Subject: CERTIFICATION OF NORMAL Date: 2/12/03 AC No:
CATEGORY ROTORCRAFT Initiated ASW-110 Change ______________________________________________
1. PURPOSE.
27-1B 1
a. This change revises exi sting material in 17 paragraphs and adds new material for 12 paragraphs.
b. The change number and the date of the changed material are shown at the top of each page.
The vertical lines in the right and left margins indicate the beginning and end of each change. Pages that have different page numbers but no text changes will retain the previous heading information.
2. CANCELLATION.
a. AC 20-95, Fatigue Evaluation of Rotorcraft Structure, May 18, 1976, is canceled in its entirety, and is replaced by material contained in AC 27 MG 11.
b. AC 20-137, Dynamic Evaluation of Seat Restraint Systems & Occupant Restraint for Rotorcraft (Normal and Transport), March 30, 1992, is canceled in its entirety, and is replaced by material contained in AC 27.562.
c. AC text containing references to AC 20-95 and AC 20-137 was either changed or deleted in paragraphs AC 27.2, 27.562, 27.613, 27.785A, 27.865A, 27.907, 27.952, MG 8, and MG 12.
3. PRINCIPAL CHANGES.
a. Paragraphs 27.562, 27.571, 27.1303, 27.1353, 27.1419, 27.1505, 27.1529, MG 5, MG 6, and MG 12 are revised.
b. New paragraphs 27.610A, 27.625A, 27.785B, 27.805, 27.807B, and 27.853A are added to Chapter 2.
c. New paragraphs MG 11, MG 13, MG 14, MG 15, and MG 16 are added to Chapter 3.
f. Appendix A (previously reserved) is added.
g. New figures AC 27.562-1, 27.562-2, 27.562-3, 27.562-4, 27.562-5, 27.562-6,
27.562-7, and 27.562-8 are added in Chapter 2.
h. New figures AC 27 MG 11-1, 11-2, 11-3, 11-4, 11-5, 11-6, 11-7, 11-8, 11-9, and AC 27 MG 14-1 are added in Chapter 3.
AC 27.1B, Chg 4 5/1/2014
4. WEBSITE AVAILABILITY. To access this AC electronically, log on to http://www.airweb.faa.gov/rgl and then click on AC’s.
AC 27-1B, Chg 1
PAGE CONTROL CHART
Remove pages Dated Insert Pages Dated iii thru xix........................................... 9/30/99 A-3 thru A-4....................................... 9/30/99 C-43 thru C-50 ................................... 9/30/99 D-7 thru D-105................................... 9/30/99 E-9 thru E-10...................................... 9/30/99 E-31 thru E-32.................................... 9/30/99 E-39 thru E-44.................................... 9/30/99 F-1 thru F-91...................................... 9/30/99 G-3 thru G-47..................................... 9/30/99 MG 5-3 thru MG 5-6.......................... 9/30/99 MG 6-5 thru MG 6-16........................ 9/30/99 MG 8-5 thru MG 8-6.......................... 9/30/99 none MG 12-21 thru MG 12-24.................. 9/30/99 MG 12-37 thru MG 12-38.................. 9/30/99 none none none none none iii thru xxi ...........................................2/12/03 A-3 thru A-4 .......................................2/12/03 C-43 thru C-86....................................2/12/03 D-7 thru D-112 ...................................2/12/03 E-9 thru E-10 ......................................2/12/03 E-31 thru E-32 ....................................2/12/03 E-39 thru E-44 ....................................2/12/03 F-1 thru F-102.....................................2/12/03 G-3 thru G-48 .....................................2/12/03 MG 5-3 thru MG 5-6 ..........................2/12/03 MG 6-5 thru MG 6-16 ........................2/12/03 MG 8-5 thru MG 8-6 ..........................2/12/03 MG 11-1 thru MG 11-28 ....................2/12/03 MG 12-21 thru MG 12-24 ..................2/12/03 MG 12-37 thru MG 12-38 ..................2/12/03 MG 13-1 thru MG 13-8 ......................2/12/03 MG 14-1 thru MG 14-8 ......................2/12/03 MG 15-1 thru MG 15-18 ....................2/12/03 MG 16-1 thru MG 16-16 ....................2/12/03 Apdx A-1 thru Apdx A-70..................2/12/03 David A. Downey Manager, Rotorcraft Directorate Aircraft Certification Service Page ii
______________________________________________
U.S. Department of Transportation Federal Aviation
Administration
Subject: CERTIFICATION OF NORMAL Date: 9/30/99 AC No: 27-1B CATEGORY ROTORCRAFT Initiated by: ASW-110 Change:
1. PURPOSE:
a. This is a total revision of AC 27-1A dated 7/30/97, with Change 1 dated 9/30/98, incorporated.
In addition, new material plus changes to existing paragraphs are incorporated. This consolidated version is now renumbered as AC 27-1B and replaces AC 27-1A in its entirety. This revises existing material in 10 paragraphs, adds new material for three paragraphs, and renumbers paragraphs to correspond with Federal Aviation Regulations (FAR) numbering.
b. Requests from the rotorcraft industry to make the document easier to use resulted in renumbering the AC paragraphs to correspond with FAR numbering. The figure numbers are also renumbered accordingly.
c. This AC does not change regulatory requirements and does not authorize changes in, or deviations from, regulatory requirements. This AC establishes an acceptable means, but not the only means, of compliance. Since the guidance material presented in this AC is not regulatory, terms having a mandatory definition, such as “shall” and “must,” etc., as used in this AC, apply either to the reiteration of a regulation itself, or to an applicant who chooses to follow a prescribed method of compliance without deviation.
d. This advisory circular provides information on methods of compliance with 14 CFR Part 27, which contains the Airworthiness Standards for Normal Category Rotorcraft. It includes methods of compliance in the areas of basic design, ground tests, and flight tests.
2. CANCELLATION. AC 27-1A, Certification of Normal Category Rotorcraft, dated 7/30/97, is canceled in its entirety.
3. BACKGROUND. Based largely on precedents set during rotorcraft certification programs spanning over 40 years, this AC consolidates guidance contained in earlier correspondence among FAA headquarters, foreign authorities, the rotorcraft industry, and certificating regions.
4. PRINCIPAL CHANGES:
a. Chapter 3 is now titled "Miscellaneous Guidance (MG), Normal Category Rotorcraft," with the following changes:
• Paragraphs that correspond to a FAR number are merged into existing AC text in Chapter 2.
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