Five Specification Pitfalls That Add Months to Defense Programs
And How to Avoid Them
Defense programs operate under demanding timelines, strict budgets, and unforgiving performance requirements. Yet some of the most significant schedule delays and cost overruns trace back to preventable specification errors made during the earliest program phases.
After seven decades manufacturing electronic enclosures for defense applications, we’ve seen these patterns repeatedly. The programs that move smoothly through design, qualification, and production avoid these five common pitfalls.
Pitfall #1: Mixing Performance Requirements with Implementation Details
The Problem
Specifications that dictate both what the system must achieve and how it must be built create over-constrained design problems. When real-world manufacturing constraints emerge—and they always do—the program faces expensive redesigns or waiver requests that could have been avoided.
Real-World Example
A recent RFQ specified:
- Shock resistance: 20G, 11ms half-sine per MIL-STD-810H
- Shock mount configuration: Four isolators at specific corner locations
- Internal component layout: Predefined equipment positions
The combination was physically impossible. The specified isolator locations created resonance modes that amplified shock transmission rather than attenuating it. The rigid equipment layout prevented repositioning mass to improve dynamic response.
Result: Three-month design iteration cycle, two failed qualification attempts, and ultimately a complete redesign that abandoned the prescribed isolator locations.
The Solution
Separate performance requirements from implementation:
Instead of this:
“Install four Barry 10127 isolators at corners with 6-32 fasteners. Structure shall withstand 20G shock.”
Write this:
“Structure shall withstand 20G, 11ms half-sine shock per MIL-STD-810H, Method 516.8, in all three axes with no permanent deformation. Maximum shock transmissibility: 2.0.”
State the performance requirement clearly. Let the engineering process determine the implementation that reliably delivers it.
When Implementation Details Matter
Sometimes you do need to specify implementation—when there are legitimate program reasons:
- Interface requirements (mounting holes, connector locations)
- Maintenance access requirements (specific panel removability)
- Commonality requirements (shared components across product family)
- Supply chain constraints (qualified vendor list, approved materials)
In these cases, document the why alongside the what. This context helps suppliers identify conflicts early and propose alternatives that preserve program intent.
Pitfall #2: Copy-Paste Specs from Unrelated Programs
The Problem
Every defense program is unique. Environmental conditions, operational profiles, interfaces, and lifecycle requirements differ. Yet we routinely receive RFQs containing specifications clearly imported from unrelated efforts—complete with requirements that don’t apply to the current application.
Real-World Example
A ground mobile program RFQ included specifications for:
- Salt fog resistance per MIL-STD-810, Method 509 (continuous exposure)
- Watertight sealing to IP67 with spray testing
- Shock resistance for naval gunfire (20G, multiple axes)
These are shipborne requirements. The system would operate in a climate-controlled vehicle shelter in CONUS—never exposed to salt spray, water immersion, or naval shock environments. The specifications weren’t just unnecessary—they drove design decisions (extensive gasketing, sealed connectors, reinforced mounting) that added cost, weight, and complexity without adding value.
When questioned, the program office acknowledged the specs were copied from a previous airborne effort. “We figured more stringent is safer.”
Result: 40% cost premium, unnecessary qualification testing, and two-month schedule extension for tests that provided zero operational value.
The Solution
Start from operational requirements, not previous specs:
- Define the operational environment
- Where will the system operate? (Aircraft, ship, ground vehicle, fixed installation)
- What environmental conditions will it experience? (Temperature, humidity, shock, vibration, altitude, salt fog)
- What is the expected operational life and duty cycle?
- Identify applicable standards
- MIL-STD-810 for ground/shipboard environmental testing
- DO-160 for airborne equipment
- MIL-STD-461 for EMI/EMC requirements
- Program-specific requirements documents
- Tailor requirements to match reality
- Select only the test methods and severity levels that reflect actual operational conditions
- Document the rationale for each selected requirement
- Review with stakeholders (engineering, test, logistics, end users)
The Validation Question
For every specification, ask: “If this system fails to meet this requirement, what operational consequence occurs?” If the answer is “none,” remove the requirement.
Pitfall #3: Incomplete Interface Definitions
The Problem
Interface requirements define how your enclosure connects to the larger system: mounting points, connectors, cable routing, cooling air paths, access panels. Vague interface definitions create ambiguity. Ambiguity creates assumptions. Assumptions create design conflicts discovered during integration—when changes are most expensive.
Real-World Example
An RFQ specified:
“Enclosure shall mount to vehicle floor. Provide cable access. Maintain access to all circuit card assemblies.”
Three months into the design, during integration planning, we discovered:
- The vehicle floor had compound curvature and non-uniform stiffness
- “Cable access” needed to accommodate 40+ cables with different bend radius requirements
- “Access to all circuit card assemblies” conflicted with shock mount locations
- Cooling air intake was blocked by vehicle structural members
The customer’s integration team had to get involved to define these requirements retroactively. Result: Complete redesign of base mounting interface, cable management approach, and internal layout. Four-month schedule slip. $150K in non-recurring engineering costs that could have been avoided with clear interface definitions upfront.
The Solution
Define interfaces explicitly and early:
Mechanical Interfaces
- Mounting surface geometry (flat, curved, irregular)
- Mounting point locations, bolt patterns, fastener specifications
- Load paths and load distribution requirements
- Clearance envelopes and keep-out zones
- Thermal interface requirements (if applicable)
Electrical Interfaces
- Connector types, orientations, and locations
- Cable routing paths (entry/exit points, bend radii, support requirements)
- Grounding and bonding requirements
- EMI gasketing or shielding at interface boundaries
Fluid/Thermal Interfaces
- Cooling air inlet/outlet locations and flow rates
- Liquid cooling connections (if applicable)
- Condensate drainage requirements
- Heat rejection interfaces
Access/Maintenance Interfaces
- Which components require field access
- Clearance required for removal/installation
- Tool access requirements
- Maintenance interval assumptions
Best Practice: Interface Control Documents
For complex programs, create a formal Interface Control Document (ICD) that both parties (customer and supplier) review and approve before design begins. This document becomes the single source of truth for interface requirements and prevents “I thought you meant…” conversations six months into the program.
Pitfall #4: Underestimating Qualification Timeline
The Problem
Qualification testing isn’t just placing a box in a chamber and pressing “start.” The process involves test fixture design, specimen fabrication, instrumentation, test procedure development, test execution, data analysis, and often, iterative refinement. Programs that allocate inadequate time for qualification create compressed schedules that lead to rushed testing, incomplete validation, or expensive expedite fees.
Real-World Example
A program timeline allocated:
- Week 1-8: Build qualification unit
- Week 9: Ship and test
- Week 10: Data review and approval
The reality:
- Week 1-12: Fabricate qualification specimen (components procurement, machining, finishing, assembly)
- Week 13-14: Design and fabricate test fixtures
- Week 15: Instrument specimen, verify instrumentation
- Week 16-18: Execute environmental test sequence
- Week 19: Initial data review reveals marginal results in one axis
- Week 20-22: Root cause analysis and design refinement
- Week 23-34: Build and test second qualification specimen
- Week 35: Final data review and approval
The Solution
Build realistic qualification timelines that account for:
Pre-Test Activities (10-14 weeks)
- Specimen fabrication and assembly (8-12 weeks for qualification units)
- Test fixture design and fabrication (2-3 weeks)
- Instrumentation installation and verification (1 week)
- Test procedure review and approval (1 week)
- Test facility scheduling
Test Execution (2-6 weeks depending on scope)
- Functional baseline testing
- Environmental exposure (shock, vibration, temperature, humidity, altitude, EMI)
- Post-exposure functional verification
- Data collection and preliminary analysis
Post-Test Activities (1-3 weeks)
- Detailed data analysis
- Test report generation
- Stakeholder review and approval
- Corrective action if needed
Margin for Iteration (12-16 weeks)
- Not every system passes qualification on the first attempt
- Build time and budget for one design iteration cycle (8-12 weeks for specimen rebuild plus re-test)
- Programs that plan for success but prepare for iteration avoid crisis when refinement is needed
Early Test Planning
Begin qualification planning during the proposal phase:
- Identify required tests and applicable standards
- Assess test facility availability and lead times
- Estimate test fixture complexity and fabrication time
- Build qualification timeline into master program schedule
- Allocate budget for potential re-test
Pitfall #5: Ambiguous Material Requirements
The Problem
Material specifications directly impact structural performance, corrosion resistance, weight, electromagnetic shielding, thermal management, and cost. Vague material requirements create opportunities for misalignment between customer expectations and supplier assumptions—misalignments typically discovered during first-article inspection when correction is expensive.
Real-World Example
An RFQ specified:
“Aluminum construction. Corrosion-resistant finish.”
The supplier interpreted this as:
- 6061-T6 aluminum (cost-effective, readily available)
- Alodine 1200 conversion coating (standard corrosion protection)
The customer expected:
- 7075-T73 aluminum (higher strength for weight-critical application)
- Type III hard anodizing (superior corrosion and wear resistance)
Neither party was wrong based on the specification as written. But the material and finish differences created:
- 30% cost delta
- Different corrosion resistance performance
- Different electromagnetic shielding effectiveness
- Different weight (7075 vs 6061)
Result: First-article rejection, complete rebuild with correct materials, three-month schedule delay, and contentious negotiations about who pays for the rework.
The Solution
Specify materials explicitly:
For Metals
- Alloy designation (e.g., 6061, 7075, 5052)
- Temper condition (e.g., T6, T73, H32)
- Form (e.g., sheet, plate, extrusion)
- Applicable specification (e.g., AMS, ASTM, QQ)
For Coatings/Finishes
- Coating type (e.g., Type II anodize, Type III hard anodize, Alodine, powder coat)
- Color/appearance if relevant
- Thickness requirements if critical
- Applicable specification (e.g., MIL-A-8625, MIL-DTL-5541)
When Material Choice is Flexible
If the specific material doesn’t matter—only the performance—specify the performance and let the supplier select appropriate materials:
Instead of this:
“6061-T6 aluminum sheet, 0.125″ thick”
Write this:
“Panel deflection under 5 psf pressure load shall not exceed 0.020″. Material: aluminum alloy, corrosion-protected finish.”
This gives the supplier flexibility to optimize material selection while ensuring the performance requirement is met.
Material Properties That Matter
Consider specifying materials based on the properties that drive your application:
- Strength-to-weight ratio for weight-critical applications
- Corrosion resistance for harsh environments (salt fog, humidity)
- Thermal conductivity for heat dissipation
- Electromagnetic shielding effectiveness for EMI-sensitive applications
- Coefficient of thermal expansion for precision applications or dissimilar material interfaces
- Machinability/formability for complex geometries
The Common Thread: Clarity and Intent
All five pitfalls share a root cause: ambiguity between intent and specification. The most successful defense programs we support have clear, unambiguous specifications that communicate both what must be achieved and why it matters—while leaving room for engineering ingenuity in the how.
Before Releasing Your Next RFQ
Ask these questions:
- Performance vs. Implementation: Have I specified outcomes or methods? Are the methods truly required?
- Relevance: Does every requirement trace to an operational need? Have I removed copy-paste specs from unrelated programs?
- Interface Completeness: Could someone build this system without asking clarifying questions about how it connects to the larger assembly?
- Timeline Realism: Have I allocated enough time for qualification, including margin for iteration?
- Material Clarity: Would two different suppliers interpret my material requirements the same way?
If you can answer confidently, you’re positioned for a smooth program. If not, invest time now to add clarity. The hours spent refining specifications prevent the months spent recovering from specification-driven problems.
Need a second set of eyes on your RFQ before release? We’ve created a simple specification review checklist based on these five pitfalls. Download a copy—it takes 10 minutes to complete and can save months of schedule headaches.
