AD 95-20-06

Effective October 25, 1995.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of October 25, 1995.

Comments for inclusion in the Rules Docket must be received on or before November 27, 1995.

Submit comments in triplicate to the Federal Aviation Administration (FAA), Central Region, Office of the Assistant Chief Counsel, Attention: Rules Docket 95-CE-60-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.

Service information that applies to this AD may be obtained from Air Tractor Incorporated, P.O. Box 485, Olney, Texas 76374. This information may also be examined at the Federal Aviation Administration (FAA), Central Region, Office of the Assistant Chief Counsel, Attention: Rules Docket 95-CE-60-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106; or at the Office of the Federal Register, 800 North Capitol Street NW., suite 700, Washington, DC.

Bob May, Aerospace Engineer, FAA, Aircraft Certification Office, 2601 Meacham Boulevard, Fort Worth, Texas 76193-0150; telephone (817) 222-5155; facsimile (817) 222-5960.

The FAA received reports of two incidents in which the front spar and rear spar failed on an Air Tractor AT-802A while in flight causing the vertical tail to lay over against the elevator creating difficulty in controlling the airplane. Both front spar failures occurred across the \3/16\-inch thick fin front spar fitting, which is made of aluminum and bolts to the fuselage frame. Investigations reveal that Air Tractor models designed with \3/16\-inch front spar attach plates are subject to fatigue failure. When front spar failure occurs the rear spar will only support the rudder loads for a short time before it also fails, which could result in loss of control of the airplane.

Air Tractor has issued Service Letter (SL) number (No.) 138, dated July 29, 1995, which specifies procedures for inspecting and modifying the fin front spar plate and the rear fin spar at the upper attachment to the fuselage frame.

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 possible in-flight structural failure to the vertical fin 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.

Since an unsafe condition has been identified that is likely to exist or develop in other Air Tractor Models AT-301, AT-302, AT-400, AT-400A, AT-401, AT-402, AT-501, and AT-502 airplanes of the same type design, this AD would require inspecting the front and rear spar attachments and, if fatigue cracks are found, modifying the airplane. The inspections and modifications are to be done in accordance with the INSTRUCTIONS section in Air Tractor SL No. 138, dated July 29, 1995. The accomplishment of the proposed modification will be considered a terminating action.

Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for public prior comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Although this action is in the form of a final rule that involves requirements affecting immediate flight safety and, thus, was not preceded by notice and opportunity to comment, comments are invited on this rule. Interested persons are invited to comment on this 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 will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 AD 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-60-AD.'' The postcard will be date stamped and returned to the commenter.

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.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a significant regulatory action under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket (otherwise, an evaluation is not required). A copy of it, if filed, may be obtained from the Rules Docket.

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

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:

1. The authority citation for part 39 continues to read as follows:

Authority: 49 USC 106(g), 40101, 40113, 44701.