02-5690. Airworthiness Directives; Air Tractor, Inc. Model AT-602 Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes to adopt a new airworthiness directive (AD) that would apply to certain Air Tractor, Inc. (Air Tractor) Model AT-602 airplanes. This proposed AD would require you to repetitively inspect the left hand upper longeron and upper diagonal tube of the fuselage frame for cracks and repair any cracks found. This proposed AD would also require eventual modification of this area to terminate the repetitive inspection. This proposed AD is the result of reports of excessive movement in the empennage due to the loss of fuselage torsional rigidity. The actions specified by this proposed AD are intended to prevent failure of the fuselage caused by cracks. Such failure could result in loss of control of the airplane.

DATES:

The Federal Aviation Administration (FAA) must receive any comments on this proposed rule on or before May 10, 2002.

ADDRESSES:

Submit comments to FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 2002-CE-03-AD, 901 Locust, Room 506, Kansas City, Missouri 64106. You may view any comments at this location between 8 a.m. and 4 p.m., Monday through Friday, except Federal holidays. You may also send comments electronically to the following address: [e-mail]. Comments sent electronically must contain “Docket No. 2002-CE-03-AD” in the subject line. If you send comments electronically as attached electronic files, the files must be formatted in Microsoft Work 97 for Windows or ASCII text.

You may get service information that applies to this proposed AD from Air Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374. You may also view this information at the Rules Docket at the address above.

FOR FURTHER INFORMATION CONTACT:

Andrew D. McAnaul, Aerospace Engineer, FAA, Fort Worth Airplane Certification Office, 2601 Meacham Boulevard, Fort Worth, Texas 76193-0150; telephone: [phone]; facsimile: [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

How Do I Comment on This Proposed AD?

The FAA invites comments on this proposed rule. You may submit whatever written data, views, or arguments you choose. You need to include the rule's docket number and submit your comments to the address specified under the caption ADDRESSES. We will consider all comments received on or before the closing date. We may amend this proposed rule in light of comments received. Factual information that supports your ideas and suggestions is extremely helpful in evaluating the effectiveness of this proposed AD action and determining whether we need to take additional rulemaking action.

Are There Any Specific Portions of This Proposed AD I Should Pay Attention to?

The FAA specifically invites comments on the overall regulatory, economic, environmental, and energy aspects of this proposed rule that might suggest a need to modify the rule. You may view all comments we receive before and after the closing date of the rule in the Rules Docket. We will file a report in the Rules Docket that summarizes each contact we have with the public that concerns the substantive parts of this proposed AD.

How Can I Be Sure FAA Receives My Comment?

If you want FAA to acknowledge the receipt of your comments, you must include a self-addressed, stamped postcard. On the postcard, write “Comments to Docket No. 2002-CE-03-AD.” We will date stamp and mail the postcard back to you.

Discussion

What Events Have Caused This Proposed AD?

The FAA has received reports of three occurrences where cracks were found on the left hand upper longeron and upper diagonal support tubes intersect on the left hand side of the fuselage frame just forward of the vertical fin front spar attachment point on Model AT-602 airplanes. The crack starts at the forward edge of the weld where the tubes come together. We have determined that the cracks are a result of high vertical tail loads during repeated hard turns. The cracks were found by the pilot and/or ground crew when they noticed excessive movement in the empennage due to the loss of torsional rigidity.

What Are the Consequences if the Condition Is Not Corrected?

This condition, if not corrected, could cause the fuselage to fail. Such failure could result in loss of control of the airplane.

Is There Service Information That Applies to This Subject?

Air Tractor has issued the following:

—Snow Engineering Co. Service Letter #195, dated February 4, 2000;

—Snow Engineering Co. Service Letter #213, dated November 13, 2001;

—Snow Engineering Co. Process Specification #102, Revised January 5, 2001;

—Snow Engineering Co. Process Specification #120, Revised December 16, 1997; and

—Snow Engineering Co. Process Specification #125, dated November 28, 1993.

What Are the Provisions of This Service Information?

These service bulletins include procedures for:

—Repetitively inspecting the upper longeron and upper diagonal tube on the left hand side of the aft fuselage structure for cracks; and

—Modifying this area by installing reinforcement parts.

The FAA's Determination and an Explanation of the Provisions of This Proposed AD

What Has FAA Decided?

After examining the circumstances and reviewing all available information related to the incidents described above, we have determined that:

—The unsafe condition referenced in this document exists or could develop on other Air Tractor Model AT-602 airplanes of the same type design;

—The actions specified in the previously-referenced service information should be accomplished on the affected airplanes; and

—AD action should be taken in order to correct this unsafe condition.

What Would This Proposed AD Require?

This proposed AD would require you to repetitively inspect the upper longeron and upper diagonal tube on the left hand side of the aft fuselage structure for cracks, repair any cracks found, and modifying this area by installing reinforcement parts.

Why Are the Air Tractor AT-400, AT-500, and AT-800 Series Airplanes Not Included in This Proposed AD?

The Air Tractor AT-400, AT-500, and AT-800 series airplanes have a similar design in the upper longeron in the aft fuselage structure. However, we have not received any reports of damage to this area on those airplanes. The only reports of damage are those previously referenced on the Model AT-602 airplanes.

Air Tractor is currently researching this subject on the AT-400, AT-500, and AT-800 series airplanes. Based on this research and if justified, we may propose additional rulemaking on this subject for these other airplanes.

Cost Impact

How Many Airplanes Would This Proposed AD Impact?

We estimate that this proposed AD affects 91 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 accomplish the proposed inspection(s):

Labor cost	Parts cost	Total cost per airplane	Total cost on U.S. operators
1 workhour × $60 = $60	No parts required	$60	$60 × 91 = $5,460

We estimate the following costs to accomplish the proposed modification:

Labor cost	Parts cost	Total cost per airplane
8 workhours × $60 = $480	Manufacturer will provide parts at no charge	$480

Regulatory Impact

Would This Proposed AD Impact Various Entities?

The regulations proposed herein 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. Therefore, it is determined that this proposed rule would not have federalism implications under Executive Order 13132.

Would This Proposed AD Involve a Significant Rule or Regulatory Action?

For the reasons discussed above, I certify that this proposed 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, under the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (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. FAA amends § 39.13 by adding a new airworthiness directive (AD) to read as follows:

Air Tractor, Inc.: Docket No. 2002-CE-03-AD.

(a) What airplanes are affected by this AD? This AD affects Model AT-602 airplanes, serial numbers 602-0337 through 602-0569, that are certificated in any category.

(b) Who must comply with this AD? Anyone who wishes to operate any of the airplanes identified in paragraph (a) of this AD must comply with this AD.

(c) What problem does this AD address? The actions specified by this AD are intended to prevent failure of the empennage caused by cracks. Such failure could result in loss of control of the airplane.

(d) What actions must I accomplish to address this problem? To address this problem, you must accomplish the following:

Actions	Compliance	Procedures
(1) Inspect the upper longeron and upper diagonal tube on the left hand side of the fuselage frame, just forward of the vertical fin front spar attachment, for cracks	Initially inspect within the next 50 hours time-in-service (TIS) after the effective date of this AD and thereafter at intervals not to exceed 100 hours TIS until 12 months after the effective date of this AD	In accordance with Snow Engineering Co. Service Letter #195, dated February 4, 2000, and applicable maintenance manual.
(2) If cracks are found during any inspection required in paragraph (d)(1) of this AD, accomplish the following: (i) Obtain a repair scheme from the manufacturer through the FAA at the address specified in paragraph (f) of this AD; and (ii) Incorporate this repair scheme	Prior to further flight after the inspection in which the cracks are found. The incorporation of the repair scheme will terminate the repetitive inspections	In accordance with the repair scheme obtained from Air Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374. Obtain this repair scheme through the FAA at the address specified in paragraph (f) of this AD.
(3) If no cracks were found during any inspection required in paragraph (d)(1) of this AD, accomplish the following: (i) Inspect as required in paragraph (d)(1) to ensure there are no cracks; and (ii) Install gusset part numbers 11946-1 and 11686-1 (or FAA-approved equivalent part numbers)	Within the next 12 calendar months after the effective date of this AD. You may install the reinforcement gussets at any time to terminate the repetitive inspections provided that you inspect prior to installation and no cracks are found	In accordance with Snow Engineering Co. Service Letter #213, dated November 13, 2001, Snow Engineering Co. Process Specification #102, revised January 5, 2001, Snow Engineering Co. Process Specification #120, revised December 16, 1997, and Snow Engineering Co. Process Specification #125, dated November 28, 1993, as specified in Service Letter #213, and the applicable maintenance manual.

(e) Can I comply with this AD in any other way? You may use an alternative method of compliance or adjust the compliance time if:

(1) Your alternative method of compliance provides an equivalent level of safety; and

(2) The Manager, Fort Worth Aircraft Certification Office (ACO), approves your alternative. Submit your request through an FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Fort Worth ACO.

Note:

This AD applies to each airplane identified in paragraph (a) of this AD, 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 (e) 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 you have not eliminated the unsafe condition, specific actions you propose to address it.

(f) Where can I get information about any already-approved alternative methods of compliance? Contact Andrew D. McAnaul, Aerospace Engineer, FAA, Fort Worth Airplane Certification Office, 2601 Meacham Boulevard, Fort Worth, Texas 76193-0150; telephone: [phone]; facsimile: [phone].

(g) What if I need to fly the airplane to another location to comply with this AD? The FAA can issue a special flight permit under sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate your airplane to a location where you can accomplish the requirements of this AD.

(h) How do I get copies of the documents referenced in this AD? You may get copies of the documents referenced in this AD from Air Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374. You may view these documents at FAA, Central Region, Office of the Regional Counsel, 901 Locust, Room 506, Kansas City, Missouri 64106.

Issued in Kansas City, Missouri, on March 4, 2002.

James E. Jackson,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.