AC 29-2C, Chg 1 2/12/03
(iii) As a recommendation, a draft copy of the manual should be available to the FAA/AUTHORITY for use during the F&R program if such a program is conducted under § 21.35(b). The content of the manual may be limited to the information necessary to maintain the aircraft during the F&R program. The manual must be completed and furnished with each aircraft receiving an airworthiness certificate, § 21.50(a) and (b).
(A) For rotorcraft certified to § 29.1529(a)(2) of Amendment 29-4, changes to the airworthiness limitations shall be furnished on request. See § 21.50(a).
(B) For rotorcraft certified to § 29.1529 of Amendment 29-20, changes to the manual shall be made available to those that need the manual. See § 21.50(b).
(iv) Service experience may dictate additional and subsequent (to type certification) changes to the airworthiness limitations section. AD’s may be used to revise the limitations. (The relationship between AD’s and the process of changing these limitations is covered in the preamble of Amendment 29-4 (33 FR 14104;
September 18, 1968.) Whenever the revised limitations are made restrictive for aircraft in service, the Administrative Procedures Act requires “notice and public procedure” to persons that may be affected and to satisfy the requirement for notification of the changes and identification of the correct issue of the airworthiness limitations, if appropriate. This procedure is also used for restrictive or reduced operation limitations in the RFM.
(v) FAA Order 8620.2, November 2, 1978, Applicability and Enforcement of Manufacturers Data, may be reviewed for further information. This does not reflect the rule changes made in October 1980 but applies to prior standards.
b. How to Prepare Instructions for Continued Airworthiness
(1) Explanation. The FAA/AUTHORITY recognized the need for Instructions for Continued Airworthiness to maintain the rotorcraft in an airworthy condition.
(i) Amendment 29-20, 45 FR 60178, September 11,1980, states the applicant must prepare Instructions for Continued Airworthiness in accordance with Appendix A of this part that are acceptable to the Administrator.
(ii) FAR/JAR § 21.50(b), Amendment 21-51, 45 FR 60170, September 11, 1980, requires the holder of a design approval to furnish at least one set of complete Instructions for Continued Airworthiness prepared in accordance with § 27.1529 of this chapter. The design approval can include either the type certificate or supplemental type certificate for an aircraft or aircraft engine for which application was made after January 28, 1981. The approved and accepted set of complete Instructions for Continued Airworthiness should be furnished upon delivery or upon issuance of the first standard airworthiness certificate for the affected aircraft, whichever occurs later.
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(iii) The ICAs or ICA supplements are also required for PMAs, major design change, or alteration approvals that the existing ICAs do not adequately cover.
In such instances, it is the responsibility of the PMA holder, or the person who receives the design change or alteration approval to produce the required ICAs and distribute them in accordance with the requirements of § 21.50(b). The acceptance for these ICAs or supplements should follow the procedure in Section b(2).
(2) Procedure
(i) General. When the rule requires Instructions for Continued Airworthiness for a rotorcraft, its rotors, and appliances, the applicant must prepare Instructions for Continued Airworthiness in accordance with Appendix A to FAR/JAR Part 29, that are acceptable to the FAA/AUTHORITY.
(ii) Guidance. The FAA/AUTHORITY has guidance material to ass ist an applicant in preparing Instructions for Continued Airworthiness for the type design change. AC 29-2C, Appendix A, provides a detailed template describing the requirements, standard industry practices, and guidance for Instructions for Continued Airworthiness.
(iii) Preparation. The applicant must prepare Instructions for Continued Airworthiness that is applicable to the type of certification. The holder of a design approval for a type certificate normally will comply with all requirements specified in Appendix A to FAR/JAR Part 29. The holder of a design approval for a supplemental type certificate would only comply with requirements specified in Appendix A to FAR/JAR Part 29 that are applicable to their type design change.
(iv) Submittal. The applicant must submit to the FAA/AUTHORITY the applicant’s Instructions for Continued Airworthiness, and any authorized publication referenced in the applicant’s Instructions for Continued Airworthiness, i.e., FAA/AUTHORITY-accepted engine and appliance Instructions for Continued Airworthiness.
(v) Evaluation (A) The FAA/AUTHORITY will evaluate the applicant’s Instructions for Continued Airworthiness to determine that they meet the requirements of FAR/JAR § 29.1529 and Appendix A to FAR/JAR Part 29.
(B) For a type certificate the determination is made in two parts. The first is an FAA/AUTHORITY review followed by FAA/AUTHORITY personnel conducting an Aircraft Maintainability Evaluation or equivalent, when requested to determine the acceptability of the Instructions for Continued Airworthiness. For a supplemental type certificate the determination is made by an FAA/AUTHORITY review, unless the supplemental type certificate affects multiple major appliances or systems; then the process for type certificate would be used.
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AC 29-2C, Chg 1 2/12/03
(vi) Acceptance as per Authority procedures. For FAA, acceptance of the Instructions for Continued Airworthiness is indicated by a signed and dated acceptance statement on the List of Effective Pages in the Instructions for Continued Airworthiness.
AC 29.1529A. § 29.1529 (Amendment 29-26) INSTRUCTIONS FOR CONTINUED AIRWORTHINESS (MAINTENANCE MANUAL).
a. Explanation. Amendment 91- 21, 54 FR 41211, October 5, 1989, recodified certain paragraphs in FAR Part 91. This revision corrects a reference from FAR § 91.163 to FAR § 91.403.
b. Procedures. Correct the references in paragraph AC 29.1529a(1) from §§ 43.15, 43.16, and 91.163(c) to §§ 43.15, 43.16, and 91.403 of the operating rules.
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SUBPART G - OPERATING LIMITATIONS AND INFORMATION
MARKINGS AND PLACARDS AC 29.1541. § 29.1541 GENERAL . (SEE PARAGRAPH AC 29.1543).
AC 29.1543. §§ 29.1541, 29.1543, 29.1545, and 29.1549 (Amendment 29-26) INSTRUMENT MARKINGS: GENERAL
a. Background and Explanation.
(1) Aircraft instruments have historically been marked in a variety of ways and with an interesting assortment of symbols. During this period, a limited number of regulatory requirements have been incorporated in the part 29, Subpart G, “Markings and Placards,” and these efforts have standardized some basic aspects of instrument marking for rotorcraft. As rotorcraft hav e become increasingly complex with increased number of engines, OEI ratings, more sophisticated instrumentation, etc., the need for more specific standards has greatly increased.
(2) It is vitally important that instrument markings be standardized among rotorcraft. When markings are not standardi zed, considerable confusion and additional workload may be introduced into the cockpit environment. If markings are not standard, it is conceivable that a marking in one rotorcraft could mean the opposite of a similar marking in another rotorcraft. The results of such a situation could be disastrous when pilots fly several rotorcraft models, and particularly in transport rotorcraft under 12,500 pounds, which do not require a pilot type rating.
(3) The following guidance is offered for the purpose of obtaining a general standardization of instrument markings. It is realized that there are a great many variations in instrument presentations for which all guidance may not apply. This is particularly true of new designs, such as cathode ray tube (CRT) displays currently being presented. It is of overriding import ance that the philosophies included here be administered, even if specific guidance cannot be applied for particular designs.
Instrument markings are provided to aid interpretation of instruments quickly and accurately. Good instrument markings should indicate operating conditions at a glance.
The best markings are ordinarily the simplest markings.
b. Procedures.
(1) Limits. Each maximum allowable lim it substantiated for safe operation must be marked with a red line. This marking should be a red radial line for circular gauges. If there is a minimum allowable limit for safe operation, this value should also be marked with a red (radial) line. The use of multip le red (radial) lines should be avoided except where their use is readily usable by the pilot. Normally, no more than one maximum and one minimum red radial line should be incorporated on any one instrument to minimize Page G – 23
AC 29-2C, Chg 4 5/1/2014 confusion and avoid potential aircrew errors; however, use of multiple red radial lines may be permitted if such marking can be presented in an acceptable manner.
(2) Normal Operating Range. Each normal operating range should be marked with a green arc or green line which does not extend beyond the maximum and minimum values for continuous safe operation. Discontinuities in width have been used when normal ranges vary with other parameters. Integrating instruments in place of these markings should be encouraged although there may be no regulatory requirement for them. An equivalent safety finding is r equired for electronic displays if the applicant decides not to use green to mark normal operating ranges.
(3) Cautionary Ranges. Time limited ranges, precautionary ranges, or ranges for which special operating procedures are required should be marked with a yellow arc or yellow line. If a yellow range is used to indicate a special operating procedure, information describing the special procedure should be included in the RFM.
(4) OEI Markings. OEI ratings repr esent a special challenge for retaining simplicity and clarity in powerplant instrument markings. OEI ratings are eligible to be used only during an extremely small portion of total flight time; therefore, they should not dominate the presentation or obscure other markings. They are needed only for reference. Indices for 2½-minute and 30-mi nute power may be marked above the takeoff power redline on engine power instruments. OEI reference markings should be clearly distinct from the normal all-engines operating markings. One acceptable means of marking OEI limits has been narrow dashed radials with yellow for 30-minute, and red for 2½-minute limits. OEI markings should be c onsistent between gauges. For example, a 30-minute marking on an N1 or torque gauge should be similar in appearance to the 30- minute marking on the engine temperature gauge.
(5) Red Arcs or Ranges. Sections 29.1549(d) and 29.1553 allow the use of red arcs. Experience has proven that when red arcs are used to indicate maximum or minimum values, the meaning of a red line loses its significance. Therefore, the use of red ranges or arcs to indicate limit values should be discouraged. Red is conventionally used to represent a limit (maximum or minimum) for which an aircraft or component has been substantiated. A “range” of limits for a given parameter is not consistent with the definition of the terms “limit,” “minimum,” or “maximum.” In addition, a red arc tends to imply that more than one value is limiting, that a scale is provided to show operation within a range of values, and that an absolute limit may not exist until the extreme of a red range is attained. These implicati ons must be avoided wherever possible by specifying a single limiting value and marking it with a single red line (radial). If readings in excess of that value were indicated, it would then be obvious to the crew that a limit had been exceeded. A red arc may be used to i ndicate a transient vibration range as indicated in § 29.1549(d); however, if the range is a cautionary range and not a prohibited range, use of a yellow arc is recommended. The fuel quantity indicator configuration described in § 29.1553 is considered a special application of red arcs.
Occasionally a red arc has been utilized when limits vary with other parameters.
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Discontinuities in width could conceivably represent limits when other parameters are considered. The use of integrating instru ments would alleviate much of the problem and should be encouraged although it is recognized that there may be no regulatory requirement for them.
(6) Flight Evaluation. In evaluat ing quantity indicator markings, the final criterion must be: “Are the markings adequate for correct interpretation by the crew?”
FAA/AUTHORITY evaluations of quantity indicator markings should begin early in a certification program utilizing a cockpit or aircraft mock-up whenever possible. All required quantity indicators and quantity indicator markings must be readable from each pilot station. Depending on cockpit and window geometry, quantity indicators should be evaluated in direct sunlight unless they are located high on the panel underneath a substantial glare shield. Evaluation in dire ct sunlight is especially important for any displays using light bars of digital lighting segments, such as digital radar altimeter presentations or vertical scale instruments using light segments. Required quantity indicators must be readable without upper body movement or extensive head movement by the crew. Evaluators should be especially alert to any scale markings or range markings which are obscured by parallax, as such features are unacceptable. If the aircraft is to be approved for night operation, each required indicator must also be evaluated during night lighting conditions. The same visibility requirements apply for night; however, the evaluator should particularly look for lighting features which may change or obscure the colored markings. Except for minor changes, lighting should be evaluated in flight in order to correctly evaluate vibration effects and various background lighting conditions.
(7) Digital Instruments.
(i) For purposes of this discussion, two types of digital indicator are considered: (1) an indicator which consists of a column of light segments which illuminate sequentially to display changing values, and (2) an indicator which consists of horizontal and vertical line segments in the configuration of a block “8” to display numerical values. Both indicator types wo rk well for parameters where trend information is generally not needed such as engine oil pressure or temperature. However, for rapidly changing parameters such as engine exhaust gas temperature, torque, or RPM, trend information may not be attainable. AC 20-88A (guidelines on the marking of power plant instruments) specifies that instrument markings are intended to provide necessary information at a glance. Trend information for power indicators is vitally important for safe operation of a rotorcraft, and this information must be obtainable at a glance. For the columnar light segments, the ability to quickly detect trend information is largely a function of the resolution provided by single segments (e.g.; if there are two segments for each percent RPM, the ability to detect trend information is better than if there is only one segment for each percent RPM). For digita l indicators displaying numerical values, trend information may be unattainable because rapidly changing parameters produce a blur, and this design may be unsuitable as a single source of information. The evaluator should use a great deal of caution to assure adequate trend information is available in primary power and rotor indicators of digital design.
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AC 29-2C, Chg 4 5/1/2014
(ii) Another area of concern in digital and moving tape instruments is the ability to determine when limits are being approached. Color code markings are frequently incorporated on the moving face of a tape or digital presentation. In such cases, it is mandatory that limit markings be affixed adjacent to the presentation, or that another means be provided so that the pilot can anticipate approaching a limit. The beginning and end of normal and cautionary ranges should be marked adjacent to the display. The entire range need not be color c oded adjacent to the display if the colors are integral on the face of the tape or in the individual digital segments. Marking of limit values solely on the tape or in the colored light segments alone is unsatisfactory.
Marking of digital indicators displaying numerical values is adequately addressed in AC 20-88A, paragraph 6.
(iii) Appropriate failure modes should be evaluated during the system analysis. This will ordinarily include portions of the digital display. Such failures should be detectable whenever they affect reading accuracy. As a result of this analysis, the system may incorporate a test feature which assures all digital segments operate satisfactorily. This feature should be encouraged.
(8) Additional Markings. To keep markings standardized and uncomplicated, only the FAA/AUTHORITY-approved ranges and limits should be included. Items such as manufacturer’s recommended values or manufacturer’s warranty information are inappropriate for instrument markings and should not be included. Such information may be presented elsewhere. Transient limit s may be indicated by a small red index such as a dot or triangle. Information def ining allowable conditions for each transient index should be in the RFM (e.g., maximum for starting, 12 seconds).
(9) Airspeed Indicator. While the foregoing information is generally applicable to airspeed indicators, some particular features warrant additional attention.
(i) A red cross-hatched radial line should be located at power-off VNE if that value is less than power-on VNE.
(ii) Many rotorcraft have erratic, unreliable, or nonrepeatable airspeed indications at low speed which warrant caution when operating in that speed range. In such cases, a yellow arc on the instrument with appropriate flight manual explanation has been found acceptable.
(iii) Indicated airspeed values should be utilized for all airspeed indicator markings.
(iv) Airspeed “bugs” may be used to highlight important takeoff, landing, or limit speeds. This concept may genera lly be encouraged; however, there are a maximum number of “bugs” that can be utilized without confusion for any given indicator. Typically, two “bugs” are accept able; three or more are questionable. “Bugs” may also be used on a variety of instruments other than the airspeed indicator.
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(10) Additional Reference Material. Additional procedures for marking powerplant instruments are contained in AC 20-88A. Where conflicts for rotorcraft exist between AC 20-88A and this document, the more recently dated publication should be utilized.
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AC 29.1543A. §§ 29.1541, 29.1543, 29.1545, AND 29.1549 (AMENDMENT 29-59) INSTRUMENT MARKINGS: GENERAL.
a. Background and Explanation.
(1) Aircraft instruments have historically been marked in a variety of ways and with an interesting assortment of symbols. A limited number of regulatory requirements have been incorporated in part 29, Subpart G, “Markings and Placards,” and these efforts have standardized some basic aspects of instrument marking for rotorcraft. As rotorcraft have become increasingly complex with an increased number of engines, OEI ratings, more sophisticated instrumentation, etc., the need for more specific standards has greatly increased.
(2) It is vitally important that instrument markings be standardized among rotorcraft. When markings are not standardized, considerable confusion and additional workload may be introduced into the cockpit environment. If markings are not standard, it is conceivable that a marking in one rotorcraft could mean the opposite of a similar marking in another rotorcraft. The results of such a situation could be disastrous when pilots fly several rotorcraft models, and particularly in transport rotorcraft under 12,500 pounds, which do not require a pilot type rating.
(3) The following guidance is offered for the purpose of obtaining a general standardization of instrument markings. The FAA recognizes that there are a great many variations in instrument presentations for which all guidance may not apply. This is particularly true of new designs, such as glass cockpit currently being presented. The overall philosophies here should be used even if specific guidance is not applicable for a particular design. Instrument markings are provided to aid interpretation of instruments quickly and accurately. Good instrument markings should indicate operating conditions at a glance. The best markings are ordinarily the simplest markings.
b. Procedures.
(1) Limits. Each maximum allowable limit substantiated for safe operation must be displayed with a red line, as required by §§ 29.1545 and 29.1549. This marking should be a red radial line for circular gauges. If there is a minimum allowable limit for safe operation, this value should also be marked in red. The use of multiple red indications should be avoided except where their use is readily apparent to the flight crewmember. Normally, no more than one maximum and one minimum red indication should be incorporated on any one instrument to minimize confusion and avoid potential Page G - 27.1
flightcrew errors; however, use of multiple red indications may be permitted if such marking can be presented in an acceptable manner.
(2) Normal Operating Range. Each normal operating range may be marked with a green arc or green line that does not extend beyond the maximum and minimum values for continuous safe operation. Discontinuities in width have been used when normal ranges vary with other parameters. Integrating instruments in place of these markings should be encouraged although there may be no regulatory requirement for them.
(3) Cautionary Ranges. Time limited ranges, precautionary ranges, or ranges for which special operating procedures are required should be displayed in yellow. If a yellow range is used to indicate a special operating procedure, information describing the special procedure should be included in the RFM.
(4) OEI Markings. OEI ratings represent a special challenge for retaining simplicity and clarity in powerplant instrument markings. OEI ratings are eligible to be used only during an extremely small portion of total flight time; therefore, they should not dominate the presentation or obscure other markings. They are needed only for reference.
Indices for 2½-minute and 30-minute power may be marked above the takeoff power redline on engine power instruments. OEI reference markings should be clearly distinct from the normal all-engines operating markings. One acceptable means of marking OEI limits has been narrow dashed radials with yellow for 30-minute, and red for 2½-minute limits. OEI markings should be consistent between gauges. For example, a 30-minute marking on an N1 or torque gauge should be similar in appearance to the 30-minute marking on the engine temperature gauge.
(5) Red Arcs or Ranges. Sections 29.1549(d) and 29.1553 allow the use of red indications. Experience has proven that when red arcs are used to indicate maximum or minimum values, the meaning of a red line loses its significance. Therefore, the use of red ranges or arcs to indicate limit values should be discouraged. Red is conventionally used to represent a limit (maximum or minimum) for which an aircraft or component has been substantiated. A “range” of limits for a given parameter is not consistent with the definition of the terms “limit,” “minimum,” or “maximum.” In addition, a red arc tends to imply that more than one value is limiting, that a scale is provided to show operation within a range of values, and that an absolute limit may not exist until the extreme of a red range is attained. These implications should be avoided wherever possible by specifying a single limiting value and marking it with a single red indication line. If readings in excess of that value were indicated, it would then be obvious to the crew that a limit had been exceeded. A red arc may be used to indicate a transient vibration range as indicated in § 29.1549(d); however, if the range is a cautionary range and not a prohibited range, use of a yellow arc is recommended. The fuel quantity indicator configuration described in § 29.1553 is considered a special application of red arcs. Occasionally a red arc has been utilized when limits vary with other parameters.
Discontinuities in width could conceivably represent limits when other parameters are considered. The use of integrating instruments would alleviate much of the problem Page G - 27.2
and should be encouraged although it is recognized that there may be no regulatory requirement for them.
(6) Flight Evaluation. In evaluating quantity indicator markings, to meet the requirements of § 29.1543, the final criterion must be: “Are the markings adequate for correct interpretation by the crew?” FAA evaluations of quantity indicator markings should begin early in a certification program utilizing a cockpit or aircraft mock-up whenever possible. All required quantity indicators and quantity indicator markings must be readable from each pilot station. Depending on cockpit and window geometry, quantity indicators should be evaluated in direct sunlight unless they are located high on the panel underneath a substantial glare shield. Evaluation in direct sunlight is especially important for any displays using light bars of digital lighting segments, such as digital radar altimeter presentations or vertical scale instruments using light segments. Required quantity indicators should be readable without upper body movement or extensive head movement by the crew. Evaluators should be especially alert to any scale markings or range markings that are obscured by parallax, as such features are unacceptable. If the aircraft is to be approved for night operation, each required indicator must also be evaluated during night lighting conditions, per § 29.773.
The same visibility requirements apply for night; however, the evaluator should particularly look for lighting features that may change or obscure the colored markings.
Except for minor changes, lighting should be evaluated in flight in order to correctly evaluate vibration effects and various background lighting conditions.
(7) Digital Instruments.
(i) For purposes of this discussion, the two types of digital indicators considered are an indicator that consists of a column of light segments that illuminate sequentially to display changing values, and an indicator that consists of horizontal and vertical line segments in the configuration of a block “8” to display numerical values.
Both indicator types work well for parameters where trend information is generally not needed such as engine oil pressure or temperature. However, for rapidly changing parameters such as engine exhaust gas temperature, torque, or RPM, trend information may not be attainable. AC 20-88A specifies that instrument markings are intended to provide necessary information at a glance. Trend information for power indicators is vitally important for safe operation of a rotorcraft, and this information should be obtainable at a glance. For the columnar light segments, the ability to quickly detect trend information is largely a function of the resolution provided by single segments (e.g.; if there are two segments for each percent RPM, the ability to detect trend information is better than if there is only one segment for each percent RPM).
For digital indicators displaying numerical values, trend information may be unattainable because rapidly changing parameters produce a blur, and this design may be unsuitable as a single source of information. The evaluator should use a great deal of caution to ensure adequate trend information is available in primary power and rotor indicators of digital design.
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(ii) Another area of concern in digital and moving tape instruments is the ability to determine when limits are being approached. Color code markings are frequently incorporated on the moving face of a tape or digital presentation. In such cases, t o meet the requirements of §§ 29.1541(b)(1), 29.1543(b), and 29.1545(a), it is mandatory that limit markings be affixed adjacent to the presentation, or that another means be provided so that the pilot can anticipate approaching a limit. The beginning and end of normal and cautionary ranges should be marked adjacent to the display.
The entire range need not be color coded adjacent to the display if the colors are integral on the face of the tape or in the individual digital segments. Marking of limit values solely on the tape or in the colored light segments alone is unsatisfactory.
Marking of digital indicators displaying numerical values is adequately addressed in AC 20-88A, paragraph 6.
(iii) Appropriate failure modes should be evaluated during the system analysis.
This will ordinarily include portions of the digital display. Such failures should be detectable whenever they affect reading accuracy. As a result of this analysis, the system may incorporate a test feature that ensures all digital segments operate satisfactorily. This feature should be encouraged.
(8) Additional Markings. To keep markings standardized and uncomplicated, only the FAA-approved ranges and limits should be included. Items such as manufacturer’s recommended values or manufacturer’s warranty information are inappropriate for instrument markings and should not be included. Such information may be presented elsewhere. Transient limits may be indicated by a small red index such as a dot or triangle. Information defining allowable conditions for each transient index should be in the RFM (e.g., maximum for starting - 12 seconds).
(9) Airspeed Indicator. While the foregoing information is generally applicable to airspeed indicators, some particular features warrant additional attention.
(i) A red cross-hatched indication should be located at power-off V NE if that value is less than power-on VNE.
(ii) Many rotorcraft have erratic, unreliable, or non-repeatable airspeed indications at low speed that warrant caution when operating in that speed range. In such cases, a yellow indication on the instrument with appropriate flight manual explanation has been found acceptable.
(iii) Indicated airspeed values should be utilized for all airspeed indicator markings.
(iv) Airspeed “bugs” may be used to highlight important takeoff, landing, or limit speeds. This concept may generally be encouraged; however, there are a maximum number of “bugs” that can be utilized without confusion for any given indicator.
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