AC 29-2C

Change 2Historical

Advisory circular · Certification of Transport Category Rotorcraft

A newer version is currentThis is a historical version. AC 29-2C CHG 9 is the version in force, approved June 23, 2023.
Approved
April 25, 2006
Last reviewed
December 4, 2008
Family
AC 29-2 · 13 versions
Revision
C, change 2
14 CFR parts
29

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed November 22, 2025.

Show pages 13–24
Page 25 · xixOpen in PDF

Figure No. Title Page

AC 29.562-7 Impulse Shape C-91

AC 29.562-8 Change in Velocity C-91

AC 29.571-1 Comparison Percent of Time in Level Flight C-96

AC 29.621-1 Example of Cast ing Load Sheet Retract D-24 Actuator Support-Landing Gear

AC 29.621-2 Castings to be Static Tested for Model XYZ D-26

AC 29.773-1 Cockpit Visibility D-73

AC 29.801-1 Sea State Code - World Meteorological D-96 Organization

AC 29.863-1 Flammable Fluids Fire Protection Flow Chart D-128

AC 29.865-1 Summary of Part 133 Rotorcraft Load D-136 Combinations Certifiable Under § 29.865

AC 29.865B-1 U.S. Operational (Part 133) Rotorcraft-Load D-146 Combination vs. Applicable Cargo Type Data And Definition Summary

AC 29.877-1 Continuous Icing-Te mperature vs. Altitude D-181 Limits

AC 29.877-2 Intermittent Icing- Temperature vs. Altitude D-182 Limits

AC 29.877-3 Mean Effective Drop Diameter-Microns D-183

AC 29.877-4 Intermittent Icing- Liquid Water Content vs. D-184 Drop Diameter

AC 29.877-5 Supercooled Clouds D-185

AC 29.903C-1 Estimated Path of Fragments E-23

AC 29.903C -2 Single One- Third Disc Fragment E-24

AC 29.903C -3 Intermediate and Small Pieces of Debris E-25

Page 26 · xxOpen in PDF

AC 29-2C, Chg 1 2/12/03 Figure No. Title Page

AC 29.903C -4 Blade Fragment Definition E-26

AC 29.903C -5 Distribution of Translational and Rotational E-27 Kinetic Energy of Rotor-Component Fragments as a Function of Fragment Size

AC 29.903C -6 Cross Section through Aircraft at Plane of E-28 Rotation of the Engine Disk Fragment

AC 29.923A-1 Rotor Drive System Endurance E-48

AC 29.923A-2 Takeoff Run Portion of Rotor Drive System E-49 Endurance Test If 2 ½ Minute OEI Rating is Requested.

AC 29.923A-3 Takeoff Run Portion of Rotor Drive System E-50 Endurance Test If 30 Second/2 Minute OEI Rating is Requested.

AC 29.931-1 Cantilevered Shaft, First Critical Speed E-62

AC 29.931-2 Shaft Between Support Bearings, First Critical E-62 Speed

AC 29.952-1 Static Tensi on and Shear Loading Modes E-87

AC 29.952-2 Hose Assembly Tests E-88

AC 29.952-3 Minimum Average and Individual Loads for E-89 Hose and Hose-End Fitting Combinations

AC 29.952-4 Typical Method of Breakaway Fuel Fitting Load E-90 Calculations

AC 29.952-5 Typical Methods of Frangible or Deformable E-91 Attachment Load Calculations (Frangible Bolts)

AC 29.952-6 Typical Methods of Frangible or Deformable E-92 Attachment Load Calculations (Frangible Baffle)

AC 29.955A-1 Fuel Flow E-102

AC 29.1041-1 Additional Cooling Test Point E-139

Page 27 · xxiOpen in PDF

Figure No. Title Page

AC 29.1045-1 All-Engine-Critical Altitude Additional Cooling E-146 Test Point

AC 29.1191-1 Table of Materials and Gages Acceptable E-190 for Fireproof Protective Devices with Flat Surface Geometries

AC 29.1309-1 Relationship Between Probability and Severity F-17 of Failure Condition Effects

AC 29.1309-2 Failure Condition Categories and Probability F-18 Definitions

AC 29.1309-3 Failure Condition Conversion F-19

AC 29.1309-4 Safety Assessment Process Overview F-24

AC 29.1309-5 Depth of Analysis Flowchart F-25

AC 29.1329-1 Deviation Profile F-57

AC 29.1329-2 Operational Limitation F-59

AC 29.1419-1 Continuous Icing-Te mperature vs. Altitude F-110 Limits

AC 29.1419-2 Intermittent Icing- Temperature vs. Altitude F-111 Limits

AC 29.1419-3 Continuous Icing-Liquid Water Content vs F-112 Drop Diameter

AC 29.1419-4 Intermittent Icing- Liquid Water Content vs. F-113 Drop Diameter

AC 29.MG 3-1 Category II A pproach Evaluation MG 3-5

AC 29.MG 3-2 Category II Approac h Evaluation (cont.) MG 3-6

AC 29.MG 5-1 Acceptable Ultim ate Load Factor for MG 5-2 Agricultural Dispensing Equipment Design

AC 29.MG 5-2 Sketch of Tank Pressure Test MG 5-6

Page 28 · xxiiOpen in PDF

AC 29-2C, Chg 2 4/25/06 Figure No. Title Page

AC 29.MG 6-1 Typical Liquid Oxygen System MG 6-18

AC 29.MG 6-2 Typical Liquid Oxygen System - Using MG 6-19 Combination Valve

AC 29 MG 8-1 Schematic Diagram of Building Block Tests MG 8-16

AC 29 MG 8-2 Characterization of Impact Damage MG 8-20

AC 29 MG 8-3 Residual St rength vs. Tiime MG 8-23

AC 29 MG 8-4 Residual Strength and Damage Size MG 8-24 Relationships for Fail-Safe Substantiation

AC 29 MG 9-1 Installed Engine Fuel Flow Capacity Check MG 9-8

AC 29 MG 11-1 Crack Growth for Single Element Structure MG 11-14

AC 29 MG 11-2 Crack Growth for Remaining Elements of MG 11-16 Multiple Element Structure

AC 29 MG 11-3 No Crack Growth Scenario MG 11-18

AC 29 MG 11-4 Slow Crack Growth Scenario MG 11-18

AC 29 MG 11-5 Detectable Crack Growth Scenario MG 11-19

AC 29 MG 14-1 Refrigeration Cycle MG 14-7

AC 29 MG 15-1 Flow Chart for Use of Mitigating Actions MG 15-8 Applied for Reduction of Software Level

AC 29 MG 15-2 Flow Chart for App lication of HUMS Specific MG 15-11 Software with a Ground Base that uses COTS Software for Operational Software

AC 29 MG 18-1 Recommended Alert Prioritization between MG 18-16 HTAWS and TCAS TA

AC 29 MG 18-2 Flight Test Matrix MG 18-19

AC 29 MG 18-2.1 TAWS Required Terrain Clearance (RTC) MG 18-25 by Phase of Flight

Page 29 · xxiiiOpen in PDF

Figure No. Title Page

AC 29.APX B-1 Rotorcraft Dynamic Stability Requirements Apdx B-20 for IFR

AC 29-2C, Chg 1 2/12/03 Abbreviations and Definitions

AC advisory circular ACO aircraft certification office ADF automatic direction finding ADI attitude direction indicator AEO all engines operating AFCS automatic flight control systems AGL above ground level AHRS attitude heading reference system Amdt. Amendment APU auxiliary power unit ATC air traffic control BIM blade inspection method Btu British thermal unit CAM cockpit area microphone CAR Civil Air Regulations CAS calibrated air speed CBIM cockpit blade inspection method CDP critical decision point CG center of gravity CPS cycles per second CRFS crash resistant fuel system CRT cathode ray tube CVR cockpit voice recorder DER designated engineering representative DME distance measuring equipment ECAS engine caution advisory systems ECU environmental control unit EFIS electronic flight instrument system EFP engine failure point EGPWS enhanced ground proximity warning system EHE exhaust heat exchanger ELT emergency locator transmitter EMI electromagnetic interference EMS emergency medical service EOL end of life FAA Federal Aviation Administration FADEC full authority digital engine control FAR Federal Aviation Regulations FLIRS Forward Looking Infrared System FMEA failure mode and effects analysis FPM feet per minute FPS feet per second GPS global positioning system HF high frequency HIRF high intensity radiated fields HRD high rate of discharge HSI horizontal situation indicator HUMS health and usage monitoring systems HV height-velocity IAS indicated airspeed ICAO International Civil Aviation Organization ICS inter-communication system IFR instrument flight rules IGE in ground effect IIDS integrated instrument display system ILS instrument landing system IMC instrument meteorological conditions INS inertial navigation system ISA international standard atmosphere ISIS integral spar inspection system ITT inter-turbine temperature KCAS knots calibrated airspeed KIAS knots indicated air speed KTAS knots true airspeed LCD liquid crystal display LDP landing decision point LWC liquid water content MCP maximum continuous power MGT measured gas temperature MSL mean sea level MVD median volume diameter NDI non-destructive inspection NM nautical mile NPRM notice of proposed rulemaking NTSB National Transportation Safety Board NVG night vision goggles OAT outside air temperature OEI one engine inoperative Page xxiv

OGE out of ground effect PBA pitch bias actuator PCF post crash fire PIO pilot induced oscillation PSIG pounds per square inch gauge QPL qualified parts list RFM rotorcraft flight manual RFMS rotorcraft flight manual supplement RPM revolutions per minute RTCA Radio Technical Commission of Aeronautics RVR runway visual range SAE Society of Automotive Engineers SAS stability augmentation system SCAS stability and control augmentation systems S/N stress vs. number of cycles SRM structural repair manual SSA system safety assessment STC supplemental type certificate STOL short takeoff and landing TBO time between overhaul TC type certificate TCDS type certificate data sheet TDP takeoff decision point TIA type inspection authorization TIR type inspection report TOT turbine outlet temperature TSO: technical standard order TVP true vapor pressure VBIM visual blade inspection method VFR visual flight rules VMC visual meteorological conditions VOR very high frequency omnidirectional range radio VSI vertical speed indicator V/STOL vertical/short takeoff and landing VTOL vertical takeoff and landing WAT weight, altitude, temperature Altitudes

HD density altitude HP pressure altitude

V speeds

VD diving speed VH 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 VY 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 CL coefficient of lift CP coefficient of power CT coefficient of thrust Page xxv

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 assure coordination with the affected agency and industry elements including the Assistant Chief Counsel. All comments will be considered and the disposition will be documented by the Rotorcraft Standards Staff. ASW-100 will issue the special conditions.

b. Basis for Development.

(1) Special conditions are justified on the basis of the existing Part 29 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 for “novel 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 assure 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 29.

AC 21.33 § 21.33 INSPECTION AND TESTS.

a. Applicant Responsibility. Section 21.33 requires the applicant to:

(1) Assure the test rotorcraft confo rms 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 shoul d assure 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 29.

(2) As changes to the rotorcraft are made during the test program, the flight test crew should assure 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 require ments 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 verify 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 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.

Page FAR 21 - 2

(2) Preflight Test Planning. After the applicant’s 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.

(i) 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.

(ii) 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 have been used during rotorcraft certification programs. FAA/AUTHORITY have Page FAR 21 - 3

supported proposals which gave F&R test time credit for certification testing in lieu of dedicated F&R testing. In establishing such credit, the following should be considered:

(A) The point in time in which t he rotorcraft reaches substantial conformity with the approved type design.

(B) The extent and complexity of the new design.

(C) For a previously certified rotorcraft, the F&R program requirement should be commensurate with the modification or change in type design and may be zero.

(ii) Historically, for major rotorcraft type certification programs, flight time credit has been limited so as to require an irreducible minimum of 50 hours of dedicated F&R flight time. For rotorcraft programs that involved new engine installations (mature engine design) or drive train/rotor system changes on previously certified aircraft (TC amendments or STC’s), flight time credit has been liberal and often resulted in very little or no dedicated F&R testing.

b. Procedures.

(1) Type Certification Flight Tests.

(i) Prior to initiating official F AA/AUTHORITY flight tests, a conformity inspection of the test aircraft must be accomplished. This is needed to assure that the test aircraft is in the proper configuration or “conforms” to the engineering drawings and documents that have been submitted to FAA/AUTHORITY, evaluated, and approved. It is absolutely essential to know the configuration being tested in any engineering flight evaluation. Conformity inspection prior to TIA flight tests assures that testing will not be wasted because of configuration uncertainties.

(ii) FAA Order 8110.4A, paragraph 67, contains a requirement that the applicant must keep the FAA/AUTHORITY advised of any configuration changes to the aircraft. The manufacturing inspector should keep the FAA/AUTHORITY flight test pilot apprised of any change which may affect safety of the test aircraft or may influence test results.

(iii) Results of the conformity inspection and the engineering flight test program must be documented. This is normally done in the Type Inspection Report (TIR). Results may be documented in any acceptable engineering format. The report should be in sufficient detail to clearly show how compliance with each appropriate section of the rules was determined.

(iv) The flight test pilot mu st assure that the FAA/AUTHORITY manufacturing inspector and certification engineer are aware of all configuration changes found necessary as a result of FAA/AUTHORITY tests. The manufacturing Page FAR 21 - 4

inspector is responsible for assuring that all changes are incorporated into production drawings after the design data reflecting the change have been approved by the certification engineer.

(v) Additional flight test res ponsibilities, procedures, and requirements during the certification flight test process are contained in FAA Order 8110.4A, Section 5, Flight.

(2) Function and Reliability Tests.

(i) A comprehensive and systematic check of all aircraft components must be made to assure that they perform their intended function and are reliable.

(ii) F&R testing should be accomplished on an aircraft which conforms to the type design. Non-conformities must be documented and accepted. F&R testing should follow the type certification testing described in paragraph AC 21.35b(1) above to assure that significant changes resulting from type certification tests are incorporated on the aircraft prior to F&R tests.

(iii) All components of the rotorc raft should be periodically operated in sequences and combinations likely to occur in service. Ground inspections should be made at appropriate intervals to identify potential failure conditions; however, no special maintenance beyond that described in the aircraft maintenance manual should be allowed.

(iv) A complete record of defects and failures should be maintained along with required servicing of aircraft fluid levels. Results of this record should be consistent with inspection and servicing information provided in the aircraft maintenance manual.

(v) A certain portion of the F& R test program may focus on systems, operating conditions, or environments found particularly marginal during type certification tests.

(vi) A substantial portion of the flying should be on a single aircraft. The flying should be carried out to an intensive schedule on an aircraft that is very close to the final certification standard, operated and maintained as though it were in service. A range of representative ambient operating conditions and sites should be considered. It is acceptable for non-F&R flight testing conducted at various sites and in varying ambient conditions to be used to satisfy the F&R requirements for those conditions.

Page FAR 21 - 5