[Federal Register Volume 72, Number 240 (Friday, December 14, 2007)]
[Proposed Rules]
[Pages 71086-71089]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-24215]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-0258; Directorate Identifier 2007-CE-090-AD]
RIN 2120-AA64


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.

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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;

[[Page 71087]]

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: (202) 493-2251.
     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: (940) 564-
5616; fax: (940) 564-5612.

FOR FURTHER INFORMATION CONTACT: Andy McAnaul, Aerospace Engineer, 
10100 Reunion Pl., San Antonio, Texas 78216; telephone: (210) 308-3365; 
fax: (210) 308-3370.

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:

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

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

----------------------------------------------------------------------------------------------------------------
                                                                                 Total cost per   Total cost on
                          Labor cost                              Parts cost        airplane      U.S. operators
----------------------------------------------------------------------------------------------------------------
24 work-hours x $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.

[[Page 71088]]

    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 (800) 647-5227) 
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.


Sec.  39.13  [Amended]

    2. The FAA amends Sec.  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,  -0001 through -1175.
 and AT-402B.
AT-502, AT-502A, AT-502B, and AT-  -0001 through -2597.
 503A.
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:

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

[[Page 71089]]

 
(iii) For all Models AT-400,  Initially within the  Follow Snow
 AT-400A, AT-402, AT-402A,     next 12 months        Engineering Co.
 AT-402B, AT-502, AT-502B,     after the effective   Service Letter
 and AT-503A airplanes.        date of this AD.      253 Rev.
                              Repetitively           B, dated November
                               thereafter at         30, 2007.
                               intervals not to
                               exceed 12 months.
------------------------------------------------------------------------

    (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: (210) 308-3365; fax: 
(210) 308-3370. 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: (940) 564-5616; fax: (940) 564-5612. 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.
 [FR Doc. E7-24215 Filed 12-13-07; 8:45 am]
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