AC 21.23-1

AC 21,23-1 DATE 1/12/81

ADVISORY CIRCULAR

DEPARTMENT OF TRANSPORTATION Federal Aviation Administration Washington, D.C.

Subject: TYPE CERTIFICATION - FIXED-WING GLIDERS (SAILPLANES) criteria, but not the only criteria, that may be used by an applicant in showing compliance with Section 21.23(a) of Federal Aviation Regulations, Part 21, (FAR 21.23) for the type certification of fixed-wing gliders (sailplanes), 1. PURPOSE. This advisory circular provides two comprehensive and detailed including self-launching (powered) gliders. Ceneral guidance relative to glide: type certification is also provided.

cancelled. 2. CANCELLATION. Advisory Circular No. 21-3, dated October 18, 1966, is

3. RELATED FEDERAL AVIATION REGULATIONS (FARS):

Section 21.5 Airplane or Rotorcraft Flight Manual.

Section 21.23 Issue of type rtificate: Gliders (including sailplanes), including fixed-wing, self-launching (powered) gliders.

Part 45, Subpart C-Nationality and Registration Marks.

Section 91.31 Civil aircraft operating limitations and marking requirements.

section 91.33 Powered civil aircraft with standard category U.S.

airworthiness certificates; instruments and equipment requirements.

4. BACKGROUND.

appropriate and applicable to the specific type design or with such other for a fixed-wing glider (sailplane) if it is shown that the glider complies with those airworthiness requirements of FAR 23 or FAR 27 that the FAA considers FAR 21.23 provides that an applicant is entitled to a type certificate Initiated by: AWS-110

1/12/81 in evaluating the glider type design. The airworthiness standards for the type certification of gliders as defined by of rotary-wing gliders which is outside the scope of this Advisory Circular. The FAA must also find that the glider has no unsafe features or characteristics. FAR 21.23 are very general and objective in nature, making it necessary for the applicant to develop comprehensive and detailed criteria to be used by the FAA to those Parts. Reference to FAR 27 in PAR 21.23 is for the type certification airworthiness criteria as the FAA may find provide an equivalent level of safety Handbook acceptable. Circular No. AC 21-3, dated October 18, 1966, advised the public that the Handbook could be used as an acceptable means, but not the only means, of showing compliance with FAR 21.23 for fixed-wing gliders. Except for self-launching (powered) gliders, the FAA still considers the criteria in the paragraphs 50, c, and g of this AC. the Handbook itself is not cancelled. b. In 1962, the FAA published a Basic Glider Criteria Handbook. Criteria for self-launching sailplanes is addressed in Although AC 21-3 is cancelled by this AC, advisory FAR 23. Moreover, the FAA has in the past, type certificated a number of of JAR 22 as criteria for showing compliance with FAR 21.23(a). equivalent level of safety to the appropriate and applicable requirements of the IFSM which was used as the basis for JAR 22. The highly satisfactory service experience gained with those gliders further supports the acceptability gliders manufactured in the Federal Republic of Germany that were designed to a self-launching (powered) glider, that is shown by an applicant to comply with found by the FAA to comply with airworthiness criteria that provides an Subparts H and J which set forth criteria for the type certification of glider Subparts H and J, the FAA determined that a fixed-wing glider design, including the criteria of JAR 22, plus the additional criteria specified herein, may be engines and propellers, respectively. After reviewing JAR 22, including new United Kingdom. the Federal Republic of Germany, France, Italy, the Netherlands, Sweden, and the Motorsegler (LPSM) published by the Luftfahrt Bundesamt), and was developed through joint participation of the Civil Airworthiness Authorities of Belgium, airworthiness code (Luftuchtigkeitsforderungen fur Segelflugzeuge und agreed to Joint Airworthiness Requirements for Sailplanes and Powered Sailplanes (JAR 22). JAR 22 is based on the Federal Republic of Germany national On April 1, 1980, certain European Civil Airworthiness Authorities After the original issuance, JAR 22 was amended to add new independently developed criteria may be used as acceptable means of showing for showing compliance with FAR 21.23(a). When approved by the FAA, such compliance with FAR 21.23(a) for the particular glider under consideration. those requirements believed to be appropriate and applicable for the type certification of its fixed-wing glider design, and propose alternative criteria d. As a third alternative, an applicant may wish to study FAR 23, identify must also comply with certain operational provisions of FAR 91. Applicants for type certification of gliders, particularly self-launching gliders, should ensure that these requirements are considered in their designs. e. In addition to the type dertification requirements of FAR 21, gliders Page 2 Par 4

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5. ACCEPTABLE CRITERIA.

the type certification of fixed-wing gliders, including self-launching (powered) gliders, or develop their own criteria using FAR 23 as a basis for compliance with FAR 21.23(a) - a. Applicants may utilize one of the following two sets of criteria for

(1) FAA Basic Glider Criteria Handbook; or this Advisory Circular. certification plus the additional criteria specified in paragraph 5.e. (6) of (2) JAR 22, as amended at the date of application for type under FAR 21.23 if- Self-launching (powered), fixed-wing gliders may be type certificated

(1) The total occupant capacity does not exceed two persons;

(2) The maximum certificated weight does not exceed 2,000 lbs; and weight and most unfavorable center of gravity position, does not exceed-- (3) The minimum descent rates for the glider, power-off, at maximum

i. 3.3 ft/sec. (1 m/sec) for single-seat gliders; or ii. 4.0 ft/sec. (1.2 m/sec) for two-seat gliders.

for powered sailplanes or develop criteria for individual FAA approval using FAR 23 as a base. Self-launching gliders that exceed the limitations in 5.b. can only be type certificated as normal, utility, or acrobatic category. airplanes under FAR 23. criteria of paragraph 5.b. of this AC, must either use the criteria of JAR-22 wishing to type certificate self-launching gliders, that comply with the considered to adequately address self-launching (powered) gliders. Applicants Chapter 6 of the FAA Basic Glider Criteria Handbook is no longer FARS 33 and 35, respectively, to be type certificated. 5.e. (4) and 5.e. (5) of this Advisory Circular, must meet the requirements of gliders that are not approved as an integral part of the glider per paragraph Engines and Propellers intended for use on self-launched (powered)

e. If JAR-22 is selected by the applicant - national variants identified by individual countries need not be applied. (1) Unless otherwise specified in subparagraph (6) below, the the FAA. (2) The "ACJ (interpretive material)" is considered acceptable to Par 5 Page 3

1/12/81 unpowered gliders. The maximum weight limit of JAR 22.1(a) (1) need not be applied for the engine on specific gliders. certificated but the type œrtificate will be limited for the installation of approved as an integral part of the glider. (4) Engines that meet the criteria of JAR 22 Subpart H, may be Engines so approved will be type approved as an integral part of the glider. Propellers so approved will be type the propeller on specific gliders. certificated but the type certificate will be limited for the installation of (5) Propellers that meet the criteria of JAR 22; Subpart J, may be associated JAR 22 sections - (6) The following additional criteria must be met to satisfy the

(a) JAR 22.177(b) - maximum rudder deflection in any flap or speed brake configuration. i. Pitch and roll control may not be adversely affected at condition. immediate corrective action to prevent an unstable or unsafe flight ii. Any rudder control force reversal must not require of the maximum unreversed force or 15 pounds force, whichever is greater. control force reversal and/or rudder lock may not be greater than 15 percent iil. The temporary control force required to overcome rudder accuracy during slip maneuvers. reversal condition, and the degradation, if any, in the airspeed system appropriate pilot action in response to a rudder control force decrease or of the glider, the speed range within which slips can be performed, the iv. The flight manual must describe the slip characteristics France, and the United Kingdom applies; that is, visual stall warning alone is not acceptable. (b) JAR 22,207(b) - The national variant specified by Belgium, a means to indicate to the pilot the appropriate limitations throughout the operating altitude range. (c) JAR 22.1545 - If VNE varies with altitude, there must be aircraft operating limitations and marking requirements of FAR 91.31. fixed-wing gliders. E. The Airplane Flight Manual requirements of FAR 21.5 are applicable to In addition, all gliders must comply with the civil aircraft for the purpose of complying with FAR 91.33. g. Self-launching (powered) gliders are considered to be powered Page 4 Par 5

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h. Regardless of the criteria selected under paragraph 5.a, wing and tail surface attachments designed for quick removal and installation by the pilot, as is permitted by FAR 43, Appendix A, paragraph (c) (25), must provide a means for direct visual inspection of the connections for placement and security.

lack of a visual inspection means is considered an unsafe feature and is prohibited by FAR 21.23 (b).

i. Nationality registration marking requirements for U.S.-registered gliders are provided by FAR 45, Subpart C.

j. The FAA will document FAR 21.23 as the type certification basis for aircraft designs approved as gliders. The type certificate data sheet will explain in summary statement form, the criteria selected by the applicant for showing compliance with FAR 21.23.

United States designers and manufacturers of fixed-wing gliders, including self-launching (powered) gliders, should be advised that strict compliance with JAR 22, including adherence to the national variants, probably will be required by participating countries of the JAR group for import airworthiness acceptance. Accordingly, unless specifically notified tol the contrary by the authority of the importing country on a particular case basis, the FAA will consider strict compliance with JAR 22 required for issuance of a U.S. Class I Export Certificate of Airworthiness for export to a JAR participating country.

6. AVAILABILITY OF DOCUMENTS.

Copies of the PAA Basic Glider Criteria Handbook may be purchased from the Superintendent of Documents, U.S. Govemment Printing Office, Washington, D.C. 20402.

Copies of Joint Airworthiness Requirements (JAR-22) Sailplanes and Powered Sailplanes, may be purchased from the Civil Aviation Authority, Printing and Publication Services, Greville House, 37 Gratton Road, Cheltenham Glos. GL50 2BN, England.

Copies of AC 21.23-1 may be obtained from the U.S. Department of Transportation, Publications Section M443.1, Washington, DC 20590.

M. C.

Director of Airworthiness Par 6 Page 5