damage to the airframe and/or engine may need to be conducted. The inspection should be accomplished per the procedures furnished by the airframe and engine manufacturers and any damage occurring due to the use of these new ratings should be detected using these inspection procedures. Section 27.923 includes requirements for qualification of the rotor drive system for 30-second and 2-minute OEI powers.
Section 27.1501(a) requires that information necessary for safe operation should be established as limitations. The limitation information provided in this paragraph should be provided in the flight manual. This includes a possible requirement for an inspection prior to further flight after the use of either 30-second or 2-minute OE rating.
Par 724B 963
725. RESERVED.
Intentionally Left Blank 964 Par 725
726. § 27.1523 MINIMUM FLIGHTCREW.
a. Explanation.
(1) This rule requires that the minimum crew necessary to show compliance with the requirements of Part 27 or for safe operation of the rotorcraft be established as an operating limitation.
(2) The determination of minimum crew requirements is typically based on a subjective pilot assessment of the crew requirements for safe operation of each rotorcraft design. Certain regulations, such as the requirements for instrument flight rules (IFR), have specific quantitative differences between single-pilot and two-pilot requirements. However, most often the minimum crew requirement will be based on more subjective considerations such as location of necessary controls, pilot workload to accomplish required tasks, type of operation, and overall complexity of the rotorcraft design.
(3) Minimum crew requirements for the same type design may vary with the kind of operation. Many rotorcraft have been approved for a single-pilot crew for visual flight rules (VFR) operations but require a two-pilot crew for IFR operations. Other kinds of operations that may require more than one crewmember to meet type certification requirements are night operations, operations into known icing conditions, operations in falling and blowing snow, extended overwater operations, and external load operations.
(4) It is important to distinguish between the minimum crew requirements for compliance with Part 27 type certification regulations and the minimum crew requirements of the various operating regulations (Parts 61, 91, 121, 133, 135, and
137). A rotorcraft may be type certified for a minimum crew of one and still be required to have a crew of two or more by the operating regulations for certain types of operation or by the workload associated with an operating environment. Therefore, an applicant should carefully consider the possible operational uses of any rotorcraft design and become familiar with the applicable operating regulations as well as the type certification requirements early in the design process.
(5) Although the rotorcraft configuration is typically certified with the pilot-in-command station in the right seat, the left seat may be used for the pilot-in-command if, in addition to the flight controls required to control the rotorcraft, the following are included for the pilot: throttle control including ability to shut down all engines, airspeed indication, altitude indication, rotor and engine RPM, and engine torque and exhaust gas temperature. The authority should evaluate a change to the pilot-in-command station.
(6) The applicant is encouraged to contact the responsible type certification office as early in the design phase as possible to initiate the qualitative assessment Par 726 965
process. Cockpit layout drawings, instrument panel mockups, and full-scale cockpit mockups can be used to determine if required controls are accessible and to begin the pilot workload assessment for certain operations.
b. Procedures.
(1) General.
(i) A systematic evaluation and test plan is required for any new or modified rotorcraft. The methods for showing compliance should emphasize the use of acceptable analytical, simulation, and flight test techniques. The crew complement should be studied through a logical process of estimating, measuring, and then demonstrating the workload imposed by a particular cockpit design. When the minimum crew requirements have been determined, they should be included in the limitations section of the Rotorcraft Flight Manual in accordance with § 27.1583(d).
(ii) Appropriate analysis should be conducted by the applicant early in the design process. The specific methods) of analysis should be selected on the basis of its predictive validity, sensitivity, reliability, applicability to the particular cockpit configuration, and availability of a suitable reference for comparison.
(2) Analytical Approach.
One analytical approach defines workload as a percentage of the time available to perform tasks (Time Line Analysis). This process may be applied to an appropriate set of flight segments in which operationally important time constraints can be identified. This method is useful for evaluation of cockpit changes relating to overt pilot work such as control movements and data inputs. The generally accepted practice involves careful selection of the limited set of flight scenarios and time segments that represent the range of operational requirements (including the range of normal and nonnormal procedures.) Time line analysis yields useful data when tasks must be performed within operationally significant time constraints. The adequacy of this method is very much dependent on an accurate determination of the time available.
Absolute standards are not available for interpretation of obtained time required scores, but such records can be used to identify high or simultaneous workload demands for later testing in a simulator or aircraft, and comparisons can be made with overt workload demands in proven aircraft. However, the impact of cockpit changes on planning and decisionmaking is difficult to quantify by this method.
(¡i) The most frequently used basis for deciding that a new design is acceptable is a comparison of a new design with previous designs proven in operational service. By making specific evaluations using the acceptable human factors techniques, and comparing new designs to a known baseline, it is possible to proceed with confidence that the changes incorporated in the new designs accomplish the intended result. When the new cockpit is considered, certain components may be 966 Par 726
proposed as replacements for conventional items, and some degree of rearrangement may be contemplated. New avionics systems may need to be fitted into existing panels, and newly automated systems may replace current indicators and controls. As a result of this evolutionary characteristic of the cockpit design process, there is frequently a reference cockpit design, which is usually a conventional aircraft that has been through the test of operational usage. If the new design represents an evolution, improvement attempt, or other deviation from this reference cockpit, the potential exists to make direct comparisons. Service experience should be researched to assure that any existing problems are understood and not perpetuated.
(ili) If preliminary analyses by the certification team identify potential problem areas, these areas should receive more extensive evaluation and data collection in order to verify compliance with § 27.1523. These concerns should be adequately addressed in the manufacturer's demonstration plan when submitted to the FAA/AUTHORITY.
(iv) If the new design represents a significant change in level of automation or pilot duties, analytic comparison to a reference design may have lessened value. Without a firm data base on the time required to accomplish both normally required and contingency duties, more complete and realistic simulation and flight testing will be required.
(3) Testing.
(i) In the case of the minimum crew determination, the final decision is reserved until the rotorcraft has been flown by experienced flight test pilots trained and current in the aircraft. More assurance is derived from actual flight tests than from earlier simulator tests or other synthetic or computer model procedures.
(її) The test program should address the workload functions and factors listed below. For example, an evaluation of communications workload should include the basic workload required to properly operate the aircraft in the environment for which approval is sought. The goal is to evaluate workload with the proposed crew complement during realistic operating conditions, including representative air traffic and weather.
(A) Basic workload functions. The following basic workload functions are considered:
(1) Flight path control.
(2) Collision avoidance.
(3) Navigation.
Par 726 967
(4) Communications.
(5) Operation and monitoring of aircraft engines and systems.
(6) Command decisions.
(B) Workload factors. The following workload factors are considered significant when analyzing and demonstrating workload for minimum flight crew determination:
(1) The accessibility, ease, and simplicity of operation of all necessary flight, power, and equipment controls, including emergency fuel shutoff valves, electrical controls, electronic controls, and engine controls.
(2) The accessibility and conspicuity of all necessary instruments and failure warning devices such as fire warning, electrical system malfunction, and other failure or caution indicators. The extent to which such instruments or devices direct the proper corrective action is also considered.
(3) The number, urgency, and complexity of operating procedures with particular consideration given to the specific fuel management schedule imposed by center of gravity, structural or other considerations of an airworthiness nature, and to the ability of each engine to operate at all times from a single tank or source which is automatically replenished if fuel is also stored in other tanks.
(4) The degree and duration of concentrated mental and physical effort involved in normal operation and in diagnosing and coping with malfunctions and emergencies.
(5) The extent of required monitoring of the fuel, hydraulic, electrical, electronic, deicing, and other systems while en route.
(6) The actions requiring a crewmember to be unavailable at his assigned duty station, including: observation of systems, emergency operation of any control, and emergencies in any compartment.
(Z) The degree of automation provided in the aircraft systems to afford (after failures or malfunctions) automatic crossover or isolation of difficulties to minimize the need for any flight crew action to guard against loss of hydraulic or electric power to flight controls or to other essential systems.
(8) The communications and navigation workload.
(9) The possibility of increased workload associated with any emergency that may lead to other emergencies.
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727. § 27.1525 (Amendment 27-21) KINDS OF OPERATION This rule states that the kinds of operation to which the rotorcraft is limited are established by demonstrated compliance with applicable certification requirements (primarily flight) and the equipment requirements established for that kind of operation.
The basic flight characteristics requirements of Part 27 are suitable for day VFR approval. Additional night considerations appear in § 27.141(c) and in the operating rules. IF requirements are addressed in § 27.141(c) and Appendix B to Part 27.
Additional IFR equipment requirements are contained in the operating rules. External load requirements for certification may be found in §§ 27.25(c) and 27.865(c) in addition to Part 133. Related § 27.1583(d) further requires that the approved kinds of operation must be listed in the operating limitations section of the Rotorcraft Flight Manual. That equipment necessary to comply with applicable airworthiness requirements of Part 27 should also be listed in the limitations section of the flight manual.
728. § 27,1527 (Amendment 27-14) MAXIMUM OPERATING ALTITUDE.
a. Explanation. This rule requires that the maximum altitude for operation of the rotorcraft must be established as an operating limitation. The rule is intended to establish en route altitude as an operating limit. The requirements for maximum takeoff and landing altitude are contained in other portions of the rule. (See discussion in Paragraph 81 of this AC.) The en route limit may be established by any of the preceding subparts of the rule involving flight, structure, powerplant, equipment or related functional requirements of those subparts. Maximum operating altitude is ordinarily specified initially by the manufacturer and substantiated throughout the type certification program by each engineering discipline. Maximum operating altitude must be established in terms of pressure altitude unless the pilot is provided with some equally functional means of observing specified altitude limits (e.g., a density altitude indicator if maximum altitude is specified in terms of density altitude). A related requirement in § 27.1583 specifies that maximum operating altitude must be established as an operating limitation in the RFM and further that any limiting factors must be identified and explained.
b. Procedures. Each FAA/AUTHORITY engineering discipline must ensure that data and testing are adequate to properly substantiate and qualify all critical components to the maximum operating altitude of the rotorcraft. The design or maximum substantiated altitude should be specified in the Type Inspection Authorization. The flight test program must include at least one test flight to the maximum approved pressure altitude. This flight should include functional testing of all critical aircraft components. Although altitude extrapolation of performance and flying qualities test results may be allowed, an altitude limit higher than the maximum pressure altitude at which functional capability of critical aircraft systems has been demonstrated by flight test should not be approved.
Par 727 969
729. § 27.1529 (Amendment 27-18) INSTRUCTIONS FOR CONTINUED AIRWORTHINESS (MAINTENANCE MANUAL).
a. Explanation. The FAA/AUTHORITY has long recognized the necessity to have a maintenance manual for rotorcraft due to the unique and generally complicated and critical design features.
(1) Amendment 27-3, in 1968, established the requirement for a specific airworthiness limitations section. Amendment 27-18, in 1980, revised the rule and added Appendix A containing requirements for preparation of instructions for continued airworthiness, including the airworthiness limitations section. The operating and maintenance rules require compliance with the airworthiness limitations section. The maintenance rules §§ 43.15 and 43.16 and § 91.163(c) of the operating rules also refer to or require compliance with certain parts of the instructions for continued airworthiness. The limitations were intended toidefine the limits of this type certification approval of the fatigue characteristics of critical flight structure.i Refer to FAA Order 8620.2, Applicability and Enforcement of Manufacturer's Data, November 2, 1978, for further information.
(2) Critical components must be identified by part number (or equivalent) and serial number (or equivalent). Section 29.1529(a)(1) and (2) of Amendment 27-3 and/or § 45.14 list the requirements. The part numbers of parts and/or components requiring inspections and/or replacement as a result of § 27.571 must be listed in the airworthiness limitations section of the manual or another separate, segregated section of the manual appropriate to the rules.
(3) Control rigging procedures are included in the manuals. Since rotorcraft are generally difficult to rig properly, it is important that these procedures be correct and complete.
(4) Rotorcraft type designs are unique in comparison to airplane designs in that transmissions and rotors have critical components that may be adversely affected by operating conditions and time in service. The FAA/AUTHORITY-approved airworthiness limitations section may include such items as gear sets, bearings, etc., of the rotorcraft type design if a finite life was established during the type certification program and if the FAA/AUTHORITY determined that mandatory inspections and/or replacement of the component (part) was necessary to maintain airworthiness of the rotorcraft. For example, a drive spline, gear, or bearing was serviceable after concluding the ground endurance test and/or FAA/AUTHORITY flight test program.
However, an FAA/AUTHORITY-mandated inspection or replacement of the component was considered essential for airworthiness of the rotorcraft type design and necessary for type certification. Time between overhaul (TBO) of components is not part of the airworthiness limitations but is a recommendation from the manufacturer (See Part 27, Appendix A, A27.3(b)(1)). If an inspection or replacement of a part in an assembly is required, the inspection interval or replacement time and the part number should be 970 Par 729
included in the limitations. The inspection interval or replacement time may or may not coincide with the recommended overhaul interval of the assembly. (See the comments for Proposal 8-25, § XX.4 in the preamble of Amendment 29-20 (45 FR 60154), September 11, 1980). Note that parts considered unserviceable at the conclusion of the ground endurance test of § 29.923 are not acceptable for type certification.
b. Procedures.
(1) General.
The rule states that the manual must contain all information that the applicant considers essential for proper maintenance. Amendment 27-3 added the requirement for an airworthiness limitations section and Amendment 27-18 revised § 27.1529 and added Appendix A that contains the requirements for preparation of the manual. The airworthiness limitations section of the manual, and any revisions thereto, must be FAA/AUTHORITY approved. The manufacturer's recommendations for continued airworthiness are not FAA/AUTHORITY approved.
The airworthiness limitations section contains information derived primarily from the data approved under § 27.571. Approval of this section of the manual (draft form is acceptable) must be accomplished before type certification. See Part 27, Appendix A, Paragraph A27.4 of Amendment 27-17. (For further information, see comments for Proposal 8-25, § XX.4, in the preamble of Amendment 27-18 (45 FR 60154, September 11, 1980).)
(iii) Part 27, Appendix A, Paragraphs A27.3(a) and (b) pertain to the content of the instructions for continued airworthiness. For example, scheduling and servicing information is included in this section of the manual.
(2) Identifying and Serializing Fatigue Critical Components.
(i) Part numbers and serial numbers must be applied to fatigue critical components as noted in § 45.14 and § 27.1529(a)(1) and (2). Electric arc marking method should not be used due to possible internal arcing, pitting of surfaces, and changes in physical or chemical characteristics due to the local high temperature at the arcs.
(ii) Vibrating pencils, name plates, or permanent inks may be used.
However, serial numbers should be applied on each part such that material is upset or displaced on the part, thereby attaining a more permanent number. This is not a requirement, however. When material is upset or displaced, the least critical or lowest stressed area should be used.
(iii) For small parts, the rule (§ 45.14) allows markings that are equivalent to part and serial numbers. Markings or symbols may be used to enable the Par 729 971
identification of a part as one for which a replacement time, inspection interval, or related procedure is specified in the airworthiness limitations section. The FAA/AUTHORITY-stated identification of such small parts is clearly essential for safety and may not be relieved. With adoption of Amendment 27-18, the marking requirements are contained in § 45.14, Amendment 45-12.
(3) The FAA/AUTHORITY inspector should witness the rigging of the controls of a test rotorcraft. This is imperative for a new rotorcraft design to ensure the practicality and feasibility of the procedure stated in the design data and/or the maintenance manual. The type design data information should be used; and the FAA/AUTHORITY should ensure the manual includes the proper information. Rigging procedures are not included in the airworthiness limitations section.
(4) 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 manual must be completed and furnished with each aircraft receiving an airworthiness certificate, § 21.50(a) and (b).
(5) Service experience may dictate additional and subsequent (to type certification) changes to the airworthiness limitations section. ADs may be used to revise the limitations. (The relationship between ADs and the process of changing the 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.
729A. § 27.1529 (Amendment 27-23) 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 729a(1) from §§ 43.15,
43.16, and 91.163(c) to §§ 43.15, 43.16, and 91.403 of the operating rules.
730.-739. RESERVED.
972 (thru 982) Par 729
SECTION 41. MARKINGS AND PLAÇARDS
740. § 27.1541 GENERAL. See Paragraph 781.
741. § 27.1543 INSTRUMENT MARKINGS: GENERAL. See Paragraph 781.
742. § 27.1545 (Amendment 27-16) AIRSPEED INDICATOR. See Paragraph 781.
743. § 27.1547 (Amendment 27-13) MAGNETIC DIRECTION INDICATOR.
a. Explanation. This section identifies the requirement and location for a calibration placard for the magnetic direction indicator.
b. Procedures. One means of accomplishing the requirements of this regulation is commonly known as swinging the compass. A surveyed compass rose is laid out on an appropriate surface. The compass rose location should be free from the influence of steel structures, underground pipes and cables, reinforced concrete, and other aircraft.
The aircraft should be in an attitude which permits an accurate result. Normally the engines are in operation; however, if the aircraft is equipped with an auxiliary power unit which can supply electrical power for all electrical/electronic equipment or systems, this can be used instead of engine driven generators. Turn the aircraft on successive headings through 360°. It is recommended that the increments be every 30°; however, the increments should not exceed 45°. Prepare a placard to show the correction to be applied at each of the selected headings. When deviations of more than 10° are introduced by operation of any electrical/electronic equipment or systems, the placard should also be marked at each calibration heading showing the correction to be applied when such equipment or systems are turned on or energized. The placard resulting from this calibration should be installed on or near the magnetic direction indicator and identify which electrical loads, or combination of loads, are the cause of the excessive deviations.
744. § 27.1549 POWERPLANT INSTRUMENTS. See Paragraph 781.
745. § 27.1551 OIL QUANTITY INDICATORS.
a. Background. This section states that each oil quantity indicator must be marked with enough increments to indicate readily and accurately the quantity of oil.
b. Procedures. There are several different ways in which the oil quantity indicator may be presented. Some of the ones more prevalent in the industry are:
(1) Oil quantity indicator. (Generally used when large amounts of reserve oil are required.)
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АС 27-1A 7/30/97
(2) Oil quantity dip stick. (Most common method of measuring engine oil.)
(3) Oil quantity sight indicator. (Generally used for measuring transmission and gearbox oil quantities.)
c. No matter what method of oil quantity indicator is used, the indicator should be marked so that the oil quantity can be accurately determined. This can range from increments marked in gallons, such as oil quantity indicators for large amounts of oil, to oil quantity indicators marked in quarts with full and add marks, such as engine dip sticks. Sight indicators with full and add marks have been used successfully for gearboxes. Sight indicators normally do not reflect quantities. These are some of the methods currently in use to indicate the oil quantity. In all cases, those methods identified above have proved to be acceptable methods of showing compliance with the § 27.1551.
746. § 27.1553 FUEL QUANTITY INDICATOR.
a. Explanation. This section describes the markings necessary to identify the portion of unusable fuel that cannot be used in level flight. Unusable fuel may be present in a design due to the relative configuration of the fuel tank to the fuel tank outlet (e.g., sumps, unusual elevations and/or configurations dictated by aircraft contours, etc.). If the unusable fuel supply for any tank is less than or equal to 1 gallon or is less than or equal to 5 percent of the tank capacity, whichever is greater, this section does not apply.
b. Procedures. For each fuel tank which has an unusable fuel capacity exceeding 1 gallon or 5 percent of the tank capacity, whichever is greater, the following should be accomplished.
(1) Calibration computations, measurements, and/or tests should determine the zero (empty) position on the fuel quantity indicator. (reference § 27.1337).
(2) The lowest reading obtainable in level flight must be determined by computation, measurement, and/or testing.
(3) Once the instrument readings defined by Paragraphs b(1) and (2) above have been determined, a red arc should be placed between the readings on the fuel quantity indicator.
(4) Appropriate notations should be made in the flight manual to define the intent of the red arc to the flightcrew (reference § 27.1585(e)).
984 Par 745