Paragraph 23.1141(d)
ADC Cross-reference: 5.53(d)
No specific policy is available as of December 31, 2002.
Paragraph 23.1141(e)
ADC Cross-reference: 5.53(e)
Are there any special considerations for special purpose, restricted category, singleengine agricultural airplanes using the normal category requirements of part 23 as a certification basis?
It is acceptable for special purpose, restricted category, single-engine agricultural airplanes using the normal category requirements of part 23 as a certification basis to delete the phrase “or probable combination thereof” when demonstrating compliance with the rule as restated below.
This regulation currently reads as follows:
For turbine engine powered airplanes, no single failure or malfunction, or probable combination thereof, in any powerplant control system, may cause the failure of any powerplant function necessary for safety.
Paragraph 23.1141(f)
ADC Cross-reference: 5.53(f)
No specific policy is available as of December 31, 2002.
Related Material:
AC 23-2, Flammability Tests
Paragraph 23.1141(g)
ADC Cross-reference: 5.53(g)
No specific policy is available as of December 31, 2002.
23.1142 Auxiliary power unit controls (Amendment 23-43)
CAR 3 Cross-reference: None
ADC Cross-reference: None
No specific policy is available as of December 31, 2002.
23.1143 Engine controls (Amendment 23-51)
CAR 3 Cross-reference: 3.628
ADC Cross-reference: 5.54
Paragraph 23.1143(a)
ADC Cross-reference: 5.54(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1143(b)
ADC Cross-reference: 5.54(c)
No specific policy is available as of December 31, 2002.
Paragraph 23.1143(c)
ADC Cross-reference: 5.54(b)
No specific policy is available as of December 31, 2002.
Paragraph 23.1143(d)
ADC Cross-reference: 5.54(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1143(e)
ADC Cross-reference: None
This guidance may be used for Airship Certification as applicable.
No specific policy is available as of December 31, 2002.
Related Material:
AC 20-136, Protection of Aircraft Electrical/Electronic Systems Against the Indirect Effects of Lightning
Paragraph 23.1143(f)
ADC Cross-reference: 5.54(d)
No specific policy is available as of December 31, 2002.
Paragraph 23.1143(g)
ADC Cross-reference: None
This guidance may be used for Airship Certification as applicable.
What is the origin of this requirement?
This regulation was introduced with Amendment 23-43 on May 10, 1993, and originated as a proposal in response to the Small Airplane Airworthiness Review conducted in 1983 and 1984. This proposal was forwarded by the National Transportation Safety Board as a response to a study of single-engine aircraft accidents involving separation of the throttle linkages with subsequent loss of propulsive power. The original wording of the proposal stated the following:
“(f) A means must be provided to assure that if throttle linkage separation occurs in a single engine airplane, the fuel control will be automatically positioned at:
(1) The full throttle position for agricultural airplanes.
(2) An intermediate throttle position for other airplanes which will allow the pilot to maintain level flight in the cruise configuration.”
A review of the minutes of the Small Airplane Airworthiness Review Conference held in St. Louis, Missouri on October 22-26, 1984, reveals that the discussion was centered around the appropriate settings for different airplane classifications.
The rule as proposed and subsequently accepted in Amendment 23-43 states the following:
“(g) For reciprocating single-engine airplanes, each power or thrust control must be designed so that if the control separates at the engine fuel metering device, the airplane is capable of continued safe flight and landing.”
The generally accepted definition of “engine fuel metering device” is a device that controls the amount of fuel flow (fuel control in the original proposal) to the engine based on throttle position. The throttle refers to the device the pilot uses to set the desired engine power level.
The intent of the rule is to keep the engine supplied with a sufficient amount of fuel to allow continued safe flight and landing in the event of a control system failure that prevents the pilot from setting the appropriate power level (i.e., fuel flow rate).
Can a design that maintains positive retention of the linkage be used to show compliance with § 23.1143(g)?
A number of Equivalent Level of Safety (ELOS) findings have been issued that have allowed linkage designs incorporating positive retention means when complying with § 23.1143(g). These ELOS findings have required a higher level of attachment reliability, establishment of mandatory inspection intervals, inspection procedures, and replacement criteria for the attachments.
23.1145 Ignition switches (Amendment 23-43)
CAR 3 Cross-reference: 3.629
ADC Cross-reference: 5.55
Paragraph 23.1145(a)
ADC Cross-reference: 5.55(a)
Does § 23.1145 apply to turbine and reciprocating engines?
This paragraph applies to both turbine and reciprocating engines. The required ignition switch may be used to select any position such as continuous, automatic, on, or off.
Paragraph 23.1145(b)
ADC Cross-reference: 5.55(b)
Is it possible to integrate the required shutoff switch with the engine power lever?
On turbine engines incorporating an auto-relight system, one acceptable means of complying with the shutoff provision would be to have the shutoff switch activated by the power lever. Adequate instruction should be available to the pilot.
Paragraph 23.1145(c)
ADC Cross-reference: 5.55(c)
No specific policy is available as of December 31, 2002.
23.1147 Mixture controls (Amendment 23-43)
CAR 3 Cross-reference: 3.630
ADC Cross-reference: 5.56
Paragraph 23.1147(a)
ADC Cross-reference: 5.56
No specific policy is available as of December 31, 2002.
Paragraph 23.1147(b)
ADC Cross-reference: None
This guidance may be used for Airship Certification as applicable.
Can a design that maintains positive retention of the linkage be used to show compliance with § 23.1147(b)?
A number of Equivalent Level of Safety (ELOS) findings have been issued that have allowed linkage designs incorporating positive retention means when complying with § 23.1147(b). These ELOS findings have required a higher level of attachment reliability, establishment of mandatory inspection intervals, inspection procedures, and replacement criteria for the attachments.
23.1149 Propeller speed and pitch controls (Original)
CAR 3 Cross-reference: None
ADC Cross-reference: 5.57
Paragraph 23.1149(a)
ADC Cross-reference: 5.57(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1149(b)
ADC Cross-reference: 5.57(b)
No specific policy is available as of December 31, 2002.
23.1153 Propeller feathering controls (Amendment 23-51)
CAR 3 Cross-reference: None
ADC Cross-reference: 5.58
No specific policy is available as of December 31, 2002.
Related Material
AC 23-8B, Flight Test Guide for Certification of Part 23 Airplanes
23.1155 Turbine engine reverse thrust and propeller pitch settings below the flight regime (Amendment 23-7)
CAR 3 Cross-reference: None
ADC Cross-reference: None
This guidance may be used for Airship Certification as applicable.
What is the history of this requirement?
The FAA has long recognized the hazard of inadvertent operation of propeller reversing systems. Prior to the commercial use of turbine-powered airplanes, a few reciprocating engine powered airplane designs included propeller-reversing systems and were addressed by Civil Air Regulations (CAR) paragraph 4b. Section 23.1155 was added to part 23 with Amendment 23-7 (1969) and applied to turbine-powered airplanes only. In the event of a part 23 reciprocating engine powered airplane using propeller-reversing systems, special conditions should be developed.
If the possibility of inadvertent operation can be shown to be remote, does it comply with § 23.1155?
No, the intent is to prevent inadvertent operation in the beta mode, even if the possibility of inadvertent operation is remote. If an operation or feature of the design can allow inflight, inadvertent placement of the control below the flight regime, the design does not comply with the regulation. The design should be evaluated considering the types of operations that will be seen in service, and it should consider items such as hardware wear modes or maintenance issues that may cause the control to be unintentionally placed or creep into the beta regime over time.
Amendment 23-7 added § 23.1155 requiring that operations of the propeller controls at pitch settings below the flight regime have a means to prevent inadvertent operation. For airplanes with a certification basis before Amendment 23-7 that are modified to add inflight beta capability, the provisions of § 21.101(b) should be used to evaluate the possible unsafe nature of inadvertent operation of propellers in the beta regime. If it is determined that such operation is unsafe, the issue may be addressed by showing compliance with § 23.1155.
What is an acceptable means of compliance with § 23.1155 relative to intentional inflight operation?
On all future type certification projects, the flight manuals should include the appropriate operational limitations and consequence statement for in-flight beta operation.
Is a Beta Lock-out system acceptable for compliance with § 23.1155?
To add an assurance that in-flight beta will not occur, some airplanes have incorporated lock-out systems. These systems remove the ability to do this operation in flight, even if intentionally commanded. It is important to note that the installation of a beta lock-out system cannot be used instead of the design requirements of § 23.1155 compliance.
Also, in some cases, propeller beta operation is used to show compliance with stopping distances in part 23, subpart B. Under subpart B, when means other than wheel brakes are used for determining stopping distances, the means must be ”safe and reliable.” If beta operation is used to show compliance with stopping distances, the reliability of a system that would prevent in-flight beta operation must be such that this capability, when required, will be available to comply with subpart B, and § 21.21(b)(2) or § 21.101(b).
With a system safety analysis, the applicant can determine the required reliability level for the beta lock-out system based on the hazard level (for example, § 23.1309 compliance).
Therefore, for new type certificated airplanes that have a beta lock-out system incorporated or previously certificated airplanes that add a beta lock-out system, the applicant should perform a system safety analysis of the installation of this system. This analysis should consider hazards such as the inability to command beta on one engine of a multiengine airplane. For example, if beta is commanded on both engines during landing roll-out, but only one propeller goes into beta mode, this might adversely affect ground controllability.
23.1157 Carburetor air temperature controls (Original)
CAR 3 Cross-reference: 3.634
ADC Cross-reference: 5.59
No specific policy is available as of December 31, 2002.