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Proposed Rule

Airworthiness Directives; Air Tractor, Inc. Models AT-300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-402, AT-602, AT-802, and AT-802A Airplanes

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for Start Printed Page 10514certain Air Tractor, Inc. (Air Tractor) Models AT-300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-402, AT-602, AT-802, and AT-802A airplanes. This proposed AD would require you to repetitively tighten the four eyebolts that attach the front and rear spar of the horizontal stabilizer to the respective stabilizer strut to the specified torque, and repetitively replace at specified intervals any eyebolts that attach the front and rear spar of the horizontal stabilizer to the respective stabilizer strut. An option for replacing the steel brace assembly inside the stabilizer with a new steel brace assembly with larger bushings and stronger eyebolts that increases the interval for replacement of eyebolts for AT-602, AT-802, and AT-802A airplanes is also included in this proposed AD. This proposed AD results from reports of failures of the subject eyebolt. We are issuing this proposed AD to detect, correct, and prevent future fatigue failure in any eyebolt that attaches the front and rear spar of the horizontal stabilizer to the respective stabilizer strut. Failure of the eyebolt could lead to an abrupt change or complete loss of pitch control and/or the airplane departing from controlled flight.

DATES:

We must receive any comments on this proposed AD by May 6, 2005.

ADDRESSES:

Use one of the following to submit comments 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 20590-001.
  • Fax: 1-202-493-2251.
  • 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.

To get the service information identified in this proposed AD, contact Air Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374.

To view the comments to this proposed AD, go to http://dms.dot.gov. The docket number is FAA-2004-19837.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Andrew D. McAnaul, Aerospace Engineer, FAA, Fort Worth Airplane Certification Office (ACO), ASW-150, 2601 Meacham Boulevard, Fort Worth, Texas 76193-0150. Current duty station: San Antonio Manufacturing Inspection District Office (MIDO-43), 10100 Reunion Place, Suite 650, San Antonio, Texas 78216; telephone: (210) 308-3365; facsimile: (210) 308-3370.

End Further Info End Preamble Start Supplemental Information

SUPPLEMENTARY INFORMATION:

Comments Invited

How do I comment on this proposed AD? We invite you to submit any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include the docket number, “FAA-2004-19837; Directorate Identifier 2004-CE-43-AD” at the beginning of your 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 with FAA personnel concerning this proposed rulemaking. Using the search function of our docket Web site, anyone can find and read the comments received into any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). This is docket number FAA-2004-19837. You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78) or you may visit http://dms.dot.gov.

Are there any specific portions of this proposed AD I should pay attention to? We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. If you contact us through a nonwritten communication and that contact relates to a substantive part of this proposed AD, we will summarize the contact and place the summary in the docket. We will consider all comments received by the closing date and may amend this proposed AD in light of those comments and contacts.

Docket Information

Where can I go to view the docket information? You may view the AD docket that contains the proposal, any comments received, and any final disposition in person at the DMS Docket Offices between 9 a.m. and 5 p.m. (eastern standard time), Monday through Friday, except Federal holidays. The Docket Office (telephone 1-800-647-5227) is located on the plaza level of the Department of Transportation NASSIF Building at the street address stated in ADDRESSES. You may also view the AD docket on the Internet at http://dms.dot.gov. The comments will be available in the AD docket shortly after the DMS receives them.

Discussion

What events have caused this proposed AD? In December 1985, Snow Engineering Co. issued Service Letter # 62 to recommend the inspection of eyebolts. This was in response to several reports of eyebolt failures on Models AT-301 and AT-400 airplanes.

In response to another failure of an eyebolt on an AT-400 airplane, Snow Engineering Co. issued Service Letter #129 in September 1995. This service letter recommended eyebolt replacement every 2,000 hours time-in-service (TIS) for Models AT-301 and AT-400 airplanes. After a report of an eyebolt failure on a Model AT-602 airplane, Snow Engineering Co. revised Service Letter #129 in November 2003 to recommend replacing eyebolts for Models AT-602, AT-802, and AT-802A airplanes every 1,350 hours TIS.

The FAA also received two service difficulty reports (SDRs) in November 2003. Both SDRs referenced Model AT-802 airplane eyebolt cracks. In December 2003, FAA issued Special Airworthiness Information Bulletin (SAIB) CE-04-23. This SAIB recommended periodic eyebolt replacement following Snow Engineering Co. Service Letter #129.

In April 2004, we received a report of both eyebolts that attach the left hand stabilizer failing in flight on a Model AT-602 airplane. These eyebolts had accumulated 1,675 hours TIS.

Engineering analysis concludes that the eyebolts failed as a result of high-cycle, low-nominal stress. This is most likely due to the loss of torque during service.

Air Tractor has since redesigned the horizontal stabilizer structure for Models AT-802 and AT-602 airplanes to accommodate a new, stronger eyebolt.

Snow Engineering Co. also revised Service Letter #129 with new eyebolt replacement intervals and issued Service Letter #129A to include procedures for optional replacement of the steel brace assembly inside the stabilizer with a new steel brace assembly with larger bushings to accommodate new stronger eyebolts on existing Models AT-602, AT-802, and AT-802A airplanes. This modification provides for increased safety and extends eyebolt replacement intervals.

What is the potential impact if FAA took no action? Failure of an eyebolt could lead to an abrupt change or complete loss of pitch control and/or aircraft departure from controlled flight.Start Printed Page 10515

Is there service information that applies to this subject? As discussed earlier, Snow Engineering Co. has issued the following Service Letters:

—Service Letter #129, revised: October 21, 2004; and

—Service Letter #129A, dated August 7, 2004.

What are the provisions of this service information? These service letters include procedures for:

—Service Letter #129 recommends tightening the eyebolt nut to a specified torque, replacing the eyebolt, and includes the inspection procedures when replacing any eyebolt; and

—Service Letter #129A, for certain eyebolts, recommends replacing eyebolts with larger eyebolts, tightening the eyebolt nut to a specified torque, and procedures for replacing the steel brace assembly inside the stabilizer with a new steel brace assembly with larger bushings.

FAA's Determination and Requirements of This Proposed AD

What has FAA decided? We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. For this reason, we are proposing AD action.

What would this proposed AD require? This proposed AD would require you to incorporate the actions in the previously-referenced service information.

How does the revision to 14 CFR part 39 affect this proposed AD? On July 10, 2002, we published a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs FAA's AD system. This regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance. This material previously was included in each individual AD. Since this material is included in 14 CFR part 39, we will not include it in future AD actions.

Costs of Compliance

How many airplanes would this proposed AD impact? We estimate that this proposed AD affects 1,011 airplanes in the U.S. registry.

What would be the cost impact of this proposed AD on owners/operators of the affected airplanes? We estimate the following costs to do the proposed tightening of the four eyebolt nuts to the specified torque:

Labor costParts costTotal cost per airplaneTotal cost on U.S. operators
1 workhour × $65 per hour = $65No parts required$65$65 × 1,011 = $65,715

We estimate the following costs to do any necessary replacement of the four eyebolts for the Models AT-300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-402 AT-602, AT-802, and AT-802A airplanes:

Average labor costAverage parts costAverage total cost per airplaneAverage total cost on U.S. operators
1 workhour × $65 per hour = $65$186.30$251.301,011 × $251.30 = $254,064.30

We estimate the following costs to do any necessary replacement of the steel brace assembly inside the stabilizer with a new steel brace assembly with larger bushings on existing Models AT-602, AT-802, and AT-802A airplanes:

Average labor costAverage parts costAverage total cost per airplaneAverage total cost on U.S. operators
22 workhours × $65 per hour = $1,430$901.65$2,331.65312 × $2,331.65 = $727,474.80

Authority for this Rulemaking

What authority does FAA have for issuing this rulemaking action? 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 AD.

Regulatory Findings

Would this proposed AD impact various entities? 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.

Would this proposed AD involve a significant rule or regulatory action? For the reasons discussed above, I certify that this proposed AD:

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 summary of the costs to comply with this proposed AD and placed it in the AD Docket. You may get Start Printed Page 10516a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include “AD Docket FAA-2004-19837; Directorate Identifier 2004-CE-43-AD” in your request.

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List of Subjects in 14 CFR Part 39

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The Proposed Amendment

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

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PART 39—AIRWORTHINESS DIRECTIVES

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

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

End Authority
[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):

Air Tractor, Inc.: Docket No. FAA-2004-19837; Directorate Identifier 2004-CE-43-AD.

When Is the Last Date I Can Submit Comments on This Proposed AD?

(a) We must receive comments on this proposed airworthiness directive (AD) by May 6, 2005.

What Other ADs Are Affected by This Action?

(b) None.

What Airplanes Are Affected by This AD?

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

ModelsSerial numbers
AT-300, AT-301, AT-302, AT-400, and AT-400AAll serial numbers.
AT-401/AT-402All through 401-0700.
AT-602All through 602-0695 that have any 7/16-inch eyebolt (P/N AN47-22A) installed; all beginning with 602-0703; and all that have any 9/16-inch eyebolt (P/N 30774-1) installed.
AT-802 and AT-802AAll through 802A-0188 that have any 7/16-inch eyebolt (P/N AN74-30A) installed; all beginning with 802A-0189; and all that have any 9/16-inch eyebolt (P/N 30775-1) installed.

What Is the Unsafe Condition Presented in This AD?

(d) This AD is the result of reports of failures of the subject eyebolt. The actions specified in this AD are intended to detect, correct, and prevent future fatigue failure in any eyebolt that attaches the front and rear spar of the horizontal stabilizer to the respective stabilizer strut. Failure of the eyebolt could lead to an abrupt change or complete loss of pitch control and/or the airplane departing from controlled flight.

What Must I Do To Address This Problem?

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

ActionsComplianceProcedures
(1) Tighten the four eyebolts that attach the front and rear spar of the horizontal stabilizer to the respective stabilizer strut using the torque values referenced in Snow Engineering Co. Service Letter #129, revised October 21, 2004Within the next 12 calendar months after the effective date of this AD, unless already done. Repetitively tighten thereafter at every 12 calendar months after the date of the initial tightening to the specified torqueFollow Snow Engineering Co. Service Letter #129, revised October 21, 2004.
(2) Repetitively replace any eyebolts that attach the front and rear spar of the horizontal stabilizer to the respective stabilizer strutInitially replace upon accumulating the applicable number of hours time-in-service (TIS) referenced in Snow Engineering Co. Service Letter #129, revised October 21, 2004, or within 50 hours TIS after the effective date of this AD, whichever occurs later. Replace repetitively thereafter at the intervals referenced in Snow Engineering Co. Service Letter #129, revised October 21, 2004Follow Snow Engineering Co. Service Letter #129, revised October 21, 2004.
(3) For Model AT-602 airplanes through serial number 602-0695 and AT-802, and 802A airplanes through serial number 802A-0188: As an alternative in order to use the increased replacement compliance times in paragraph (e)(2) of this AD, you may replace the steel brace assembly inside the stabilizer with a new steel brace assembly with larger bushings, andAt any time after the effective date of this AD. Use the applicable time in Snow Engineering Co. Service Letter #129A, dated August 7, 2004. The repetitive replacement of paragraph (e)(2) of this AD is still requiredFollow Snow Engineering Co. Service Letter #129A, dated August 7, 2004.
(i) For the Model AT-602 airplane: replace any 7/16-inch eyebolt with the 9/16-inch eyebolt (P/N 30774-1)
(ii) For the Model AT-802 and AT-802A airplanes: replace any 7/16-inch eyebolt with the 9/16-inch eyebolt (P/N 30775-1)
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(4) Do not install any 5/16-inch eyebolt (P/N AN44-17A or AN44-21A), 7/16-inch eyebolt (AN47-22A or AN47-30A), or 9/16-inch eyebolt (P/N 30774-1 or 30775-1) that exceeds the corresponding cumulative hours TIS specified in paragraphs (e)(2) or (e)(3) of this AD.As of the effective date of this AD.Not Applicable.

May I Request an Alternative Method of Compliance?

(f) You may request a different method of compliance or a different compliance time for this AD by following the procedures in 14 CFR 39.19. Unless FAA authorizes otherwise, send your request to your principal inspector. The principal inspector may add comments and will send your request to the Manager, Fort Worth Aircraft Certification Office (ACO), FAA. For information on any already approved alternative methods of compliance, contact Andrew D. McAnaul, Aerospace Engineer, FAA, Fort Worth Airplane Certification Office (ACO), ASW-150, 2601 Meacham Boulevard, Fort Worth, Texas 76193-0150. Current duty station: San Antonio Manufacturing Inspection District Office (MIDO-43), 10100 Reunion Place, Suite 650, San Antonio, Texas 78216; telephone: (210) 308-3365; facsimile: (210) 308-3370.

May I Get Copies of the Documents Referenced in This AD?

(g) To get copies of the documents referenced in this AD, contact Air Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374. To view the AD docket, go to the Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, S.W., Nassif Building, Room PL-401, Washington, DC, or on the Internet at http://dms.dot.gov. The docket number is FAA-2004-19837.

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Issued in Kansas City, Missouri, on February 28, 2005.

David R. Showers,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.

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[FR Doc. 05-4238 Filed 3-3-05; 8:45 am]

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