Title 14 CFR, part 23, Sec. 23.221 contains spin requirements for normal, utility, and acrobatic category airplanes. When part 3 of the Civil Air Regulations was recodified in 1965 as 14 CFR, part 23, spin requirements for acrobatic category airplanes were presented in Sec. 23.221(c). Since 1965, the spin requirements in Sec. 23.221(c) have been amended three times.

The original version of Sec. 23.221(c) required an acrobatic category airplane to perform spins of at least six turns and recover without exceeding an airspeed limit or positive load factor limit. Spins were required for flapsup configuration and flapsdown configuration. In addition, the airplane could not enter an uncontrollable spin with any use of the controls.

Amendment 237 revised the presentation of the acrobatic category spin requirements and revised the minimum turn requirement to six turns or three seconds, whichever takes longer. Amendment 2342 revised Sec. 23.221(c)(3) and clarified the term ``controls'' in the previous version of the rule by identifying flight controls and engine controls. It also clarified that the use of the controls could be at spin entry or during the spin. Neither of these two amendments changed the basic acrobatic category spin requirements.

In July 1994, the FAA proposed changes to the flight airworthiness standards for normal, utility, acrobatic, and commuter category airplanes. The proposals arose from the joint effort of the FAA and the European Joint Aviation Authorities (JAA) to harmonize 14 CFR regulations and the Joint Aviation Requirements (JAR). The proposed changes were intended to provide nearly uniform flight airworthiness standards for airplanes certificated in the United States under 14 CFR, part 23 and in the JAA countries under JAR 23.

Proposed changes to the introductory paragraph of Sec. 23.221(c) required acrobatic category airplanes to meet the oneturn spin requirements of Sec. 23.221(a) as well as the emergency egress requirements of Sec. 23.807, and to meet the spin requirements of Sec. Sec. 23.221(c)(1) through (4) in each configuration approved for spins. The addition of normal category spin requirements was necessary because acrobatic category airplanes should have sufficient controllability to recover from the developing oneturn spin under the same conditions as normal category airplanes. The configuration requirement was added to recognize the common practice of approving intentional spins only for a specific configuration (e.g, gear and flaps up). The proposed changes were incorporated into the rule by Amendment 2350.

There was never any discussion or intent by the FAA or JAA to approve an acrobatic category airplane that met only the normal category spin requirements. The assumption has always been that an inadvertent spin could result during the performance of a variety of acrobatic maneuvers.

FAA Position

Title 14 CFR, part 23, Sec. 23.221(c), as amended by Amendment 23 50, presents acrobatic category airplane spin requirements. As the rule is currently written, the acrobatic category airplane must comply with normal category spin requirements, acrobatic category emergency egress requirements in Sec. 23.807, and acrobatic spin requirements for each configuration requested for spin approval.

ATG proposes to prohibit intentional spins and requests that no configuration be approved for spins. This proposal leads to an acrobatic category airplane that meets only normal category spin requirements. This proposal is unacceptable since the FAA has always maintained that an acrobatic category airplane must comply with acrobatic category spin requirements despite the wording in the current rule. The rule's history, coupled with preamble information for Amendment 2350, reveals that the rule was changed to add the normal category spin requirements and to accommodate an applicant's desire to comply with the acrobatic spin requirements for at least one configuration, but not necessarily all configurations.

Type Certification Basis

Under the provisions of 14 CFR, part 21, Sec. 21.17, ATG must show that the Model 100 meets the applicable provisions of part 23, as amended by Amendment 231 through 2355 thereto. If the Administrator finds that the applicable airworthiness regulations (i.e., 14 CFR, part 23) do not contain adequate or appropriate safety standards for the ATG Model 100 series because of a novel or unusual design feature, special conditions are prescribed under the provisions of Sec. 21.16.

Special conditions, as appropriate, as defined in Sec. 11.19, are issued in accordance with Sec. 11.38, and become part of the type certification basis in accordance with Sec. 21.17.

Special conditions are initially applicable to the model for which they are issued. Should the type certificate for that model be amended later to include any other model that incorporates the same novel or unusual design feature, the special conditions would also apply to the other model under the provisions of Sec. 21.101.

Novel or Unusual Design Features

The ATG Model 100 will incorporate the following novel or unusual design features: High thrusttoweight ratio, military training jet configuration with a higher fuselage mass compared to typical part 23 acrobatic airplanes.

Applicability

As discussed above, these special conditions are applicable to the ATG Model 100 series. Should ATG apply at a later date for a change to the type certificate to include another model incorporating the same novel or unusual design feature, the special conditions would apply to that model as well under the provisions of Sec. 21.101.

Conclusion

This action affects only certain novel or unusual design features on the ATG Model 100 series airplanes. It is not a rule of general applicability and affects only the applicant who applied to the FAA for approval of these features on the airplane.
[[Page 4663]]
List of Subjects in 14 CFR Part 23

Aircraft, Aviation safety, Signs and symbols.

Citation

The authority citation for these special conditions is as follows:

Authority: 49 U.S.C. 106(g), 40113 and 44701; 14 CFR 21.16 and 21.17; and 14 CFR 11.38 and 11.19.

The Special Conditions

Accordingly, the Federal Aviation Administration (FAA) proposes the following special conditions as part of the type certification basis for the ATG Model 100 airplanes.

Title 14 CFR, part 23, Sec. 23.221(c) as amended by Amendment 23 50 presents acrobatic category airplane spin requirements. As the rule is currently written, the acrobatic category airplane must comply with normal category spin requirements, acrobatic category emergency egress requirements in Sec. 23.807, and acrobatic spin requirements for each configuration requested for spin approval.

ATG proposes to prohibit intentional spins and requests that no configuration be approved for spins. This proposal leads to an acrobatic category airplane that meets only normal category spin requirements. This proposal is unacceptable since the FAA has always maintained that an acrobatic category airplane must comply with acrobatic category spin requirements despite the wording in the current rule. The rule's history coupled with preamble information for Amendment 2350 reveals that the rule was changed to add the normal category spin requirements and to accommodate an applicant's desire to comply with the acrobatic spin requirements for at least one configuration, but not necessarily all configurations.

Since the wording of the current rule combined with ATG's proposal does not provide the level of safety envisioned for an acrobatic category airplane, the FAA proposes the following special condition under the authority of 14 CFR, part 21, Sec. 21.16 to replace Sec. 23.221(c) in its entirety:
SC 23.221 Spinning
(c) Acrobatic category airplanes. An acrobatic category airplane must meet the spin requirements of paragraph (a) of this section and Sec. 23.807(b)(5). In addition, the following requirements must be met in an applicantdesignated acrobatic configuration, and in each other configuration for which approval for spinning is requested: (1) The airplane must recover from any point in a spin up to and including six turns, or any greater number of turns for which certification is requested, in not more than one and onehalf additional turns after initiation of the first control action for recovery. However, beyond three turns, the spin may be discontinued if spiral characteristics appear.
(2) The applicable airspeed limits and limit maneuvering load factors must not be exceeded. For flaps extended configurations for which approval is requested, the flaps must not be retracted during the recovery.
(3) It must be impossible to obtain unrecoverable spins with any use of the flight or engine power controls either at the entry into or during the spin.
(4) There must be no characteristics during the spin (such as excessive rates of rotation or extreme oscillatory motion) that might prevent a successful recovery due to disorientation or incapacitation of the pilot.
(5) The airplane is considered to meet the requirements of paragraph (c) of this special condition with a specific demonstration. The applicant must demonstrate that it is extremely remote for the airplane in the applicantdesignated acrobatic configuration, and in each other configuration for which approval for spinning is requested, to enter a spin with any use of the flight or engine power controls, either at or after entry into the stall maneuver.

Issued in Kansas City, Missouri on January 24, 2007. Kim Smith,
Manager, Small Airplane Directorate, Aircraft Certification Service. [FR Doc. E71610 Filed 13107; 8:45 am]
BILLING CODE 491013P

FOR FURTHER INFORMATION CONTACT J. Lowell Foster, Federal Aviation Administration, Aircraft Certification Service, Small Airplane Directorate, ACE111, 901 Locust, Room 301, Kansas City, Missouri, 816 3294125, fax 8163294090.