[Federal Register Volume 62, Number 33 (Wednesday, February 19, 1997)] [Proposed Rules] [Pages 7377-7378] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 97-3958] [[Page 7377]] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 96-CE-47-AD] RIN 2120-AA64 Airworthiness Directives; Air Tractor Incorporated Models AT-301, AT-302, AT-400, AT-400A, AT-401, AT-402, AT-501, and AT-502 Airplanes AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes to supersede AD 95-20-06, which currently requires inspecting the front spar attachment lugs and the rear spar for fatigue cracks and modifying the vertical fin if cracks are found. If no cracks are found, continue repetitively inspecting the area until cracks are found; and then incorporate the modification as a terminating action. The proposed action would retain the actions required in AD 95-20-06 for all Air Tractor models that have a \3/16\- inch fin front spar fitting. Air Tractor models that are fitted with a \1/4\-inch fin front spar fitting would not be required to accomplish this action. This action is prompted by two incident reports involving the failure of the front and rear spar attachment of the vertical fin. The actions specified by this AD are intended to prevent in-flight vertical fin structural failure of the front spar attachments and eventually the rear spar attachment, which, if not detected and corrected, could result in loss of directional control and loss of control of the airplane. DATES: Comments must be received on or before April 21, 1997. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Central Region, Office of the Assistant Chief Counsel, Attention: Rules Docket No. 96-CE-47-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 Air Tractor Incorporated, P. O. Box 485, Olney, Texas 76374. This information also may be examined at the Rules Docket at the address above. FOR FURTHER INFORMATION CONTACT: Bob May, Aerospace Engineer, FAA, Airplane Certification Office, 2601 Meacham Boulevard, Fort Worth, Texas 76193-0150; telephone (817) 222-5156; facsimile (817) 222-5960. 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. 96-CE-47-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. 96-CE-47-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106. Discussion It has been brought to the attention of the FAA that AD 95-20-06, which is applicable to Air Tractor Models AT-301, AT-302, AT-400, AT- 400A, AT-401, AT-402, AT-501, and AT-502 airplanes, should not have included models that are fitted with \1/4\-inch thick fin front spar attach fittings. The current AD requires inspecting for cracks on all of the models referenced above, regardless of whether they have \1/4\- inch or \3/16\-inch thick front spar attachment fitting, and if no cracks are found, repetitively inspecting at different time intervals. The time interval would depend on the thickness of the fin front spar attach fitting on the airplane. If cracks are found, the current AD requires modifying the front spar attachment. Since publication of AD 95-20-06, further investigation has revealed that the only Air Tractor models developing cracks are the models fitted with a \3/16\-inch thick front spar attachment fitting. For this reason, the FAA is proposing to supersede the current AD to change the instructions of the AD. Relevant Service Information Air Tractor has issued a revised Service Letter (SL) No. 138, Revised August 7, 1996, which specifies procedures for inspecting, repetitively inspecting, and modifying the Air Tractor Models that have the 3/16-inch thick front spar attach fitting. FAA's Determination After examining the circumstances and reviewing all available information related to the incidents described above, the FAA has determined that AD action should be taken to prevent in-flight vertical fin structural failure of the front spar attachments and eventually the rear spar attachment, which, if not detected and corrected, could result in loss of directional control and loss of control of the airplane. Explanation of the Provisions of the Proposed AD Since an unsafe condition has been identified that is likely to exist or develop in other Air Tractor Incorporated Models AT-301, AT- 302, AT-400, AT-400A, AT-401, AT-402, AT-501, and AT-502 airplanes of the same type design that are fitted with 3/16-inch thick front spar attachment fittings, the proposed AD would supersede AD 95-20-06 with a new AD that would require inspecting the fin front spar attach fitting lugs of models that have 3/16-inch thick fin front spar attach fittings for cracks and if cracks are found, prior to further flight, modifying the front spar attachment lugs. If no cracks are found, the proposed AD would require repetitively inspecting the front spar attachment lugs until cracks are found. Accomplishing the modification would terminate the repetitive inspections. Cost Impact The FAA estimates that 24 airplanes in the U.S. registry would be affected by the proposed AD, that it would take approximately 16 workhours per airplane to accomplish the proposed action, and that the average labor rate is approximately $60 an hour. Parts cost approximately $10 per airplane. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $970 per airplane and [[Page 7378]] $23,280 for the U.S. fleet. The FAA has no way of determining how many owners/operators of these affected airplanes have accomplished this action. Regulatory Impact 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 14 CFR part 39 of the Federal Aviation Regulations 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 removing Airworthiness Directive (AD) 95-20-06, Amendment 39-9384, and by adding a new AD to read as follows: Air Tractor Incorporated: Docket No. 96-CE-47-'AD; Supersedes AD 95- 20-06, Amendment 39-9384. Applicability: The following airplane models and serial numbers that have not accomplished the modification in Snow Engineering Company Report No. 138, dated July 29, 1995, which is referenced in superseded AD 95-20-06, certificated in any category: Note 1: The modification in Snow Engineering Company Report No. 138, dated July 29, 1995 and AD 95-20-06 required the airplanes to replace 3/16-inch thick fin front spar attach fittings with 1/4-inch thick fin front spar attach fittings. ------------------------------------------------------------------------ Models Serial Nos. ------------------------------------------------------------------------ AT-301 and AT-401................... 301-0261 through 301-0736, and 401- 0662 through 401-0736 that have been converted to turbine powerplants and equipped with the all metal rudder, part number (P/ N) 30456-1. AT-302.............................. All aircraft equipped with the all metal rudder, P/N 30456-1. AT-400 and AT-400A.................. All aircraft equipped with the all metal rudder, P/N 30456-1. AT-402.............................. 402-0694 and 402-0695 through 402- 0736. AT-501.............................. 501-0002 through 501-0030 that have been converted to turbine powerplants and equipped with the all metal rudder, P/N 30456-1. AT-502.............................. 502-0002 through 502-0030. ------------------------------------------------------------------------ Note 2: 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 (f) 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 initially within the next 25 hours time-in- service (TIS) after the effective date of this AD, unless already accomplished, and thereafter as indicated in the body of this AD. To prevent in-flight vertical fin structural failure of the front spar attachments and eventually the rear spar attachment, which, if not detected and corrected, could result in loss of directional control and loss of control of the airplane, accomplish the following: (a) Inspect the fin front spar attachment fittings for fatigue cracks in accordance with the INSTRUCTIONS section of the Snow Engineering Report (SER) number (No.) 138, Revised August 7, 1996. (b) If no cracks are found during the initial inspection, repeat the inspection required by paragraph (a) of this AD at intervals not to exceed 25 hours TIS thereafter in accordance with the INSTRUCTIONS section of the SER No. 138, Revised August 7, 1996. (c) If cracks are found during any inspections required by this AD, prior to further flight, modify the fin front spar attachment fittings in accordance with the INSTRUCTIONS section of the SER No. 138, Revised August 7, 1996. (d) Incorporating the modification specified in paragraph (c) of this AD is considered terminating action for the repetitive inspection requirements of this AD. (e) Special flight permits may be issued in accordance with 14 CFR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished. (f) 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, Fort Worth Airplane Certification Office, 2601 Meacham Boulevard, Fort Worth, Texas 76193-0150. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Fort Worth Airplane Certification Office. Alternative methods of compliance approved in accordance with AD 95-20-06 are considered approved as alternative methods of compliance for this AD. Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Fort Worth Aircraft Certification Office. (g) All persons affected by this directive may obtain copies of the document referred to herein upon request to Air Tractor Incorporated, P. O. Box 485, Olney, Texas 76374; or may examine this document at the FAA, Central Region, Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106. (h) This amendment supersedes AD 95-20-06, Amendment 39-9384. Issued in Kansas City, Missouri, on February 10, 1997. Henry A. Armstrong, Acting Manager, Small Airplane Directorate, Aircraft Certification Service. [FR Doc. 97-3958 Filed 2-18-97; 8:45 am] BILLING CODE 4910-13-U