user interface design guidance for rtca/do-160

Manufacturing That Eliminates Risk & Improves Reliability

User Interface Design Guidance

for RTCA-DO/160

08.30.17


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Agenda

Key Considerations Before Testing

Dynamic Tests

Environmental Tests

EMI / EMC Tests

Summary


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What is RTCA/DO-160?

The Radio Technical Commission for Aeronautics (RTCA) was founded in 1935 and provides standards and guidelines across key aviation policies. The performance standards form the basis of the Federal Aviation Administration regulatory requirements.

– Largely derived from Mil-STD-810 & Mil-STD-461

– Standardized way of defining and simulating conditions on aircraft.

– Initial Release 1975

– Current Revision: RTCA/DO-160 Rev G


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Key Considerations Before Testing

1. Who will be obtaining FAA certification?

2. How will your unit be tested?

a) Standalone Unit vs Next Higher Assembly

3. Sequence of environmental tests.

1. Consideration must be given for units that will be damaged or exhibit residue

2. Perform Dust, Fluids Susceptibility, Salt Fog last

4. How will the unit be powered / operated during testing?

5. What is the PASS / FAIL Criteria?

a) “Determine compliance with applicable equipment performance standards”

Why are these important?


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RTCA/DO-160 Revision G

Dynamic / Environmental

Section 4.0 Altitude

Section 5.0 Temperature Variation

Section 6.0 Humidity

Section 7.0 Shock & Crash Safety

Section 8.0 Vibration

Section 9.0 Explosion Proofness

Section 10.0 Waterproofness

Section 11.0 Fluids Susceptibility

Section 12.0 Sand and Dust

Section 13.0 Fungus Resistance

Section 14.0 Salt Spray

EMI / EMC

Section 20.0 RF Susceptibility

Section 21.0 RF Emissions

Section 25.0 ESD


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Dynamic Tests


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Dynamic Tests - Conditions

Section 7.0: Shocks & Crash Safety

– Sustained Acceleration (20g)

– Shock Pulse (11ms or 20ms)

Section 8.0: Vibration

– Sinusoidal Vibration

– Random Vibration

– Sine on Random

Control & Response Accelerometers

– Measure input & transmissibility

Estimate total energy from “area under the curve”

With “g” constant, low frequency requires higher displacement



Fixed Wing Vibration ≠ Helicopter Vibration

Shaker Table

Helicopter Blade

Frequencies

Centrifuge


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Locking Fasteners

Aerospace Grade

Aluminum

Ruggedized Connector

Dynamic Tests - Design Guidance

Failure Modes

– Ultimate / yield failure

– Fatigue from cyclic vibration

– Sway

– False key actuation

– Loosening fasteners, components

Design Guidance

– Materials selection

– Shock mounts / isolators

– Shift natural frequency (ωo)

– Locking fasteners

– Strain relief

Testing is typically necessary to validate performance




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Environmental Tests


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Environmental Tests - Altitude

Low pressure ranges from 15,000 ft – 70,000 ft

Overpressure to -15,000 ft

Rapid Decompression from 8,000 ft to max attitude

Can be tested in conjunction with temperature

Failure Modes

– Ballooning of elastomeric members

– Rupturing of sealed areas

Design Guidance

– Modify stiffness of elastomeric members

– Structural reinforcement

– Venting

Section 4.0: Altitude


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Environmental Tests - Temperature & Humidity

Failure Modes

– Condensation

– Thermal expansion

– Material breakdown at temperatureextremes

Design Guidance

– Select materials for Operating and Storage Temps

– Tolerances account for thermal expansion

– Drain ports for condensation

Operating Temps are less severe than Storage Temps

Components &

materials selected

for temperature

extremes

Section 5.0: Temperature Variation

Section 6.0: Humidity


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Environmental Tests - Explosion Proofness

Operating unit cannot ignite fuel-airmixture.

Failure Modes

– Exposed live electrical components

– Arcing

– Excessive heat source

Design Guidance

– Eliminate heat and sparks

– Enclosing live components

– Conformal coating

– Hermetically sealed

Unit must be able to be operated during the test

Conformal coating of

live components

Section 9.0: Explosion Proofness


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Environmental Tests - Waterproofness

Failure Modes

– Gasket or sealing failure

– Circuit failure

– Ingress and pooling

Design Guidance

– Hermetically sealed (exempt from test)

– Gasketing

– Elastomeric boots

– Conformal coatings

– Drain holes

Ingress does not necessarily constitute a test failure

Elastomeric boot

with pressure

sensitive adhesive

Gasket groove

Perimeter seal

Waterproof design for

custom dome switch

Section 10.0: Explosion Waterproofness

Category Y - Condensing Water

Category W - Drip Proof

Category R - Spray Proof

Category S - Continuous Stream


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Environmental Tests - Sand and Dust

Failure Modes

– Gasket or sealing failure

– Circuit failure

– Fouling of moving parts

– Clogging of filters

– Pollution of reservoirs

Design Guidance

– Pressure sensitive adhesive

– Gasketing

– Elastomeric boots


Ingress does not necessarily constitute a test failure

Redesigned

concept with

perimeter sealing

solution

Dust Contamination

on contacts

Pressure Sensitive

Adhesive

Section 11.0: Sand and Dust

Category D - Blowing Dust

Category S - Blowing Sand and Dust


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Environmental Tests - Salt Spray

Failure Modes

– Corrosion

– Material breakdown

Design Guidance

– Material selection

– Plating & processing

– Properly sealed unit


Salt Fog Chamber

Gold Plated

Components

Pressure Sensitive

Adhesive

Section 14.0: Salt Spray

Category S - Normal aircraft operations

Category T - Severe with direct exposure


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Environmental Tests - Fungus

Material coupon testing.

Failure Modes

– Material promotes fungus growth

Design Guidance

– Qualification through previous testing

– Material selection

Section 11.0: Fungus Resistance

Category F - Severe fungus exposure


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Environmental Tests - Fluids

7 General Fluid ClassesFuels Hydraulic Fluids

Lubricating Oils Solvents / Cleaners

De-Icing Fluid Insecticides

Sullage Disinfectant

Dielectric Fluid Fire Extinguishants

Failure Modes

– Material Degradation

Design Guidance

– Material & finish selection

– Conformal coating

Section 13.0: Fluids Susceptibility

Category F - 7 General Fluid Classes


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EMI / EMC Test Conditions


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EMI / EMC Test Conditions

Section 20: RF Susceptibility

– Conducted 10 kHz – 400 MHz

– Radiated 100 MHz – 18 GHz

– Sect 20.5 Radiated Susceptibility is directional

• Anechoic chamber

– Sect 20.6 Radiated Susceptibility is 360°

• Reverberation chamber

Section 21: RF Emissions

– Equipment does not emit undesired RF noise

– Scan of the entire frequency range applicable

Section 25: ESD

– Human contact induced ESD event

– Directed at specific human contact locations

– Must withstand multiple 15KV discharges

Reverberation Test Method for Radiated Susceptibility is Worst Case

Measurements from 14 kHz to 1 GHz

EMI Chamber Test Setup

Section 20: RF Susceptibility

Section 21: RF Emissions

Section 25: ESD


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EMI / EMC Tests - Design Guidance

Failure Modes

– Loss of function

– Undesired performance

– Excessive emissions

Design Guidance

– Shielding layers

– Passive components (diodes, chokes)

– Effective bonding & grounding

– Conductive elastomers

– Conductive coatings

Shielding effectiveness testing can help predict RF behavior

Grounding terminal

Shielding layer

Conductive Chem Film per

Mil-DTL-5541 Class 3

Shielding layer

Overbraid shielding


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Summary

RTCA-DO/160 is one of the last hurdles in obtaining airworthiness certification.

A comprehensive understanding of the test conditions and requirements helps obtain certification.

A design fix for one test may cause a failure on another in the system.

Development Testing BEFORE formal DO-160 qualification is recommended.


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Our Products

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Flex & Rigid Flex – Toronto, Canada

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Our Engineering and Design teams are ready to help our customers create world class and cost effective product solutions.


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Q&A

Questions?

– Enter any questions you may have in the Control Panel

– If we don’t have time to get to it, wewill reply via email


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user interface design guidance for rtca/do-160

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