E6-12940. Airworthiness Directives; Air Tractor, Inc. Models AT-502, AT-502A, AT-502B, AT-602, AT-802, and AT-802A Airplanes

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for certain Air Tractor, Inc. (Air Tractor) Models AT-502, AT-502A, AT-502B, AT-602, AT-802, and AT-802A airplanes. This proposed AD would require you to repetitively visually inspect the rudder and vertical fin hinge attaching structure for loose fasteners, any cracks in the rudder or vertical fin skins, spars, hinges or brackets, or corrosion. The AD would also require you to replace any damaged parts found as a result of the inspection and install an external doubler at the upper rudder hinge. Installation of the external doubler at the upper rudder hinge is terminating action for the repetitive inspection requirements. This proposed AD results from two reports (one Model AT-602 airplane and one Model AT-802A airplane) of in-flight rudder separation from the vertical fin at the upper attach hinge area, and other reports of Models AT-502B, AT-602, and AT-802/802A airplanes with loose hinges, skin cracks, or signs of repairs to the affected area. We are proposing this AD to detect and correct loose fasteners; any cracks in the rudder or vertical fin skins, spars, hinges or brackets, or corrosion of the rudder and vertical fin hinge attaching structure. Hinge failure adversely affects ability to control yaw and has led to the rudder folding over in flight. This condition could allow the rudder to contact the elevator and affect ability to control pitch with consequent loss of control of the airplane.

DATES:

We must receive comments on this proposed AD by October 10, 2006.

ADDRESSES:

Use one of the following addresses to comment on this proposed AD:

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC 20590-0001.
• Fax: [phone].
• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact Air Tractor, Inc., P.O. Box 485, Olney, Texas 76374; telephone: [phone]; facsimile: [phone].

FOR FURTHER INFORMATION CONTACT:

Andrew McAnaul, Aerospace Engineer, ASW-150 (c/o MIDO-43), 10100 Reunion Place, Suite 650, San Antonio, Texas 78216; telephone: [phone]; facsimile: [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include the docket number, “FAA-2006-25260; Directorate Identifier 2006-CE-37-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive concerning this proposed AD.

Discussion

We have received two reports (one Air Tractor Model AT-602 airplane and one Model AT-802A airplane) of in-flight rudder separation at the upper attach hinge area and other reports of Models AT-502B, AT-602, and AT-802/802A airplanes with loose hinges, skin cracks, or signs of repairs to the affected area.

Hinge failure adversely affects ability to control yaw and has led to the rudder folding over in flight. This condition could allow the rudder to contact the elevator and affect ability to control pitch with consequent loss of control of the airplane.

Relevant Service Information

We have reviewed Snow Engineering Co. Service Letter #247, dated August 14, 2005, revised May 17, 2006, and Snow Engineering Co. Process Specification Number 145, dated December 6, 1991. The service information describes procedures for:

• Inspecting (visually) the rudder and fin hinge attaching structure for loose fasteners, any cracks in the rudder or vertical fin skins, spars, hinges or brackets, or corrosion;
• Replacing any damaged parts found as a result of the inspection;
• Installing an external doubler at the upper rudder hinge; and
• Balancing of the rudder.

FAA's Determination and Requirements of the Proposed AD

We are proposing this AD because we evaluated all information and determined the unsafe condition described previously is likely to exist or develop on other products of the same type design. This proposed AD would require you to repetitively visually inspect the rudder and vertical fin hinge attaching structure for loose fasteners, any cracks in the rudder or vertical fin skins, spars, hinges or brackets, or corrosion. This AD would also require you to replace any damaged parts found as a result of the inspection and install an external doubler at the upper rudder hinge. Installation of the external doubler at the upper rudder hinge is terminating action for the repetitive inspection requirements.

Costs of Compliance

We estimate that this proposed AD would affect 945 airplanes in the U.S. registry.

We estimate the following costs to do the proposed inspection:

Labor cost	Parts cost	Total cost per airplane	Total cost on U.S. operators
1 work-hour × $80 per hour = $80	Not Applicable	$80	$75,600

We have no way of determining the number of airplanes that may need any replacements that would be required based on the results of the proposed inspection.

We estimate the following costs to do the installation of the external doubler at the upper rudder hinge:

Labor cost	Parts cost	Total cost per airplane	Total cost on U.S. operators
5 work-hours × $80 per hour = $400	$217	$617	$583,065

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in subtitle VII, part A, subpart III, section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect 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.

For the reasons discussed above, I certify that the proposed regulation:

1. Is not a “significant regulatory action” under Executive Order 12866;

2. Is not a “significant rule” under the 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.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket.

Examining the AD Docket

You may examine the AD docket that contains the proposed AD, the regulatory evaluation, any comments received, and other information on the Internet at http://dms.dot.gov;​; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone [phone]) is located at the street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

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

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39—AIRWORTHINESS DIRECTIVES

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

Authority : 49 U.S.C. 106(g), 40113, 44701.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new AD:

Air Tractor, Inc.: Docket No. FAA-2006-25260; Directorate Identifier 2006-CE-37-AD.

Comments Due Date

(a) We must receive comments on this airworthiness directive (AD) action by October 10, 2006.

Affected ADs

(b) None.

Applicability

(c) This AD affects the following airplane models and serial numbers that are certificated in any category:

Model	Serial Nos.
(1) AT-502 and AT-502B	502/502B-0003 through 502/502B-2600.
(2) AT-502A	502A-0003 through 502A-2582.
(3) AT-602	602-0337 through 602-1138.
(4) AT-802 and AT-802A	802/802A-0001 through 802/802A-0215.

Unsafe Condition

(d) This AD results from two reports (one Model AT-602 airplane and one Model AT-802A airplane) of in-flight rudder separations at the upper attach hinge area and other reports of Models AT-502B, AT-602, and AT-802/802A airplanes with loose hinges, skin cracks, or signs of repairs to the affected area. We are issuing this AD to detect and correct loose fasteners; any cracks in the rudder or vertical fin skins, spars, hinges or brackets, or corrosion of the rudder and vertical fin hinge attaching structure. Hinge failure adversely affects ability to control yaw and has led to the rudder folding over in flight. This condition could allow the rudder to contact the elevator and affect ability to control pitch with consequent loss of control of the airplane.

Compliance

(e) To address this problem, you must do the following:

Actions	Compliance	Procedures
(1) Inspect visually the rudder and vertical hinge attachment for loose fasteners; any cracks in the rudder or vertical fin skins, spars, hinges or brackets, or corrosion	Initially inspect upon reaching 3,500 hours time-in-service (TIS), or within the next 100 hours TIS after the effective date of this AD, whichever occurs later, unless already done. Thereafter, repetitively inspect every 100 hours TIS. Installation of the external doubler at the upper rudder hinge required by paragraph (e)(2)(ii) or (e)(3) of this AD is terminating action for the repetitive inspections required by this AD	Follow Snow Engineering Co. Service Letter #247, dated August 14, 2005, revised May 17, 2006.
(2) If you find any damage as a result of any inspection required by paragraph (e)(1) of this AD, you must: (i) Replace any damaged parts with new parts; and (ii) Do the installation of the external doubler at the upper rudder hinge.	Before further flight after any inspection required by paragraph (e)(1) of this AD where you find any damaged parts. The installation of the external doubler at the upper rudder hinge required by paragraph (e)(2)(ii) or (e)(3) of this AD is the terminating action for the repetitive inspections required by this AD	Follow Snow Engineering Co. Service Letter #247, dated August 14, 2005, revised May 17, 2006, and Snow Engineering Co. Process Specification Number 145, dated December 6, 1991.
(3) Do the installation of the external doubler at the upper rudder hinge	Upon accumulating 5,000 hours TIS or within the next 100 hours TIS after the effective date of this AD, whichever occurs later, unless already done. The installation of the external doubler at the upper rudder hinge required by paragraph (e)(2)(ii) or (e)(3) of this AD is the terminating action for the repetitive inspections required by this AD	Follow Snow Engineering Co. Service Letter #247, dated August 14, 2005, revised May 17, 2006, and Snow Engineering Co. Process Specification Number 145, dated December 6, 1991.
(4) Do not install any rudder without the external doubler at the upper rudder hinge required by paragraph (e)(3) of this AD	As of the effective date of this AD	Not Applicable.

Alternative Methods of Compliance (AMOCs)

(f) The Manager, Fort Worth Aircraft Certification Office, FAA, ATTN: Andrew McAnaul, Aerospace Engineer, ASW-150 (c/o MIDO-43), 10100 Reunion Place, Suite 650, San Antonio, Texas 78216; telephone: [phone]; facsimile: [phone], has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19.

Related Information

(g) To get copies of the service information referenced in this AD, contact Air Tractor, Inc., P.O. Box 485, Olney, Texas 76374; telephone: [phone]; facsimile: [phone]. To view the AD docket, go to the Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC, or on the Internet at http://dms.dot.gov. The docket number is Docket No. FAA-2006-25260; Directorate Identifier 2006-CE-37-AD.

Issued in Kansas City, Missouri, on August 3, 2006.

John R. Colomy,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.