Flammability Test — RTCA DO-160 Part 26 · Plastics Testing

What Is Flammability?

This test is carried out to evaluate the ignition, burning rate and self-extinguishing behavior of equipment materials within the scope of Chapter 26 (“Fire, Flammability”) of the RTCA DO-160 “Environmental Conditions and Test Procedures for Airborne Equipment” standard. DO-160 is the exact same text as EUROCAE ED-14 and is recognized by ISO as ISO 7137.

Purpose of Flammability

The aim is to certify that aviation equipment meets the requirements regarding the evaluation of ignition, burning rate and self-extinguishing behavior of equipment materials in flight and ground conditions and to complete equipment qualification.

Which Products Is Flammability Applied To?

Avionics units and displays
In-flight electronic equipment
Communication and navigation devices
Cabin and cargo compartment equipment
Sensors and actuators

In Which Sectors Is Flammability Used?

PlasticsAutomotivePackagingConsumer Products

Standards Related to Flammability

RTCA DO-160Environmental conditions and test methods in aviation equipment test
EUROCAE ED-14
ISO 7137

Flammability Conditions

Method: Vertical or horizontal burning test; by category
Flame application time: Defined in standard
Assessment: Burning time, burning length and flaming drop
Specimen: Material sample or actual part

Equipment for Flammability

Flammability test cabin
burner and timer
Numune tutucu
ventilation pattern

Sample Requirements for Flammability

Malzeme listesi belgelenmeli
Sample thickness should represent the most unfavorable use
Conditioning must be applied

Duration of Flammability

It is short per sample; one set is typically completed in one business day.

Flammability Procedure

1The method and flame duration are determined.
2The sample is placed in the holder.
3Flame defined time is applied.
4Burning time and length are measured.
5Flaming drop behavior is observed.

Flammability Acceptance Criteria

Acceptance criteria are maximum burning time, maximum burning length and flaming drop limits defined in the standard.

Evaluation of Results

Aviation flammability requirements for cabin interior materials also apply.

Flammability Report

Applicable standard, revision and Part 26
Selected equipment category and justification
Applied conditions and measurement results
Function monitoring method and observations
Environmental Qualification Form (DO-160 Environmental Qualification Form) entry

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

Aviation equipment qualification requirements
EASA/FAA certification principles

Plastics Testing — What Does This Testing Field Cover?

The section below describes the field that the Flammability test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Plastics testing determines the mechanical, thermal and burning behaviour of a polymer material. Unlike metals, plastics are VISCOELASTIC: their behaviour depends on loading rate, temperature and moisture. The same material therefore gives different results under different conditions, and the test conditions are an inseparable part of the result.

The practical consequence of viscoelasticity is this: a plastic part continues to deform over time under a constant load (creep) and the stress it carries at constant deformation falls over time (stress relaxation). A screwed joint loosens, a clamp loses its clamping force, a shelf sags over time. A short-term tensile test does not show this behaviour; a long-term test or an accelerated model is needed.

Thermal behaviour is the second main axis. Melt flow rate indicates the processability of the material and lot-to-lot consistency; heat deflection temperature and the Vicat softening point give a rough limit for service temperature. Thermal analysis (DSC, TGA, DMA) reveals the identity of the material: glass transition temperature, melting behaviour, crystallinity, filler content and decomposition temperature.

Burning behaviour is the third axis and ties directly into product standards. The UL 94 class and the limiting oxygen index are written into the material data sheet; a particular class is required for the housing of an electrical appliance, while a different classification system applies to a construction product.

Ageing is the most frequently skipped part of the field. Plastics degrade under UV, heat, moisture and oxygen: colour changes, the surface cracks, impact strength falls. For a part intended for outdoor use, what matters is not its values on day one but its values after ageing. Xenon arc and fluorescent UV equipment accelerate this degradation and allow comparison.

The output of this family is usually written into the material data sheet, and product standards refer to that sheet. But there can be a difference between the data sheet value and the behaviour of the actual part: orientation formed during moulding, weld lines and internal stresses make the part behave differently from the specimen.

The use of recycled content has added a new question to the field. Recycled resin varies from lot to lot; mechanical properties, colour and burning behaviour can shift between batches. For a manufacturer using recycled material, incoming material control is therefore not a choice but a necessity.

Method groups in this field

Mechanical
Tension, compression, bending, Charpy and Izod impact, hardness (Shore), creep and environmental stress cracking.
Thermal
Melt flow index (MFI), heat deflection temperature (HDT), Vicat softening temperature, linear thermal expansion.
Thermal analysis
Transition temperatures and crystallinity by DSC, composition and decomposition by TGA, dynamic mechanical behaviour by DMA.
Burning
UL 94 classification, limiting oxygen index (LOI), glow wire and needle flame tests.
Ageing
Accelerated ageing by xenon arc and fluorescent UV, hot air ageing, humidity and condensation.
Physical
Density, water absorption, ash content, gas and water vapour permeability of films and sheets.

Commonly confused in this field

A plastics result without a stated test rate and temperature cannot be interpreted; viscoelastic behaviour depends on these parameters.
A specimen result does not transfer directly to the actual part; moulding orientation and weld lines are decisive.
HDT and Vicat values are NOT service temperatures; they are a rough indication of an upper limit and do not apply under load.
The UL 94 class depends on thickness; a different wall thickness requires re-verification.
For moisture-absorbing polymers (such as polyamide), results are misleading unless conditioning is carried out.
ASTM D638 and ISO 527 results are not directly equivalent; the specimen geometries and rate definitions differ.

Which decisions these results support

Material selection and supplier approval
Meeting the flammability and thermal requirements of the product standard
Verifying the use of recycled content and lot control
Moulding process control and lot consistency
Demonstrating ageing resistance for outdoor use

Related Tests

Frequently Asked Questions About Flammability

How is the equipment category determined?

The category is selected based on the equipment's mounting location on the aircraft (pressurized/non-pressurized, heated/unheated area) and aircraft type. Category selection directly determines the test conditions and is declared in the qualification form.

Is there any difference between DO-160 and ED-14?

No. RTCA DO-160 and EUROCAE ED-14 are exactly the same text; the two are considered equivalent.