AD 97-11-12

This amendment adopts a new airworthiness directive (AD) that applies to Aerospace Technologies of Australia Pty Ltd. (ASTA) Models N22B, N22S, and N24A airplanes. This action requires repetitively inspecting the stub wing upper front spar cap flanges for cracks, and repairing any cracked part. This AD results from fatigue tests that show that the stub wing upper front spar cap flanges could fail over time because of fatigue. The actions specified by this AD are intended to prevent structural failure of the front spar caused by cracks in the stub wing upper front spar cap flanges, which could result in loss of control of the airplane.

Final rule.

97-11-12 AEROSPACE TECHNOLOGIES OF AUSTRALIA PTY LTD: Amendment 39-10041; Docket No. 95-CE-98-AD.

Applicability: Models N22B, N22S, and N24A airplanes (all serial numbers), certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated in the bodyof this AD, unless already accomplished.

To prevent structural failure of the front spar caused by cracks in the stub wing upper front spar cap flanges, which could result in loss of control of the airplane, accomplish the following:

(a) Prior to accumulating 1,700 hours time-in-service (TIS) or within the next 300 hours TIS after the effective date of this AD, whichever occurs later, and thereafter at intervals not to exceed 2,650 hours TIS, inspect, using both visual and eddy current methods, the stub wing front spar cap flanges in the area of Buttock Line (BL) 47.6 for fatigue cracks in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of Nomad Service Bulletin NMD-53-6, dated October 21, 1986.

(b) If any crack is found during any inspection required by this AD, prior to further flight, obtain a repair scheme from the manufacturer through the Los Angeles Aircraft Certification Office (ACO) at the address specified in paragraph (d) of this AD, and incorporate this repair scheme. This repair does not eliminate the repetitive inspection requirement of this AD.

(c) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(d) An alternative method of compliance or adjustment of the compliance time that provides an equivalent level of safety may be approved by the Manager, FAA, Los Angeles ACO, 3960 Paramount Boulevard, Lakewood, California 90712. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Los Angeles ACO.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO.

(e) The inspections required by this AD shall be done in accordance with Nomad Service Bulletin NMD-53-6, dated October 21, 1986. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Aerospace Technologies of Australia Pty Ltd., ASTA DEFENCE, Private Bag No. 4, Beach Road Lara 3212, Victoria, Australia. Copies may be inspected at the FAA, Central Region, Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(f) This amendment becomes effective on July 11, 1997.

Events Leading to the Issuance of This AD
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to ASTA Models N22B, N22S, and N24A airplanes was published in the Federal Register as a notice of proposed rulemaking (NPRM) on December 10, 1996 (61 FR 65002). The NPRM proposed to require repetitively inspecting the stub wing upper front spar cap flanges for cracks, and repairing any cracked part. Accomplishment of the proposed inspections as specified in the NPRM would be in accordance with Nomad Service Bulletin NMD-53-6, dated October 21, 1986. Accomplishment of any proposed repair (if necessary) as specified in the NPRM would be in accordance with a scheme obtained from the FAA, Los Angeles Aircraft Certification Office.

The NPRM resulted from fatigue tests that show that the stub wing upper front spar cap flanges could fail over time because of fatigue.

Interested persons have beenafforded an opportunity to participate in the making of this amendment. No comments were received on the proposed AD or the FAA's determination of the cost to the public.

The FAA's Determination
After careful review of all available information related to the subject presented above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for minor editorial corrections. The FAA has determined that these minor corrections will not change the meaning of the AD and will not add any additional burden upon the public than was already proposed.

Cost Impact
The FAA estimates that 15 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 6 workhours per airplane to accomplish the required action, and that the average labor rate is approximately $60 an hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $5,400 or $360 per airplane. This figure does not take into account the cost of repetitive inspections or the cost to repair any cracked stub wing upper front spar cap flanges. The FAA has no way of determining the number of repetitive inspections each operator will incur over the life of each affected airplane or the number of stub wing upper front spar cap flanges that may be found cracked and need to be repaired.

Regulatory Impact
The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the final evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption "ADDRESSES".

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 USC 106(g), 40113, 44701.
39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: