E7-24215. Airworthiness Directives; Air Tractor, Inc. AT-400, AT-500, AT-600, and AT-800 Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

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

SUMMARY:

We are revising an earlier proposed airworthiness directive (AD) that applies to certain Air Tractor, Inc. (Air Tractor) AT-400, AT-500, AT-600, and AT-800 series airplanes. The earlier NPRM proposed to supersede Airworthiness Directive (AD) 2007-13-17, which applies to certain Air Tractor Models AT-602, AT-802, and AT-802A airplanes. AD 2007-13-17 currently requires you to repetitively inspect the engine mount for any cracks, repair or replace any cracked engine mount, and report any cracks found to the FAA. The earlier NPRM proposed to retain the inspection actions of AD 2007-13-17 for Models AT-602, AT-802, and AT-802A airplanes, including the compliance times and effective dates; establish new inspection actions for the AT-400 and AT-500 series airplanes; incorporate a mandatory terminating action for all airplanes; and terminate the reporting requirement of AD 2007-13-17. The earlier NPRM resulted from a Model AT-502B with a crack located where the lower engine mount tube is welded to the engine mount ring, and the manufacturer developing gussets that, when installed according to their service letter, terminate the repetitive inspection requirement. Since issuance of the NPRM, the manufacturer revised the service information and the FAA has determined that it is necessary to address the unsafe condition. Therefore, we are incorporating the service letter revision into the proposed AD, and we are extending the comment period to allow the public additional time to comment.

DATES:

We must receive comments on this proposed AD by February 29, 2008 (an additional 30 days after the comment close date for the NPRM, which was January 30, 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]; fax: [phone].

FOR FURTHER INFORMATION CONTACT:

Andy McAnaul, Aerospace Engineer, 10100 Reunion Pl., San Antonio, Texas 78216; telephone: [phone]; fax: [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-2007-0258; Directorate Identifier 2007-CE-090-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

On November 23, 2007, 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 all Air Tractor AT-400, AT-500, AT-600, and AT-800 series airplanes. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on November 30, 2007 (72 FR 67687). The NPRM proposed to supersede AD 2007-13-17 with a new AD that would retain the inspection actions of AD 2007-13-17 for Models AT-602, AT-802, and AT-802A airplanes, including the compliance times and effective dates; establish new inspection actions for the AT-400 and AT-500 series airplanes; incorporate a mandatory terminating action for all airplanes; and terminate the reporting requirement of AD 2007-13-17. That proposed AD would have required you to use Snow Engineering Co. Service Letter #253 Rev. A, dated October 16, 2007.

Since issuance of the NPRM, Snow Engineering Company revised the Snow Engineering Co. Service Letter #253, Rev. A to the Rev. B level (dated November 30, 2007).

FAA's Determination and Requirements of This Proposed AD

We have carefully reviewed the available data and determined that:

• The unsafe condition referenced in this document exists or could develop on other products of the same type design;
• Doing the actions following the revised service letter is necessary to address the unsafe condition; and
• We should take AD action to correct this unsafe condition.

Therefore, we are incorporating the service letter revision into the proposed AD, and we are issuing a supplemental NPRM and extending the comment period to allow the public additional time to comment.

Costs of Compliance

We estimate that this proposed AD would affect 1,264 airplanes in the U.S. registry, including those airplanes affected by AD 2007-13-17.

We estimate the following costs to do the proposed inspection:

Labor cost	Parts cost	Total cost per airplane	Total cost on U.S. operators
1.5 work-hours × $80 per hour = $120	$0	$120	$151,680

We estimate the following costs to do the repair/modification:

Labor cost	Parts cost	Total cost per airplane	Total cost on U.S. operators
24 work-hours × $80 per hour = $1,920	$80	$2,000	$2,528,000

The estimated total cost on U.S. operators includes the cumulative costs associated with AD 2007-13-17 and those airplanes and actions being added in this proposed AD.

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 removing Airworthiness Directive (AD) 2007-13-17, Amendment 39-15121 (72 FR 36863, July 6, 2007), and adding the following new AD:

Air Tractor, Inc.: Docket No. FAA-2007-0258; Directorate Identifier 2007-CE-090-AD.

Comments Due Date

(a) We must receive comments on this airworthiness directive (AD) action by February 29, 2008 (an additional 30 days after the comment close date for the NPRM of January 30, 2008).

Affected ADs

(b) This AD supersedes AD 2007-13-17, Amendment 39-15121.

Applicability

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

Model	Serial Nos.
AT-400, AT-400A, AT-402, AT-402A, and AT-402B	-0001 through -1175.
AT-502, AT-502A, AT-502B, and AT-503A	-0001 through -2597.
AT-602	-0001 through -1141.
AT-802 and AT-802A	-0001 through -0227.

Unsafe Condition

(d) This AD results from a report of a Model AT-502B airplane with a crack located where the lower engine mount tube is welded to the engine mount ring. The airplane had 8,436 total hours time-in-service (TIS). We are issuing this AD to detect and correct cracks in the engine mount, which could result in failure of the engine mount. Such failure could lead to separation of the engine from the airplane.

Compliance

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

(1) For all airplanes with less than 5,000 hours total TIS that do not have gussets installed on the engine mount in accordance with Snow Engineering Co. Service Letter #253 Rev. A, dated October 16, 2007: Visually inspect the engine mount as follows:

Affected airplanes	Compliance	Procedures
(i) For all Models AT-602, AT-802, and AT-802A airplanes	Initially before the airplane reaches a total of 1,300 hours TIS or within the next 100 hours TIS after August 10, 2007 (the effective date of AD 2007-13-17), whichever occurs later. Repetitively thereafter at intervals not to exceed 300 hours TIS	Follow one of the following: (A) Snow Engineering Co. Service Letter #253, Rev. B, dated November 30, 2007; (B) Snow Engineering Co. Service Letter #253, Rev. A, dated October 16, 2007; or (C) Snow Engineering Co. Service Letter #253, revised January 22, 2007.
(ii) For all Model AT-502A airplanes	Initially before the airplane reaches a total of 1,300 hours TIS or within the next 100 hours TIS after the effective date of this AD, whichever occurs later. Repetitively thereafter at intervals not to exceed 300 hours TIS	Follow Snow Engineering Co. Service Letter #253 Rev. B, dated November 30, 2007.
(iii) For all Models AT-400, AT-400A, AT-402, AT-402A, AT-402B, AT-502, AT-502B, and AT-503A airplanes	Initially within the next 12 months after the effective date of this AD Repetitively thereafter at intervals not to exceed 12 months	Follow Snow Engineering Co. Service Letter #253 Rev. B, dated November 30, 2007.

(2) For all airplanes: Before further flight after any inspection required by paragraph (e)(1) of this AD where crack damage is found, repair and modify the engine mount by installing gussets following Snow Engineering Co. Service Letter #253 Rev. B, dated November 30, 2007. This modification terminates the repetitive inspections required in paragraphs (e)(1)(i), (e)(1)(ii), and (e)(1)(iii) of this AD.

(3) For all airplanes: Before the airplane reaches 5,000 hours total 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; inspect, repair if cracked, and modify the engine mount by installing gussets following Snow Engineering Co. Service Letter #253 Rev. B, dated November 30, 2007. This modification terminates the repetitive inspections required in paragraphs (e)(1)(i), (e)(1)(ii), and (e)(1)(iii) of this AD.

Note:

As a terminating action to the repetitive inspections required in paragraphs (e)(1)(i), (e)(1)(ii), and (e)(1)(iii) of this AD, you may install the gussets before finding cracks or reaching 5,000 hours total TIS.

Alternative Methods of Compliance (AMOCs)

(f) The Manager, Forth 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: Andy McAnaul, Aerospace Engineer, ASW-150, FAA San Antonio MIDO-43, 10100 Reunion Place, San Antonio, Texas 78216; phone: [phone]; fax: [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]; fax: [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 December 10, 2007.

John R. Colomy,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.