[Federal Register Volume 61, Number 57 (Friday, March 22, 1996)] [Proposed Rules] [Pages 11784-11786] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 96-6882] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 95-CE-75-AD] Airworthiness Directives; Aerospace Technologies of Australia, Nomad Models N22B, N22S, and N24A Airplanes AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes to adopt a new airworthiness directive (AD) that would apply to certain Aerospace Technologies of Australia (ASTA) Nomad Models N22B, N22S, and N24A airplanes. The proposed action would require repetitively inspecting the tailplane stabilizer center section and repairing any cracked tailplane structure. This proposal also provides an optional modification as a terminating action, after an inspection in which no cracks are found. A tailplane failure on one of the affected airplanes prompted the proposed action. The actions specified by the proposed AD are intended to prevent cracking in the stabilizer center section, which, if not detected and corrected, could result in tailplane failure and loss of control of the airplane. DATES: Comments must be received on or before June 28, 1996. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Central Region, Office of the Assistant Chief Counsel, Attention: Rules Docket No. 95-CE-75-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106. Comments may be inspected at this location between 8 a.m. and 4 p.m., Monday through Friday, holidays excepted. Service information that applies to the proposed AD may be obtained from AeroSpace Technologies of Australia, Limited, ASTA DEFENCE, Private Bag No. 4, Beach Road Lara 3212, Victoria, Australia. This information also may be examined at the Rules Docket at the address above. FOR FURTHER INFORMATION CONTACT: Mr. Ron Atmur, Aerospace Engineer, Aircraft Certification Office, FAA, 3960 Paramount Blvd., Lakewood, California, 90712; telephone (310) 627-5224; facsimile (310) 627-5210; SUPPLEMENTARY INFORMATION: Comments Invited Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket. Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket No. 95-CE-75-AD.'' The postcard will be date stamped and returned to the commenter. Availability of NPRMs Any person may obtain a copy of this NPRM by submitting a request to the FAA, Central Region, Office of the Assistant Chief Counsel, Attention: Rules Docket No. 95-CE-75-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106. Discussion The Civil Airworthiness Authority (CAA), which is the airworthiness authority for Australia, has notified the FAA that an unsafe condition may exist on ASTA Nomad N22 and N24 series airplanes that have not incorporated ASTA Modification N663 and N768. The Australian CAA reported one accident and several incidents of cracking in the tailplane stabilizer center section of the airplanes. The accident was caused by the loss of a tailplane during flight. Investigation of the accident revealed undetected cracking around the center lightening hole which was significantly accelerated by long periods of engine ground running. Subsequent testing also indicated that engine ground running at moderate to high power settings during ground maneuvers create unexpected fatigue loads and accelerate the crack growth. ASTA has issued Nomad Alert Service Bulletin (Nomad SB) ANMD-55-26, Revision 8, dated April 15, 1994, which specifies procedures for inspecting and modifying the stabilizer center section on Nomad Models N22B, N22S, and N24A airplanes. Accomplishment of these procedures incorporates Modifications (Mod.) N663 and N768. Mod. N663 reworks the horizontal stabilizer to incorporate a strengthened main spar assembly that includes a gust stop spring box and modified mass balance arm. The trim tab hinges are moved 0.17 inches aft and farings are added to the bottom skin of the horizontal stabilizer to permit increased trim tab movement. Mod. N768 replaces the pivot brackets, attachment bolts, and spar web doubler with strengthened components. The Australian CAA classified this service bulletin as mandatory and issued AD/GAF-N22/58 amdt 4, issued November, 1991, in order to assure the continued airworthiness of these airplanes in Australia. These airplane models are manufactured in Australia and are type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement between Australia and the United States. Pursuant to this bilateral airworthiness agreement, the Australian CAA has kept the FAA informed of the above-described situation. The FAA has examined the findings of the Australian [[Page 11785]] CAA, reviewed all available information, and determined that AD action is necessary for airplanes of this type design that are certificated for operation in the United States. Since an unsafe condition has been identified that is likely to exist or develop in other ASTA Nomad Models N22B, N22S, and N24A airplanes of the same type design that do not have Modifications N663 and N768 incorporated in the area of the tailplane stabilizer center section, the proposed AD would require inspecting (using both visual and eddy current methods) the tailplane stabilizer section for cracks and, prior to further flight, repairing any cracked tailplane stabilizer center section. This AD also provides the option of modifying the tailplane stabilizer center section (Mod. N663 and N768) as a terminating action. Accomplishment of the proposed inspection would be in accordance with Nomad SB ANMD-55-26, Revision 8, dated April 15, 1994. If the tailplane stabilizer center section is found cracked, the repair would be in accordance with a scheme obtained from the Los Angeles Aircraft Certification Office. The FAA estimates that 15 airplanes in the U.S. registry would be affected by the proposed AD, that it would take approximately 15 workhours per airplane to accomplish the proposed action, and that the average labor rate is approximately $60 an hour. The total cost impact of the proposed AD upon U.S. operators of the affected airplanes is estimated to be $13,500. This figure only includes the cost for the initial inspection and does not include replacement costs if the tailplane stabilizer center section is found cracked, nor does it include repetitive inspection costs. Additionally, the FAA has no way of determining how many tailplane stabilizer center sections may be cracked or how many repetitive inspections each owner/operator may incur over the life of the airplane. The regulations proposed herein would 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 proposal would 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) if promulgated, 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 draft regulatory evaluation prepared for this action has been placed 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, Safety. The Proposed Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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. Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: Aerospace Technologies of Australia (ASTA): Docket No. 95-CE-75-AD. Applicability: Nomad Models N22B, N22S, and N24A airplanes (all serial numbers), certificated in any category, that have not incorporated ASTA Modification N663 and N768 in the area of the tailplane stabilizer. 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 within the next 100 hours time-in-service (TIS) after the effective date of this AD, unless already accomplished, and thereafter at intervals not to exceed 100 hours TIS. To prevent cracking in the tailplane stabilizer center section, which, if not detected and corrected, could result in tailplane failure and loss of control of the airplane, accomplish the following: (a) Inspect the tailplane stabilizer center section and center lightening hole for cracks (using both visual and eddy current methods) in accordance with section ``C. Description, (1) Part 1-- Inspection.'' of ASTA Nomad Alert Service Bulletin (Nomad SB) ANMD- 55-26, Revision 8, dated April 15, 1994. (b) If cracks are found during any inspection required by this AD, prior to further flight, repair the stabilizer center section in accordance with a repair scheme obtained from the manufacturer through the Manager, Los Angeles Aircraft Certification Office, at the address specified in paragraph (d). (1) This repair scheme does not eliminate the repetitive inspection requirement. (2) The repetitive inspection requirement of this AD may be terminated by incorporating both Modification (Mod.) N663 and N768 in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of Nomad SB ANMD-55-26, Revision 8, dated April 15, 1994. These modifications may only be incorporated, prior to further flight, after any inspection provided no cracks are found. (3) Modifications N663 and N768 may also be incorporated as terminating action to the repetitive inspections of this AD on airplanes that have cracks repaired in the tailplane stabilizer center section provided the modifications are incorporated prior to further flight after an inspection where no cracks were found. Note 2: Mod. N663 reworks the horizontal stabilizer to incorporate a strengthened main spar assembly that includes a gust stop spring box and modified mass balance arm. The trim tab hinges are moved 0.17 inches aft and farings are added to the bottom skin of the horizontal stabilizer to permit increased trim tab movement. Mod. N768 incorporates Mod. 663 and replaces the pivot brackets, attachment bolts, and spar web doubler with strengthened components. (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 initial or repetitive compliance times that provides an equivalent level of safety may be approved by the Manager, Los Angeles Aircraft Certification Office, FAA, 3960 Paramount Blvd., 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 Aircraft Certification Office. Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles Aircraft Certification Office. (e) All persons affected by this directive may obtain copies of the document referred to herein upon request to AeroSpace Technologies of Australia, Limited, ASTA DEFENCE, Private Bag No. 4, Beach Road Lara 3212, Victoria, Australia; or may examine this/these document(s) at the FAA, Central Region, Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106. [[Page 11786]] Issued in Kansas City, Missouri, on March 15, 1996. James E. Jackson, Acting Manager, Small Airplane Directorate, Aircraft Certification Service. [FR Doc. 96-6882 Filed 3-21-96; 8:45 am] BILLING CODE 4910-13-P