RTCA/DO-160: Aerospace Qualification Testing
DNB Engineering Covers All RTCA/DO-160 Sections
DNB Engineering offers Complete RTCA/DO-160 Environmental and EMC Test Program. RTCA/DO-160 standard stands for Environmental Conditions and Test Procedures for Airborne Equipment), maintained by the Radio Technical Commission for Aeronautics (RTCA). It specifies a series of minimum standard environmental test conditions and applicable test procedures for airborne equipment. The standard provides means of demonstrating performance characteristics of airborne equipment in operating environmental conditions. The scope includes electromagnetic compatibility, electrical, climatic, lightning, mechanical, and fire testing of avionics equipment for the entire spectrum of an aircraft. RTCA/DO-160 applies to the United States, and its latest revision came out in 2010. There is a European equivalent, known as EUROCAE ED-14, and the joint document is RTCA/DO-160G/EUROCAE ED14-G.
The categories within each environmental test procedure have a practical set of boundary conditions to meed the requirements of real-world installations. Here at DNB, we have the knowledge, expertise, and necessary equipment to help our customers to develop detailed test procedures based on RTCA/DO-160.
Environmental Simulations
Section 4.0 Temperature & Altitude
The Temperature and Altitude tests define the performance characteristics of equipment at the applicable categories for the temperatures and altitudes. The following categories cover a wide range of environments known to exist in most aircraft types and installation locations.
Section 5.0 Temperature Variation
Temperature Variation test determines the efficiency of the equipment characteristics during temperature variations between high and low operating temperature extremes.
Note: The test does not intend to verify the behavior of the equipment in wet or icing conditions. In conducting this test, the test chamber may incorporate the capability of controlling or altering humidity to the extent that condensation is minimized or does not occur. Temperature Change Rate by category:
- Category A – For equipment external to the aircraft or internal to the aircraft: 10 degrees Celsius minimum per minute;
- Category B – For equipment in a non-temperature-controlled or partially temperature-controlled internal section of the aircraft: 5 degrees Celsius minimum per minute;
- Category C – For equipment in a temperature-controlled internal section of the aircraft: 2 degrees Celsius minimum per minute;
- Category S1 – For equipment external to the aircraft or internal to the aircraft: known rate of change greater than 10 degrees Celsius per minute. The rate of change shall be noted in the Qualification Form;
- Category S2 – For equipment external to the aircraft or internal to the aircraft: unknown rate of change greater than 10 degrees Celsius per minute.
Section 6.0 Humidity
The Humidity test determines the ability of the equipment to withstand either natural or induced humid atmospheres. The main aftereffects are corrosion and change of equipment characteristics resulting from the absorption of humidity.
Equipment Categories and Test Procedures:
- Category A – For equipment external to the aircraft or internal to the aircraft: 10 degrees Celsius minimum per minute;
- Category B – For equipment in a non-temperature-controlled or partially temperature-controlled internal section of the aircraft: 5 degrees Celsius minimum per minute;
- Category C – For equipment in a temperature-controlled internal section of the aircraft: 2 degrees Celsius minimum per minute;
- Category S1 – For equipment external to the aircraft or internal to the aircraft: known rate of change greater than 10 degrees Celsius per minute. The rate of change shall be noted in the Qualification Form;
- Category S2 – For equipment external to the aircraft or internal to the aircraft: unknown rate of change greater than 10 degrees Celsius per minute.
Equipment Categories and Test Procedures:
- Category A – Standard Humidity Environment;
- Category B – Severe Humidity Environment;
- Category C – External Humidity Environment.
Section 7.0 Operational Shock and Crash Safety
This test checks that the equipment will continue to function within standards after exposure to shocks experienced during regular aircraft operations. These shocks may appear during taxiing, landing, or when the aircraft encounters sudden gusts in flight. This test applies to all equipment installed on fixed-wing aircraft and helicopters.
The Crash Safety Test verifies that specific equipment will not detach from its mountings or separate in a manner that presents a hazard during an emergency landing. It applies to equipment installed in compartments and other areas of the aircraft where the hazard to occupants, fuel systems, or emergency evacuation equipment.
Test Procedure:
- Alternate Test Procedure
- Crash Safety
- Test Procedure 1 (Impulse)
- Alternate Test Procedure (Impulse)
- Test Procedure Sustained
Section 8.0 Vibration
The Vibration tests demonstrate that the equipment complies with the applicable equipment performance standards (including durability requirements) when subjected to vibration levels specified for the appropriate installation.
The appropriate category (or categories) selected from the groups should be based upon the level of assurance required for the equipment demonstration of performance. Equipment on fixed-wing aircraft may require either standard or a robust vibration test. The need to do the high-level short duration test depends upon the equipment performance requirements. Equipment on helicopters requires a robust test. Category Definitions:
- Standard Vibration Test (Category S)
- Robust Vibration Test (Categories R, U, U2)
- High-Level, Short Duration Vibration Test (Categories H, Z)
Section 9.0 Explosion Atmosphere
The Explosive Atmosphere test specifies requirements and procedures for aircraft equipment that may come into contact with flammable fluids and vapors. It also refers to normal and faults conditions that could occur in areas of potentially exposure to flammable fluids and vapors during flight operations.
The flammable test fluids, vapors, or gases in this section simulate those common in conventional aircraft, and that require oxygen for combustion.
Section 10.0 Waterproofness
Waterproofness tests help discover whether the equipment can resist the effects of liquid water falling on the equipment or the effects of condensation. These tests are not intended to verify the performance of hermetically sealed equipment. Hermetically sealed equipment does not require testing.
Test Procedure:
- Condensing Waterproof Test
- Drip Proof Test
- Spray proof Test
- Continuous Proof Test
Section 11.0 Fluids Susceptibility
Fluids Susceptibility tests determine whether the equipment materials can withstand the deleterious effects of fluid contaminants. Fluid susceptibility tests are for equipment located in areas with expected fluid contamination. The fluids are representative of those commonly present in airborne and ground operations. Fluids not listed herein and for which susceptibility tests are indicated are included in the relevant equipment specification.
Test Procedure:
- Spray Test
- Immersion Test
Section 12.0 Sand and Dust
This test determines the resistance of the equipment to the effects of blowing sand and dust by air movement at moderate speeds.
The main adverse effects are:
- Penetration into cracks, crevices, bearings, and joints, causing fouling and/or clogging of moving parts, relays, filters, etc.
- Formation of electrically conductive bridges.
- Action as a nucleus for the collection of water vapor, including secondary effects of possible corrosion.
- Pollution of fluids.
Section 13.0 Fungus Resistance
These tests determine effects of equipment material exposure to fungi under conditions favorable for their development, namely, high humidity, warm atmosphere, and presence of inorganic salts.
Test Procedure:
- Preparation of Mineral-Salts Solution
- Purity of Reagents
- Purity of Water
- Preparation of Mixed Spore Suspension
- Viability of Inoculum Control
- Control Items
- Inoculation of Test Control
- Incubation
- Inspection
- Analysis of Results
- Precautions
Section 14.0 Salt Spray
This test determines the effects on the equipment of prolonged exposure to a salt atmosphere or to salt fog in normal operations.
The main adverse effects are the corrosion of metals, clogging or binding of moving parts as a result of salt deposits, insulation fault, damage to contacts and uncoated wiring.
Test Procedure:
- Temperature
- Atomization
- Placement of Salt Fog Collection Receptacles
- Measurement of Salt Solution
- Preparation of Test Item
- Performance of Normal Salt Fog Test (Category S)
- Performance of Normal Salt Fog Test (Category T)
- Failure Considerations
Section 24.0 Icing
These tests determine performance characteristics for equipment that must operate in icing conditions of rapid changes in temperature, altitude, and humidity. Three icing test procedures differ according to the equipment category.
The procedures specify test methods for evaluating the effects of various icing conditions on the performance or aircraft equipment, namely:
- The effects of external ice or frost adhering to it
- The effects of ice caused by freezing of water condensation or by re-freezing of melted ice
- The effects of ice build-up caused by direct water exposure
Section 26.0 Fire, Flammability
Flammability and fire tests apply to equipment installed on fixed-wing propeller-driven aircraft, fixed-wing turbojet aircraft, turbofan aircraft, prop fan aircraft, and helicopters.
These tests are applicable for equipment:
- Mounted in pressurized zones
- Mounted in fire zones
- Installed in non-pressurized, non-fire zones
There are three Equipment Categories:
- Category A: Fireproof
- Category B: Fire Resistant
- Category C: Flammability
Electromagnetic Compatibility (EMC) Testing
Section 15.0 Magnetic Effect
Magnetic Effect test determines the magnetic effect of the equipment and helps find or prove the closest distance to compasses or compass sensors (flux gates) at which that unit can be installed. This test ensures that equipment can operate properly without interference, which may affect the nearby computer, determining equipment compliance with the applicable equipment performance standard, or assisting the installer in choosing the proper location of the equipment in the aircraft.
Test Description:
To determine the magnetic effect of the equipment, we measure the equivalent deflection of a free magnet in a uniform magnetic field (as produced by the earth) having a horizontal intensity of 14.4 A/m ±10% when the equipment under test is positioned on the east-west line through the pivot of a magnet.
This measurement may be performed with either an uncompensated compass or an equivalent magnetic sensor.
- Category Y: D = 0.0 m. The deflection of the compass is ≤1˚ when measured immediately adjacent to the equipment. This category is for equipment placement between 0.0 m and 0.3 m from the magnetic compasses or flux gates.
- Category Z: 0< D ≤ 0.3 m. The deflection of the compass is equal to 1˚ when measured >0.0 m to ≤0.3 m to the equipment. This category is for equipment placement ≥ 0.3m to magnetic compasses or flux gates.
- Category A: 0.3< D ≤ 1 m. The deflection of the compass is equal to 1˚ when measured >0.3 m to ≤1.0 m to the equipment. This category is for equipment placement ≥ 1 m to magnetic compasses or flux gates.
- Category B: 1 m < D ≤ 3 m The deflection of the compass is equal to 1˚ when measured >1.0 m to ≤3.0 m to the equipment. This category is for equipment placement ≥3 m to magnetic compasses or flux gates.
- Category C: The deflection of the compass is equal to 1˚ when measured >3.0 m to the equipment. This category is for equipment placement >3 m to magnetic compasses or flux gates. Minimum distance for deviation of 1˚ requires a report in the test form; the equipment location onboard changes accordingly.
Section 16.0 Power Input
This section defines test conditions and procedures for AC and DC electrical power applied to the terminals of the equipment under test. It covers the following electrical power supplies:
– 14 V DC, 28 V DC, and 270 V DC
– 115 Vrms AC and 230 Vrms AC at either a nominal 400 Hz frequency or over a variable frequency range which includes 400 Hz
Equipment categories and frequency classes, test conditions, and procedures for equipment using other electrical power supplies must be defined in applicable equipment performance standards.
Section 17.0 Voltage Spike
The Lightning Direct Effect tests determine the ability of externally mounted equipment to withstand the direct effects of a lightning strike. The term “externally mounted equipment” refers to all equipment mounted externally to the main skin of the aircraft and includes all such equipment that is covered only by a dielectric skin or fairing that is an integral part of the equipment. It also includes connecting cables and associated terminal equipment furnished by the equipment manufacturer as a part of the equipment.
Examples of equipment covered by this section are antennae, exterior lights, air data probes, external sensors, and anti-ice and de-ice equipment which is mounted external to the structure (i.e. electrically heated anti-ice boots), magnetic fluid level indicators, fuel filler caps, and drain valves.
There are two types of direct effect tests:
- High voltage strike attachment tests to determine likely lightning attachment locations on the test object.
- High current physical damage tests to determine the damage that may occur to the test object during a lightning channel attachment to or near the test object. The high current physical damage test shows:
- Arc root damage
- Hot spot formation
- Melt-through behavior
- Adequacy of protection
- The behavior of joints (sparking and damage)
- Level of voltage and current impact on electrical conductors interfacing with the test object
Section 18.0 Audio Frequency Conducted Susceptibility – Power Inputs
The test determines whether the equipment will accept frequency components of a normal magnitude for the aircraft equipment. These frequency components have a normally harmonic relation to the power source fundamental frequency. This section of DO-160 provides test procedures and test levels for audio frequency conducted susceptibility of power input lines. It is the responsibility of the installer to make sure the test results satisfy the certification requirements of the proposed installation.
Section 19.0 Induced Signal Susceptibility
This test determines whether the equipment interconnect circuit configuration will accept a level of induced voltages coming from the installation environment. This section relates specifically to interfering signals of power frequency and its harmonics, audio frequency signals, and electrical transients. These typically come from other on-board equipment or systems coupling to sensitive circuits within the EUT through its wiring.
Section 20.0 Audio Frequency Susceptibility (Radiated and Conducted)
The AF Susceptibility tests determine whether the equipment will operate within performance specifications when the equipment and its interconnecting wiring encounter a level of RF modulated power, either by a radiated RF field or by injection probe induction onto the power lines and interface circuit wiring.
Two test procedures are used, and there is an intentional overlap of the tests from 100 to 400 MHz:
- From 10 kHz to 400 MHz, the equipment under test (EUT) receives RF signals coupled by means of injection probes into its cable bundles;
- For frequencies between 100 MHz and the upper-frequency limit, the EUT receives radiated RF fields.
Section 21.0 Emission of Radio Frequency Energy
These tests determine that the equipment does not emit undesired RF noise in excess of the levels specified below. The notches specified in the RE limits intend to protect aircraft RF sensors operating frequencies.
The categories relate to location and separation between the equipment and aircraft radio antennas. As these parameters are common to certain aircraft type and size, there are some examples with each category definition.
This test determines the immunity of equipment to perform without permanent degradation after an air discharged pulse.
Test description:
- The immunity means the ability to withstand a series of ESD pulses at 15,000 volts. The test directs them at specific human contact locations on the EUT. The number of pulses is ten n each of locations, and in both positive and negative voltage.
Section 25.0 Electrostatic Discharge
The ESD test relates to airborne equipment which may be involved in static electricity discharges from human contact. ESD factors: low relative humidity, temperature, use of artificial fiber carpets, vinyl seats and plastic structures. This test is applicable for all equipment and surfaces which are accessible during normal operation and/or maintenance of the aircraft. This test is not applicable to connector pins.
Test Procedure:
- Spray Test
- Immersion Test
Lightning Simulation
Lightning Simulation Under RTCA/DO-160
Section 22.0 Lightning Induced Transient Susceptibility
These test methods verify the capability of the equipment to withstand test transients intended to represent the induced effects of lightning. The wave-forms and levels, and the pass/fail criteria for equipment performance are listed in the applicable equipment specification.
Two groups of tests may be used for equipment qualification. The first is a damage tolerance test performed using pin injection. The second group evaluates the functional upset tolerance of equipment when transients are applied to interconnecting cable bundles. Cable bundle tests include single stroke, multiple stroke, and multiple burst, response tests (hereafter referred to as a single stroke, multiple stroke and multiple burst. Cable bundle tests can also provide an indication of damage tolerance.
Section 23.0 Lightning Direct Effects
The tests determine the ability of externally mounted equipment to withstand the direct effects of a lightning strike. The term “externally mounted equipment” refers to all equipment mounted externally to the main skin of the aircraft. It includes all such equipment that is covered only by a dielectric skin or fairing that is an integral part of the equipment. It also includes connecting cables and associated terminal equipment furnished by the equipment manufacturer as a part of the equipment.
Examples of equipment covered by this section are antennae, exterior lights, air data probes, external sensors, and anti-ice and de-ice equipment, magnetic fluid level indicators, fuel filler caps, and drain valves.
There are two types of direct effect tests:
- High voltage strike attachment tests. It is used to determine likely lightning attachment locations on the test object.
- High current physical damage tests. It is used to determine the damage that may occur to the test object during a lightning channel attachment to or near the test object. The high current physical damage test can be used to assess:
- Arc root damage
- Hot spot formation
- Melt-through behavior
- Adequacy of protection
- The behavior of joints (sparking and damage)
- Level of voltage and current induced on electrical conductors interfacing with the test object
Typically, high voltage strike attachment tests are performed first to determine the likely lightning attachment locations on the test object. The high current physical damage test is then applied to an attachment location identified during the high voltage testing. Test objects that do not have a dielectric covering may not require high strike voltage attachment tests prior to the high current testing if the likely lightning attachment points can be identified. In such cases, the test plan shall define the location on the test object where the high current is to be applied.