Federal Aviation Administration, DOT § 23.1311

INSTRUMENTS: INSTALLATION (b) The electronic display indicators, including their systems and installa- § 23.1311 Electronic display instru- tions, and considering other airplane ment systems. systems, must be designed so that one (a) Electronic display indicators, in- display of information essential for cluding those with features that make continued safe flight and landing will isolation and independence between remain available to the crew, without powerplant instrument systems im- need for immediate action by any pilot practical, must: for continued safe operation, after any (1) Meet the arrangement and visi- single failure or probable combination bility requirements of § 23.1321. of failures. (2) Be easily legible under all lighting (c) As used in this section, ‘‘instru- conditions encountered in the cockpit, ment’’ includes devices that are phys- including direct sunlight, considering ically contained in one unit, and de- the expected electronic display bright- vices that are composed of two or more ness level at the end of an electronic physically separate units or compo- display indictor’s useful life. Specific nents connected together (such as a re- limitations on display system useful mote indicating gyroscopic direction life must be contained in the Instruc- indicator that includes a magnetic tions for Continued Airworthiness re- sensing element, a gyroscopic unit, an quired by § 23.1529. amplifier, and an indicator connected (3) Not inhibit the primary display of together). As used in this section, attitude, , altitude, or power- ‘‘primary’’ display refers to the display plant parameters needed by any pilot to set power within established limita- of a parameter that is located in the tions, in any normal mode of oper- instrument panel such that the pilot ation. looks at it first when wanting to view (4) Not inhibit the primary display of that parameter. engine parameters needed by any pilot [Doc. No. 27806, 61 FR 5168, Feb. 9, 1996] to properly set or monitor powerplant limitations during the engine starting EFFECTIVE DATE NOTE: By Amdt. 23–62, 76 FR 75760, Dec. 2, 2011, § 23.1311 was amended mode of operation. by revising paragraphs (a)(5), (a)(6), (a)(7), (5) Have an independent magnetic di- and paragraph (b), effective Jan. 31, 2012. For rection indicator and either an inde- the convenience of the user, the revised text pendent secondary mechanical altim- is set forth as follows: eter, , and attitude instrument or individual electronic § 23.1311 Electronic display instrument sys- display indicators for the altitude, air- tems. speed, and attitude that are inde- (a) * * * pendent from the airplane’s primary (5) For certification for Instrument Flight electrical power system. These sec- Rules (IFR) operations, have an independent ondary instruments may be installed in magnetic direction indicator and either an independent secondary mechanical altim- panel positions that are displaced from eter, airspeed indicator, and attitude instru- the primary positions specified by ment or an electronic display parameters for § 23.1321(d), but must be located where the altitude, airspeed, and attitude that are they meet the pilot’s visibility require- independent from the airplane’s primary ments of § 23.1321(a). electrical power system. These secondary in- (6) Incorporate sensory cues for the struments may be installed in panel posi- pilot that are equivalent to those in tions that are displaced from the primary po- the instrument being replaced by the sitions specified by § 23.1321(d), but must be electronic display indicators. located where they meet the pilot’s visibility (7) Incorporate visual displays of in- requirements of § 23.1321(a). strument markings, required by (6) Incorporate sensory cues that provide a quick glance sense of rate and, where appro- §§ 23.1541 through 23.1553, or visual dis- priate, trend information to the parameter plays that alert the pilot to abnormal being displayed to the pilot. operational values or approaches to es- (7) Incorporate equivalent visual displays tablished limitation values, for each of the instrument markings required by parameter required to be displayed by §§ 23.1541 through 23.1553, or visual displays this part. that alert the pilot to abnormal operational

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values or approaches to established limita- adjacent to and directly below the in- tion values, for each parameter required to strument in the top center position; be displayed by this part. and (b) The electronic display indicators, in- cluding their systems and installations, and (5) Electronic display indicators may considering other airplane systems, must be be used for compliance with paragraphs designed so that one display of information (d)(1) through (d)(4) of this section essential for continued safe flight and land- when such displays comply with re- ing will be available within one second to the quirements in § 23.1311. crew by a single pilot action or by automatic (e) If a visual indicator is provided to means for continued safe operation, after indicate malfunction of an instrument, any single failure or probable combination of it must be effective under all probable failures. cockpit lighting conditions. * * * * * [Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as amended by Amdt. 23–14, 38 FR 31824, Nov. 19, § 23.1321 Arrangement and visibility. 1973; Amdt. 23–20, 42 FR 36968, July 18, 1977; Amdt. 23–41, 55 FR 43310, Oct. 26, 1990; 55 FR (a) Each flight, navigation, and pow- 46888, Nov. 7, 1990; Amdt. 23–49, 61 FR 5168, erplant instrument for use by any re- Feb. 9, 1996] quired pilot during takeoff, initial climb, final approach, and landing § 23.1322 Warning, caution, and advi- must be located so that any pilot seat- sory lights. ed at the controls can monitor the air- If warning, caution, or advisory plane’s flight path and these instru- lights are installed in the cockpit, they ments with minimum head and eye must, unless otherwise approved by the movement. The powerplant instru- Administrator, be— ments for these flight conditions are (a) Red, for warning lights (lights in- those needed to set power within pow- dicating a hazard which may require erplant limitations. immediate corrective action); (b) For each multiengine airplane, (b) Amber, for caution lights (lights identical powerplant instruments must indicating the possible need for future be located so as to prevent confusion as corrective action); to which engine each instrument re- (c) Green, for safe operation lights; lates. and (c) Instrument panel vibration may (d) Any other color, including white, not damage, or impair the accuracy of, for lights not described in paragraphs any instrument. (a) through (c) of this section, provided (d) For each airplane, the flight in- the color differs sufficiently from the struments required by § 23.1303, and, as colors prescribed in paragraphs (a) applicable, by the operating rules of through (c) of this section to avoid pos- this chapter, must be grouped on the sible confusion. instrument panel and centered as near- (e) Effective under all probable cock- ly as practicable about the vertical pit lighting conditions. plane of each required pilot’s forward vision. In addition: [Amdt. 23–17, 41 FR 55465, Dec. 20, 1976, as (1) The instrument that most effec- amended by Amdt. 23–43, 58 FR 18976, Apr. 9, tively indicates the attitude must be 1993] on the panel in the top center position; (2) The instrument that most effec- § 23.1323 Airspeed indicating system. tively indicates airspeed must be adja- (a) Each airspeed indicating instru- cent to and directly to the left of the ment must be calibrated to indicate instrument in the top center position; (at sea level with a stand- (3) The instrument that most effec- ard atmosphere) with a minimum prac- tively indicates altitude must be adja- ticable instrument calibration error cent to and directly to the right of the when the corresponding pitot and stat- instrument in the top center position; ic pressures are applied. (4) The instrument that most effec- (b) Each airspeed system must be tively indicates direction of flight, calibrated in flight to determine the other than the magnetic direction indi- system error. The system error, includ- cator required by § 23.1303(c), must be ing , but excluding the

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airspeed indicator instrument calibra- (1) From 0.8 of the minimum value of V1 to tion error, may not exceed three per- the maximum value of V2, considering the cent of the or five approved ranges of altitude and weight; and knots, whichever is greater, through- (2) The ground run calibration must be de- termined assuming an engine failure at the out the following speed ranges: minimum value of V1. (1) 1.3 VS1 to VMO/MMO or VNE, which- ever is appropriate with flaps re- tracted. * * * * * (2) 1.3 V 1 to V with flaps extended. S FE § 23.1325 system. (c) The design and installation of each airspeed indicating system must (a) Each instrument provided with provide positive drainage of moisture static pressure case connections must from the pitot static plumbing. be so vented that the influence of air- (d) If certification for instrument plane speed, the opening and closing of flight rules or flight in icing conditions windows, airflow variations, moisture, is requested, each airspeed system or other foreign matter will least af- must have a heated or an fect the accuracy of the instruments equivalent means of preventing mal- except as noted in paragraph (b)(3) of function due to icing. this section. (e) In addition, for commuter cat- (b) If a static pressure system is nec- egory airplanes, the airspeed indi- essary for the functioning of instru- cating system must be calibrated to de- ments, systems, or devices, it must termine the system error during the comply with the provisions of para- accelerate-takeoff ground run. The graphs (b) (1) through (3) of this sec- ground run calibration must be ob- tion. tained between 0.8 of the minimum (1) The design and installation of a value of V1, and 1.2 times the maximum static pressure system must be such value of V1 considering the approved that— ranges of altitude and weight. The (i) Positive drainage of moisture is ground run calibration must be deter- provided; mined assuming an engine failure at (ii) Chafing of the tubing, and exces- the minimum value of V1. sive distortion or restriction at bends (f) For commuter category airplanes, in the tubing, is avoided; and where duplicate airspeed indicators are (iii) The materials used are durable, required, their respective pitot tubes suitable for the purpose intended, and must be far enough apart to avoid dam- protected against corrosion. age to both tubes in a collision with a (2) A proof test must be conducted to bird. demonstrate the integrity of the static [Amdt. 23–20, 42 FR 36968, July 18, 1977, as pressure system in the following man- amended by Amdt. 23–34, 52 FR 1834, Jan. 15, ner: 1987; 52 FR 34745, Sept. 14, 1987; Amdt. 23–42, (i) Unpressurized airplanes. Evacuate 56 FR 354, Jan. 3, 1991; Amdt. 23–49, 61 FR the static pressure system to a pres- 5168, Feb. 9, 1996] sure differential of approximately 1 EFFECTIVE DATE NOTE: By Amdt. 23–62, 76 inch of mercury or to a reading on the FR 75761, Dec. 2, 2011, § 23.1323 was amended , 1,000 feet above the by revising paragraph (e), effective Jan. 31, elevation at the time of the test. With- 2012. For the convenience of the user, the re- out additional pumping for a period of vised text is set forth as follows: 1 minute, the loss of indicated altitude § 23.1323 Airspeed indicating system. must not exceed 100 feet on the altim- eter. (ii) Pressurized airplanes. Evacuate * * * * * the static pressure system until a pres- (e) In addition, for normal, utility, and ac- sure differential equivalent to the max- robatic category multiengine jets of more imum cabin pressure differential for than 6,000 pounds maximum weight and com- which the airplane is type certificated muter category airplanes, each system must be calibrated to determine the system error is achieved. Without additional pump- during the accelerate-takeoff ground run. ing for a period of 1 minute, the loss of The ground run calibration must be deter- indicated altitude must not exceed 2 mined— percent of the equivalent altitude of

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the maximum cabin differential pres- § 23.1559(b) of this part, paragraph (b)(3) sure or 100 feet, whichever is greater. of this section does not apply. (3) If a static pressure system is pro- [Amdt. 23–1, 30 FR 8261, June 29, 1965, as vided for any instrument, device, or amended by Amdt. 23–6, 32 FR 7586, May 24, system required by the operating rules 1967; 32 FR 13505, Sept. 27, 1967; 32 FR 13714, of this chapter, each static pressure Sept. 30, 1967; Amdt. 23–20, 42 FR 36968, July port must be designed or located in 18, 1977; Amdt. 23–34, 52 FR 1834, Jan. 15, 1987; such a manner that the correlation be- Amdt. 23–42, 56 FR 354, Jan. 3, 1991; Amdt. 23– tween air pressure in the static pres- 49, 61 FR 5169, Feb. 9, 1996; Amdt. 23–50, 61 FR sure system and true ambient atmos- 5192, Feb. 9, 1996] pheric static pressure is not altered when the airplane encounters icing § 23.1326 Pitot heat indication systems. conditions. An antiicing means or an If a flight instrument pitot heating alternate source of static pressure may system is installed to meet the require- be used in showing compliance with ments specified in § 23.1323(d), an indi- this requirement. If the reading of the cation system must be provided to in- altimeter, when on the alternate static dicate to the flight crew when that pressure system differs from the read- pitot heating system is not operating. ing of the altimeter when on the pri- The indication system must comply mary static system by more than 50 with the following requirements: feet, a correction card must be pro- (a) The indication provided must in- vided for the alternate static system. corporate an amber light that is in (c) Except as provided in paragraph clear view of a flightcrew member. (d) of this section, if the static pressure (b) The indication provided must be system incorporates both a primary designed to alert the flight crew if ei- and an alternate static pressure source, ther of the following conditions exist: the means for selecting one or the (1) The pitot heating system is other source must be designed so switched ‘‘off.’’ that— (2) The pitot heating system is (1) When either source is selected, the switched ‘‘on’’ and any pitot tube heat- other is blocked off; and ing element is inoperative. (2) Both sources cannot be blocked off simultaneously. [Doc. No. 27806, 61 FR 5169, Feb. 9, 1996] (d) For unpressurized airplanes, para- § 23.1327 Magnetic direction indicator. graph (c)(1) of this section does not apply if it can be demonstrated that (a) Except as provided in paragraph the static pressure system calibration, (b) of this section— when either static pressure source is (1) Each magnetic direction indicator selected, is not changed by the other must be installed so that its accuracy static pressure source being open or is not excessively affected by the air- blocked. plane’s vibration or magnetic fields; (e) Each static pressure system must and be calibrated in flight to determine the (2) The compensated installation may system error. The system error, in in- not have a deviation in level flight, dicated pressure altitude, at sea-level, greater than ten degrees on any head- with a standard atmosphere, excluding ing. instrument calibration error, may not (b) A magnetic nonstabilized direc- exceed ±30 feet per 100 speed for tion indicator may deviate more than the appropriate configuration in the ten degrees due to the operation of speed range between 1.3 VS0 with flaps electrically powered systems such as extended, and 1.8 VS1 with flaps re- electrically heated windshields if ei- tracted. However, the error need not be ther a magnetic stabilized direction in- less than 30 feet. dicator, which does not have a devi- (f) [Reserved] ation in level flight greater than ten (g) For airplanes prohibited from degrees on any heading, or a gyroscopic flight in instrument meteorological or icing conditions, in accordance with

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direction indicator, is installed. Devi- one control axis. If the automatic pilot ations of a magnetic nonstabilized di- integrates signals from auxiliary con- rection indicator of more than 10 de- trols or furnishes signals for operation grees must be placarded in accordance of other equipment, positive interlocks with § 23.1547(e). and sequencing of engagement to pre- [Amdt. 23–20, 42 FR 36969, July 18, 1977] vent improper operation are required. (g) There must be protection against § 23.1329 Automatic pilot system. adverse interaction of integrated com- If an automatic pilot system is in- ponents, resulting from a malfunction. stalled, it must meet the following: (h) If the automatic pilot system can (a) Each system must be designed so be coupled to airborne navigation that the automatic pilot can— equipment, means must be provided to (1) Be quickly and positively dis- indicate to the flight crew the current engaged by the pilots to prevent it mode of operation. Selector switch po- from interfering with their control of sition is not acceptable as a means of the airplane; or indication. (2) Be sufficiently overpowered by [Doc. No. 4080, 29 FR 17955, Dec. 18, 1964; 30 one pilot to let him control the air- FR 258, Jan. 9, 1965, as amended by Amdt. 23– plane. 23, 43 FR 50593, Oct. 30, 1978; Amdt. 23–43, 58 (b) If the provisions of paragraph FR 18976, Apr. 9, 1993; Amdt. 23–49, 61 FR 5169, (a)(1) of this section are applied, the Feb. 9, 1996] quick release (emergency) control must be located on the control wheel § 23.1331 Instruments using a power (both control wheels if the airplane can source. be operated from either pilot seat) on For each instrument that uses a the side opposite the throttles, or on power source, the following apply: the stick control, (both stick controls, (a) Each instrument must have an in- if the airplane can be operated from ei- tegral visual power annunciator or sep- ther pilot seat) such that it can be op- arate power indicator to indicate when erated without moving the hand from power is not adequate to sustain proper its normal position on the control. instrument performance. If a separate (c) Unless there is automatic syn- indicator is used, it must be located so chronization, each system must have a that the pilot using the instruments means to readily indicate to the pilot can monitor the indicator with min- the alignment of the actuating device imum head and eye movement. The in relation to the control system it op- power must be sensed at or near the erates. point where it enters the instrument. (d) Each manually operated control For electric and vacuum/pressure in- for the system operation must be read- struments, the power is considered to ily accessible to the pilot. Each control be adequate when the voltage or the must operate in the same plane and vacuum/pressure, respectively, is with- sense of motion as specified in § 23.779 in approved limits. for cockpit controls. The direction of (b) The installation and power supply motion must be plainly indicated on or systems must be designed so that— near each control. (1) The failure of one instrument will (e) Each system must be designed and not interfere with the proper supply of adjusted so that, within the range of energy to the remaining instrument; adjustment available to the pilot, it and cannot produce hazardous loads on the (2) The failure of the energy supply airplane or create hazardous deviations from one source will not interfere with in the flight path, under any flight con- the proper supply of energy from any dition appropriate to its use, either other source. during normal operation or in the (c) There must be at least two inde- event of a malfunction, assuming that pendent sources of power (not driven corrective action begins within a rea- by the same engine on multiengine air- sonable period of time. planes), and a manual or an automatic (f) Each system must be designed so means to select each power source. that a single malfunction will not produce a hardover signal in more than [Doc. No. 26344, 58 FR 18976, Apr. 9, 1993]

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EFFECTIVE DATE NOTE: By Amdt. 23–62, 76 level flight when the quantity of fuel FR 75761, Dec. 2, 2011, § 23.1331 was amended remaining in the tank is equal to the by revising paragraph (c), effective Jan. 31, unusable fuel supply determined under 2012. For the convenience of the user, the re- § 23.959(a); vised text is set forth as follows: (2) Each exposed sight gauge used as § 23.1331 Instruments using a power source. a fuel quantity indicator must be pro- tected against damage; * * * * * (3) Each sight gauge that forms a trap in which water can collect and (c) For certification for Instrument Flight freeze must have means to allow drain- Rules (IFR) operations and for the heading, age on the ground; altitude, airspeed, and attitude, there must (4) There must be a means to indicate be at least: (1) Two independent sources of power (not the amount of usable fuel in each tank driven by the same engine on multiengine when the airplane is on the ground airplanes), and a manual or an automatic (such as by a stick gauge); means to select each power source; or (5) Tanks with interconnected outlets (2) A separate display of parameters for and airspaces may be considered as one heading, altitude, airspeed, and attitude that tank and need not have separate indi- has a power source independent from the air- cators; and plane’s primary electrical power system. (6) No fuel quantity indicator is re- quired for an auxiliary tank that is § 23.1335 Flight director systems. used only to transfer fuel to other If a flight director system is in- tanks if the relative size of the tank, stalled, means must be provided to in- the rate of fuel transfer, and operating dicate to the flight crew its current instructions are adequate to— mode of operation. Selector switch po- (i) Guard against overflow; and sition is not acceptable as a means of (ii) Give the flight crewmembers indication. prompt warning if transfer is not pro- [Amdt. 23–20, 42 FR 36969, July 18, 1977] ceeding as planned. (c) Fuel flowmeter system. If a fuel § 23.1337 Powerplant instruments in- flowmeter system is installed, each stallation. metering component must have a means to by-pass the fuel supply if (a) Instruments and instrument lines. malfunctioning of that component se- (1) Each powerplant and auxiliary verely restricts fuel flow. power unit instrument line must meet (d) Oil quantity indicator. There must the requirements of § 23.993. be a means to indicate the quantity of (2) Each line carrying flammable oil in each tank— fluids under pressure must— (1) On the ground (such as by a stick (i) Have restricting orifices or other gauge); and safety devices at the source of pressure (2) In flight, to the flight crew mem- to prevent the escape of excessive fluid bers, if there is an oil transfer system if the line fails; and or a reserve oil supply system. (ii) Be installed and located so that the escape of fluids would not create a [Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as hazard. amended by Amdt. 23–7, 34 FR 13096, Aug. 13, (3) Each powerplant and auxiliary 1969; Amdt. 23–18, 42 FR 15042, Mar. 17, 1977; Amdt. 23–43, 58 FR 18976, Apr. 9, 1993; Amdt. power unit instrument that utilizes 23–51, 61 FR 5138, Feb. 9, 1996; Amdt. 23–49, 61 flammable fluids must be installed and FR 5169, Feb. 9, 1996] located so that the escape of fluid would not create a hazard. ELECTRICAL SYSTEMS AND EQUIPMENT (b) Fuel quantity indication. There must be a means to indicate to the § 23.1351 General. flightcrew members the quantity of us- (a) Electrical system capacity. Each able fuel in each tank during flight. An electrical system must be adequate for indicator calibrated in appropriate the intended use. In addition— units and clearly marked to indicate (1) Electric power sources, their those units must be used. In addition: transmission cables, and their associ- (1) Each fuel quantity indicator must ated control and protective devices, be calibrated to read ‘‘zero’’ during must be able to furnish the required

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