POWERPLANT FIRE PROTECTION
23.1181 Designated fire zones; regions included (Amendment 23-51)
CAR 3 Cross-reference: None
ADC Cross-reference: None
This guidance may be used for Airship Certification as applicable.
What is the intent of § 23.1181?
The intent of § 23.1181 is to identify areas where a high degree of safety precaution must be taken. These areas are designated fire zones because of the presence of both ignition sources and flammable fluids where a single failure that releases these fluids may result in a fire. Sections 23.1182 through 23.1203 address precautions for areas identified in § 23.1181.
Paragraph 23.1181(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1181(b)
No specific policy is available as of December 31, 2002.
Paragraph 23.1181(c)
No specific policy is available as of December 31, 2002.
Paragraph 23.1181(d)
Can the guidance in § 23.1181 through § 23.1203 be applied to other systems that use combustible materials other than combustion heaters?
Yes, the guidance provided can and should be considered when certificating other equipment using combustible materials. Examples of these systems include the following:
1. Smoke, alcohol and dispensing systems that might carry flammable fluids;
2. Liquid cargo tanks that carry flammable fluids; and
3. Other systems that produce heat/flames such as pyrotechnic systems for rainmakers, flares, chaff dispensers.
23.1182 Nacelle areas behind firewalls (Amendment 23-14)
CAR 3 Cross-reference: None
ADC Cross-reference: 5.64
What are the acceptable means of compliance with § 23.1182?
In general, compliance with § 23.1182 must be shown by tests that demonstrate the fireresistant and fireproof properties of the components and their installation. Consideration should be given to component temperature limits, structural properties at elevated temperatures, and the possibility of gaseous emissions from heated components entering the cabin when finding compliance.
Related Material
AC 20-135, Powerplant Installation and Propulsion System Component Fire Protection Test Methods, Standards, and Criteria
AC 20-107A, Composite Aircraft Structure
23.1183 Lines, fittings, and components (Amendment 23-51)
CAR 3 Cross-reference: 3.638
ADC Cross-reference: 5.65
Related Material
AC 20-107A, Composite Aircraft Structure
AC 20-135, Powerplant Installation and Propulsion System Component Fire Protection Test Methods, Standards, and Criteria
Paragraph 23.1183(a)
ADC Cross-reference: 5.65(a)
What is the intent of § 23.1183(a)?
The intent of § 23.1183(a) is to ensure that lines and components in the fire zone carrying flammable fluids do not fail in a manner that contributes additional fuel to a fire.
Compliance with this rule is demonstrated by testing the lines and components under the conditions expected in the event of a fire. Conditions such as worst-case flow rates of fluids and air, lowest dispatchable fluid quantities, and highest fluid and air temperatures should be considered as test parameters.
Can the fire prevention certification of the engine components under 14 CFR part 33, § 33.17 be used to show compliance with § 23.1183?
Components certified with the engine under § 33.17 may or may not meet the requirements in § 23.1183 for a specific airplane installation, depending upon the test/analysis performed to certify them. In particular, the test conditions, such as fluid flow rates and quantities used during the part 33 certification, may not be representative of the conditions expected during a fire in the airplane fire zone. Consequently, the components approved during engine type certification can only be used for compliance with the part 23 installation requirements when the test conditions were equal to or more severe than those expected for the installation. Coordination with the engine manufacturer is generally required to determine the test conditions applicable to the original certification of the components.
To what extent must components be shielded?
The intent of this requirement is to prevent leaking flammable fluids from contacting ignition sources, including hot surfaces and components that produce electrical arcs.
Compliance with this paragraph has been shown by installation of shrouds around the entire high-pressure fuel manifold, installation of shrouds around only the fittings, and installation of spray shields to deflect leaking fuel away from hot surfaces. The level of shielding necessary depends upon the type of leaks possible and the ignition sources.
Shielding should be provided for any component that would be an ignition source if contacted by leaking flammable fluid.
It is possible to have complex shroud arrangements that are difficult to maintain and result in increased incidence of leaks. In addition, sharp spray shield edges may cause damage to fuel lines. Therefore, it is important to carefully consider both the benefits and potential hazards of a given shielding configuration.
Related Material
AC 23-2, Flammability Tests
Paragraph 23.1183(b)
ADC Cross-reference: 5.65(b)
No specific policy is available as of December 31, 2002.
23.1189 Shutoff means (Amendment 23-43)
CAR 3 Cross-reference: None
ADC Cross-reference: 5.67
Related Material
AC 20-135, Powerplant Installation and Propulsion System Component Fire Protection Test Methods, Standards, and Criteria
Paragraph 23.1189(a)
ADC Cross-reference: 5.67(a), 5.67(b), 5.67(c), 5.67(d), 5.67(e), 5.67(f)
What are the typical means of complying with § 23.1189?
The intent of § 23.1189 is to provide a means to shut off lines containing flammable fluids in the event of a fire in the fire zone to prevent hazardous quantities of fluid from entering into and feeding a fire in the zone. Typically, shutoff valves or flow prevention means located outside the engine fire zone have been used on fuel supply, hydraulic, external oil supply, and deicer lines. If shutoff valves are located within the fire zone, the valves as well as their actuation means, including wiring or cables, are required to be fireproof.
What is considered a hazardous quantity?
The quantity that is considered hazardous depends on the particular engine installation design. It is important to consider the potential fuel, the worst-case state of the fluid, such as mist, and the other fuel sources feeding the fire during the fire event. Ultimately, the intent is to limit the potential fuel sources for the fire such that it loses intensity and self-extinguishes.
Paragraph 23.1189(b)
ADC Cross-reference: 5.67(g)
No specific policy is available as of December 31, 2002.
Related Material
AC 23-2, Flammability Tests
AC 23-8B, Flight Test Guide for Certification of Part 23 Airplanes 170
Paragraph 23.1189(c)
ADC Cross-reference: None
No specific policy is available as of December 31, 2002.
23.1191 Firewalls (Amendment 23-51)
CAR 3 Cross-reference: 3.623, 3.624
ADC Cross-reference: 5.68
Related Material
AC 23-2, Flammability Tests
AC 20-135, Powerplant Installation and Propulsion System Component Fire Protection Test Methods, Standards, and Criteria
Paragraph 23.1191(a)
ADC Cross-reference: 5.68(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1191(b)
ADC Cross-reference: 5.68(b)
No specific policy is available as of December 31, 2002.
Paragraph 23.1191(c)
ADC Cross-reference: 5.68(c)
No specific policy is available as of December 31, 2002.
Paragraph 23.1191(d)
Reserved.
Paragraph 23.1191(e)
ADC Cross-reference: 5.68(d)
No specific policy is available as of December 31, 2002.
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.