Aircraft Fire Testing to ISO 2685, AC 20-135 & RTCA DO-160 | Resonate Testing

Aircraft Fire Testing to ISO 2685, AC 20-135 & RTCA DO-160

Aircraft fire testing supporting qualification, certification, compliance and engineering validation of propulsion systems, nacelles, thrust reversers, firewalls, fluid systems, wiring and electrical components to ISO 2685, AS6826, AC 20-135 A and Change 1 and RTCA DO-160 Section 26 requirements.

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Resonate Testing service supports calibrated fire exposure, flame penetration testing, firewall testing, direct flame impingement, operational system simulation, mechanical loading and dynamic fire testing with vibration where required by the installation environment.

From our clients perspective, it supports type certification, STC programs, qualification testing, design validation, product development, compliance demonstrations, failure investigations and risk reduction.

What is Powerplant Fire Testing?

Powerplant fire testing evaluates whether components, structures and systems installed in or associated with an aircraft fire zone can withstand a defined fire exposure while maintaining their required safety function. Depending on the component and certification basis, the assessment may consider fire resistance, fireproof performance, flame penetration, loss of containment, hazardous leakage, structural integrity or continued operation.

The purpose is not simply to apply a flame to a test article. A meaningful programme must reproduce the conditions that could influence performance in the aircraft installation. These can include fluid flow and pressure, cooling airflow, structural loading, vibration, electrical operation, pneumatic pressure, mounting orientation and thermal gradients.

Typical test articles include:

Engine-zone and propulsion-system components
Nacelle structures, cowling and nacelle skins
Thrust reverser structures, mechanisms and actuator-related hardware
Firewalls, shrouds, barriers, seals and penetrations
Fuel, oil and hydraulic hoses, tubes, fittings and fluid assemblies
Pneumatic ducts and air-handling components
Electrical wiring, connectors, controls and protected equipment
Fire-resistant metallic, composite and thermal-protection structures

Related Testing Services

Vibration Testing
Environmental Testing
Altitude Testing

Powerplant Fire Testing in the UK & Ireland

Resonate Testing supports UK and Ireland aerospace manufacturers, equipment suppliers, propulsion-system developers and aircraft modification programmes requiring independent fire-performance evidence. Testing can be planned around ISO 2685, FAA AC 20-135, AS6826, RTCA DO-160 Section 26, customer specifications and the relevant certification basis, subject to technical and accreditation review.

Programmes may range from development testing intended to identify design weaknesses to formal qualification or certification-support campaigns using production-representative hardware. Early review helps align the component configuration, installation assumptions, operating conditions, instrumentation, acceptance criteria and reporting package before testing begins.

Send your component description, drawings and applicable requirement for an initial engineering review.

When is Powerplant Fire Testing needed?

Powerplant fire testing is normally considered when hardware is installed in, adjacent to or functionally connected with a designated fire zone, or where a customer, prime contractor, certification authority or programme safety case requires objective evidence of fire performance.

Common programme triggers include:

New aircraft or engine certification: demonstrating fireproof or fire-resistant performance against the applicable certification basis.
STC or modification activity: assessing whether a changed design affects previously accepted fire-protection features.
Engineering changes or material substitutions: confirming that legacy evidence remains applicable to the revised configuration.
Supplier qualification or customer acceptance: providing independent evidence before design release or programme progression.
Product development: exposing potential weaknesses before a formal qualification campaign.
Failure investigation: investigating leakage, flame penetration, burn-through, structural damage, backside ignition or loss of function.
Requalification: supporting a revised component, production process, installation or operating condition.

The FAA specifically notes that modifications to previously certified components may require kerosene-burner testing where fire-protection design features could be affected, and recommends early coordination of the proposed compliance approach.

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Aircraft cabin flammability

AC20-135

AC20-135, ISO2685, AS6826: Powerplant Fire Testing Standards and Certification Guidance

The correct standard depends on the component, aircraft location, certification basis and route agreed with the relevant customer or authority. Regulations establish the required safety outcome, while standards and advisory material help define the laboratory method and evidence needed to support that outcome.

Aircraft powerplant fire testing is driven by a combination of certification regulations, advisory material, industry standards and customer-specific requirements. The applicable route depends on the component being tested, its installation location, the aircraft certification basis and the agreed Means of Compliance (MoC).

While regulations define the safety objective, standards such as ISO 2685 and SAE AS6826 provide recognised methods for demonstrating compliance through repeatable, calibrated testing. Understanding the relationship between these documents is essential when planning a qualification, certification or development programme.

Important: A test report supports the certification or compliance process; it does not itself grant product or installation approval. Applicability, acceptance criteria and accredited scope should be confirmed during technical review.

Certification Regulations Supported by Fire Testing

Fire testing is typically performed to support compliance with aircraft and engine certification regulations including:

CS/FAR 25.867 – Fire Protection

Requires systems and structures to provide appropriate protection against fire hazards.

CS/FAR 25.1181 – Designated Fire Zones

Defines which aircraft areas are considered designated fire zones and therefore subject to specific fire protection requirements.

CS/FAR 25.1191 – Firewalls

Specifies requirements for firewalls and firewall installations separating fire zones from protected areas.

CS/FAR 25.1183 – Flammable Fluid Carrying Components

Addresses the fire resistance of components carrying fuel, oil and hydraulic fluids within fire zones.

CS/FAR 25.1193 – Cowling and Nacelle Structure

Requires nacelle and cowling structures to provide adequate fire protection performance.

FAR 33.17 / CS-E 130 – Engine Fire Protection

Defines fire protection requirements for aircraft engines and engine installations.

External links

Reference standards

Standard / Guidance	Primary Focus	Typical Relevance to Testing
QS00118 In House Powerplant Fire Test Method	UKAS-accredited in-house aircraft powerplant fire testing methodology covering aircraft powerplant components, firewalls, nacelle structures, hose assemblies and related hardware.	Provides an accredited route for qualification, certification support, compliance demonstrations and development testing within the scope of the UKAS schedule.
FAA AC 20-135 / Change 1	Powerplant fire protection test methods and compliance guidance.	Legacy programme and certification reference that may remain relevant to existing specifications and historic qualification evidence.
FAA AC20-135A	Current FAA guidance for aircraft powerplant fire testing and compliance.	Current FAA powerplant fire-testing guidance. It recognises AS6826 as an acceptable Means of Compliance and cancels AC 20-135 Change 1.
FAA Engineering Report 3A	Standardised fire-test apparatus, burner design and calibration methodology.	Frequently referenced for burner configuration, flame calibration and fire-test apparatus requirements.
ISO 2685 1990 / ISO 2685 1998	Resistance-to-fire testing of aircraft components, equipment and structures within designated fire zones.	Resistance-to-fire testing for components, equipment and structures located in designated aircraft fire zones.
DOT/FAA/AR-00/12 Chapter 11 and DOT/FAA/AR-00/12 Chapter 12	FAA Aircraft Fire Test Handbook guidance covering hose assemblies and fire penetration testing.	Powerplant hose-assembly and fire-penetration test references.
SAE AS1055 / AIR1377 / AS4273	Fire testing and qualification of aerospace hoses, fittings, tubes and fluid-handling components.	References associated with hoses, tubes, fittings, test equipment and fluid-handling components.
SAE AS6826	Harmonised aircraft powerplant fire-test methodology for fireproof and fire-resistant qualification.	Modern powerplant fire-test standard providing harmonised methodologies and pass/fail criteria for propulsion components and installations.
RTCA DO-160G Section 26	Fire and flammability qualification of airborne equipment and electrical systems.	Fire and flammability requirements for airborne equipment; the applicable category and equipment classification must be reviewed.
CS/FAR and engine requirements	Aircraft and engine certification requirements governing fire protection and fire-zone compliance.	Certification context for designated fire zones, firewalls, flammable-fluid components, nacelles, cowling and engine fire protection.

Selecting the Correct Fire Testing Standard

The correct test route depends on several factors:

Component type
Installation location
Designated fire zone classification
Aircraft certification basis
Customer specification
Authority expectations
Existing qualification evidence
Required accreditation route

A fuel hose, firewall panel, nacelle skin and electrical connector may all require different test configurations despite being installed within the same fire zone.

For this reason, successful programmes begin with a technical review that confirms:

Applicable regulations
Relevant standards
Required operating conditions
Acceptance criteria
Accreditation requirements
Reporting expectations

The objective is not simply to complete a fire test, but to generate meaningful evidence that supports certification, qualification, engineering validation and programme risk reduction.

ISO 2685 – Aircraft Environmental Conditions and Test Procedures for Airborne Equipment

ISO 2685 is one of the most widely recognised fire test standards for aircraft powerplant components. It defines methods for evaluating the fire resistance of components, equipment and structures located within designated aircraft fire zones.

The standard establishes controlled fire exposure conditions that allow manufacturers and certification authorities to assess whether a component can continue to perform its intended function while subjected to a representative powerplant fire environment.

ISO 2685 is commonly applied to:

Nacelle structures and cowling
Firewalls and shrouds
Fluid carrying components
Engine accessories
Electrical and control system hardware
Aircraft propulsion system components

For many aerospace programmes, ISO 2685 remains the benchmark standard for demonstrating fireproof or fire-resistant performance within designated fire zones.

SAE AS6826 – Modern Powerplant Fire Testing

SAE AS6826 was developed to provide a more modern and harmonised approach to aircraft powerplant fire testing.

The standard builds upon decades of industry experience and introduces clearer guidance for:

Fireproof testing
Fire-resistant testing
Component-specific requirements
Operating condition simulation
Acceptance criteria
Burner calibration requirements
Installation representation

AS6826 is increasingly becoming the preferred test methodology for new aerospace programmes because it provides a more consistent framework for demonstrating compliance across different aircraft and engine platforms.

The FAA’s AC 20-135A recognises AS6826 as an acceptable Means of Compliance for many powerplant fire protection requirements.

FAA AC 20-135A – Powerplant Fire Protection Test Methods

FAA Advisory Circular AC 20-135A provides guidance on demonstrating compliance with aircraft and engine fire protection regulations.

Rather than being a test standard itself, AC 20-135A explains acceptable methods for:

Selecting test configurations
Defining representative operating conditions
Burner calibration
Instrumentation requirements
Fireproof testing
Fire-resistant testing
Component-specific qualification

The guidance applies to a broad range of aircraft powerplant hardware including:

Fluid systems
Fuel lines
Oil systems
Hydraulic components
Firewalls
Nacelles
Electrical systems
Engine accessories

For certification programmes, AC 20-135A often serves as the bridge between regulatory requirements and the detailed laboratory test method.

RTCA DO-160 Section 26 – Fire and Flammability

RTCA DO-160 is widely used for airborne equipment qualification. Section 26 specifically addresses fire and flammability requirements for aircraft equipment and electrical systems.

Testing under DO-160 Section 26 may be relevant for:

Avionics installed within fire zones
Electrical equipment
Wiring systems
Connectors
Control units
Engine-mounted electronic hardware

Although not a substitute for powerplant fire testing, DO-160 Section 26 is frequently used alongside ISO 2685 or AS6826 to build a complete qualification package for airborne equipment.

Resonate’s Powerplant Fire Testing Capability

Aircraft powerplant fire testing is rarely a simple pass-or-fail exercise. Certification, qualification and development programmes often require the test environment to replicate the conditions experienced by the component in service. Resonate Testing supports this requirement through an engineer-led approach that combines calibrated fire exposure with representative operating conditions, instrumentation and detailed reporting.

Every fire-testing programme begins with a review of the hardware, installation environment and certification objectives. This allows the test configuration, operating conditions, instrumentation strategy and acceptance criteria to be aligned before testing starts.

Resonate’s fire-testing capability can support:

Fireproof and fire-resistant qualification testing
Powerplant fire-zone compliance programmes
Nacelle and thrust reverser fire testing
Firewall and fire penetration testing
Fuel, oil and hydraulic system testing
Hose and fluid assembly fire testing
Electrical component fire qualification
Simultaneous fire and vibration testing
Certification and Means of Compliance support
Development and design validation programmes
Supplier qualification and customer acceptance testing
Failure investigation and root-cause analysis

By combining technical review, representative test conditions and detailed evidence generation, Resonate helps aerospace organisations move from design assumptions to objective fire-performance data.

Fire Testing Capability at a Glance

Our capability supports the testing of aircraft propulsion-system components installed within designated fire zones, including nacelles, thrust reversers, firewalls, shrouds, fluid systems, hose assemblies, electrical equipment and engine-zone structures. Programmes can be configured to assess fireproof and fire-resistant performance, flame penetration, leakage, structural integrity, backside ignition and functional continuity under controlled fire exposure.

Unlike basic fire testing that evaluates a component in isolation, Resonate can incorporate representative installation conditions such as fluid flow, hydraulic pressure, fuel pressure, engine oil circulation, cooling airflow, electrical loading, pneumatic operation, structural loading and vibration. This helps generate evidence that is more representative of the real aircraft environment and provides greater confidence during certification and qualification activities.

Test Features

Calibrated kerosene and oil-burner fire exposure
Fireproof and fire-resistant assessments
Representative fluid, pressure and airflow conditions
Structural load application
Simultaneous fire and vibration testing
Temperature, pressure and performance monitoring
Detailed data acquisition and reporting

Programme Support

Certification testing
Qualification testing
Development testing
Design validation
Engineering change assessment
Supplier approval testing
Customer acceptance testing
Failure investigation support

This capability enables customers to generate meaningful fire-performance evidence while reducing certification, technical and programme risk.

Specification	Capability
Calibrated fire exposure	Kerosene or oil-burner exposure selected and calibrated for the applicable test plan.
Fire resistance and fireproof testing	Assessment against agreed duration, operating conditions and acceptance criteria.
Firewall and fire penetration testing	Evaluation of barriers, penetrations, seals, joints and representative openings.
Nacelle and thrust reverser hardware	Cowling, skins, structures, mechanisms, hinges, latches and adjacent components.
Hoses and fluid systems	Fuel, oil, hydraulic, skydrol and other fluid assemblies under agreed pressure, flow and temperature conditions.
Representative airflow	“Cooling, differential or installation-related airflow where required by the test basis.
Structural and mechanical loading	Loads, restraint systems, fan-cowl hinges and latch arrangements where applicable.
Fire with vibration	Simultaneous fire and vibration exposure where required by the installation environment and confirmed during test-plan review.
Electrical and pneumatic operation	Electrical loading, functional monitoring, pneumatic pressure and flow where agreed.
Instrumentation	Temperature, pressure, flow, vibration, structural and operational-performance monitoring.

Why Resonate for Powerplant Fire Testing?

Engineer-led review of the standard, installation and certification basis
Test planning around the actual hardware and required safety function
UKAS-accredited QS00118 testing for the scope listed in the current schedule
Support for ISO 2685, AC 20-135, AS6826 and related aerospace requirements
Representative fluid, pressure, airflow, load and functional conditions
Fire exposure combined with vibration where the requirement demands it
Instrumented testing with agreed observations and evidence capture
Reporting aligned with the method, accreditation position and customer requirements
Related environmental, vibration and shock services available through the same test organisation

How a Powerplant Fire Test Campaign Works

Requirement review
Review the drawings, specification, installation, certification basis and acceptance criteria.
Test definition
Confirm the applicable standard, fireproof or fire-resistant classification, flame target, mounting orientation and operating conditions.
Fixture and instrumentation planning
Define the representative fixture, fluid circuits, airflow, loading, vibration, electrical or pneumatic operation and measurement channels.
Installation and pre-test inspection
Mount and inspect the test article, verify its configuration and connect the agreed instrumentation and services.
Burner calibration
Verify the required flame temperature and heat-transfer conditions using the applicable method.
Fire exposure and monitoring
Apply the calibrated exposure while operating conditions are controlled and temperatures, pressures, leakage, structural response and functional behaviour are monitored.
Post-test assessment
Inspect for flame penetration, burn-through, hazardous leakage, backside ignition, structural degradation and loss of required function.
Review and reporting
Compile the agreed calibration records, achieved conditions, data, observations, photographs, deviations and results against the acceptance criteria.

Fire Testing Terms & Definitions

Fireproof:

15-Minute Exposure

Withstands a 2000 °F ±150 °F flame for at least 15 minutes whilefulfilling its design purpose.

Applies to firewalls, shrouds and barriers separating designated firezones.

No burn-through or flame penetration for the full exposure duration.

Components must continue to function or fail in a safe, predictablemanner.

Drives longer exposure, more boundary conditions and a longerinstrumented run.

Fire Resistant

5-Minute Exposure

Withstands the same 2000 °F ±150 °F flame for at least 5 minutes while maintaining intended function.

Typically applied to fluid-carrying lines, hoses and less critical equipment.

Hazardous leakage, ignition and loss of function are the primary failure modes.

Shorter exposure, but the same calibrated flame and set-up discipline.

Test timing and boundary conditions scale to the shorter duration.

Sonic Burner / Nex-Gen Burner

The Sonic Burner, also known as the NexGen Burner, is a next-generation oil burner developed by the Federal Aviation Administration (FAA) to replace traditional oil burners used for fire certification tests on aircraft materials. It is designed to provide precise control over fuel and air flow rates, ensuring robust and repeatable flame properties during tests. The NexGen Burner generates a “sooting” flame, which is representative of real-life fire situations, and is capable of achieving flame temperatures of at least 2000°F, making it suitable for evaluating the fire resistance of aircraft interiors and components.

Designated Fire Zone

An aircraft area identified as having a potential fire risk and therefore subject to specific fire-protection requirements. Examples include engine power sections, accessory compartments and certain APU installations.

Flame Penetration

The passage of flame through a barrier, firewall, seal, joint, penetration or test article during fire exposure. Flame penetration is often a critical pass/fail criterion.

Backside Ignition

Ignition occurring on the protected side of a component or barrier due to heat transfer through the test article. Backside ignition is commonly assessed during firewall and barrier testing.

Burn-Through

The creation of an opening or structural failure caused by prolonged fire exposure. Burn-through may compromise fire containment and aircraft safety.

Hazardous Leakage

The release of fuel, hydraulic fluid, oil, pneumatic media or other substances at a level that exceeds the agreed acceptance criteria during or after fire exposure.

Fire Containment

The ability of a structure, enclosure or component to prevent the spread of fire, heat or flames beyond the intended boundary.

Representative Operating Conditions

The fluid pressures, temperatures, airflow rates, vibration levels, structural loads, electrical loads or pneumatic conditions applied during testing to replicate the real aircraft installation.

Burner Calibration

The process of verifying that the fire source produces the required temperature, heat flux and flame characteristics specified by the applicable test method before testing begins.

Certification Support Testing

Testing performed to generate objective evidence for FAA, EASA, TCCA or customer certification programmes. The test report supports compliance but does not itself grant certification approval.

What to Provide Before a Fire Test Quotation

Component name, part number, revision and quantity
Drawings, dimensions, materials and production configuration
Installation orientation, mounting arrangement and fire-zone location
Required standard, regulation, customer specification or qualification plan
Fireproof, fire-resistant or other requested classification
Acceptance criteria and required exposure duration
Burner orientation and flame target location
Fluid type, temperature, pressure, flow and leakage criteria
Airflow or cooling conditions
Structural load, hinge, latch, restraint or vibration requirements
Electrical, pneumatic or functional operating conditions
Thermocouple, pressure, flow, vibration and customer instrumentation needs
Hazardous materials, fuels, stored energy and safe shutdown information
Conformity, witnessing, photography and video requirements
Required report format and evidence-pack contents

Early provision of these details helps determine whether the proposed article, fixture and operating conditions represent the intended installation. Typically these requirement are provided in a customer Qualification/Development Test Plan.

Not sure if your hardware requires fire testing?

Aircraft fire programmes do not always begin with a complete test specification. You may have a component drawing, a fire-zone classification, an aircraft requirement or a customer acceptance criterion without a fully defined test method.

Share what is available and Resonate can review:

The component’s installation location and fire-zone context
Whether fireproof, fire-resistant or another classification is being requested
Applicable standards, regulations and customer specifications
Whether the test article is representative of the production installation
Required flame direction and exposure location
Fluid, pressure, temperature, airflow, electrical and pneumatic conditions
Structural loading or vibration during exposure
Instrumentation, witnessing and reporting expectations
The proposed accreditation position

The review should be completed before quotation because the method, component configuration, operating conditions and evidence expectations determine the practical test route.

Powerplant Fire Testing Reports and Data Packs

Report content is agreed before testing so the evidence matches the programme requirement. Depending on the quotation and method, the package may include:

Test objective, agreed scope and applicable standard
Test article identification and configuration
Fixture, mounting and flame-target description
Representative operating and boundary conditions
Burner setup and relevant calibration information
Instrumentation list and measurement channels
Actual temperatures, pressures, flows, loads or vibration conditions achieved
Timed test-conduct record and key events
Observations of leakage, penetration, ignition, structural response and function
Photographs and video references where agreed
Post-test inspection results
Deviations, interruptions and anomalies
Results assessed against the agreed acceptance criteria
Raw data, plots, customer forms or additional evidence where included in scope

A report supports qualification, validation, customer acceptance, failure investigation or certification evidence. It should not be described as guaranteeing certification approval.

Powerplant and systems Fire testing FAQs

Basics

What is the difference between fireproof and fire-resistant testing?
What does powerplant fire testing prove?

Standards and guidence

Does ISO 2685 cover all aircraft fire testing?
What is AS6826?

Fire Testing at Resonate

Can you test nacelle and thrust reverser components?
Can hoses and fluid systems be pressurised during testing?
Can fire exposure be combined with vibration?
What instrumentation can be used?
Is all Powerplant Fire Testing UKAS accredited?
What will I receive after testing?

Send Your Powerplant Fire Testing Requirement for Engineer Review

Discuss your aircraft powerplant fire-testing requirement with an engineer. Send the component type, installation location, drawings, operating conditions, applicable standard, acceptance criteria and certification basis.

Resonate Testing can review the proposed route, test configuration, instrumentation, accreditation position and evidence package before quotation.