AC 27-1B

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Subject: CERTIFICATION OF NORMAL

CATEGORY ROTORCRAFT Date:

Initiated 4/25/06 ASW-110 AC No:

Change 27-1B 2 ______________________________________________

1. PURPOSE.

a. This change incorporates all the previously revised AC paragraphs that were posted as accepted and finalized AC material on the FAA RGL website since 2/12/03.

b. This change revises existing material in 16 paragraphs and adds new material for one paragraph.

c. 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.

d. 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.

2. PRINCIPAL CHANGES.

a. Paragraphs 27.351, 27.602, 27.672, 27.683, 27.777, 27.1321, 27.1585, MG 1, MG 4, MG 8, MG 16, Appendix A, and Appendix B are revised.

b. The AC material in paragraphs 27.801 and 27.1411 has been revised.

c. The AC material in MG 12 has been revised and is now contained in AC 27.865B, in Subpart D.

d. New paragraph MG 18, Helicopter Terrai n and Awareness Systems (HTAWS), is added to Chapter 3.

e. New figures AC 27.351-2 and AC 27.865B-1 are added in Chapter 2.

f. New figures AC 27 MG 8-1, MG 8-2, MG 8-3, MG 8-4, MG 18-1, MG 18-2, and MG 18-

2.1 are added in Chapter 3.

3. 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 2 4/25/06

AC 27-1B, Chg 2

PAGE CONTROL CHART Remove pages Dated Insert Pages Dated v thru xxi........................... 9/30/99 & 2/12/03 C-9 thru C-86.................... 9/30/99 & 2/12/03 D-1 thru D-58 ................... 9/30/99 & 2/12/03 D-67 thru D-70 ...................................9/30/99 D-83 thru D-112 ............... 9/30/99 & 2/12/03 F-33 thru F-102...................................9/30/99 G-43 thru G-48 ...................................9/30/99 MG 1-15 thru MG 1-17 ......................9/30/99 MG 4-9 thru MG 4-13 ........................9/30/99 MG 8-1 thru MG 8-15 ...... 9/30/99 & 2/12/03 MG 12-1 thru MG 12-42 .. 9/30/99 & 2/12/03 MG 16-1 thru MG 16-16 ....................2/12/03 none none Apdx A-47 thru Apdx A-70................2/12/03 Apdx B-11 thru Apdx B-20 ................9/30/99

v thru xxii ...........................................4/25/06 C-9 thru C-87......................................4/25/06 D-1 thru D-58 .....................................4/25/06 D-67 thru D-70 ...................................4/25/06 D-83 thru D-134 .................................4/25/06 F-33 thru F-103 ..................................4/25/06 G-43 thru G-49 ...................................4/25/06 MG 1-15 thru MG 1-16 ......................4/25/06 MG 4-9 thru MG 4-13 ........................4/25/06 MG 8-1 thru MG 8-31 ........................4/25/06 MG 12-1 .............................................4/25/06 MG 16-1 thru MG 16-18 ....................4/25/06 MG 17-1 .............................................4/25/06 MG 18-1 thru MG 18-27 ....................4/25/06 Apdx A-47 thru Apdx A-71 ...............4/25/06 Apdx B-11 thru Apdx B-20................4/25/06

David A. Downey Manager, Rotorcraft Directorate Aircraft Certification Service

Subject: CERTIFICATION OF NORMAL

CATEGORY ROTORCRAFT Date:

Initiated 2/12/03 ASW-110 AC No:

Change 27-1B 1 ______________________________________________

1. PURPOSE.

a. This change revises existing 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.

d. Appendix A (previously reserved) is added.

e. 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.

f. 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.

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 2

U.S. Department of Transportation

Federal Aviation Administration

Subject: CERTIFICATION OF NORMAL

CATEGORY ROTORCRAFT Date:

Initiated by:

9/30/99 ASW-110 AC No:

Change:

27-1B

______________________________________________

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.

• 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.

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.

Eric Bries Acting Manager, Rotorcraft Directorate Aircraft Certification Service

CONTENTS

CHAPTER 1 - FAR 21 CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS

Page No.

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 ................................................................ FAR 21-6 and Correction Report

CHAPTER 2 - FAR 27 AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT

SUBPART A - GENERAL

GENERAL

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

SUBPART B - FLIGHT

GENERAL

AC 27.21 Proof

of ComplianceB-1

AC 27.25 Weight LimitsB-3

AC 27.27 Center

of Gravity LimitsB-4

AC 27.29 Empty Weight and Corresponding Center of GravityB-6

AC 27.31 Removable BallastB-7

AC 27.33 Main Rotor Speed and Pitch LimitsB-7

PERFORMANCE

AC 27.45 Performance

- GeneralB-9

AC 27.45A GeneralB-18

AC 27.45B GeneralB-18

AC 27.51 TakeoffB-25

SUBPART B - FLIGHT (continued)

PERFORMANCE (continued)

Page No.

AC 27.65 Climb: All Engines OperatingB-26

AC 27.65A Climb: All Engines OperatingB-28

AC 27.67 Climb: One Engine InoperativeB-28

AC 27.71 Glide PerformanceB-29

AC 27.73 Performance at Minimum Operating SpeedB-32

AC 27.75 LandingB-34

AC 27.79 Limiting Height - Speed EnvelopeB-37

AC 27.79A Limiting Height - Speed EnvelopeB-45

FLIGHT CHARACTERISTICS

AC 27.141 Flight Characteristics - GeneralB-46

AC 27.143 Controllability and ManeuverabilityB-47

AC 27.151 Flight ControlsB-52

AC 27.161 Trim ControlB-53

AC 27.171 Stability: GeneralB-53

AC 27.173 Static Longitudinal StabilityB-54

AC 27.175 Demonstration of Static Longitudinal StabilityB-55

AC 27.177 Static Directional StabilityB-59

GROUND AND WATER HANDLING CHARACTERISTICS

AC 27.231 Ground and Water Handling Characteristics - GeneralB-61

AC 27.235 Taxiing Condition..................................................................................................B- 61

AC 27.239 Spray CharacteristicsB-62

AC 27.241 Ground ResonanceB-63

MISCELLANEOUS FLIGHT REQUIREMENTS

AC 27.251 VibrationB-68

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

SUBPART C - STRENGTH REQUIREMENTS (continued)

GENERAL (continued)

Page No.

AC 27.307A Proof of Structure.................................................................................................. .C - 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

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 27-1B, Chg 2 4/25/06 SUBPART C - STRENGTH REQUIREMENTS( continued)

GROUND LOADS (continued)

Page No.

AC 27.497 Ground Loading Conditions:C-32

Landing Gear With Tail Wheels

AC 27.501 Ground Loading Conditions:C-34

Landing Gear With Skids

AC 27.501A Ground Loading Conditions:C-35

Landing Gear With Skids

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-43

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 CertificationC-86

SUBPART D - DESIGN AND CONSTRUCTION

GENERAL

Page No.

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-5

SUBPART D - DESIGN AND CONSTRUCTION

GENERAL (continued)

Page No.

AC 27.609 Protection of StructureD-5

AC 27.610 Lightning ProtectionD-6

AC 27.610A Lightning and Static Electricity ProtectionD-9

AC 27.611 Inspection ProvisionsD-13

AC 27.613 Material Strength PropertiesD-14

and Design Values

AC 27.613A Material Strength PropertiesD-16

and Design Values

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,D-36

and Power-Operated Systems

AC 27.673 Primary Flight ControlD-37

AC 27.674 Interconnected ControlsD-37

AC 27.675 StopsD-38

AC 27.679 Control System LocksD-39

AC 27.681 Limit Load Static TestsD-40

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