AC 27.1B, Chg 4 5/1/2014
• Paragraphs that do not correspond with a FAR number either remain in Chapter 3 and are renumbered as MG paragraphs, or are now an appendix.
• In order to stay aligned with FAR numbering, Appendices A and C are reserved for future AC material.
b. Paragraphs revised to incorporate technical guidance are AC 21.35, 27.561, 27.952, 27.1305,
27.1309, 27.1351, 27.1353, MG 2, and MG 4 (FADEC). AC 27.661, Rotorblade Clearance, contains new material added as a result of National Transportation Safety Board (NTSB) recommendations.
c. New paragraphs added are AC 27.1B and 27.2A, Gross Weight; AC 27.602, Critical Parts; and AC MG 12, External Loads. These paragraphs correspond with recent harmonized regulatory changes.
d. The AC is now divided by Subparts and page numbers reflect the relevant FAR Subpart.
e. “FAA/AUTHORITY” as used in this document means FAA or another airworthiness authority that has adopted this AC as a means of compliance with the appropriate regulation referenced.
5. DEVIATIONS. As rotorcraft designs vary from conventional configurations, it may become necessary to deviate from the methods and procedures outlined in this AC. These procedures are only one acceptable means of compliance with Part 27. Any alternate means proposed by an applicant will be given due consideration. Applicants are encouraged to use their technical ingenuity and resourcefulness to develop more efficient and less costly methods of achieving the objectives of Part 27. Regulatory personnel and designees should respond to such efforts by the use of engineering judgment in fostering any such efforts as long as the letter and spirit of Part 27 and the Federal Aviation Act are respected. It is recommended that unusual or unique projects be coordinated a sufficient time in advance with the Rotorcraft Standards Staff, ASW-110, or with the appropriate airworthiness authority, to ensure timely and uniform consideration.
6. APPLICABILITY. This material is not to be construed as having any legally binding status and must be treated as advisory only. However, to ensure standardization in the certification process, these procedures should be considered during all rotorcraft type certification and supplemental type certification activities.
7. PARAGRAPHS KEYED TO FAR PART 27. Each paragraph has the applicable amendment to Part 27 shown in the title. All of the original guidance material has been retained as appropriate, even as changes are made to the regulations. This is accomplished through the use of “A,” “B,” etc., paragraphs that follow the original numbered paragraphs. These subsequent paragraphs provide updated guidance information or changes to policy that parallel a specific rule change. The guidance material in the original paragraph (for earlier amendments) still applies and is modified as explained in each of the later paragraphs for later amendments. The applicable amendment number will only appear in the title line for the “A,” “B,” etc., paragraphs. The guidance material in the initial paragraph is intended to apply to all amendments except as modified by the later paragraphs. Each ensuing “A,” “B,” etc., paragraph will be identified with an amendment level to indicate the rule change that precipitated the policy change.
Page ii
Eric Bries
5/1/2014 AC 27-1B, Chg 4
8. RELATED PUBLICATIONS. FAA Certification personnel and designees should be familiar with Order 8110.4, Type Certification, and Order 8100.5, Aircraft Certification Directorate Procedures.
Acti ng Manager, Rotorcraft Directorate Aircraft Certification Service Page iii
CONT ENTS Pag e No.
CHA PTER 1 - PART 21 CERTIFICATION PROCEDURES FOR
PRODUCTS AND PARTS AC
21.16 Special Conditions ........................................................................ FAR 21-1 AC 21.31 Type Design.................................................................................. FAR 21-2 AC 21.33 Inspection and Tests ..................................................................... FAR 21-2 AC 21.35 Flight Tests.................................................................................... FAR 21-2 AC 21.39 Flight Test Instrument Calibration and Correction Report .............FAR 21-6 CH APTER 2 - PART 27 AIRWORTHINESS STANDARDS:
NORMAL CATEGORY ROTORCRAFT SUBP ART A GEN ERAL AC
27.1 ApplicabilityA-1
AC 27.1A ApplicabilityA-1
AC 27.1B ApplicabilityA-2
AC 27.2 Special Retroactive RequirementsA-2
AC 27.2A Special Retroactive RequirementsA-4
SUBP
ART B - FLIGHT GEN ERAL AC
27.21 Proof of ComplianceB-1
AC 27.25 Weight LimitsB-3
AC 27.25A Weight LimitsB-4
AC 27.27 Center of Gravity Limits..................................................................... B-4.2 AC 27.29 Empty Weight and Corresponding Center of Gravity ........................ B-6.2
AC 27.31 Removable BallastB-7
AC 27.33 Main Rotor Speed and Pitch LimitsB-7
PE
RFORMANCE AC
27.45 Performance - GeneralB-9
AC 27.45A GeneralB-18
AC 27.45B GeneralB-18
AC 27.45C Performance – GeneralB-18
Pag e No.
Pag e iii
AC 27.1B, Chg 9 AC
27.49 AC 27.51 AC 27.51A AC 27.65 AC 27.65A AC 27.67 AC 27.71 AC 27.73 AC 27.75 AC 27.75A AC 27.79 AC 27.79A AC 27.87 AC 27.87A AC 27.141 AC 27.143 AC 27.143A AC 27.151 AC 27.161 AC 27.171 AC 27.173 AC 27.173A AC 27.175 AC 27.175A AC 27.177 AC 27.177A AC 27.231 AC 27.235 AC 27.239 AC 27.241 AC 27.251 Page iv SUBP ART B - FLIGHT (c ontinued) PE RFORMANCE (continued) Performance at Minimum Operating Speed ...................................... B-24.2
TakeoffB-25
TakeoffB-26
Climb: All Engines Operating ........................................................... B-26.2
Climb: All Engines OperatingB-28
Climb: One Engine InoperativeB-28
Autorotation PerformanceB-29
Performance at Minimum Operating SpeedB-32
Landing ............................................................................................. B-34.1
LandingB-35
Limiting Height - Speed EnvelopeB-37
Limiting Height - Speed EnvelopeB-45
Height-Speed EnvelopeB-45
Height-Velocity Envelope .................................................................. B-45.1 FLI
GHT CHARACTERISTICS
Flight Characteristics - GeneralB-46
Controllability and ManeuverabilityB-48
Controllability and Maneuverability.................................................... B-52.2 Flight Controls................................................................................... B-52.8
Trim ControlB-53
Stability: GeneralB-53
Static Longitudinal StabilityB-54
Static Longitudinal StabilityB-55
Demonstration of Static Longitudinal StabilityB-58
Demonstration of Static Longitudinal Stability ................................... B-60.2 Static Directional Stability.................................................................. B-60.6 Static Directional Stability.................................................................. B-60.7
GROUND AND WATER HANDLING CHARACTERISTICS
Ground and Water Handling Characteristics - GeneralB-61
Taxiing ConditionB-61
Spray CharacteristicsB-62
Ground ResonanceB-63
MISCELLANEOUS FLIGHT REQUIREMENTS
VibrationB-68
Page No.
SUBPART C - STRENGTH REQUIREMENTS
GENERAL
AC 27.301 LoadsC-1
AC 27.303 Factor of SafetyC-1
AC 27.305 Strength and DeformationC-2
AC 27.307 Proof of StructureC-2
AC
27.307A Pro
of of StructureC-3
AC 27.309 Design LimitationsC-4
FLIGHT LOADS
AC 27.321 Flight Loads - GeneralC-5
AC 27.337 Limit Maneuvering Load FactorC-5
AC 27.339 Resultant Limit Maneuvering LoadsC-8
AC 27.341 Gust LoadsC-8
AC 27.351 Yawing ConditionsC-9
AC 27.361 Engine TorqueC-14
CONTROL SURFACE AND SYSTEM LOADS
AC 27.391 Control Surface and System Loads - GeneralC-15
AC 27.391A Control Surface and System Loads - GeneralC-15
AC 27.395 Control SystemC-15
AC 27.395A Control SystemC-17
AC 27.397 Limit Pilot Forces and TorquesC-17
AC 27.399 Dual Control SystemC-18
AC 27.401 Auxiliary Rotor AssembliesC-18
AC 27.401A Auxiliary Rotor AssembliesC-20
AC 27.403 Auxiliary Rotor Attachment StructureC-20
AC 27.403A Auxiliary Rotor Attachment StructureC-21
AC 27.411 Ground Clearance: Tail Rotor GuardC-21
AC 27.413 Stabilizing and Control SurfacesC-22
AC 27.413A Stabilizing and Control SurfacesC-24
AC 27.427 Unsymmetrical LoadsC-24
GROUND LOADS
AC 27.471 Ground Loads - GeneralC-28
AC 27.473 Ground Loading Conditions and AssumptionsC-28
AC 27.475 Tires and Shock AbsorbersC-29
AC 27.477 Landing Gear ArrangementC-29
Page v
AC 27.1B, Chg 4 5/1/ 2014 Page No.
SUBPART C - STRENGTH REQUIREMENTS (continued) GROUND LOADS (continued)
AC 27.479 Level Landing ConditionsC-29
AC 27.481 Tail-Down Landing ConditionsC-30
AC 27.483 One-Wheel Landing ConditionsC-31
AC 27.485 Lateral Drift Landing ConditionsC-31
AC 27.493 Braked Roll ConditionsC-32
AC 27.497 Ground Loading Conditions: Landing Gear With Tail WheelsC-32
AC 27.501 Ground Loading Conditions: Landing Gear With SkidsC-34
AC 27.501A Ground Loading Conditions: Landing Gear With SkidsC-35
AC 27.505 Ski Landing ConditionsC-35
WATER LOADS
AC 27.521 Float Landing ConditionsC-37
MAIN COMPONENT REQUIREMENTS
AC 27.547 Main Rotor StructureC-38
AC 27.549 Fuselage, Landing Gear, and Rotor Pylon StructureC-38
EMERGENCY LANDING CONDITIONS
AC 27.561 Emergency Landing Conditions - GeneralC-40
AC 27.561A Emergency Landing Conditions - GeneralC-41
AC 27.561B Emergency Landing Conditions - GeneralC-42
AC 27.561C Emergency Landing Conditions - GeneralC-43
AC 27.562 Emergency Landing Dynamic ConditionsC-44
AC 27.563 Structural Ditching ProvisionsC-81
AC 27.563A Structural Ditching ProvisionsC-81
FATIGUE EVALUATION
AC 27.571 Fatigue Evaluation of Flight StructureC-83
AC 27.571A Fatigue Evaluation of Flight Structure for Category A Certification ... C-86
AC 27.573 Damage Tolerance and Fatigue Evaluation of CompositeC-88
Rotorcraft Structures Page vi
Page No.
SUBPART D - DESIGN AND CONSTRUCTION
GENERAL
AC 27.601 DesignD-1
AC 27.602 Critical PartsD-2
AC 27.603 MaterialsD-4
AC 27.605 Fabrication MethodsD-4
AC 27.607 FastenersD-6
AC 27.609 Protection of StructureD-6
AC 27.610 Lightning ProtectionD-8
AC 27.611 Inspection ProvisionsD-11
AC 27.613 Material Strength Properties and Design ValuesD-13
AC 27.613A Material Strength Properties and Design ValuesD-14
AC 27.619 Special FactorsD-16
AC 27.621 Casting FactorsD-17
AC 27.623 Bearing FactorsD-27
AC 27.625 Fitting FactorsD-28
AC 27.625A Fitting FactorsD-29
AC 27.629 FlutterD-29
ROTORS
AC 27.653 Pressure Venting and Drainage of Rotor BladesD-31
AC 27.659 Mass BalanceD-31
AC 27.661 Rotor Blade ClearanceD-31
AC 27.663 Ground Resonance Prevention MeansD-33
AC 27.663A Ground Resonance Prevention MeansD-35
CONTROL SYSTEMS
AC 27.671 Control Systems - GeneralD-36
AC 27.672 Stability Augmentation, Automatic, and Power-Operated Systems... D-36
AC 27.673 Primary Flight ControlD-37
AC 27.674 Interconnected ControlsD-37
AC 27.675 StopsD-38
AC 27.679 Control System LocksD-40
AC 27.681 Limit Load Static Tests...................................................................... D-40.1
AC 27.683 Operation TestsD-41
AC 27.685 Control System DetailsD-41
AC 27.685A Control System DetailsD-42
AC 27.687 Spring DevicesD-43
AC
27.691 Autorotation Control MechanismD-43
AC 27.695 Power Boost and Power-Operated Control SystemD-44
Page vii
AC 27.1B, Chg 4 5/1/2014 Page No.
SUBPART D - DESIGN AND CONSTRUCTION (continued)
LANDING GEAR
AC 27.723 Shock Absorption TestsD-47
AC 27.725 Limit Drop TestD-50
AC 27.727 Reserve Energy Absorption Drop TestD-50
AC 27.727A Reserve Energy Absorption Drop TestD-51
AC 27.729 Retracting MechanismD-51
AC 27.731 WheelsD-54
AC 27.733 TiresD-55
AC 27.735 BrakesD-56
AC 27.737 SkisD-58
FLOATS AND HULLS
AC 27.751 Main Float BuoyancyD-59
AC 27.753 Main Float DesignD-60
AC 27.755 HullsD-60
PERSONNEL AND CARGO ACCOMMODATIONS
AC 27.771 Pilot CompartmentD-62
AC 27.773 Pilot Compartment ViewD-63
AC 27.775 Windshields and WindowsD-68
AC 27.775A Windshields and WindowsD-68
AC 27.777 Cockpit ControlsD-68
AC 27.779 Motion and Effect of Cockpit ControlsD-69
AC 27.783 Doors ................................................................................................ D-72.2
AC 27.783A DoorsD-74
AC 27.785 Seats, Berths, Safety Belts, and HarnessesD-74
AC 27.785A Seats, Berths, Safety Belts, and HarnessesD-78
AC 27.785B Seats, Berths, Litters, Safety Belts, and HarnessesD-80
AC 27.787 Cargo and Baggage CompartmentsD-80
AC 27.787A Cargo and Baggage CompartmentsD-82
AC 27.801 DitchingD-82
AC 27.805 Flight Crew Emergency ExitsD-91
AC 27.807 Emergency ExitsD-91
AC 27.807A Emergency ExitsD-93
AC 27.807B Emergency ExitsD-93
AC 27.831 VentilationD-94
AC 27.833 HeatersD-96
Page viii
AC 27-1B, Chg 9 AC 27.853 AC 27.853A AC 27.855 AC 27.859 AC 27.861 AC 27.861A AC 27.863 AC 27.865 AC 27.865A AC 27.865B AC 27.871 AC 27.873 AC 27.901 AC 27.901A AC 27.903 AC 27.903A AC 27.903B AC 27.903C AC 27.907 AC 27.917 AC 27.921 AC 27.923 AC 27.923A AC 27.923B AC 27.927 AC 27.927A AC 27.931 Page No.
SUBPART D - DESIGN AND CONSTRUCTION (continued)
FIRE PROTECTION
Compartment InteriorsD-98
Compartment InteriorsD-99
Cargo and Baggage CompartmentsD-99
Heating SystemsD-101
Fire Protection of Structure, Controls, and Other PartsD-105
Fire Protection of Structure, Controls, and Other PartsD-106
Flammable Fluid Fire ProtectionD-107
EXTERNAL LOADS
External Load Attaching MeansD-109
External Load Attaching MeansD-110
External Loads (previously MG 12)D-111
MISCELLANEOUS
Leveling MarksD-133
Ballast ProvisionsD-133
SUBPART E - POWERPLANT
GENERAL
InstallationE-1
InstallationE-5
Engines ............................................................................................. E-5.2
EnginesE-7
EnginesE-9
Engines ............................................................................................. E-10.1 Engine Vibration................................................................................ E-1 0.1a ROT
OR DRIVE SYSTEM Design............................................................................................... E-10.2
Rotor BrakeE-11
Rotor Drive System and Control Mechanism TestsE-12
Rotor Drive System and Control Mechanism TestsE-17
Rotor Drive System and Control Mechanism TestsE-18
Additional TestsE-19
Additional TestsE-21
Shafting Critical SpeedsE-21
Page ix
AC 27-1B, Chg 4 5/1/2014 Page No.
SUBPART E – POWERPLANT (continued) ROTOR DRIVE SYSTEM (continued)
AC 27.935 Shafting JointsE-26
AC 27.939 Turbine Engine Operating CharacteristicsE-26
FUEL SYSTEM
AC 27.951 Fuel System - GeneralE-29
AC 27.952 Fuel System Crash ResistanceE-31
AC 27.953 Fuel System IndependenceE-56
AC 27.954 Fuel System Lightning ProtectionE-57
AC 27.955 Fuel FlowE-58
AC 27.955A Fuel FlowE-62
AC 27.959 Unusable Fuel SupplyE-64
AC 27.961 Fuel System Hot Weather OperationE-65
AC 27.961A Fuel System Hot Weather OperationE-67
AC 27.963 Fuel Tanks: GeneralE-67
AC 27.963A Fuel Tanks: GeneralE-68
AC 27.963B Fuel Tanks: GeneralE-68
AC 27.965 Fuel Tank TestsE-69
AC 27.967 Fuel Tank InstallationE-70
AC 27.969 Fuel Tank Expansion SpaceE-72
AC 27.969A Fuel Tank Expansion SpaceE-72
AC 27.971 Fuel Tank SumpE-73
AC 27.971A Fuel Tank SumpE-74
AC 27.973 Fuel Tank Filler ConnectionE-74
AC 27.973A Fuel Tank Filler ConnectionE-75
AC 27.975 Fuel Tank VentsE-76
AC 27.975A Fuel Tank VentsE-77
AC 27.975B Fuel Tank VentsE-77
AC 27.977 Fuel Tank OutletE-78
FUEL SYSTEM COMPONENTS
AC 27.991 Fuel PumpsE-80
AC 27.991A Fuel PumpsE-81
AC 27.993 Fuel System Lines and FittingsE-81
AC 27.995 Fuel ValvesE-82
AC 27.997 Fuel Strainer or FilterE-82
AC 27.997A Fuel Strainer or FilterE-83
AC 27.999 Fuel System DrainsE-84
AC 27.999A Fuel System DrainsE-85
Page x
Page No.
SUBPART E - POWERPLANT (continued)
OIL SYSTEM
AC 27.1011 Engines - GeneralE-86
AC 27.1013 Oil TanksE-86
AC 27.1015 Oil Tank TestsE-87
AC 27.1017 Oil Lines and FittingsE-88
AC 27.1019 Oil Strainer or FilterE-88
AC 27.1019A Oil Strainer or FilterE-89
AC 27.1021 Oil System DrainsE-90
AC 27.1027 Transmission and Gearboxes: GeneralE-90
COOLING
AC 27.1041 Cooling - GeneralE-92
AC 27.1041A GeneralE-94
AC 27.1043 Cooling TestsE-94
AC 27.1045 Cooling Test ProceduresE-97
AC 27.1045A Cooling Test ProceduresE-98
INDUCTION SYSTEM
AC 27.1091 Air InductionE-99
AC 27.1091A Air InductionE-100
AC 27.1093 Induction System Icing ProtectionE-101
AC 27.1093A Induction System Icing Protection..................................................... E-112.1
EXHAUST SYSTEM
AC 27.1121 GeneralE-113
AC 27.1123 Exhaust PipingE-114
POWERPLANT CONTROLS AND ACCESSORIES
AC 27.1141 Powerplant Controls: GeneralE-117
AC 27.1141A Powerplant Controls: GeneralE-118
AC 27.1143 Engine ControlsE-118
AC 27.1143A Engine ControlsE-119
AC 27.1143B Engine ControlsE-119
AC 27.1145 Ignition SwitchesE-120
AC 27.1147 Mixture ControlsE-120
AC 27.1151 Rotor Brake ControlsE-121
AC 27.1163 Powerplant AccessoriesE-122
Page No.
Page xi
AC 27-1B, Chg 9 AC 27.1183 AC 27.1185 AC 27.1187 AC 27.1189 AC 27.1191 AC 27.1193 AC 27.1193A AC 27.1194 AC 27.1195 AC 27.1301 AC 27.1303 AC 27.1305 AC 27.1305A AC 27.1305B AC 27.1305C AC 27.1307 AC 27.1309 AC 27.1309A AC 27.1309B AC 27.1316 AC 27.1317 AC 27.1321 AC 27.1322 AC 27.1323 AC 27.1325 AC 27.1327 AC 27.1329 AC 27.1329A AC 27.1329B AC 27.1335 AC 27.1335A AC 27.1337 AC 27.1337A SUBPART E - POWERPLANT (continued)
POWERPLANT FIRE PROTECTION
Lines, Fittings, and ComponentsE-124
Flammable FluidsE-125
Ventilation and DrainageE-126
Shutoff MeansE-127
FirewallsE-128
Cowling and Engine Compartment CoveringE-132
Cowling and Engine Compartment CoveringE-133
Other SurfacesE-134
Fire Detector SystemsE-135
SUBPART F - EQUIPMENT
GENERAL
Function and InstallationF-1
Flight and Navigation InstrumentsF-1
Powerplant InstrumentsF-7
Powerplant InstrumentsF-8
Powerplant InstrumentsF-9
Powerplant Instruments .................................................................... F-11.1 Miscellaneous
EquipmentF-12
Equipment, Systems, and InstallationsF-13
Equipment, Systems, and InstallationsF-30
Equipment, Systems, and Installations ............................................ F-30.1
Electrical and Electronic System Lightning ProtectionF-31
High-Intensity Radiated Fields (HIRF) ProtectionF-32
INSTRUMENTS: INSTALLATION
Arrangement and VisibilityF-34
Powerplant Instruments .................................................................... F-54.2 Powerplant Instruments .................................................................... F-54.3 W arning, Caution, and Advisory Lights ............................................. F-34.2
Airspeed Indicating SystemF-39
Static Pressure SystemsF-40
Magnetic Direction IndicatorF-41
Automatic Pilot SystemF-41
Automatic Pilot SystemF-51
Automatic Pilot System and Flight Guidance System. ...................... F-52.1 F
light Director SystemsF-53
Flight Director Systems ..................................................................... F-54.1 P age xii