U.S. Department of Transportation Circular Federal Aviation Administration
Subject: Engine Fire Protection
Date: 8/3/09
AC No: 33.17-lA
PURPOSE: This advisory circular (AC) provides definitions, guidance, and acceptable methods, but not the only methods, that may be used to demonstrate compliance with the engine fire protection requirements of Title 14 Code of Federal Regulations (14 CPR 33.17). The guidance provided in this AC supersedes information contained in AC 33-2B titled "Aircraft Engine Type Certification Handbook" (Chapter 3, Section 22, titled "Section 33.17, Fire Prevention").
Installation Analysis Method: For this method, the test plan may consider all potential sources of fire in the intended installation when determining the test flame impingement location requirements. The intent is to identify locations or features that cannot be directly impinged by fire and evaluate the critical features at locations that can be directly impinged. If the applicant chooses this installation analysis approach, it should be based on the actual intended installation, and should consider, as a minimum, the potential factors noted above, and specifically the following potential installation factors:
Cowling and nacelle structure Adjacent structure shielding Undercowl airflowAircraft Engine build up (EBU) hardwareFuel sourcesAir sourcesOther factors not listed may also apply
Such installation analyses should avoid simple generalities, such as "the most likely flame direction is vertical assuming fuel collects at the bottom of the cowl," and should generally be coordinated with the installer before the test plan is submitted. If this approach is used, each new installation will need to be re-evaluated against the original fire protection substantiation to confirm its applicability to the new installation. A notation in the installation instructions may be necessary to explain this limitation. Lastly, due consideration should be given to fire protection features such as fire shields, fire protective coatings, or other methods, so as to not discourage or invalidate their use for fire prevention purposes.
Annex 16 - Environmental Protection - Volume Iii - Aeroplane CO2 Emissions
Definition:
Aeroplane. A power-driven heavier than-air aircraft, deriving its lift in flight chiefly from aerodynamic reactions on surfaces which remain fixed under given conditions of flight
Cockpit crew zone. The part of the cabin that is exclusively designed for flight crew use.
Derived version of a CO2-certified aeroplane An aeroplane which incorporates changes in type design that either increase its maximum take-off mass, or that increase its CO2 emissions evaluation metric value by more than: a) 1.35 per cent at a maximum take-off mass of 5,700 kg, decreasing linearly to; b) 0.75 per cent at a maximum take-off mass of 60,000 kg, decreasing linearly to; c) 0.70 per cent at a maximum take-off mass of 600,000 kg; and d) a constant 0.70 per cent at maximum take-off masses greater than 600,000 kg.
Derived version of a non-CO2-cerfited aeroplane. An individual aeroplane that conforms to an existing Type Certificate, but which is not certified to Annex 16, Volume III, and to which changes in type design are made prior to the issuance of the aeroplane’s first certificate of airworthiness that increase its CO, emissions evaluation metric value by more than 1.5 per cent or are considered to be significant CO, changes.
Equivalent procedure. A test or analysis procedure which while differing from the one specified in the volume of Annex 16 the technical judgement of the certificating authority yields effectively the same CO2 emissions evaluation metric value as the specified procedure.
Maximum passenger seating capacity. The maximum certificated number of passengers for the aeroplane type design
Maximum take-off mass. The highest of all take off masses for the type design configuration.
Details On FAA Noise Levels, Stages, And Phaseouts
Noise Levels
The FAA regulates the maximum noise level that an individual civil aircraft can emit by requiring the aircraft to meet certain noise certification standards. These standards label changes in maximum noise level requirements by "stage" designation. The U.S. noise standards are defined in the Code of Federal Regulations (CFR) Title 14 Part 36 – Noise Standards: Aircraft Type and Airworthiness Certification (14 CFR Part 36). The FAA provides certified noise levels in the advisory circular, Noise Levels for U.S Certificated and Foreign Aircraft. This advisory circular provides noise level data for aircraft certificated under 14 CFR Part 36 and categorizes aircraft into their appropriate "stages". Any aircraft that is certified for airworthiness in the US, also must comply with noise standards requirements in order to receive a noise certification. The motive of the noise certification process is to ensure that the latest available safe and airworthy noise reduction technology is incorporated into aircraft design and enables the noise reductions offered by those technologies to be reflected in reductions of noise experienced by communities. As the noise reduction technology matures, the FAA works with the international community to decide if a new stringent noise standard is needed. If yes, the international community through the International Civil Aviation Organization (ICAO) commences a comprehensive analysis to determine what that new standard will be.
Noise Stages
The present FAA noise standards are applicable to new type certifications of jet and large turboprop aircraft is Stage 4. It is equal to the ICAO Annex 16, Volume 1 Chapter 4 standards. Recently, the international community has developed and approved a more stringent standard within the ICAO Annex 16, Volume 1 Chapter 14, which became effective July 14, 2014. The FAA is adopting this standard and promoting the rule for Stage 5 that is anticipated to be effective for new type certificates after December 31, 2017 and December 31, 2020, depending on the weight of the aircraft. The Notice of Proposed Rule Making (NPRM) for Stage 5 was published on January 14, 2016.
Prohibitions
The FAA Modernization and Reform Act of 2012, in Section 513, had prohibited on operating certain aircraft weighing 75,000 pounds or less not complying with Stage 3 noise levels, and on July 2, 2013, the FAA published a Final Rule in the Federal Register for the Adoption of Statutory Prohibition the Operation of Jets Weighing 75,000 Pounds or Less That Are Not Stage 3 Noise Compliant. In 1990, Congress passed the Aviation Noise and Capacity Act, which required that by the year 2000 all jet and large turboprop aircraft at civilian airports be Stage 3.
Engine Nacelle Integrated With Heat Exchanger
An engine nacelle includes an exterior housing partially surrounding the engine. This nacelle also helps cool the engine and other hot fluids. The engine nacelle integrated with the heat exchanger is configured to exchange heat between a fluid flowing within the heat exchanger and air in the interior of the nacelle. The high-velocity air through nacelle ensures efficient cooling of hot fluids.
Electric De-Icing Device
The electric de-icing device includes a heating assembly, which includes the first and second heating stages positioned in the nacelle element—an electricity supply circuit delivering a primary voltage to the first heating stage of the heating assembly. The electricity supply circuit includes an electricity source and a de-icing/anti-icing circuit, which is connected to the heating assembly and supplied voltage by the electricity source. Furthermore, the de-icing/anti-icing device includes components to supply a complimentary voltage to the second heating stage of the heating assembly. This helps in the de-icing of the engine nacelle.
Aircraft Propulsion Assembly With Fire Extinguishing System
An aircraft propulsion assembly includes an engine and a nacelle surrounding the engine. This assembly, when incorporated with a fire extinguishing system, can be used to extinguish fires that may occur in the engine and nacelle. The extinguishing system supplies an extinguishant to at least one extinguishant distribution pipe, which opens into a cavity of the engine and a cavity of the nacelle.
Integrated Propulsion System
An integrated propulsion system is a system that is lighter, quieter, and easier to maintain. This system is focused on acoustics and helps reduce aircraft noise. It uses advanced materials to reduce weight to ensure higher fuel efficiency and implements electric actuation systems for both weight savings and reliability. Integrated propulsion systems have an advanced manufacturing process to reduce costs and increase production quality. Many major market players, such as Safran, Nexcelle, and Rolls-Royce, are focused on designing and developing integrated propulsion systems.
For example, Nexcelle (a joint venture owned 50/50 by Safran Nacelles & GE) is exploring new technologies to reduce fuel consumed, noise, and maintenance, while improving the reliability of the integrated propulsion system. Key projects of the joint venture include developing a one-piece O-duct for the thrust reverser that reduces weight and complexity compared to current two-piece ducts and designing an electric engine inlet heater that is embedded in the composite material to reduce generator requirements and increase engine efficiency.
Likewise, in 2017, the COMAC C919 jetliner successfully completed its first flight with integrated propulsion system, which optimizes interfaces between the pylon, nacelle and engine, offering benefits in enhanced performance and reduced weight.
More Electric Systems & Sensors
With the growth and innovation in civil and military aviation, there has been a significant shift in the aircraft market dynamics towards the use of electric aircraft. Many next-generation aircraft are being equipped with more electrical systems to minimize the use of mechanical, hydraulic, and pneumatic non-propulsive power systems. This has resulted in reduced aircraft weight, use of less fuel, limited maintenance, reduced noise, and lower emissions, leading to a low cost of ownership and increased reliability.
For example, the Safran developed an Electric Thrust Reverser Actuation System (ETRAS) that replaced thrust reversers with hydraulically-controlled systems. These systems offer simplified designs, lower maintenance costs, reduced weight, and the elimination of hydraulic liquids. Ongoing R&D projects are further expected to offer new dimensions to electric aircraft. The increasing use of electric systems requires smart sensors for accurate feedback and ease of control. Sensors help in measuring parameters such as monitoring and control. All sensors installed in an aircraft are connected to flight instruments, which include tachometers, engine temperature gauges, fuel and oil-quantity gauges, pressure gauges, flow meters, altimeters, and airspeed-measurement meters.
