FAA AC 20-135 Powerplant Installation and Propulsion System Component Fire Protection Test Methods

The standard "FAA AC 20-135 Powerplant Installation and Propulsion Component Fire Protection Test Methods, Standards, and Criteria," published by the Federal Aviation Administration (FAA), provides guidance for use in demonstrating compliance with the powerplant fire protection requirements of the Federal Aviation Regulations. This standard specifies methods and justifications for fire testing materials and components used in propulsion engine and auxiliary power unit facilities and in areas adjacent to designated fire zones. The compliance method presented here is not mandatory.

For the purposes of this standard, the following definitions apply:

• Fire resistant: The ability of a material or component to withstand a flame of 1090°C plus or minus 66°C for at least 15 minutes, as good as or better than steel, also meets the design intent. When used for materials and parts used to confine fires within designated fire zones, fireproof means that the material or component will perform this function under conditions likely to occur in such zones and will withstand a flame of 1090°C plus or minus 66°C for at least 15 minutes.
• Fire resistant: When applied to power plant installations such as liquid carrying lines, flammable liquid system components, wiring, air ducts, fittings, and power plant controls, fire resistant refers to the ability of a material or component to perform its intended functions under heat and other conditions likely to occur at a particular location and to withstand a flame of 1090 degrees plus/minus 66 degrees for 5 minutes (e.g., a fire resistant hose that will withstand a flame of 1090 degrees for 5 minutes).
• Engine case burn: A fire inside the engine burns the engine case, causing a high pressure and temperature gas flow to escape from the engine.
• Heat flux density: The ratio of the flame to thermal energy. To measure the heat flux density of the test flame, one of the following devices should be used: a calorimeter or a BTU heat transfer device.
• Thermocouples: Thermocouples used should be bare-connect 1,6 mm to 3,2 mm metal-sheathed, ceramic-filled, chrome-aluminum, nominal 22 to 30 AWG (United States wire gauge) conductors or equivalent. An air-aspirated, shielded thermocouple should not be used.

In short, FAA standard AC 20-135 provides guidance for demonstrating compliance with fire protection requirements for aircraft powerplants and propulsion systems. This standard outlines acceptable methods for fire testing materials and components used in propulsion engines, auxiliary power units, and areas adjacent to designated fire zones. This standard addresses the principles and objectives of fire protection in aircraft powerplant facilities. It covers installation and design features that contribute to fire protection in powerplant facilities. It also includes criteria for engine case fire.

Although the methods presented in this standard are not mandatory These are considered acceptable means of complying with Federal Aviation regulations. Applicants may choose to follow these methods or propose alternative methods, provided they can demonstrate that the alternative methods meet applicable fire protection requirements.

FAA AC 20-135 is required because it helps ensure safety in aircraft powerplant installations, particularly regarding fire protection. This standard is considered critical for the following reasons:

• Reducing fire hazards: Aircraft engines and propulsion systems involve high temperatures, fuel lines, and electrical systems. All of these create potential fire hazards. This standard provides:
  • Test methods to evaluate how well materials and components resist or control fire.
  • Design criteria for fire zones to prevent or delay the spread of fire.
• Compliance with Federal Aviation regulations: Many of these (such as Part 23 and Part 25) require aircraft powerplant areas to have effective fire protection. This standard
  • It serves as an acceptable means of complying with these requirements.
  • It provides manufacturers and engineers with a clear, standardized method to demonstrate that their designs meet safety standards.
• Consistency in testing and certification: Without this standard, each company might use different methods for fire resistance testing, making certification inconsistent and less reliable. This makes it difficult for the Federal Aviation Administration to assess it. This standard brings uniformity to the process.
• Enhanced design guidance: FAA AC 20-135 not only tells you how to test, it also helps you:
  • Understanding design considerations for firewalls, hoods, and fire zones
  • Understanding fire resistance and how to select appropriate materials
• Safety assurance for passengers and crew: As a result, this standard supports:
  • Preventing in-flight fires
  • Increasing survival rate in engine-related incidents
  • Maintaining aircraft airworthiness

In short, the FAA AC 20-135 standard is essential for protecting lives, ensuring regulatory compliance, and maintaining confidence in aviation safety systems through rigorous and standardized fire protection practices.

Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, has a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services in accordance with the FAA AC 20-135 Power plant installation and propulsion system component fire protection test methods, standards, and criteria.