[Federal Register Volume 72, Number 24 (Tuesday, February 6, 2007)]
[Proposed Rules]
[Pages 5359-5362]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-1874]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-26775; Directorate Identifier 2007-CE-01-AD]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain Air Tractor, Inc. (Air Tractor) Model AT-602 airplanes. This 
proposed AD would require you to install access holes to do repetitive 
detailed visual inspections for cracks in the horizontal stabilizer 
brace tube assembly, and if any cracks are found as a result of a 
visual inspection, to replace the horizontal stabilizer brace tube 
assembly with a new design horizontal stabilizer brace tube assembly. 
The installation of the new design horizontal stabilizer brace tube 
assembly is terminating action for the repetitive inspection 
requirement. This proposed

[[Page 5360]]

AD results from two reports of Model AT-602 airplanes with cracked 
horizontal stabilizer brace tube assemblies. We are proposing this AD 
to detect and correct cracks in the horizontal stabilizer brace tube 
assembly, which could result in failure of the horizontal stabilizer. 
This failure could affect the ability to control pitch with consequent 
loss of control.

DATES: We must receive comments on this proposed AD by April 9, 2007.

ADDRESSES: Use one of the following addresses to comment 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 20590-0001.
     Fax: (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.
     Federal eRulemaking Portal: http://www.regulations.gov. 
Follow the instructions for submitting comments.
    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: Andrew McAnaul, Aerospace Engineer, 
ASW-150 (c/o MIDO-43), 10100 Reunion Place, Suite 650, 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-
2006-26775; Directorate Identifier 2007-CE-01-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://dms.dot.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

    We have received two reports of Model AT-602 airplanes with cracked 
horizontal stabilizer brace tube assemblies. One tube was cracked 
completely in two. The horizontal stabilizer brace tube assemblies 
failed as a result of fatigue. Air Tractor has also identified 
excessive corrosion as a potential contributing factor.
    This condition, if not corrected, could result in failure of the 
horizontal stabilizer. This failure could affect the ability to control 
pitch with consequent loss of control.
    Air Tractor has developed an improved design horizontal stabilizer 
brace tube assembly with a larger shank.

Relevant Service Information

    We have reviewed Snow Engineering Co. Service Letter 129A, 
dated August 7, 2004, revised November 15, 2005; Service Letter 
235, dated August 25, 2004, revised October 23, 2006; and 
Drill Template--602, Drawing Number SL129-602, dated August 2, 2004.
    The service information describes procedures for:
     Installing access holes for visual inspection of the 
horizontal stabilizer brace tube assembly (part number (P/N) 30012-7);
     Conducting a detailed visual inspection for cracks in the 
horizontal stabilizer brace tube assembly (P/N 30012-7); and
     Replacing the horizontal stabilizer brace tube assembly 
(P/N 30012-7) with a new design horizontal stabilizer brace tube 
assembly (P/N 30766-1).

FAA's Determination and Requirements of the Proposed AD

    We are proposing this AD because we evaluated all information and 
determined the unsafe condition described previously is likely to exist 
or develop on other products of the same type design. This proposed AD 
would require you to:
     Install access holes to do visual inspections;
     Do repetitive detailed visual inspections for cracks in 
the horizontal stabilizer brace tube assembly; and
     If any cracks are found as a result of a visual 
inspection, replace the horizontal stabilizer brace tube assembly with 
a new design horizontal stabilizer brace tube assembly.
    The installation of the new design horizontal stabilizer brace tube 
assembly is terminating action for the repetitive inspection 
requirement.

Costs of Compliance

    We estimate that this proposed AD would affect 128 airplanes in the 
U.S. registry.
    We estimate the following costs to do the proposed installation of 
access holes to do visual inspections:

----------------------------------------------------------------------------------------------------------------
                                                                                  Total cost per   Total cost on
                           Labor cost                               Parts cost       airplane     U.S. operators
----------------------------------------------------------------------------------------------------------------
 1 work-hour x $80 per hour = $80...............................              $5             $85         $10,880
----------------------------------------------------------------------------------------------------------------

    We estimate the following costs to do each visual inspection for 
cracks of the horizontal stabilizer brace tube assembly:

----------------------------------------------------------------------------------------------------------------
                                                                                                   Total cost on
                                                                                  Total cost per  U.S. operators
                  Labor cost                               Parts cost                airplane       for initial
                                                                                                    inspection
----------------------------------------------------------------------------------------------------------------
1 work-hour x $80 per hour = $80..............  Not Applicable..................             $80         $10,240
----------------------------------------------------------------------------------------------------------------

    We estimate the following costs to do any necessary replacement of 
the horizontal stabilizer brace tube assembly with a new design 
horizontal stabilizer brace tube assembly that would be required based 
on the results

[[Page 5361]]

of the proposed inspection or as the terminating action for the 
repetitive inspection requirement. We have no way of determining the 
number of airplanes that may need this replacement:

------------------------------------------------------------------------
                                                         Total cost  per
               Labor cost                  Parts cost        airplane
------------------------------------------------------------------------
35 work-hours x $80 per hour = $2,800..            $896           $3,696
------------------------------------------------------------------------

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 (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 adding the following new AD:

Air Tractor Inc.: Docket No. FAA-2006-26775; Directorate Identifier 
2007-CE-01-AD.

Comments Due Date

    (a) We must receive comments on this airworthiness directive 
(AD) action by April 9, 2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Model AT-602 airplanes, all serial 
numbers through 602-0695 that:
    (1) have horizontal stabilizer brace tube assembly, part number 
(P/N) 30012-7, installed; and
    (2) are certificated in any category.

Unsafe Condition

    (d) This AD results from two reports of Model AT-602 airplanes 
with cracked horizontal stabilizer brace tube assemblies. We are 
issuing this AD to detect and correct cracks in the horizontal 
stabilizer brace tube assembly, which could result in failure of the 
horizontal stabilizer. This failure could affect the ability to 
control pitch with consequent loss of control.

Compliance

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

[[Page 5362]]



------------------------------------------------------------------------
            Actions                   Compliance           Procedures
------------------------------------------------------------------------
(1) Do the following:           Install the access      Follow Snow
(i) Install access holes for     holes and do the        Engineering Co.
 visual inspection of the part   initial inspection      Service Letter
 number (P/N) 30012-7            upon accumulating       235,
 horizontal stabilizer brace     2,000 hours time-in-    dated August
 tube assembly.                  service (TIS) or        25, 2004,
(ii) Conduct a detailed visual   within the next 60      revised October
 inspection for cracks in the    days after the          23, 2006.
 P/N 30012-7 horizontal          effective date of
 stabilizer brace tube           this AD, whichever
 assembly.                       occurs later.
                                 Repetitively inspect
                                 thereafter at
                                 intervals not to
                                 exceed 100 hours TIS.
                                 Replacement of the P/
                                 N 30012-7 horizontal
                                 stabilizer brace tube
                                 assembly with a new
                                 design P/N 30766-1
                                 horizontal stabilizer
                                 brace tube assembly
                                 following paragraph
                                 (e)(2) of this AD is
                                 terminating action
                                 for the repetitive
                                 inspection
                                 requirement of this
                                 AD.
(2) Replace the P/N 30012-7     Before further flight   Follow Snow
 horizontal stabilizer brace     after any inspection    Engineering Co.
 tube assembly with a new        required by paragraph   Service Letter
 design P/N 30766-1 horizontal   (e)(1) of this AD       129A,
 stabilizer brace tube           where cracks are        dated August 7,
 assembly.                       found. The              2004, revised
                                 installation of a new   November 15,
                                 design P/N 30766-1      2005; Snow
                                 horizontal stabilizer   Engineering Co.
                                 brace tube assembly     Service Letter
                                 is terminating action   235,
                                 for the repetitive      dated August
                                 inspection              25, 2004,
                                 requirement of this     revised October
                                 AD.                     23, 2006; and
                                                         Snow
                                                         Engineering Co.
                                                         Drill Template--
                                                         602, Drawing
                                                         Number SL129-
                                                         602, dated
                                                         August 2, 2004.
(3) Do not install any P/N      As of the effective     Not Applicable.
 30012-7 horizontal stabilizer   date of this AD.
 brace tube assembly.
------------------------------------------------------------------------

Alternative Methods of Compliance (AMOCs)

    (f) The Manager, Fort Worth Airplane Certification Office, FAA, 
ATTN: Andrew McAnaul, Aerospace Engineer, ASW-150 (c/o MIDO-43), 
10100 Reunion Place, Suite 650, San Antonio, Texas 78216; telephone: 
(210) 308-3365; fax: (210) 308-3370, has the authority to approve 
AMOCs for this AD, if requested using the procedures found in 14 CFR 
39.19.

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 the Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-
401, Washington, DC, or on the Internet at http://dms.dot.gov. The 
docket number is Docket No. FAA-2006-26775; Directorate Identifier 
2007-CE-01-AD.

    Issued in Kansas City, Missouri, on January 31, 2007.
Margaret Kline,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-1874 Filed 2-5-07; 8:45 am]
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