E8-15456. Airworthiness Directives; Air Tractor, Inc., Models AT-402, AT-402A, and AT-402B 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-402, AT-402A, and AT-402B airplanes. This proposed AD would require you to repetitively visually inspect the rudder and vertical fin hinge attaching structure for loose fasteners and inspect the rudder or vertical fin skins, spars, hinges or brackets for cracks and/or corrosion. The AD would also require you to replace any damaged parts found as a result of the inspections 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 a report of a Model AT-402 airplane with a loose upper rudder hinge caused by fatigue. 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.

DATES:

We must receive comments on this proposed AD by September 8, 2008.

ADDRESSES:

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

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, 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-2008-0749; Directorate Identifier 2008-CE-044-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://www.regulations.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 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.

Consequently, we issued AD 2006-23-14 (71 FR 66661, November 16, 2006). AD 2006-23-14 requires you to repetitively visually inspect the rudder and vertical fin hinge attaching structure (vertical fin skins, spars, hinges, and brackets) for loose fasteners, cracks, and/or corrosion. This AD also requires you to replace any damaged parts found as a result of the inspection and install an external doubler at the upper rudder hinge.

Since issuing AD 2006-23-14, we have received a report of a Model AT-402 airplane with a loose upper rudder hinge caused by fatigue. Therefore, we are proposing this AD to address the unsafe condition on the Model AT-402 airplanes.

Relevant Service Information

We have reviewed Snow Engineering Co. Service Letter #247, revised June 2, 2008; 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 proposed 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 220 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	$17,600

Any required repairs will vary depending upon the damage found, and any replacements required will vary based on the results of the inspection. Based on this, we have no way of determining the potential repair and/or replacement costs for each airplane or the number of airplanes that will need the repairs and/or replacements based on the result of the inspections.

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

Labor cost	Parts cost	Total cost per airplane
5 work-hours × $80 per hour = $400	$217	$617

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://www.regulations.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-2008-0749; Directorate Identifier 2008-CE-044-AD.

Comments Due Date

(a) We must receive comments on this airworthiness directive (AD) action by September 8, 2008.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Models AT-402, AT-402A, and AT-402B airplanes, serial numbers 0694 through 1176, that are certificated in any category.

Unsafe Condition

(d) This AD results from a report of a Model AT-402 airplane with a loose upper rudder hinge caused by fatigue. 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.

Compliance

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

Actions	Compliance	Procedures
(1) Inspect visually the rudder and vertical fin hinge attachment for loose fasteners; and inspect the rudder or vertical fin skins, spars, hinges or brackets for cracks and/or corrosion	Initially inspect when the airplane reaches a total of 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 at intervals not to exceed 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, revised June 2, 2008.
(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 terminates the action for the repetitive inspections required by this AD	Follow Snow Engineering Co. Service Letter #247, revised June 2, 2008; 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	When the airplane reaches a total of 5,000 hours TIS after the effective date of this AD 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 terminates the action for the repetitive inspections required by this AD	Follow Snow Engineering Co. Service Letter #247, revised June 2, 2008; 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, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to ATTN: Andrew McAnaul, Aerospace Engineer, ASW-150 (c/o MIDO-43), 10100 Reunion Place, Suite 650, San Antonio, Texas 78216; telephone: [phone]; facsimile: [phone]. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.

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 U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, or on the Internet at http://www.regulations.gov.

Issued in Kansas City, Missouri, on July 1, 2008.

John Colomy,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.