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Final Design Review. Fri aeiynCucfed JanineCrsohrO Mihe erncT io. MEMS-based Corrosion Health Monitoring. Liaison Engineers: Pec uces Tr lw Faculty Coach: Jh .AboePD E. Introduction. Corrosion occurs on electronic chassis of aircraft causes loss of integrity of EMI seal

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Final Design Review

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Final design review

Final Design Review

Fri aeiynCucfed


Mihe erncT io

MEMS-based Corrosion Health Monitoring

Liaison Engineers:Pec uces

Tr lw

Faculty Coach:Jh .AboePD E



  • Corrosion occurs on electronic chassis of aircraft

    • causes loss of integrity of EMI seal

  • Lockheed Martin technicians

    • responsible for avoiding critical corrosion damage

    • monitor the health of the chassis on a scheduled basis

      • the chassis is relatively inaccessible within the aircraft

      • in most cases, the chassis is corrosion free

      • time and money are wasted by this inefficiency

Final design review


  • To reduce unnecessary corrosion related service activities with a stand alone system that can alert a technician of a needed inspection

    • Reliable measurement of the environmental corrosivity seen by the chassis

    • LED alert system

      • viewed from exterior of the chassis

      • 1-10 level of need for service activity

Business case

Business Case

  • Life cycle cost for the Apache Helicopter fleet* $14.3 billion

  • Percent Dedicated to Inspection**x 25%


  • Inspection cost for the Apache Helicopter$3.575 billion

  • Percent inspections eliminated by SDX-4912 x 33%


  • TOTAL PROGRAM SAVINGS $1.18 billion

  • Life cycle of Apache helicopter* ÷ 20 years


  • TOTAL ANNUAL SAVINGS* $59 million

  • TOTAL LIFE CYCLE SAVINGS/helicopter*** $1.5 million

    *These estimates, in constant fiscal 1994 dollars, are provided in Annex D of the Longbow Apache Test and Evaluation Master Plan, which cites December 1993 estimates from the Longbow Program Office and the President’s fiscal 1995 budget as the original source.

    **Provided from the Military Analysis Network created by the FAS, Federation of American Scientists (non-profit, tax exempt, 501c3organization)

    ***Costs assuming that the SDX-4912 is installed in full apache fleet (assuming fleet size ≈ 800)

Elements of chassis

Elements of Chassis

  • Galvanic coupling of aluminum and nickel

  • Aluminum = anode

  • Nickel = cathode

  • Electrolyte provides driving force for corrosion

Galvanic corrosion

Galvanic Corrosion

  • As a result of nickel contact:

    • Corrosion potential of aluminum (M) increased

    • Corrosion rate of aluminum (M) is increased




Customer requirements

Customer Requirements


Operate Under Harsh Conditions

Non-Intrusive Feedback

Long Life Span

MEMS Based

Light Weight

Small Size

Final design review

Hardware Design

Hardware design

Hardware Design

Functional Diagram

Hardware design1

Dimmed elements denote exploratory efforts not included

in final design

Hardware Design

Macroscopic system

Macroscopic System

Hardware design2

Hardware Design

Electrical Resistance Sensor Concept:

  • Near Linear Approximation

  • Module Expiration Detection

  • Manufacturability

R = V / Iappl

R = ρL / πr2

Sensor sampling

Sensor Sampling

  • Data sample taken hourly

  • All data stored on Flash

  • Light Emitting Diodes (LEDs)

    • 4 red, 3 yellow, 2 green

    • 1-10 level of corrosion damage

      • Relate to need for technician to perform service activity

      • Level 7 (1st Red LED) correlates to critical corrosion damage

Output method


Output Method

  • Corrosion will cause reduction in ER sensor’s cross-sectional area

  • At critical % area reduction critical voltage

Sensor sampling1

Sensor Sampling

Control Wire

Final design review


Verification testing

Verification Testing

  • Hardware Unit Test

    • Sensor Proof of Concept

    • 5 days in Salt Spray Machine

  • Software Unit Test

    • Data Interface to software and LED display

  • Acceptance Testing

    • Functional Acceptance Test (Integration)

    • Environmental Acceptance Test (Survivability)

Proof of sensor concept

Proof of Sensor Concept

  • 48 hour test

    -24 hours immersed in salt bath

    -24 hours in atmosphere

Proof of sensor concept1

Proof of Sensor Concept

  • Ground to 50% diameter along longitudinal plane and polished

  • Large cathode (Ni) to anode (Al) ratio

Damage to nickel plating on aluminum wire



  • ASTM B117 Salt Fog Chamber

    • Constant corrosive vapor applied for 5 days

    • 5 Test coupons removed at daily intervals

    • Data samplings recorded as voltages

      • Recorded using a datalogger

      • Data sampling = once per minute

Example of Salt Spray Chamber

Wireless zigbee

Wireless - ZigBee

  • Proven feasible up to 6” thickness of casing

    • Due mainly to chamber reflections

    • Minimal aperture required

  • Wireless communication

    pursuit ended 2/7/05

    given risk and manpower

Final design review

Testing Results





  • ASTM D3359 Coating Adherence Test

    • Measures Amount of Undercut Nickel Plating

    • Designations: 5A (Least Corrosion)–0A (Most Corrosion)

    • 5 coupons tested

      • 24 hr: 5A

      • 48 hr: 4A

      • 71 hr: 2A

      • 139 hr (1): 1A

      • 139 hr (2): 2A

Coupon 139 hr (1)

Measurement correlation

Measurement Correlation

  • Coupons

    • Minimal corrosion product for 24 & 48 hr coupons

    • Visible Al203 for 71 &139 hr coupons

  • Measurements

    • Rapid Increase in ER sensor at onset

      • Minimal Corrosion Product forming

      • Al+3 ions lost in aqueous solution

    • Resistance change levels off

      • Corrosion product protection

Sensor lifespan

Sensor Lifespan

  • Electrical resistance sensor

    • Survived 5-day salt fog

    • Provided data throughout lifespan of operating board

  • Temperature

    • Survived 2-day salt fog

  • Humidity

    • Survived 1-day salt fog

    • Potentially a conformal coating problem on board

Environmental survivability

Environmental Survivability

  • Harshest of Possible Environments

    • Environmental Sensors

      • not conformally coated

      • survivable in constant spray for 1-2 days

    • Macroscopic System

      • conformal coating spot failures spot corrosion

        • emitted heat from conducting wires

      • survivable in constant spray for 4 days

Final design review

Prototype Demonstration

Final design review


Final design review








Final design review




  • Wireless Link

  • Stand-Alone Custom GUI

  • Additional Low Power Research

  • Laser Etched Sensor Manufacturing



  • Thank You…

    • Lockheed Martin

      • eyunss

      • lew

      • ling

      • Kaara

  • University of Florida

    • ohnAoPE

    • ithanfillD,

    • an M

    • Marilyn Marlow

  • Final design review


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