Paragraph 23.1191(f)
ADC Cross-reference: 5.68(e)
No specific policy is available as of December 31, 2002.
Paragraph 23.1191(g)
ADC Cross-reference: 5.68(f)
No specific policy is available as of December 31, 2002.
Paragraph 23.1191(h)
ADC Cross-reference: 5.68(g)
No specific policy is available as of December 31, 2002.
23.1192 Engine accessory compartment diaphragm (Amendment 23-14)
CAR 3 Cross-reference: None
ADC Cross-reference: 5.69
No specific policy is available as of December 31, 2002.
Related Material
AC 23-2, Flammability Tests
AC 20-135, Powerplant Installation and Propulsion System Component Fire Protection Test Methods, Standards, and Criteria
23.1193 Cowling and nacelle (Amendment 23-43)
CAR 3 Cross-reference: 3.625
ADC Cross-reference: 5.70
Related Material
AC 23-2, Flammability Tests
AC 20-107A, Composite Aircraft Structure
AC 20-135, Powerplant Installation and Propulsion System Component Fire Protection Test Methods, Standards, and Criteria
Paragraph 23.1193(a)
ADC Cross-reference: 5.70(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1193(b)
ADC Cross-reference: 5.70(b)
No specific policy is available as of December 31, 2002.
Paragraph 23.1193(c)
ADC Cross-reference: 5.70(c)
What typical cowling materials are considered fire resistant?
Cowlings fabricated of Alclad Aluminum Alloy 2024-T3 (minimum 0.032-in. thickness) are considered fire resistant. Materials considered fireproof, according to § 23.1191, by definition, are also considered fire resistant.
Many airplanes are constructed from fiber reinforced (carbon, fiberglass, Nomex, Kevlar, etc.) composite materials. These materials vary widely in the composition of the fiber and matrix materials, the lay-up of the fibers, and their processing, all factors that could affect their fire resistance. Because of this, testing of these materials according to the methods described in AC 23-2, AC 20-107A, and AC 20-135 is typically required to show compliance with § 23.1193(c).
Can airflow on the exterior of the cowling be used to meet the fire resistant test criteria?
Conduct tests to substantiate alternate materials using an airflow velocity not more than the minimum stall speed of the airplane on the exterior side of the test specimen.
Paragraph 23.1193(d)
ADC Cross-reference: 5.70(d)
No specific policy is available as of December 31, 2002.
Paragraph 23.1193(e)
ADC Cross-reference: 5.70(e)
No specific policy is available as of December 31, 2002.
Paragraph 23.1193(f)
ADC Cross-reference: None
No specific policy is available as of December 31, 2002.
Paragraph 23.1193(g)
ADC Cross-reference: None
No specific policy is available as of December 31, 2002.
23.1195 Fire extinguishing systems (Amendment 23-43)
CAR 3 Cross-reference: None
ADC Cross-reference: None
This guidance may be used for Airship Certification as applicable.
What methods for complying with the fire extinguishing requirements of § 23.1195 are acceptable?
Flight testing of the engine and APU compartments on the airplane is the accepted method for demonstrating compliance with § 23.1195. The tests should be designed and performed to show that an extinguishing agent concentration sufficient to extinguish fires is attained in all the protected compartments within the nacelle simultaneously. The use of an actual fire during the test is not recommended or required, as this is both dangerous and destructive. Laboratory testing is used to establish the required concentrations of the selected agent to extinguish flames for all of the flammable materials in the protected area according to § 23.1197. The concentrations established in the laboratory should be used in the flight testing. The flight test should encompass the worst-case operational conditions under which the extinguishing system would be expected to operate. The instrumentation for the testing should be designed to make sure there is sufficient coverage of the nacelle area. Some of the conditions to consider for the testing include the following:
1. Maximum and minimum airflow in the nacelle
The amount of airflow in the nacelle affects the distribution as well as the concentration of the agent over time.
2. Airflow patterns in the nacelle
The airflow patterns in the nacelle are generally for meeting cooling and venting requirements. An understanding of the patterns is necessary for determining the affects on the extinguishing agent concentrations.
3. Likely fire locations in the nacelle
The likely fire locations should be considered along with the airflows in the nacelle to account for the airflow affects on agent concentration.
4. Maximum and minimum temperatures in the nacelle
The temperatures in the nacelle or APU compartment in which the extinguishing agent is expected to work should be considered for their effect on the dispersion of the agent.
5. Maximum and minimum operational temperatures of the extinguishing agent (agent soak temperatures)
Minimum operational temperature testing with the typical extinguishing agents cannot be sufficiently simulated with lower pressures in the system because of the presence of multi-phase flow in the system during discharge. These tests should be performed with agent filled containers that have been conditioned at the appropriate temperatures.
6. Type of extinguishing agent
Advisory Circular 20-100, referenced under related material below, contains minimum concentration values sufficient to extinguish turbine engine fires for five different agents (CO2, CH3Br, CH2BrCl, CF2Br2, and CF3Br), except for the carbon dioxide all are chlorofluorocarbons. Environmental concerns have led to worldwide restrictions on the production and use of the chlorofluorocarbons, and work has been ongoing for over a decade to find replacement agents. The use of agents other than those currently in use will require special consideration to validate their efficacy.
Consult with the Small Airplane Directorate in these situations.
7. Type of fuel
The majority of aircraft extinguishing systems have been used on turbine-powered aircraft using turbine fuel. As a result, the agents and their required concentrations have developed around extinguishing fires common to turbine engines and not reciprocating, or exotic engines. Other fuels, such as Avgas, alcohol, bio-diesel, and hydrogen, may require additional work to determine the appropriate concentrations, measurement, and testing techniques to show compliance with § 23.1195.
Related Material
AC 20-100, General Guidelines for Measuring Fire Extinguishing Agent Concentrations in Powerplant Compartments
Paragraph 23.1195(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1195(b)
No specific policy is available as of December 31, 2002.
23.1197 Fire extinguishing agents (Amendment 23-34)
CAR 3 Cross-reference: None
ADC Cross-reference: None
Paragraph 23.1197(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1197(b)
No specific policy is available as of December 31, 2002.
23.1199 Extinguishing agent containers (Amendment 23-34)
CAR 3 Cross-reference: None
ADC Cross-reference: None
Paragraph 23.1199(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1199(b)
No specific policy is available as of December 31, 2002.
Related Material
AC 23.1419-2B, Certification of Part 23 Airplanes for Flight in Icing Conditions
Paragraph 23.1199(c)
No specific policy is available as of December 31, 2002.
Paragraph 23.1199(d)
No specific policy is available as of December 31, 2002.
Paragraph 23.1199(e)
No specific policy is available as of December 31, 2002.
23.1201 Fire extinguishing systems materials (Amendment 23-34)
CAR 3 Cross-reference: None
ADC Cross-reference: None
Paragraph 23.1201(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1201(b)
No specific policy is available as of December 31, 2002.
23.1203 Fire detector system (Amendment 23-51)
CAR 3 Cross-reference: None
ADC Cross-reference: 5.72
Paragraph 23.1203(a)
ADC Cross-reference: 5.72(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1203(b)
ADC Cross-reference: 5.72(b)
No specific policy is available as of December 31, 2002.
Paragraph 23.1203(c)
ADC Cross-reference: 5.72(c)
No specific policy is available as of December 31, 2002.
Paragraph 23.1203(d)
ADC Cross-reference: 5.72(d)
No specific policy is available as of December 31, 2002.
Paragraph 23.1203(e)
ADC Cross-reference: 5.72(e)
No specific policy is available as of December 31, 2002.
Related Material
AC 23-2, Flammability Tests