23.1103 Induction system ducts (Amendment 23-43)
CAR 3 Cross-reference: 3.611
ADC Cross-reference: 5.47
Paragraph 23.1103(a)
ADC Cross-reference: 5.47(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1103(b)
ADC Cross-reference: 5.47(b)
No specific policy is available as of December 31, 2002.
Paragraph 23.1103(c)
ADC Cross-reference: None
No specific policy is available as of December 31, 2002.
Paragraph 23.1103(d)
ADC Cross-reference: None
No specific policy is available as of December 31, 2002.
Paragraph 23.1103(e)
ADC Cross-reference: None
No specific policy is available as of December 31, 2002.
Paragraph 23.1103(f)
ADC Cross-reference: None
No specific policy is available as of December 31, 2002.
23.1105 Induction system screens (Amendment 23-51)
CAR 3 Cross-reference: 3.612
ADC Cross-reference: 5.48
Paragraph 23.1105(a)
ADC Cross-reference: 5.48(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1105(b)
ADC Cross-reference: 5.48(b)
No specific policy is available as of December 31, 2002.
Paragraph 23.1105(c)
ADC Cross-reference: 5.48(c)
No specific policy is available as of December 31, 2002.
Paragraph 23.1105(d)
ADC Cross-reference: 5.48(d)
No specific policy is available as of December 31, 2002.
23.1107 Induction system filters (Amendment 23-51)
CAR 3 Cross-reference: None
ADC Cross-reference: None
This guidance may be used for Airship Certification as applicable.
Paragraph 23.1107(a)
What should be considered in the design of induction system filters to comply with § 23.1107?
The filter media, gasket materials, and adhesives used in the induction system should be resistant to fuel, oil, water, cleaning materials, and other engine/airplane fluids in the powerplant installation. They should be flame resistant and should not deteriorate from exposure to engine compartment temperatures.
Paragraph 23.1107(b)
What design features should be considered for filter installations?
Design the filter installation to preclude the release of pieces of the filter and/or gasket material into the intake airstream. These failures are critical as they can result in a power loss. Consider the performance of the filter under the operating conditions of the installation such as rain impingement at airplane speeds. One methodology is to provide screens or other restraints to prevent failed pieces from moving downstream and interfering with the fuel metering components.
23.1109 Turbocharger bleed air system (Amendment 23-42)
CAR 3 Cross-reference: None
ADC Cross-reference: None
Paragraph 23.1109(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1109(b)
No specific policy is available as of December 31, 2002.
23.1111 Turbine engine bleed air system (Amendment 23-17)
CAR 3 Cross-reference: None
ADC Cross-reference: 5.49
Paragraph 23.1111(a)
ADC Cross-reference: 5.49(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1111(b)
ADC Cross-reference: 5.49(b)
How can the bleed air effects on the engine and airplane be established?
The engine manufacturer provides information on the engine bleed air limits. This information should be used as a starting point for determining the effects on the installed engine and the airplane that are usually established through testing. It is important not to exceed the certificated engine limits as this could invalidate the engine certification for the installation required in § 23.903(a)(1).
Paragraph 23.1111(c)
ADC Cross-reference: 5.49(c)
No specific policy is available as of December 31, 2002.
EXHAUST SYSTEM
23.1121 General (Amendment 23-51)
CAR 3 Cross-reference: 3.615
ADC Cross-reference: 5.50
Are there any general guidelines for exhaust system installations?
Use the following guidelines for exhaust system installations:
1. Provide sufficient clearance and/or heat shielding between exhaust components and spark plugs, plug leads, mount isolators, induction systems, engine controls, fuel systems, and other heat-sensitive airframe components.
2. The exhaust system should be accessible for inspections. Adequately support all exhaust components such as tail pipes, heat exchangers, and mufflers.
3. Provide slip joints or other suitable components in the exhaust system to address thermal expansion and engine movement. Locate any such components so minor leakage does not impinge on components or contaminate the cabin air.
Related Material
AC 20-135, Powerplant Installation and Propulsion System Component Fire Protection Test Methods, Standards, and Criteria
Paragraph 23.1121(a)
ADC Cross-reference: 5.50(a)
What are acceptable means of compliance with § 23.1121(a)?
Compliance with § 23.1121(a) should be demonstrated through testing using any acceptable carbon monoxide detection method. The test should be conducted with the airplane’s heater system in operation if there is any possibility of the system containing carbon monoxide and with aircraft thermal deicing systems, if installed, in full operation.
The effect of different airplane configurations and flight and ground conditions on the induction of carbon monoxide into the passenger cabin should be considered in establishing the test procedures. Flight test guidance is provided in chapter 166 of AC 23-8B.
Is a system that employs a carbon monoxide (CO) detector to warn the pilot of unsafe concentrations during normal operations acceptable to show compliance with § 23.1121(a)?
No, a system with a CO detector to warn the pilot of unsafe concentrations is not sufficient to show compliance. Section 23.1121(a) requires that the system be designed to prevent CO contamination of the personnel compartment in the first place.
Related Material
AC 20-32B, Carbon Monoxide (CO) Contamination in Aircraft—Detection and Prevention
AC 23-8B, Flight Test Guide for Certification of Part 23 Airplanes
Paragraph 23.1121(b)
ADC Cross-reference: 5.50(b)
No specific policy is available as of December 31, 2002.
Paragraph 23.1121(c)
ADC Cross-reference: 5.50(c)
No specific policy is available as of December 31, 2002.
Related Material
AC 23-2, Flammability Tests
AC 20-107A, Composite Aircraft Structure
Paragraph 23.1121(d)
ADC Cross-reference: 5.50(d)
No specific policy is available as of December 31, 2002.
Paragraph 23.1121(e)
ADC Cross-reference: 5.50(f)
No specific policy is available as of December 31, 2002.
Paragraph 23.1121(f)
ADC Cross-reference: 5.50(e)
No specific policy is available as of December 31, 2002.
Paragraph 23.1121(g)
ADC Cross-reference: 5.50(g)
No specific policy is available as of December 31, 2002.
Paragraph 23.1121(h)
ADC Cross-reference: 5.50(h)
No specific policy is available as of December 31, 2002.
Paragraph 23.1121(i)
ADC Cross-reference: None
No specific policy is available as of December 31, 2002.
23.1123 Exhaust system (Amendment 23-43)
CAR 3 Cross-reference: 3.616
ADC Cross-reference: 5.51
Related Material
AC 20-135, Powerplant Installation and Propulsion System Component Fire Protection Test Methods, Standards, and Criteria
Paragraph 23.1123(a)
ADC Cross-reference: 5.51(a)
What are the general considerations relative to compliance with § 23.1123(a)?
Exhaust components are typically constructed of stainless steel or steel alloys of appropriate wall thickness to withstand the highly corrosive high temperature exhaust gases in order to comply with § 23.1123(a). Proper material selection and corrosion protective design should be performed and validated during certification. Analysis and validation tests are done to ensure thermal and structural integrity and to ensure thermal expansion does not cause structural overload, failure, unintentional contact of adjacent components, or hazardous heating of surrounding components. The thermal expansion analysis and test should be done at the maximum in-service temperature excursions expected for the installation.
Related Material
AC 23-2, Flammability Tests
Paragraph 23.1123(b)
ADC Cross-reference: 5.51(b)
What loading cases are typically considered?
Typically, the worst-case static design load conditions are either the inertia loads from an emergency impact, such as that specified in § 23.561, or combined loading from thermal expansion, in-flight deflections, and internal exhaust gas flow. The exhaust system components should be designed and supported to avoid critical frequencies and to minimize the effects of the vibration environment. Flight test vibration surveys may be necessary to properly define or validate the critical modes and vibration environment. In addition, the strength reduction in the system materials at the operating and worst-case 145
temperatures should be properly accounted for during the design and structural substantiation.
Paragraph 23.1123(c)
ADC Cross-reference: 5.51(c)
What should be considered in the design of an exhaust system with components having relative motion between them?
Section 23.1123(c) requires that exhaust system components with relative motion between them have a means for flexibility. This is typically provided by different types of flexible joints employing metal bellows, metal rings, or carbon rings. These components typically have limited lives because of the high temperatures and corrosive nature of the exhaust gases. For this reason, experience has shown that it is good to design the system to avoid relative motion between components to eliminate the use of these failure prone components.
23.1125 Exhaust heat exchangers (Amendment 23-17)
CAR 3 Cross-reference: 3.617, 3.618
ADC Cross-reference: 5.52
Paragraph 23.1125(a)
ADC Cross-reference: 5.52(a)
Does the heat exchanger require constant cooling airflow?
Yes, the intent of § 23.1125(a)(3) is to require cooling airflow when and where the exhaust gasses are in contact with the heat exchanger.
Paragraph 23.1125(b)
ADC Cross-reference: 5.52(b)
No specific policy is available as of December 31, 2002.
POWERPLANT CONTROLS AND ACCESSORIES
23.1141 Powerplant controls: General (Amendment 23-51)
CAR 3 Cross-reference: 3.627
ADC Cross-reference: 5.53
Related Material
AC 20-135, Powerplant Installation and Propulsion System Component Fire Protection Test Methods, Standards, and Criteria
AC 23-8B, Flight Test Guide for Certification of Part 23 Airplanes
Paragraph 23.1141(a)
ADC Cross-reference: 5.53(a)
Do single-lever power controls comply with § 23.1141?
Airplanes may be equipped with single-lever power controls (a control arrangement allowing the engine throttle, propeller pitch control, and possibly mixture control to operate via one lever) where the propeller pitch varies with engine r.p.m. by means of a mechanical cam or slider device as a function of throttle position. Any such propeller control system must be shown to have the level of integrity and reliability of a typical installation with independent propeller and throttle controls. Specific guidance for this is contained in the related material listed below under § 23.777.
Related Material
AC 23-17A, Systems and Equipment Guide for Certification of Part 23 Airplanes
Paragraph 23.1141(b)
ADC Cross-reference: 5.53(b)
No specific policy is available as of December 31, 2002.
Paragraph 23.1141(c)
ADC Cross-reference: 5.53(c)
No specific policy is available as of December 31, 2002.