AC 23.1311-1A

Subject: INSTALLATION OF ELECTRONIC DISPLAYS IN PART 23 AIRPLANES Date: 3/12/99 Initiated By: ACE-100 AC No: 23.1311-1A Change:

1. PURPOSE.

This advisory circular (AC) provides an acceptable means, but not the only means, of showing compliance with Title 14 of the Code of Federal Regulations (14 CFR) applicable to the installation of electronic displays in Part 23 airplanes. This material is neither mandatory nor regulatory in nature and does not constitute a regulation.

2. CANCELLATION.

AC 23.1311-1, Installation of Electronic Display Instrument Systems in Part 23 Airplanes, dated June 11, 1993, is canceled.

3. RELATED REGULATIONS AND DOCUMENTS.

3.1 REGULATORY SECTIONS:

These acceptable means of compliance refer to the applicable sections of 14 CFR Part 23.

The corresponding paragraphs of the former Civil Air Regulations (CAR) are shown in parenthesis for airplanes certificated under CAR, Paragraph 3.

§ 23.771 (3.381) Pilot compartment.

§ 23.773 (3.382) Pilot compartment view.

§ 23.777 (3.3841) Cockpit controls.

§ 23.901 (3.411) Powerplant: Installation.

§ 23.1301 (3.651 Equipment: Function and installation.

and 3.652)

2 § 23.1303 Flight and navigation instruments.

(3.655(a)) § 23.1305 Powerplant instruments.

(3.655(b)) § 23.1309 Equipment, systems, and installations.

§ 23.1311 Electronic display instrument systems.

§ 23.1321 (3.661 Arrangement and visibility.

and 3.662) § 23.1322 Warning, caution, and advisory lights.

§ 23.1323 (3.663) Airspeed indicating system.

§ 23.1326 Pitot heat indication systems.

§ 23.1331 (3.668) Instruments using a power source.

§ 23.1335 (3.669) Flight director systems.

§ 23.1337 (3.6.71, Powerplant instruments installation.

(3.672, 3.673, and 3.674) § 23.1351 (3.681, Electrical Systems and Equipment: General.

3.682, and

3.685) § 23.1353 (3.683) Storage battery design and installation.

§ 23.1357 (3.690, Circuit protective devices.

3.691, and

3.692) § 23.1359 Electrical system fire protection.

§ 23.1361 Master switch arrangement.

§ 23.1365 (3.693) Electric cables and equipment.

§ 23.1367 (3.694 Switches.

and 3.695) § 23.1381 (3.696 Instrument lights.

and 3.697) § 23.1431 (3.721) Electronic equipment.

§ 23.1501 (3.735 Operating Limitations and Information: General.

and 3.737) § 23.1529 Instructions for Continued Airworthiness.

§ 23.1541 (3.755) Markings and Placards: General.

§ 23.1543 (3.756) Instrument markings: General.

§ 23.1545 (3.757) Airspeed indicator.

§ 23.1549 (3.759) Powerplant and auxiliary power unit instruments.

§ 23.1551 (3.760) Oil quantity indicator.

§ 23.1553 (3.761) Fuel quantity indicator.

§ 23.1555 (3.762) Control markings.

§ 23.1559 Operating limitations placard.

§ 23.1581 (3.777) Airplane Flight Manual and Approved Manual Material: General.

3 § 23.1583 (3.761 Operating limitations.

and 3.778) § 91.205 Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements.

§ 121.305 Flight and navigational equipment.

§ 135.149 Equipment requirements: General.

§ 135.159 Equipment requirements: Carrying passengers under VFR at night or under VFR over-the-top conditions.

§ 135.163 Equipment requirements: Aircraft carrying passengers under IFR.

Note: Part 23 contains many sections that indicate the need for an indicator or a warning.

These sections may be met with lights, mechanical, or electro-mechanical means, to which this AC would not apply. However, these sections could also be met by electronic displays. If so, then this AC would apply to those electronic displays.

3.2 ADVISORY CIRCULARS AND RELATED DOCUMENTS :

Copies of current editions of the following publications may be obtained free of charge from the U.S. Department of Transportation, Subsequent Distribution Office, Ardmore East Business Center, 3341 Q 75th Avenue, Landover, MD 20785:

AC 20-115B Radio Technical Commission for Aeronautics (RTCA), Inc., RTCA/DO-178B AC 20-136 Protection of Aircraft Electrical/Electronic Systems Against the Indirect Effects of Lightning AC 21-16D RTCA, Inc. Document DO-160C AC 23-15 Small Airplane Certification Compliance Program AC 23.1309-1C Equipment, Systems, and Installations in Part 23 Airplanes AC 25-11 Transport Category Airplane Electronic Display Systems DOT/FAA/CT-96/1 Human Factors Design Guide DOT/FAA/AAR-95/3 FAA Aircraft Certification Human Factors and Operations Checklist for Standalone GPS Receivers

4 Copies of current editions of the following AC’s may be purchased from the Superintendent of Documents, P. O. Box 371954, Pittsburgh, PA l5250-7954. Make check or money order payable to the Superintendent of Documents:

AC 20-88A Guidelines on the Marking of Aircraft Powerplant Instruments (Displays) AC 23-8A and Flight Test Guide for Certification of Part 23 Airplanes AC 23-8A, Change 1

3.3 TECHNICAL STANDARD ORDER:

A copy of the current edition of the following publication may be obtained from the Federal Aviation Administration, Aircraft Certification Service, Aircraft Engineering Division, Technical Programs and Continued Airworthiness Branch—AIR-120, 800 Independence Avenue, SW, Washington, DC 20591:

TSO-C113 Airborne Multipurpose Electronic Displays

3.4 INDUSTRY DOCUMENTS:

Copies of current editions of the following publications may be obtained as follows and are an excellent resource material for additional information, guidance, and standards:

3.4.1 The RTCA documents are available from RTCA, Inc., Suite 1020, 1140 Connecticut Avenue, NW, Washington, DC 20036-4001:

RTCA/DO-160D Environmental Conditions and Test Procedures for Airborne Equipment RTCA/DO-178A/B Software Considerations in Airborne Systems and Equipment Certification RTCA/DO-187 Minimum Operational Performance Standards for Airborne Area Navigation Equipment using Multi-Sensor Inputs

3.4.2 The documents are available from Society of Automotive Engineers (SAE), Inc., 400 Commonwealth Drive, Warrendale, PA 15096-0001:

ARP 268G Location and Actuation of Flight Deck Controls for Transport Aircraft ARP 450D Flight Deck Visual, Audible, and Tactile Signals

5 ARP 571C Flight Deck Controls and Displays for Communication and Navigation Equipment for Transport Aircraft ARP 926A/B Fault/Failure Analysis Procedure ARP 1068B Flight Deck Instrumentation, Display Criteria and Associated Controls for Transport Aircraft AIR 1093 Numeral, Letter and Symbol Dimensions for Aircraft Instrument Displays ARP 1161 Crew Station Lighting—Commercial Aircraft ARP 1782 Photometric and Colorimetric Measurement Procedures for Airborne Direct View CRT Displays ARP 1834/A Fault/Failure Analysis for Digital Systems and Equipment ARP 1874 Design Objectives for CRT Displays for Part 25 (Transport) Aircraft ARP 4032 Human Engineering Considerations in the Application of Color to Electronic Aircraft Displays ARP 4033 Pilot System Integration ARP 4067 Design Objectives for CRT Displays for Part 23 Aircraft ARP 4101 Flight Deck Layout and Facilities ARP 4102 Flight Deck Panels, Controls, and Displays ARP 4102/7 Electronic Displays ARP 4103 Flight Deck Lighting for Commercial Transport Aircraft ARP 4105 Abbreviations and Acronyms for Use on the Flight Deck (Revision A) ARP 4256 Design Objectives for Liquid Crystal Displays for Part 25 (Transport) Aircraft ARP 4260 Photometric and Colorimetric Measurement Procedures for Airborne Flat Panel Displays (When Released)

6 ARP 4754 Certification Considerations for Highly Integrated or Complex Aircraft Systems ARP 4761 Guidelines and Methods for Conducting the Safety Assessment Process on Civil Airborne Systems and Equipment AS 8034 Minimum Performance Standard for Airborne Multipurpose Electronic Displays AS 8055 Minimum Performance Standard for Airborne Head Up Display (HUD) ARP 5287 Optical Measurement Procedures for Airborne HUD

3.4.2.1 NOTE: Aerospace Recommended Practice’s (ARP) 926A and 1834 have historically provided appropriate guidance for safety assessment of Part 23 airplanes. ARP’s 926A and 1834 have been revised by ARP’s 926B and 1834A, respectively. The scope sections of ARP’s 926B and 1834A state that ARP 4761 provides updated methods and processes for use on civil aircraft safety assessment. When performing civil aircraft safety assessments, we recommend using ARP 4761, instead of ARP’s 926B or 1834A. If ARP’s 926B and/or 1834A are used, consider specific processes addressed in ARP 4761.

3.4.2.2 ARP’s 4754 and 4761 state that these documents describe guidelines and methods of performing the safety assessment for certification of civil aircraft. They further state the guidance material in these Aerospace Recommended Practices (ARP’s) were developed in the context of 14 CFR Part 25 and the Joint Aviation Requirements 25 (JAR 25). It is primarily associated with showing compliance with Part 25, § 25.1309/JAR 25.1309. A subset of this material may be applicable to non-25.1309 equipment. However, some of the processes included are not necessary or appropriate for Part 23 airplanes. ARP 4754 contains tutorial information on applying specific engineering methods that an applicant may wish to utilize in whole or in part.

NOTE: This AC is not intended to constrain the applicant to the use of these documents in the definition of their particular methods of satisfying the objectives of this AC.

However, these documents do contain material and methods of performing the System Safety Assessment that an applicant may choose to use.

3.5 The Underwriter’s Laboratories (UL), Inc., document listed below can be obtained from Global Engineering Documents, 15 Inverness Way East, Englewood, CO 80112:

UL 1418 Implosion Protected Cathode Ray Tubes for Television Type Appliances, Revised 1992

4. BACKGROUND.

Title 14 CFR Part 23 was amended by Amendment 23-41, effective November 26, 1990.

This amendment established airworthiness standards, in § 23.1311, for the installation of electronic display instrument systems in normal, utility, acrobatic, and commuter category airplanes. At the time the first electronic displays were developed, they were direct replacements for the conventional electromechanical components. Extensive integration of information is found in later designs. Prior to Amendment 23-41, most electronic display instrument systems were approved for installation in Part 23 airplanes by means of special conditions. Title 14 CFR Part 23 was further amended by Amendment 23-49, effective March 11, 1996, to harmonize the Federal Aviation Regulations with the Joint Aviation Requirements (JAR). The last revision of § 23.1311 removed redundant requirements and clarifies which secondary instruments are required, including the visibility requirements for those instruments.

5. APPLICABILITY.

This AC is generally applicable only to an applicant seeking issuance of a type certificate (TC), an amended type certificate (ATC), or a supplemental type certificate (STC) for the approval of a new type design or a change in the type design.

6. DEFINITIONS.

Refer to AC 23.1309-1C for the appropriate definitions.

7. DISPLAY DESCRIPTION.

The following paragraphs give a very brief description of an electronic display. They do not cover all the capabilities and details of these displays or the information presented on them.

7.1 General:

7.1.1 Electronic displays have replaced many of the traditional electromechanical and analog instruments, which provide flight and powerplant information. The major display technologies now used are multicolor cathode-ray tubes (CRT’s), liquid crystal displays (LCD’s), electroluminescence, plasma, and light emitting diodes (LED’s). The initial electronic displays mimicked the electromechanical flight and powerplant instruments.

Colors, symbols, and formats resemble the conventional instruments.

7.1.2 Human Factors (HF) Considerations for Design of Electronic Displays.

Electronic displays can be programmed to provide many innovative display flexibilities and features. Technology improvements in display design and integration can enhance pilot performance and improve situation awareness provided that these innovations are

8 designed using sound processes and appropriate design criteria that adequately account for human performance. The process should to be in place at the beginning of the design effort to be of benefit. An example of an acceptable process can be found in SAE ARP 4033, Pilot System Integration. This document provides an example of a structured approach that will ensure development, verification, and application of all human factors requirements to enhance overall system performance and integration. An example of appropriate human factors design criteria can be found in a multitude of places; however, one good source of data generated by the FAA is the “Human Factors Design Guide,” document number DOT/FAA/CT-96/1. This document contains appropriate human factors guidance for displays and human computer interface and is available on the internet through the FAA website. An example of an appropriate HF evaluation for electronic equipment can be found in FAA report DOT/FAA/AAR-95/3, titled “FAA Aircraft Certification Human Factors and Operations Checklist for Standalone GPS Receivers.”

7.1.3 A Functional Hazard Assessment (FHA) should be performed to identify and classify failure conditions including determining probable combinations of failures. Guidelines and reference material that can be used in performing an FHA can be found in AC 23.1309-1C.

7.2 Configuration:

Electronic displays may be installed in several configurations. A basic electronic display may provide only one flight or powerplant parameter, while more sophisticated systems integrate many parameters on one electronic display. One of the major design goals for these systems is the elimination of separate conventional gauges, instruments, and annunciators. Recent installations show a trend toward a higher degree of integration, which reduces visual scanning requirements. For example, an integrated primary flight display provides several parameters such as attitude, direction (heading), airspeed, and altitude. Other parameters are also being placed on the primary flight displays, including vertical speed, flight mode annunciators, and other types of guidance cues.

8. FLIGHT, POWERPLANT, AND NAVIGATION DISPLAYS.

8.1 Required Parameters:

Sections 23.1303, 23.1305, 23.1311, and 23.1321, in conjunction with the applicable operating rules (14 CFR Part 91 and Part 135), incorporate flight and powerplant instrument requirements for Part 23 airplanes. The navigation equipment requirements are given in operational rules specified in §§ 91.205, 135.161, and 135.165. Display requirements for navigation information are dependent on the navigation system installed in the aircraft. Instruments and equipment required for flights under Part 91 and Part 135 may be affected by the electronic display installation. These instruments and equipment

9 include gyroscopic bank and pitch, gyroscopic direction, gyroscopic rate-of-turn, slip-skid instruments, and other required communication and navigational equipment. Electronic displays permit presentation of this information on one display. Under these conditions, a failure in the electronic display may affect more than one required display parameter.

8.2 Instrument Function:

8.2.1 Regulations promulgated prior to Amendment 23-41 were based on single-fault or failsafe concepts. A single failure would cause the loss of only one primary instrument function. Only mechanical or electromechanical instruments that function independently for the primary parameter display were envisioned; that is, flight and powerplant instruments were isolated and independent. In some cases, several other instrument functions (indication of the function, display, or indicator) are housed in a common case.

Section 23.1309, Amendment 23-41, approved more advanced, complex systems which perform critical functions. Amendment 23-41 also incorporated § 23.1311 into 14 CFR Part 23, which provides the standards for electronic displays. Section 23.1311, Amendment 23-49 revised and clarified the secondary instruments and the visibility requirements.

8.2.2 Section 23.1311(b) states that “the electronic display indicators, including their systems and installations, and considering other airplane systems, must be designed so that one display of information essential for continued safe flight and landing will remain available to the crew, without need for immediate action by any pilot for continued safe operation, after any single failure or probable combination of failures.” In general, without considering specific characteristics of an airplane design, information essential to continued safe flight and landing are attitude, airspeed, altitude, direction (track or heading) and any applicable propulsion parameter(s). Major common-mode failures should be addressed. These include such failures induced by software errors, lightning effects, electromagnetic interference, power transients, etc., that could simultaneously affect the display of more than one parameter.

8.3 Aircraft Electrical Power Source:

8.3.1 Each electronic display instrument system should be installed so that it receives electrical power from a bus that provides the necessary reliability per the § 23.1309 safety assessment without jeopardizing other essential or critical electrical loads connected to that bus. The applicant should provide a means indicating when adequate power is available for proper operation of the instrument.

8.3.2 Electronic displays may be sensitive to momentary power interruptions. Use techniques that reduce the momentary power interruptions or design the equipment so momentary power interruptions will not adversely affect the availability or integrity of essential information required for continued safe flight and landing. The category selected from RTCA/DO-160D for momentary power interruptions should be appropriate for the intended use. The attitude display being used by the pilot during the takeoff phase of

10 flight should be usable within one second after a momentary power interruption resulting from an engine failure. Large electrical loads required to restart an engine (e.g., turboprops and small jets) should not affect the availability or integrity of essential information required for continued safe flight and landing.

8.3.3 Each reversionary display should be powered from a source that is independent of the source for the primary display and should function independently from the primary display.

The power source for each reversionary display should provide for uninterrupted operation for at least 30 minutes after failure of the power source for the primary display.

The independent power source may be provided by manual or automatic means. Section

23.1353(h) requires a minimum supply of 30 minutes of electrical power to the essential loads for continued safe flight and landing of the airplane should a complete loss of the primary electrical power generating system occur, including the reversionary displays.

The airplane's primary electrical power includes the airplane's electrical generating system and the airplane's starter battery when only one battery is installed.

8.4 FLIGHT DISPLAYS:

8.4.1 Primary Flight Parameters:

Attitude, airspeed, altitude, and direction (track or heading) are the primary flight parameters required in § 23.1311(a)(3) and (5). The primary flight parameters should be continuously displayed in the pilot’s primary field-of-view. For the purpose of this paragraph, the acceptable primary field-of-view is approximately +/- 30° horizontally from the centerline of the pilot’s seat forward, with the seat adjusted for the pilot’s nominal eye position. Minimal head and eye movement is allowed to evaluate display positions that may fall outside this criterion. Pilot evaluation is required to determine if display positions that fall outside the criterion are acceptable. For additional guidance refer to SAE ARP 1068B listed in paragraph 3.4.2 of this AC. Secondary displays of primary flight parameters may be placed outside the primary field-of-view.

8.4.2 Reversionary Flight Displays (Modes):

Reversionary flight displays are additional displays that can provide a secondary means to provide primary flight parameters.

8.4.2.1 Reversionary flight parameters should be presented by an independent (secondary) display to prevent complete loss of primary flight parameters due to a single failure. Reversionary flight parameters need not be continuously displayed as long as the parameters are available without crewmember action for any single failure or probable combination of failures. Primary parameters displayed continuously on the reversionary displays during critical phases of flight (e.g., example, takeoff, landing, and missed or final approach) are acceptable. Manual activation of reversionary displays through single action by the pilot is acceptable when procedures to activate them are accomplished prior to entering critical phases of flight.

8.4.2.2 Display of primary flight parameters on reversionary (secondary) displays need not be arranged in the basic T-configuration. However, the displays should be legible and usable from the pilot’s position with minimal head movement.

8.4.3 Secondary Instrument:

A secondary instrument is an instrument that provides an additional means of information to the pilot in a different manner than the primary flight information. The secondary instrument, or combination thereof, provides the equivalent information. For additional information see the requirements cited in the reversionary flight displays in paragraph 8.4.2.

8.4.4 Display Usability:

Displays should be located in a position so the pilot(s) can monitor them with minimal head and eye movement between displays. Flight information should be legible, accurate, easily interpreted, sufficiently free of visual cutoff (viewing angle), parallax and distortion, for the pilot to correctly interpret it. The required secondary display(s) for attitude, airspeed, and altitude may be located at the co-pilot’s position if usable from the pilot’s position with minimal head movement.

8.4.5 Display of Attitude:

For flights under IFR conditions in Part 91 and Part 135 operations and under VFR at night for Part 135 operations, attitude information is required. The loss of all attitude information or the presentation of misleading attitude information could result in conditions where the pilot could not continue safe flight and landing of the airplane.

8.4.6 Display of Direction (heading or track):

The loss of direction (heading or track) information could result in reduced capability of the pilot to cope with adverse operating conditions. For flights under IFR conditions, the primary display of the direction parameter may be provided by a stabilized heading indicator. The reversionary display of direction may be provided by a non-stabilized magnetic direction indicator (compass).

8.4.7 Display of Altitude, Airspeed, and Magnetic Compass Information:

When the requirements of § 23.1303 (a), (b), and (c) were adopted into CAR, paragraph 3 and Part 23, it was envisioned that airspeed, altitude, and magnetic compass information would remain available to the pilot upon the loss of the airplane's primary electrical power.

Airspeed and altitude functions were provided by pneumatically driven displays. For electronic displays, § 23.1311(a)(3) requires that the primary display of attitude, airspeed, and altitude not be inhibited in any normal mode of operation. Section 23.1311(a)(5)

12 requires an independent magnetic direction indicator, and either an independent secondary mechanical altimeter, airspeed indicator, and attitude instrument or individual electronic display indicators for the altitude, airspeed, and attitude. Guidance provided in paragraph

8.3 of this AC provides a means of compliance to satisfy the regulatory requirements for reversionary display power sources. Primary altitude or airspeed displays that require electrical power are acceptable, if means are provided for their continued operation upon loss of the airplane's primary electrical power, or if pneumatically driven instruments are available for the pilot's use.

8.4.8 Other Flight Parameters:

8.4.8.1 Rate-of-Turn Instrument:

In accordance with §§ 91.205 and 135.159, a rate-of-turn instrument is not required if a third attitude instrument usable though flight attitudes of 360° of pitch-and-roll is installed in accordance with the instrument requirements prescribed in § 121.305(j).

8.4.8.2 Slip-Skid Instrument:

The slip-skid information is required by §§ 91.205(d)(4) and 135.159(b), as applicable. It is suggested that the slip-skid display be located directly below the rate-of-turn instrument or the attitude display.

8.5 Powerplant Displays:

This section defines a means of presenting powerplant performance and condition information pertaining to the airplane’s operation, and provides guidelines as to when these functions should be displayed to the pilot. In general, there have been two methods used to accomplish this: (1) display raw engine parameters to the pilot for interpretation, or (2) collect powerplant data and have an automatic monitoring system interpret and report the powerplant condition to the pilot. The following evaluation criteria should be used when considering incorporating electronic powerplant displays.

8.5.1. Each airframe, engine, and airframe/engine interface with the operational characteristics of these systems needs to be evaluated by the FAA to determine the primary powerplant parameter requirements. For this evaluation, and as used in this section, a primary powerplant parameter is one needed to start the engine and set and monitor engine power within powerplant limitations.

8.5.2 For multiengine airplanes, arrange the display of powerplant parameters (function) so they are isolated from each other (electronically or mechanically). A failure or malfunction affecting the display or accuracy of any propulsion system parameter for one engine should not cause the loss of display or accuracy of any parameter for the remaining engine(s). If multiple propulsion parameters are integrated on one display, and the display fails, it is acceptable to provide a secondary propulsion parameter display.