Page No.
CHAPTER 3 - MISCELLANEOUS GUIDANCE (MG),
NORMAL CATEGORY ROTORCRAFT AC 27 MG 1 Certification Procedure for Rotorcraft Avionics Equipment MG 1-1 AC 27 MG 2 Standardized Test Procedure for Rotorcraft DC Electrical MG 2-1 System Tests AC 27 MG 3 Definition of Engine Isolation Features as Applied to MG 3-1 §§ 27.79(b)(2), 27.141(b)(1), and 27.143(d)(1) AC 27 MG 4 Full Authority Digital Electronic Controls (FADEC). MG 4-1 AC 27 MG 5 Agricultural Dispensing Equipment Installation. MG 5-1 AC 27 MG 6 Emergency Medical Service (EMS) Systems, Installations, MG 6-1 Including: Interior Arrangements, Equipment, Helicopter Terrain Awareness and Warning System (HTAWS), Radio Altimeter, and Flight Data Monitoring System.
AC 27 MG 7 Hour Meters or Time-in-Service Recording Devices in Rotorcraft.. MG 7-1 AC 27 MG 8 Substantiation of Composite Rotorcraft Structure. MG 8-1 AC 27 MG 9 Rotorcraft One-Engine-Inoperative (OEI) Power Assurance MG 9-1 AC 27 MG 10 Advisory Material for Substantiation of Emergency Flotation MG 10-1 System AC 27 MG 11 Fatigue Evaluation of Rotorcraft Structure. MG 11-1 AC 27 MG 12 External Loads (see AC 27.865B) MG 12-1 AC 27 MG 13 Systems Certification Considerations. MG 13-1 AC 27 MG 14 Certification Procedure for Installation of Vapor Cycle MG 14-1 Air Conditioning Systems AC 27 MG 15 Airworthiness Approval of Rotorcraft Health Usage Monitoring MG 15-1 Systems (HUMS) AC 27 MG 16 Certification Procedure for Rotorcraft Night Vision Imaging MG 16-1 Systems (NVIS) Equipment AC 27 MG 17 Guidance on Analyzing an Advanced Flight Controls (AdFC).. .. MG 17-1 System AC 27 MG 18 Helicopter Terrain Awareness and Warning System (HTAWS).. MG 18-1 AC 27 MG 19 Guidance on Electronic Display Systems (EDS) for Rotorcraft MG 19-1 Installations AC 27 MG 20 Human Factors (HF).. MG 20-1 AC 27 MG 21 Guidance on Creating a System Level Functional Hazard MG 21-1 Assessment (FHA) AC 27 MG 22 Rotorcraft One Engine Inoperative (OEI) Training Mode MG 22-1 AC 27 MG 23 Automatic Flight Guidance and Control systems (AFGCS) .. MG 23-1 Installation in Part 27 Rotorcraft Page xv
AC 27-1B, Chg 9 6/23/23
APPENDICES AC 27 Appendix A - Instructions for Continued Airworthiness................ ... Apdx A-1 AC 27 Appendix B - Airworthiness Guidance for Rotorcraft Instrument Flight........... Apdx B-1 AC 27 Appendix C - (reserved) (Criteria for Category A) ............................. ... Apdx C-1 Page xvi
FIGURES The first digits in the figure number are the same as the related section number.
Figure No. Title Page
AC 27.45-1 H-V RequirementsB-20
AC 27.45-2 IGE Controllability Requirements.. B-21 AC 27.45-3 Shaft Horsepower vs. Turbine Outlet .. B-22 Temperature - Sea Level Standard Day AC 27.45-4 Uninstalled Takeoff Power Available. B-23 AC 27.45-5 Installed Takeoff Power Available, Anti-Ice Off, .. B-24 400 RPM AC 27.45-6 Power Assurance Check Chart B-24.1 AC 27.71-1 Autorotational Characteristics - Typical B-31 AC 27.79-1 Height-Velocity Diagram. B-43 AC 27.79-2 Altitude/Weight Accountability. B-44 AC 27.175-1 Static Longitudinal Stability B-60.1 AC 27.175A-1 Static Longitudinal Stability B-60.5 AC 27.251-1 Demonstration Points B-70 AC 27.337-1 Load Factor Gross Weight Curve C-7 AC 27.351-1 Sample Yaw/Forward Speed Diagram.. C-12 AC 27.351-2 Safety Factors for Probability of Failure C-13 AC 27.427-1 View Looking Forward C-26 AC 27.427-2 View Looking Forward. C-27 AC 27.562-1 Seat Restraint System Dynamic Tests. C-47 AC 27.562-2 Schematic Floor Deformation Fixture; Seat Legs C-54 Attached at Floor Level AC 27.562-3 Schematic Test Fixture; Side Wall Mounted Seat. C-58 AC 27.562-4 Installation of Pelvic-Lumbar Spine Load Cell in C-62 Part 572B Anthropomorphic Dummy AC 27.562-5 Measurement to be Taken Over Full Width of. C-74 Seat Bottom Cushion AC 27.562-6 Post Test Condition C-74 Page xvii
AC 27.1B, Chg 4 5/1/2014 FIGURES (continued) Figure No. Title Page
AC 27.562-7 Impulse ShapeC-80
AC 27.562-8 Change in Velocity ... C-80 AC 27.571-1 Comparison Percent of Time in Level Flight C-85 AC 27.573-1. Schematic diagram of building block tests C102 AC 27.573-2. Characterization of Impact Damage. C-107 AC 27.573-3. Residual Strength vs. Time. C-112 AC 27.573-4. Illustration of Residual Strength and Damage Size Relationships for Fail-Safe Substantiation C113 AC 27.621-1 Example of Casting Load Sheet Retract D-24 Actuator Support-Landing Gear AC 27.621-2 Example of Castings to be Static Tested for D-26 Model XYZ
AC 27.773-1 Cockpit VisibilityD-67
AC 27.801-1 Sea State Code - World Meteorological D-90 Organization...
AC 27.865B-1 U.S. Operational (Part 133) Rotorcraft-Load Combination D-116 Versus Applicable Cargo Type Data and Definition Summary AC 27.931-1 Cantilevered Shaft, First Critical Speed E-25 AC 27.931-2 Shaft Between Support Bearings, First Critical Speed E-25 AC 27.952-1 Static Tension and Shear Loading Modes E-50 AC 27.952-2 Hose Assembly Tests E-51 AC 27.952-3 Minimum Average and Individual Loads for Hose and E-52 Hose-End Fitting Combinations AC 27.952-4 Typical Method of Breakaway Fuel Fitting Load E-53 Calculations AC 27.952-5 Typical Methods of Frangible or Deformable Attachment E-54 Load Calculations, Frangible Bolts AC 27.952-6 Typical Methods of Frangible or Deformable Attachment E-55 Load Calculations, Frangible Baffle
AC 27.955-1 Fuel Flow E-61E-61
Page xviii
FIGURES (continued) Figure No. Title Page AC 27.1041-1 Additional Cooling Test Point E-93 AC 27.1191-1 Table of Materials and Gauges Acceptable for E-131 Fireproof Protective Devices with Flat Surface Geometries AC 27.1309-1 Relationship between Probability and Severity of F-30.5 Failure Condition Effects AC 27.1309-2 Failure Condition Categories and Probably Definitions F-30.6 AC 27.1309-4 Safety Assessment Process Overview F-30.10 AC 27.1309-5 Depth of Analysis Flowchart F-30.11 AC 27.1321-1 Primary Fields of View. F - 34 AC 27, 1321-2 Secondary Fields of View F - 34.1 AC 27.1329-1 Height Loss Method. F-45
AC 27.1329-2 Deviation ProfileF-49
AC 27.1329-3 Deviation ProfileF-50
AC 27.1419-1 Continuous Icing-Temperature vs. Altitude Limits. F-93 AC 27.1419-2 Intermittent Icing-Temperature vs. Altitude Limits F-94 AC 27.1419-3 Continuous Icing-Liquid Water Content vs Drop F-95 Diameter AC 27.1419-4 Intermittent Icing-Liquid Water Content vs. Drop F-96 Diameter AC 27 MG 3-1 Part 29 Engine Isolation Rules MG 3-5 AC 27 MG 5-1 Acceptable Ultimate Load Factor for Agricultural MG 5-3 Dispensing Equipment Design AC 27 MG 5-2 Sketch of Tank Pressure Test. .. MG 5-7 AC 27 MG 6-1 Typical Liquid Oxygen System MG 6-21 AC 27 MG 6-2 Typical Liquid Oxygen System - Using Combination MG 6-22 Valve AC 27 MG 8-1 Schematic Diagram of Building Block Tests MG 8-16 AC 27 MG 8-2 Characterization of Impact Damage MG 8-20 AC 27 MG 8-3 Residual Strength vs. Time MG 8-23 AC 27- MG 8-4 Residual Strength and Damage Size Relationships. MG 8-24 for Fail-Safe Substantiation AC 27 MG 9-1 Installed Engine Fuel Flow Capacity Check MG 9-8 AC 27 MG 11-1 Example of Variation in Time Spent in Level Flight MG 11-7 for Three Rotorcraft Types AC 27 MG 11-2 Flight Regime to be Investigated Power-On Operation MG 11-17 Page xix
AC 27.1B, Chg 7 xx/xx/2014 FIGURES (continued) Figure No. Title Page AC 27 MG 11-3 Flight Regime to be Investigated for Power-Off MG 11-17 Operation AC 27 MG 11-4 Simplified Analytical Method for Safe Life Evaluation MG 11-18 AC 27 MG 11-5 Typical S/N Curve for Safe Life Evaluation MG 11-18 AC 27 MG 11-6 Elements of Safe Life Determination. MG 11-19 AC 27 MG 11-7 Flight Load Measurement Program Conditions to be. MG 11-20 Investigated AC 27 MG 11-8 Lifting Helicopter Load Measurement.. ..MG 11-23 AC 27 MG 11-9 Example of Twin Turbine Usage Spectrum MG 11-24 AC 27 MG 14-1 Refrigeration Cycle... MG 14-7 AC 27 MG 15-1 Flow Chart for Use of Mitigating Actions Applied for MG 15-8 Reduction of Software Level AC 27 MG 15-2 Flow Chart for Application of HUMS Specific MG 15-11 Software with a Ground Base that uses COTS Software for Operational Software AC 27 MG 17-1 Verification Methodology. MG 17-4 AC 27 MG 19-1 Primary Field of View. MG 19-15 AC 27 MG 19-2 Secondary Field of View. MG 19-16 AC 27 MG 20-1 Primary and Secondary Horizontal Fields of View MG 20-18 AC 27 MG 20-2 Primary and Secondary Vertical Fields of View MG 20-19 AC 27 MG 20-3 Sample HF Compliance Matrix.. MG 20-27 AC 27 MG 21-1 Generic Examples by ATA.. .. MG 21-5 AC 27 APX B-1 Rotorcraft Dynamic Stability Requirements for IFR. Apax B-27 Page xx
Acronyms advisory circular EFIS electronic flight instrument ACO aircraft certification office System[Replaced by EDS.] ADF automatic direction finding EFP engine failure point ADI attitude direction indicator EHE exhaust heat exchanger AEH airborne electronic hardware ELOS equivalent level of safety AEO all engines operating ELT emergency locator transmitter AdFC advanced flight control EMC electromagnetic compatibility AFCS automatic flight control EMI electromagnetic interference systems EMS emergency medical service AFGCS automatic flight guidance and EOL end of life control systems EUROCAE European Organization for AGL above ground level Civil Aviation Equipment AHRS attitude heading reference EVS enhanced vision system system FAA Federal Aviation Amdt. Amendment Administration APU auxiliary power unit FADEC full authority digital engine ATC air traffic control control BIM CAM CAR CAS CBIM blade inspection method cockpit area microphone Civil Air Regulations calibrated air speed cockpit blade inspection method FAR FEM FHA FMEA [OBSOLETE term.] failure mode and effects finite element modeling Federal Aviation Regulations functional hazard assessment analysis CDP critical decision point CFR Code of Federal Regulations FPM feet per minute CG center of gravity FPS feet per second COTS commercial off-the-shelf FTA fault tree analysis CPS cycles per second GPS global positioning system CRFS crash resistant fuel system GW gross weight CRI certification review item HEC human external cargo HF high frequency CRT cathode ray tube CVR cockpit voice recorder HIRF high intensity radiated fields DER representative designated engineering HUMS HRD high rate of discharge health and usage monitoring DME distance measuring systems HV height-velocity EASA equipment European Aviation Safety ICA IAS indicated airspeed instructions for continued Agency airworthiness ECAS engine caution advisory ICAO International Civil Aviation systems Organization ECU environmental control unit ICS inter-communication system EDS electronic data system IFR instrument flight rules Page xxi
AC 27.1B, Chg 4 5/1/2014 PCDS personnel carrying device IGE in ground effect Systems IIDS integrated instrument display system PCF post crash fire ILS instrument landing system PIO pilot induced oscillation IMC instrument meteorological PSA preliminary safety assessment conditions PSIG pounds per square inch INS inertial navigation system gauge ISA international standard QPL qualified parts list atmosphere RFM rotorcraft flight manual ISIS integral spar inspection system RFMS rotorcraft flight manual ITT inter-turbine temperature supplement KCAS knots calibrated airspeed RGL Regulatory and Guidance KIAS knots indicated air speed Library KTAS knots true airspeed RPM revolutions per minute LDP landing decision point RTCA Radio Technical Commission LPV localizer performance with Of Aeronautics vertical guidance RVR runway visual range LRU line replaceable unit SAE Society of Automotive LWC liquid water content Engineers MC maximum continuous SAR search and rescue MCP maximum continuous power SAS stability augmentation system MEL minimum equipment list MG misce laneous guidance SCAS stability and control augmentation systems MGB main gearbox MGT measured gas temperature SHP shaft horsepower MGW MMEL maximum gross weight master minimum equipment S/N SRM structural repair manual stress vs. number of cycles list SSA system safety assessment STC supplemental type certificate MSL mean sea level STOL short takeoff and landing MVD median volume diameter NASA National Aeronautics and time between overhaul Space Administration type certificate type certificate data sheet NDI non-destructive inspection takeoff decision point NM nautical mile type inspection authorization NPRM notice of proposed type inspection report rulemaking takeoff power NTSB National Transportation turbine outlet temperature Safety Board technical standard order NVG night vision goggles NVIS night vision imaging systems true vapor pressure OAT outside air temperature VBIM visual blade inspection method OEI one engine inoperative VER visual flight rules OGE out of ground effect VMC visual meteorological PBA pitch bias actuator conditions Page xxii
VOR very high frequency Altitudes omnidirectional range radio density altitude VSI vertical speed indicator Hp pressure altitude VISTOL vertical/short takeoff and V speeds landing VTOL vertical takeoff and landing diving speed WAT weight, altitude, temperature speed in level flight with maximum continuous power VMO maximum operating limit speed VNE never-exceed speed VTOSS takeoff safety speed for Category A rotorcraft Vx speed for best angle of climb Vr speed for best rate of climb MMO maximum operating mach number N speeds NF free turbine speed NG gas generator speed Np power turbine speed NR rotor speed Coefficients CD coefficient of drag GL coefficient of lift coefficient of power Ст coefficient of thrust Page xxili
CHAPTER 1. PART 21 FAR 21 - GENERAL
CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS (Amendment 21-50) AC 21.16. § 21.16 SPECIAL CONDITIONS.
a. The Process. Chapter 2, Section 1, Paragraph 8 of the Type Certificate Handbook, Order 8110.4A, provides detailed guidance on the special conditions process. However, much of that material has been outdated with the implementation of the Aircraft Certification Directorate Program. Rotorcraft special conditions are processed through the Rotorcraft Standards Staff, ASW-110. That office will ensure coordination with the affected agency and industry elements including the Assistant Chief Counsel. All comments will be considered and the disposition documented by the Rotorcraft Directorate. ASW-100 will issue the special conditions.
b. Basis for Development.
(1) Special conditions are justified on the basis of the existing Part 27 being inadequate or inappropriate due to novel or unusual design features of the rotorcraft to be certificated.
(2) The phrase "novel or unusual" as used in § 21.16 is a very relative term. As used hereafter in applying § 21.16 to justify the issuance of special conditions, "novel or unusual" will be taken with respect to the state of technology envisaged by the applicable airworthiness standards of this subchapter. It must be recognized that in some areas which will vary from time to time, the state of the regulations may somewhat lag the state of the art in new design because of the rapidity in which the state of the art is advancing in civil aeronautical design and because of the time required to develop the experience base needed by the FAA/AUTHORITY to proceed with general rulemaking.
Applicants for type certification of a new design have the opportunity to mitigate the impact of not knowing the precise airworthiness standards to be applied forinovel or unusual design features" by consulting with the FAA/AUTHORITY early in their certification planning when such features are suspected or known by the applicant to exist. It should also be recognized that, because of the intentional objective nature of the airworthiness standards of this subchapter, many new design features which might be thought of as "novel or unusual" may already be adequately covered by existing regulations, thus obviating the need to issue special conditions.
(3) Before proposing special conditions, the certification staff should very thoroughly analyze the existing regulations and ensure they are inadequate or inappropriate in light of a new and novel design feature.
Page FAR 21 - 1
AC 21.31. § 21.31 TYPE DESIGN.
The regulatory basis for requiring data to define the design is contained in § 21.31.
This section is self-explanatory and broad enough in scope to give the certification staff access to sufficient data to determine compliance with Part 27.
AC 21.33. § 21.33 INSPECTION AND TESTS.
a. Applicant Responsibility. Section 21.33 requires the applicant to:
(1) Ensure the test rotorcraft conforms to the type design. This must be accomplished prior to presentation to the FAA/AUTHORITY for testing.
(2) Conduct all inspections and tests necessary to determine compliance with the airworthiness and noise requirements.
b. FAA/AUTHORITY Responsibility.
(1) The design evaluation engineers should ensure that the type design is adequate in their technical area and that the inspections and tests to be conducted are appropriate and sufficient to show compliance with Part 27.
(2) As changes to the rotorcraft are made during the test program, the flight test crew should ensure that the appropriate design evaluation engineer concurs with the change and the conformity inspection of the change has been conducted.
AC 21.35 § 21.35 (Amendment 21-59) FLIGHT TESTS.
a. Explanation.
(1) This section outlines the requirements of the applicant for aircraft type certification and should be used in conjunction with FAA Order 8110.4A, Section 5.
Section 21.35 requires, in part, that the applicant conduct sufficient flight tests to show compliance with the flight requirements throughout the proposed flight envelope. The results of the applicant's flight test should be submitted to the FAA AUTHORITY in report form for evaluation to determine what verification flight tests the FAA AUTHORITY may elect to conduct. The report should conclude that in the applicant's opinion the test aircraft complies with the applicable certification requirements. The FAA/AUTHORITY verification flight test should include, but not be limited to, the critical or marginal results contained in the applicant's flight test report.
The FAA/AUTHORITY's role in the certification effort is not envisioned to be one of conducting day-to-day routine flight tests with the applicant, but only to verity his results through limited sampling. In certain tests, such as high altitude testing at a remote mountain site, there is an advantage in conducting flight tests concurrently with the applicant. Additionally, the FAA/AUTHORITY can provide technical flight test Page FAR 21 - 2
assistance to the applicant in certain cases. This can be done after a cursory review and a letter of authorization is issued to the flight test crew.
(2) Preflight Lest Planning. After the applicants flight test report is reviewed, it should be determined what FAA/AUTHORITY engineering flight tests are necessary.
These tests are normally specified in the Type Inspection Authorization (TIA). At the same time the FAA/AUTHORITY must know and agree to the applicant's proposed means of data acquisition, reduction, and expansion of the flight test data. The adequacy of the test instrumentation should be evaluated prior to official type certification tests (reference paragraph AC 21.39).
(3) Order of Testing. The Federal Aviation Regulations are so worded that the results of some flight tests have a definite bearing on the conduct of other tests. For this reason, and to minimize retesting, careful attention should be given to the order of testing. The exact order of testing will be determined only by considering the particular rotorcraft and test program involved. Tests which are particularly important in the early stages of the program are:
(i) Airspeed calibration: All tests involving airspeed depend upon the calibration.
(ii) Engine power available determination.
(iii) Engine cooling.
(4) Test Groupings.
Weight and c.g.: In addition to the regulatory relationship of one test to another, efficient testing requires that consideration be given to the accomplishment of as many tests on a single flight as can be accommodated successfully.
(•) Special Instrumentation. Similarly, consideration should be given to grouping of tests that involve special instrumentation. Examples of these are takeoff and landing tests which usually require group equipment to record horizontal distance, height, and time. Ground calibration of the airspeed indicating system can be accomplished at the same time. It is the applicant's responsibility to provide the necessary instrumentation.
(5) Functional and Reliability Testing
(i) Section 21.35(b)(2) requires that the applicant determine that "there is reasonable assurance that the aircraft, its components, and its equipment are reliable and function properly." Section 21.35(f)(1) requires a Function and Reliability (F&R) program of 300 hours for turbine engine powered aircraft incorporating engines of a type not previously used in a type certificated aircraft. Section 21.35(f)(2) requires a 150-hour F&R program for all other aircraft. The following reflects general practices that Page FAR 21 - 3