The goal of the Metals AffordabilityInitiative is to reduce the cost of metalliccomponents by 50 percent while acceleratingthe implementation time.

INTRODUCTION

Metallic materials and processing tech-nologies are critical in meeting the near-

Reducing Costs in Aircraft: The MetalsAffordability Initiative Consortium

Rick Martin and Daniel Evans

Figure 1. (a) Material usage and (b) typical system cost distribution trends for fighter aircraft.

a b

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Engines

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term affordability objectives of militaryand commercial aircraft systems. Untilrecently, system-performance objectivesrelated to range, acceleration, velocity,maneuverability, and low observabilitywere the primary objectives during sys-tem-concept development stages of air-craft programs. Achieving these perfor-mance goals was often accomplished atthe expense of life-cycle cost economy.

The escalation in system costs, despiteefficiency improvements in engineeringand manufacturing operations at con-tractor facilities, can be attributed pri-marily to the increased use of more ex-pensive structural components and as-semblies; the trend in aircraft produc-tion has been a growing use of high-costcomposites and titanium components tomaximize weight efficiency (Figure 1).Figure 1b highlights where the largestcost factors exist at the system level.Typically, the engine(s) represent 20–25percent of the acquisition cost of a jetaircraft; the largest cost factor is relatedto the engineering, fabrication, and as-sembly of airframe structure.

Metal alloys account for 80% of jet-engine components due to the severeoperating environment and the need forexcellent fabricability to accommodatecomponent complexity within a limited

volume. Although the use of organicmatrix composites for wing and fuse-lage skins has been steadily increasingto minimize airframe weight, structuralmetals still account for at least two-thirdsof airframe weight. With the continuedwidespread use of metallic materials forengine components and for the fabrica-tion of airframe assemblies, applyingstate-of-the-art metals processing tech-nology and advanced structural designconcepts can provide breakthrough costsavings for military aircraft systems.

To meet this goal, a team comprisingaircraft and jet-engine manufacturers,aircraft-component suppliers, and ma-terial suppliers has been formed to se-lect, consolidate, streamline, and lever-age ongoing and future industry activi-ties for affordable metal-technology de-velopment. Under the direction of theU.S. Air Force Research Laboratory’s(AFRL’s) Materials and ManufacturingDirectorate, the Metals AffordabilityInitiative Consortium’s (MAIC’s) goalis to reduce the cost of metallic compo-nents by 50% while accelerating imple-mentation time. The MAIC team—Boeing, Lockheed-Martin Corporation,Pratt & Whitney Aircraft, General Elec-tric Company, Honeywell, Rolls Royce-Allison, Howmet Corporation, Brush-

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Figure 2. The MAIC roadmap.

Figure 3. Operation and support cost distributions from life-cycle costs.

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Wellman, Ladish Company, Allegheny-Teledyne, and Carpenter Technologies—has the resources, experience, and cov-erage of the entire metals-supply chainto successfully develop, demonstrate,and implement metals technologies andmanufacturing processes that can pro-vide revolutionary cost savings to mili-tary aircraft.

The accurate measurement of specificcost reductions associated with chang-ing any given approach to producingairframe structure or jet-engine hard-ware has been problematic when at-tempting to prioritize development ac-tivities. To address this issue, the MAICindustry team utilized a systematicpairwise assessment method (Expert-ChoiceTM software) to prioritize and se-lect metal-technology topics that offerthe greatest cost-reduction impact foraircraft and jet engines. Rather than se-lecting program activities based on indi-vidual projected business cases, pro-grams that offer the best combination ofrapid implementation, efficient planning,manageable technical risk, effectiveteaming, and insertion viability are be-ing conducted. The MAIC has devel-oped weighted affordability objectives,identified and ranked the technical chal-lenges related to meeting these objec-tives, and produced scores for variousmetal-technologies topics that addressthe technical challenges. Based on theseactivities, a roadmap was generated toguide the investment of funding and theselection of affordable metal-technologydevelopment projects (Figure 2).

COST IMPACT

A structured development, demon-stration, and implementation strategy isnecessary for measurable and pervasivecost savings. The MAIC conducted a“top down” approach to determining

development paths that provide theframework necessary to ensure maxi-mum payoff from technology tasks thatachieve the affordability objectives ofthe program. The initial step in this ap-proach is determining the key technicalchallenges in aircraft design and pro-duction that most significantly impactsystem life-cycle costs. The MAIC re-viewed traditional materials, design, andmanufacturing approaches utilized foraircraft and engine production.

In airframe construction, the centerand aft fuselages represent the highestcosts on a dollar per pound basis. This isprimarily attributed to factors such ashigh part count and the use of titaniumcomponents needed to construct highly-loaded assemblies (e.g., tightly spacedframe assemblies and titanium bulkheadcomponents). Airframe construction hastraditionally relied on thebuilt-up mechanical as-sembly of machinedhogouts, sheet metal, andforged/machined com-ponents to build aircraftassemblies. This philoso-phy currently representsthe lowest risk approachsince there is a historicalknowledge base. Designand analysis activitiescan be segmented tosmall subassembly lev-els with individual loadcases, and airframe-com-ponent manufacturingcan be rapid, flexible,and straightforwardsince part details are rela-tively simple in geom-etry. The disadvantage ofthe current design andmanufacturing philoso-phy is that part count is

high, resulting in excessive engineeringlogistics costs. Also, material efficiencycan be poor, component assembly is of-ten problematic due to part distortionand tolerance build-up, and modularityis difficult at the system level. The disad-vantage in relying heavily on traditionaltitanium components is that the costs ofmanufactured components are increas-ing due to reduced availability, escalat-ing material costs, and the relative diffi-culty in machining and forming compo-nent geometries. The largest percentageof airframe costs is touch labor; othercosts accounted for about 25% of costs,followed by procured hardware and rawmaterials.

Although no specific jet-engine sub-system stands alone in relative cost inef-ficiency, a review determined that thenozzles, high-pressure compressor, andhigh-pressure turbine sections representthe best opportunity to maximize costbenefits resulting from metals-develop-ment activities. In simple terms, the es-calating cost of purchased parts (e.g.,airfoils/cases and forged disks), reducedcomponent-quantity requirements, anda continued increase in performancedemands are primary factors contribut-ing to poor cost efficiency. Performance-driven jet-engine design is less reliant onmechanical fastening as compared toairframe construction due to the severeknockdown in component life associ-ated with localized stress concentrationand the unique volume and geometricalconsiderations of turbofan engines.These issues, combined with the highraw-material cost of the alloys neededfor severe temperature environments,have already driven manufacturing phi-losophies toward near-net-shape forg-ing and casting. Materials and process-development activities have includednear-net-shape processing improve-

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26 JOM • March 2000

Figure 4. The use of superplastic forming-diffusion bonding to reduce the fuselage part count in F-15E aft fuselage (blats SPF-DB) showing (a) beforeand (b) after SPF-DB.

a b

Figure 5. A cast titanium side-of-body formilitary aircraft.

ments, but have primarily focused onalloy development for improved high-temperature properties and weight effi-ciency. Disadvantages with the currentapproach range from the high costs as-sociated with the extensive list of spe-cialized and limited volume metal al-loys and specifications, resulting in anescalation of supplier costs, to an ineffi-cient supplier-prime infrastructure, caus-ing inflated final-component costs.

In addition to acquisition-related costs,operation and support (O&S) costs foraircraft in service typically representnearly half of the overall life-cycle cost ofmilitary aircraft (Figure 3). Most of theO&S costs are related to personnel andmaterial used to support scheduled andunscheduled maintenance actions, soreduction in aircraft-support coststhrough application of advanced metaltechnologies has been identified as aprimary affordability target. The elimi-nation of premature failures in the field,efficient inspection techniques, reducedmaintenance actions, and rapid toollessproduction of spare parts are areas iden-tified as having significant cost impact.

Other critical factors related to costimpact have been identified that are ge-neric to all metal components and as-semblies, regardless of specific systemsand applications. These factors are re-lated to quality cost, which is often notaccounted for during initial cost projec-tions when selecting materials, designs,and manufacturing concepts for aero-space hardware. Examples are the im-position of specific inspection require-ments that result in very poor materialefficiency (e.g., excess forging stock forsonic inspection), high realization fac-tors due to excessive inspection laborhours, and manufacturing and geomet-ric design approaches that require ex-cessive machining and cause distortionduring subsequent manufacturing op-erations. These critical factors can beresolved by applying analytical simula-tion and design tools to support robustcomponent production and advancedinspection techniques that streamline

component qualification steps.Another factor that bears emphasis is

the high cost associated with the use oforganic matrix composites for high-per-formance, lightweight components onaircraft systems. The performance gainsachieved through the use of these mate-rials has sacrificed affordability. Ad-vanced metallic materials are substitu-tion candidates for composites due tocomparable performance characteristics.By maintaining the inherent affordabilitycharacteristics of metal, they can pro-vide substantial cost savings. Thus, it isimperative to continually improve the

efficiencies of manufacturing and main-tain and/or increase the yield of emerg-ing advanced metallic materials.

In addition to the key factors that havebeen identified, the selection of develop-ment activities must also take into ac-count the changing nature of the aero-space industry. Production quantities inthe military sector are diminishing, andnew-generation aircraft acquisitions arerare. As a result, high nonrecurring costsassociated with a new material or pro-cessing approach can be prohibitive dueto undesirable break-even analyses. Newmetallic materials and processes thatcan forego high up-front investmentsduring component implementation (e.g.,tooling) are necessary. For this reason, acritical enabling factor related to reducednonrecurring airframe and engine costsis a primary consideration in determin-ing which technologies offer the greatestopportunity for meeting the affordabilityobjectives of this program.

The collected information was used tosupport the comparison of factors re-lated to aircraft and engine costs and theweighting of technical challenges. Theresults of studies conducted by the MAICidentified several key technical chal-lenges that have the most significantimpact on airframe and engine costs ofmilitary aircraft. Scoring the effect thatvarious metal-technology topics have onmeeting the identified technical chal-lenges provides a guideline on technolo-gies that are critical to meeting af-fordability objectives. Using the resultsof cost-impact studies produced byExpertChoice, a quantified assessmentof high cost-impact metal technologiesillustrated in Figure 2 was developed bythe MAIC.

INITIAL MAIC PROJECTACTIVITIES

Some recent initiatives aimed at re-ducing aircraft weight have also demon-strated the feasibility of incorporatingoutput from the MAIC to achieveaffordability goals. For example, the F-15E has implemented a superplastically

SPF/DB ProvidedPart Reduction726 Part Details

Eliminated10,000 Fewer Fasteners

272000 March • JOM

Figure 6. Examples of cost-reduction opportunities by implementing metal-process technologies.(a) Machined titanium frames, (b) composite pylon skins, (c) titanium hinge forgings, and (d)machined titanium support ribs.

c d

a b

Figure 7. The MAIC management structure.

formed and diffusion-bonded (SPF/DB)Ti-6Al-4V airframe structure as a replace-ment for built-up assemblies used inearlier models. This initiative has re-sulted in a dramatic part count reduc-tion and demonstrated the successfuluse of unitized construction in service(Figure 4). Another historical exampleof utilizing an advanced metals technol-ogy for weight reduction that also ad-dresses a technical challenge related tocost reduction is the incorporation ofhigh-speed machined aluminum com-ponents on the F/A-18E/F airframe. Thisinitiative resulted in the elimination of1,600 part details in the forward fuselageas compared to earlier models. The wide-spread implementation of structural ti-tanium castings (Figure 5) during thetransition from the YF-22 to the F-22aircraft for applications such as flapperonhinge fittings, aileron hinge fittings,canopy decks, wing side-of-body joints,rudder-hinge fittings, rudder-actuatorsupports, APU inlet door frames, cantedbulkheads, and aileron bay strongbacksis another example. By conducting suchinitiatives within the framework of theMAIC, greater resources will be avail-able to effectively resolve technical is-sues for risk mitigation and more rap-idly transition the technology to othersystems.

Under the sponsorship of the AFRLand the Dual Use Science and Technol-ogy Office, the MAIC is initiating techni-cal activities based on the output of MAICcost-impact studies and technology as-sessments. These activities began inAugust 1999 and are directed towardthe pervasive technical challenges of ef-ficient manufacturing processes, collabo-rative design and manufacturing, andpart-count reduction. The topics selectedfor immediate development are deemedto have sufficient technical maturity and

directly address the se-lection criteria outlinedby the MAIC.

Metal-product tech-nologies that are cur-rently under develop-ment can have a dramaticimpact on the cost of air-craft components by re-ducing buy-to-fly mate-rial costs and eliminat-ing manufacturing steps.An illustration of howsome of these selectedprocess technologies canbe applied to aircraftcomponents to meet theaffordability objectivesoutlined by the MAIC is shown in Figure6. These technologies include the fol-lowing.

• Direct production of high-quality,titanium-alloy slabs using advancedmelting techniques will streamlinethe production of plate product usedto manufacture engine and aircraftcomponents, allowing the use of ahigher percentage of low-costmeltstock (recycled titanium) andeliminating ingot-breakdown steps.

• Laser forming, a process currentlybeing commercialized by AeroMet,produces titanium components byusing localized deposition of alloyedtitanium, driven by an electronic-component description, to build upcomponent features on a generic,wrought, titanium workpiece. Thisoffers an alternative to machinedtitanium-plate hogouts and forgingsthat have poor material utilizationand high machining costs.

• Vacuum-die casting of titaniumcomponents is an emerging processtechnology that has the potential toshorten casting lead times, improve

product quality, and further reducecasting costs. Developing and imple-menting this advanced casting tech-nique will broaden the applicationbase for castings in critical struc-tural applications and provide wide-spread cost savings.

• Advanced wrought aluminum-be-ryllium products possess a uniquecombination of extremely low-den-sity and high-structural properties.Successful development and dem-onstration of this class of metalswill provide a low-cost, weight-equivalent replacement for organicmatrix composites currently usedfor lightweight structural skins.

• Development of a streamlined pro-cessing route for powder-metal-lurgy superalloy components willhave a substantial effect on finalproduct costs. Establishing the ac-ceptability of ultrasonic inspectionof pancake forgings will eliminateexpensive forging and machining.

• Direct production of high-qualitypowder-metallurgy superalloy bil-lets will eliminate deformation pro-cessing steps needed for producingmanufactured components. By de-veloping a modified powder-atomi-zation technique, billet quality willbe sufficient to allow direct machin-ing of component geometries to pro-vide significant reductions in cost.

• Roll forming turbine-engine com-ponents uses novel metal-spinningand shear-forming techniques toproduce near-net-shape nickel andtitanium geometries. Successful de-velopment and implementation ofthis processing technology will in-crease material-utilization factorsand eliminate costly machining.

• Modeling distortion that occurswhen machining forged productsby quantifying residual stresses thatexist and using analytical tools tosimulate the elastic response causedby material removal can increasecost efficiency by optimizing forg-ing geometry and machining se-quences.

Executive SteeringCommittee

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Plate Cost Is 65% ofComponent Costs

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Machined Forging

Laserforming ofFlanges EliminatesMaterial Waste fromMachining Ti Plate

28 JOM • March 2000

Figure 8. The task-gate approach to project development.

• Metallurgically joining titaniumcastings can combine the afforda-bility of near-net-shape castings andunitized construction to maximizecost savings. By demonstrating andqualifying the novel approach toproducing titanium assemblies, per-vasive cost savings for aircraft sys-tems will be achieved.

In addition to the systematic approachto selecting affordable technology top-ics, the MAIC is positioned to ensurethat all performance standards are met,and that insertion paths are establishedto support widespread implementationin supplier facilities and production air-craft programs. Execution of the techni-cal projects will emphasize the use ofadvanced analytical tools for processoptimization and integrated design andmanufacturing to ensure maximum costefficiency. Additional technology topicswere selected by the MAIC to increasecoverage of the technical challenges thathave been identified; these projects arebeing initated in April under the spon-sorship of the Materials and Manufac-turing Directorate.

FUTURE MAIC PROJECTACTIVITIES

As additional resources are identified,the MAIC will continue to launch devel-opment activities that provide a founda-tion for a metals-development infrastruc-ture that addresses the broad spectrumof technical challenges in meeting goalsfor breakthrough system affordability.The MAIC consortium has establishedthe Executive Steering Committee, com-posed of high-level managers from eachof the member companies, to define howthe consortium will operate and to iden-tify and distribute the resources neces-sary for supporting technical activities.The Technical Oversight Committee,composed of managers from the mem-ber companies, has also been establishedto identify the primary cost drivers, de-velop the metals-development infra-structure plan, and select and overseemetal-development activities. The se-lected projects will be led by ActivityIntegrated Product Teams that will con-

sist of companies ranging from the sup-ply chain through system integrators.

The management approach is illus-trated in Figure 7. Although the devel-opment of the Metals Affordability Ini-tiative has been the result of the efforts ofthe 11 charter company members work-ing with the AFRL Materials and Manu-facturing Directorate, the membershipof the MAIC may be broadened. TheAFRL Materials and Manufacturing Di-rectorate will manage the size and com-position of the MAIC. Further, it will berequired that resource flow be estab-lished such that interested companiesthat are not part of the MAIC can alsoparticipate; this is most easily accom-plished by teaming those companies withan MAIC member on individual projectsand programs.

Project selection and initiation will bebased on a project’s criticality in ad-dressing high-cost-impact needs for aresponsive metals-development in-dustry infrastructure. The MAIC hasadopted a task/gate process that willmaximize progress and allow go/no-godecisions. This is a risk-minimizationplan based on business decision-makingmethods used by industries that makesignificant investments in technology.The plan will structure all MAIC projectsin a task-gate process in which the selec-tion, development, and implementationprocess is divided into tasks that repre-sent a step-wise progression of develop-ment and gate reviews at critical pointsto assess plan progress, test the pro-posed economics, and approve continu-ation into the next task. This process isschematically summarized in Figure 8.There are five gates, from Task 1 (con-cept) to Task 6 (full production). Thegate reviews are designed to allow theprocess owners, customers, and Techni-cal Oversight Committee members toassess the technical progress and eco-nomic benefit of a project. The gates arethe primary cost-control mechanism forthe management of the program.

CONCLUSIONS

It is the belief of the MAIC that thetiming for revitalizing the metals-devel-

opment infrastructure is excellent due tothe overwhelming need to addressaffordability needs in the military-air-craft industry. The coordination of theentire metal-product-supplier chain hasbeen accomplished by the consortium,and the potential for reviving and el-evating the opportunity for dramatic andwidespread change within the aerospacemetals-development community cannow be realized.

As the momentum of the industrialconsortium grows, it is anticipated thatthe investment of industry and govern-ment resources will increase. The result-ing high-level improvement in aircraft-system af-fordability will be realizedthrough the efficient development andapplication of advanced metals tech-nologies.

BibliographyEdgar, Thomas W. “Overview: The Quiet Revolution in

Materials Manufacturing and Production.” JOM 50 (4)(1998): pp. 19–21.

Expert Choice. Vendor Literature. Pittsburgh, PA.Furrer, D. “Forging Aerospace Components.” JOM 155 (3)

(1999): pp. 33–38.Imberman, Woodruff. “Material Matters: Outsourcing Pres-

sure on Suppliers to Expand Services and Lower Costs.”JOM 50 (12) (1998): p. 80.

Larsen, D. and G. Colvin. “Vacuum Die Casting TitaniumFor Aerospace and Commercial Components.” JOM 51 (6)(1999): pp. 26–27.

Lovelace, A.M. Air Force/Industry Manufacturing Cost Reduc-tion Study (for period 28 August 1972–1 September 1972).AFRL-ML-WP-TR-1998-4131, Materials and Manufactur-ing Technology Directorate, Air Force Research Labora-tory (June 1998).

Manufacturing Technology For Aerospace Materials TechnologyDemonstration and Information Exchange. Technology Infor-mation Exchange Proceedings, Contract No. N00140-92-C-BC49. Concurrent Technologies Corporation submis-sion (20–21 April 1999).

Martin, R. “Affordable Metal Technologies For Military Air-craft.” ASM Aeromat Conference Proceedings, WashingtonD.C. (1998).

Moore, D. “Naval Aircraft Materials and Processes.” JOM155 (3) (1999): pp. 27–32.

Ruhman, D., L. Pionke, and R. Martin, “Missiles and SpaceSystems with a Material Difference.” Aerospace America.Reston, VA: American Institute of Aerospace and Aero-nautics, 1982.

Talwar, R. Supportable Technologies for Affordable Fighter Struc-tures (for period 8/92–12/95). AFRL Contract #F33615-92-3206 Final Report, Flight Dynamics Directorate, Air ForceResearch Laboratory (June 1997).

Rick Martin is manager of metallic processes develop-ment at Boeing–Phantom Works. Daniel Evans is metalstechnology development leader with the Air Force Re-search Laboratory–Materials and Manufacturing Direc-torate.

For more information, contact R. Martin, Boe-ing–Phantom Works, MC 276-1240, P.O. Box516, St. Louis, Missouri 63166; (314) 233-0258;fax (314) 234-5410; e-mail ricky.l.martin@boeing.com.

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