02-16309. Airworthiness Directives; Air Tractor, Inc. Models AT-402, AT-402A, AT-402B, AT-602, AT-802, and AT-802A Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Supplemental notice of proposed rulemaking (NPRM); Reopening of the comment period.

SUMMARY:

This document proposes to revise an earlier proposed airworthiness directive (AD) that would apply to certain Air Tractor, Inc. (Air Tractor) Model AT-602 airplanes. The earlier NPRM would have required you to repetitively inspect the left hand upper longeron and upper diagonal tube of the fuselage frame for cracks and repair any cracks found. The earlier NPRM would have also required eventual modification of this area to terminate the repetitive inspection. The manufacturer has identified additional airplane models on which the unsafe condition exists or could develop and has determined that the required modification is not eliminating the cracks from occurring. This proposed AD adds additional airplanes to the applicability and makes the inspection repetitive for all airplanes even if the modification is incorporated. Since these actions impose an additional burden over that proposed in the NPRM, we are reopening the comment period to allow the public the chance to comment on these additional actions.

DATES:

The Federal Aviation Administration (FAA) must receive any comments on this proposed rule on or before August 26, 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 Is the Background of the Subject Matter?

The FAA received reports of three occurrences of cracks found on the left hand upper longeron and upper diagonal support tubes where they intersect on the left hand side of the fuselage frame just forward of the vertical fin front spar attachment point on Air Tractor Model AT-602 airplanes. The crack starts at the forward edge of the weld where the tubes come together. We initially determined that the cracks resulted from 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.

Has FAA Taken any Action to This Point?

We issued a proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to certain Air Tractor Model AT-602 airplanes. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on March 11, 2002 (67 FR 10862).

The NPRM proposed to 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 modify this area by installing reinforcement parts.

You would have to accomplish the proposed actions in accordance with the following service information:

—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;

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

—the applicable maintenance manual.

Was the Public Invited To Comment?

The FAA encouraged interested persons to participate in the making of this amendment. We did not receive any comments on the proposed rule or on our determination of the cost to the public.

What Events Have Caused FAA To Issue a Supplemental NPRM?

Since we issued the earlier NPRM, further cracking has been reported on 3 more AT-602 airplanes, as well as 1 AT-402 series and 3 AT-802 series airplanes. One of the AT-802 airplanes had the extended reinforcement gusset installed during factory production.

Air Tractor discovered that the factory installed extended reinforcement gusset, which runs further forward than the original gusset, is also cracking at the forward end of the extended gusset. Therefore, we have determined that installing the reinforcement gussets is not transferring the loads away from the joint and does not alleviate the crack condition from occurring.

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-402, AT-402A, AT-402B, AT-602, AT-802, and AT-802A airplanes of the same type design;

—The originally proposed modification should not be considered as a terminating action for the repetitive inspections and all referenced airplanes should be repetitively inspected; and

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

The Supplemental NPRM

How Will the Changes to the NPRM Impact the Public?

Proposing that the NPRM apply to certain Air Tractor Models AT-402, AT-402A, AT-402B, AT-602, AT-802, and AT-802A airplanes and requiring you to repetitively inspect without a terminating action present actions that go beyond the scope of what was already proposed. Therefore, we are issuing a supplemental NPRM and reopening the comment period to allow the public additional time to comment on the proposed AD.

What Are the Provisions of the Supplemental NPRM?

The 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 and contact the manufacturer for a repair scheme if cracks are found.

Is There a Modification I Can Incorporate Instead of Repetitively Inspecting the Left Hand Upper Longeron and Upper Diagonal Tube of the Fuselage Frame for Cracks?

The FAA has determined that long-term continued operational safety would be better assured by design changes that remove the source of the problem rather than by repetitive inspections or other special procedures. With this in mind, FAA will continue to work with Air Tractor in performing further tests to determine the cause of the cracking and to provide a corrective action for terminating the need for repetitive inspections.

Why Are Air Tractor AT-500 Series Airplanes Not Included in This Proposed AD?

The Air Tractor AT-500 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 AT-402 series airplanes, Model AT-602 airplanes, and AT-802 series airplanes.

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

How Many Airplanes Would This Proposed AD Impact?

We estimate that this proposed AD affects 248 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 × 248 = $14,880.

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 the following airplane models and serial numbers that are certificated in any category.

Model	Serial No.
AT-402	All serial numbers beginning with 402-0694.
AT-402A	All serial numbers beginning with 402A-0738.
AT-402B	All serial numbers beginning with 402B-0966.
AT-602	All serial numbers
AT-802	All serial numbers.
AT-802A	All serial numbers.

(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 100 hours time-in-service (TIS) after the effective date of this AD and thereafter at intervals not to 100 hours TIS	In accordance with Snow Engineering Co. Service Letter #195, dated February 4, 2000, and the applicable maintenance exceed 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 address specified in paragraph (f) of this AD; and   (ii) Incorporate this repair scheme	Obtain and incorporate the repair scheme prior to further flight after the inspection in which the cracks are found. Continue to inspect as specified in paragraph (d)(1) of this AD	In accordance with the repair scheme obtained from Air Tractor, Incorporated, P.O. Box 485, the Olney, Texas 76374. Obtain this repair scheme through the FAA at the address specified in paragraph (f) of this AD.

(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 June 20, 2002.

Michael Gallagher,

Manager, Small Airplane Directorate, Aircraft Certification Service.