DFMA Application on the AH-64D Longbow Apache

DESIGN FOR MANUFACTURING AND ASSEMBLY APPLICATION ON THE DESIGN OF THE AH64D HELICOPTER

Alfredo Herrera
Dimensional Management Technical Lead
McDonnell Douglas Helicopter Systems
Mesa, Arizona

Abstract

This study examines the effectiveness of Design for Manufacturing and Assembly (DFMA) methodology used by design, manufacturing, quality, and supporting engineers for the development of the Longbow Apache Helicopter. Data were gathered through an Integrated Product Development (IPD) team for several redesigned areas of the Longbow prototype helicopter crew station. Results indicate significant cost and weight savings.

Introduction

DFMA is a design philosophy for reducing part count, assembly time, and subassembly complexity—applicable across environments regardless of part complexity or technological maturity. DFMA encourages concurrent engineering so that product quality is owned by both designers and the broader development team.

Hundreds of companies have used DFMA to cut manufacturing and assembly time. The implementation may occur at: (1) initial design—envisioning a minimal-part, easy-to-install concept; or (2) redesign—optimizing existing assemblies for manufacturing, installation, reliability, and maintainability. Maximizing DFMA benefits requires working knowledge of available processes and capabilities, and close collaboration between design and manufacturing. A review of state-of-the-art processes (and availability of SPC) clarifies this synergy.

High Speed Machining (HSM)

HSM—machining at >10,000 RPM—was the primary DFMA enabler in airframe structural design. With spindle technologies in the 24,000–40,000 RPM range, HSM can combine roughing and finishing in a single operation, reducing heat buildup and thermal growth for stable, close-tolerance machining.

Its use has converted complex, multi-part sheet-metal assemblies into fewer, machined parts, cascading into lower part cost, fabrication/assembly time, and tooling. Models transfer directly from CAD (e.g., Unigraphics) to NC and CMM programming—often eliminating dedicated tooling—while improving quality, design flexibility, and weight (fewer fasteners). HSM has been successfully applied across multiple aircraft programs.

Composite Design

Composites aid assembly by combining parts, reducing count and time much like HSM. Trade-offs include labor intensity (ply cutting/stacking/bonding and autoclave cure), expensive forming tools and wear, and potential moisture-related damage or delamination risks depending on application and environment.

Superplastic Forming (SPF)

SPF forms specific aluminum alloys by blowing heated gas against sheet over tooling inside an oven, enabling compound curvature at the plastic point. Benefits include low tool wear and fewer auxiliary parts (integration), though oven size can limit part dimensions.

Across military and commercial programs, DFMA has yielded substantial reductions in parts, cost, weight, and assembly time. For the Longbow Apache avionics upgrade, DFMA was used alongside HSM/SPF (airframe) and composites (ECS).

Statement of the Problem

Traditional methods alone could not meet aggressive budget and schedule objectives. New design/production approaches were required.

Review of the Literature

Published DFMA case studies report reductions in cycle time, part count/cost, time-to-market, assembly time, and improvements in quality/reliability. The DFMA practices originated in academia and have been heavily adopted in industry, with a strong emphasis on Design for Assembly.

DFMA addresses key assembly factors early—appearance, part quantity, and motions/processes—before prototyping.

Statement of Hypothesis

Applying DFMA to the Longbow Apache crew station should reduce part count, manufacturing time, and assembly time, and through simplification and fastener reduction, lower weight.

Methodology

An IPD team redesigned and optimized one Longbow prototype helicopter configuration and applied lessons learned to a broader initiatives effort. DFMA supported design/producibility planning to improve prior configurations.

Within the crew station and the Improved Extended Avionics Bay (IEFAB), DFMA was applied to selected parts. Data were collected and compared to baseline prototypes designed without DFMA.

Each DFMA case study redesigned existing assemblies. The team reviewed requirements (materials, function, location), then iterated to reduce parts, weight, and assembly time.

Data from team members (estimates, tables, schedules, weight and cost data, DFMA plans) were consolidated. Analyses were loaded into DFA software to quantify assembly and recommend improvements consistent with DFMA philosophy.

Results

Pilot’s Instrument Panel. Baseline: 74 parts, 3.00 kg, 305 fabrication hours, significant assembly/installation time, and dedicated tooling for forming and final assembly. DFMA + IPD + HSM yielded a redesign to 9 parts.

CPG Instrument Panel. Complex baseline (87 parts; many rivets; UFD/MFD tray subassemblies; bench tooling) was simplified to 12 parts (7 machined, 5 sheet-metal/composite), with minimal sub-assembly, driving cost/time/weight savings.

DFA software provided complete task analyses, minimum-parts estimates, cost rollups, and redesign suggestions (e.g., hardware reduction via integral fastening, chamfers/leads; part combinations; improved visibility/access for assembly). The “Design for Assembly Analysis Totals” summarized total time, cost, weight, parts/subassemblies, theoretical minimum parts, and labor rate.

Overall, DFMA yielded approximate savings where applied of ~74% cost, ~8% weight, and ~74% schedule.

Conclusions

DFMA requires supportive attitudes and practices to be fully realized. Many organizations attribute world-class competitiveness to DFMA. Its focused application on the Longbow Apache showed strong results; broader use would likely have increased benefits. In the most significant crew-station redesign: part count fell by 87%, fabrication time by 93%, assembly time by 94%, weight by 10%, and cost by 74%.

Training is critical so team members understand goals, tools, and processes; management commitment is essential.

For DFMA to be effective, design teams must understand production capabilities and set requirements within those limits.

Recommendations

Further opportunities include: design for disassembly (environmental end-of-life), expansion of DFMA beyond structures/ECS (e.g., flight controls, engines, transmissions, hydraulics, electromechanical housings), organizational change management to ease adoption, and deeper management involvement/empowerment.

Process re-engineering tools—such as Dimensional Management (DM)—can complement DFMA by defining datums, allowable variation, key characteristics, part-count reduction, and acceptance criteria early in IPD, improving assembly ease and reducing non-conformance.

Disclaimer

The views and findings summarized here reflect the author’s analysis and are not intended to represent the official position of McDonnell Douglas Helicopter Systems.

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