[Federal Register Volume 69, Number 69 (Friday, April 9, 2004)]
[Proposed Rules]
[Pages 18848-18851]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-8056]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2004-CE-05-AD]
RIN 2120-AA64


Airworthiness Directives; Air Tractor, Inc. Models AT-401, AT-
401B, AT-402, AT-402A, AT-402B, AT-501, AT-502, AT-502A, AT-502B, AT-
503A, AT-602, AT-802, and AT-802A Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD) 
2002-19-10, which applies to certain Air Tractor, Inc. (Air Tractor) 
Models AT-402, AT-402A, AT-402B, AT-602, AT-802, and AT-802A airplanes. 
AD 2002-19-10 currently requires 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. This proposed AD is the result of reports 
of the same cracks recently found on AT-500 series airplanes. The 
manufacturer has also issued new and revised service information that 
incorporates a modification to terminate the repetitive inspection 
requirements. Consequently, this proposed AD would retain the 
inspection actions required in AD 2002-19-10, would add certain AT-500 
series airplanes to the applicability section, would change the 
compliance times, and would incorporate new and revised manufacturer 
service information that contains a terminating action for the 
repetitive inspection requirement. We are issuing this proposed AD to 
detect and correct cracks in the upper aft longeron, which could cause 
the fuselage to fail. Such failure could result in loss of control of 
the airplane.

DATES: We must receive any comments on this proposed AD by June 7, 
2004.

ADDRESSES: Use one of the following to submit comments on this proposed 
AD:
     By mail: FAA, Central Region, Office of the 
Regional Counsel, Attention: Rules Docket No. 2004-CE-05-AD, 901 
Locust, Room 506, Kansas City, Missouri 64106.
     By fax: (816) 329-3771.
     By e-mail: [email protected]. Comments sent 
electronically must contain ``Docket No. 2004-CE-05-AD'' in the subject 
line. If you send comments electronically as attached electronic files, 
the files must be formatted in Microsoft Word 97 for Windows or ASCII.
    You may get the service information identified in this proposed AD 
from Air Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374.
    You may view the AD docket at FAA, Central Region, Office of the 
Regional Counsel, Attention: Rules Docket No. 2004-CE-05-AD, 901 
Locust, Room 506, Kansas City, Missouri 64106. Office hours are 8 a.m. 
to 4 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Andrew D. McAnaul, Aerospace Engineer, 
FAA, Fort Worth Airplane Certification Office (ACO), 2601 Meacham 
Boulevard, Fort Worth, Texas 76193-0150. Current duty station: San 
Antonio Manufacturing Inspection District Office (MIDO), 10100 Reunion 
Place, Suite 650, San Antonio, Texas 78216; telephone: (210) 308-3365; 
facsimile: (210) 308-3370.

SUPPLEMENTARY INFORMATION:

Comments Invited

    How do I comment on this proposed AD? We invite you to submit any 
written relevant data, views, or arguments regarding this proposal. 
Send your comments to an address listed under ADDRESSES. Include ``AD 
Docket No. 2004-CE-05-AD'' in the subject line of your comments. If you 
want us to acknowledge receipt of your mailed comments, send us a self-
addressed, stamped postcard with the docket number written on it. We 
will date-stamp your postcard and mail it back to you.
    Are there any specific portions of this proposed AD I should pay 
attention to? We specifically invite comments on the overall 
regulatory, economic, environmental, and energy aspects of this 
proposed AD. If you contact us through a nonwritten communication and 
that contact relates to a substantive part of this proposed AD, we will 
summarize the contact and place the summary in the docket. We will 
consider all comments received by the closing date and may amend this 
proposed AD in light of those comments and contacts.

Discussion

    Has FAA taken any action to this point? We received reports 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. Additional cracking was later reported 
on AT-400, AT-602, and AT-802 series airplanes.
    Air Tractor started installing extended reinforcement gussets on 
AT-402 and AT-802 series airplanes at the factory to alleviate the 
crack condition from occurring. The extended reinforcement gussets were 
intended to transfer the loads away from the joint. However, an AT-802 
airplane with the extended reinforcement gusset installed during 
factory production was discovered cracked in service at the forward end 
of the gusset.
    These conditions caused us to issue AD 2002-19-10, Amendment 39-
12890 (67 FR 61481, October 1, 2002). AD 2002-19-10 currently requires 
you to do the following on certain Air Tractor Models AT-402, AT-402A, 
AT-402B, AT-602, AT-802, and AT-802A airplanes:

--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.

    What has happened since AD 2002-19-10 to initiate this proposed 
action? We have received additional reports of the same cracks found on 
an Air Tractor Model AT-502 and AT-502A airplane.
    The manufacturer has also issued new and revised service 
information. The new service information contains procedures for 
replacing and modifying the upper aft longeron as a terminating action 
for the repetitive inspection requirement.
    What is the potential impact if FAA took no action? This condition, 
if not detected and 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? Snow

[[Page 18849]]

Engineering Co. has issued the following Service Letters:

--Service Letter 195, reissued: November 10, 2003;
--Service Letter 195A, revised: November 10, 2003;
--Service Letter 195B, dated November 10, 2003;
--Service Letter 213A, dated November 10, 2003;
--Service Letter 213B, revised November 10, 2003;
--Service Letter 217A, dated November 10, 2003;
--Service Letter 217B, revised November 10, 2003;
--Service Letter 218A, dated November 10, 2003; and
--Service Letter 218B, revised November 10, 2003.

    What are the provisions of this service information? These service 
letters include procedures for:

--Service Letter 195 specifies inspecting the upper longeron 
in the aft fuselage structure on all the affected model airplanes;
--Service Letter 195B, Service Letter 213A, Service 
Letter 217A, and Service Letter 218A provides the 
inspection requirements for all affected model airplanes; and
--Service Letter 195A, Service Letter 213B, Service 
Letter 217B, and Service Letter 218B give the 
procedures for replacing and modifying the upper aft longeron if cracks 
are found for all affected model airplanes and is the terminating 
action for the repetitive inspection requirements.

FAA's Determination and Requirements of This Proposed AD

    What has FAA decided? We have evaluated all pertinent information 
and identified an unsafe condition that is likely to exist or develop 
on other products of this same type design. Therefore, we are proposing 
AD action.
    What would this proposed AD require? This proposed AD would 
supersede 2002-19-10 with a new AD that 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. If cracks are 
found, this proposed AD would also require you to replace and modify 
the upper aft longeron. Replacing and modifying the upper aft longeron 
would terminate the repetitive inspection requirement.
    How does the revision to 14 CFR part 39 affect this proposed AD? On 
July 10, 2002, we published a new version of 14 CFR part 39 (67 FR 
47997, July 22, 2002), which governs FAA's AD system. This regulation 
now includes material that relates to altered products, special flight 
permits, and alternative methods of compliance. This material 
previously was included in each individual AD. Since this material is 
included in 14 CFR part 39, we will not include it in future AD 
actions.

Costs of Compliance

    How many airplanes would this proposed AD impact? We estimate that 
this proposed AD affects 1,194 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 inspections:

----------------------------------------------------------------------------------------------------------------
                                                                   Total cost per
              Labor cost                        Parts cost            airplane      Total cost on U.S. operators
----------------------------------------------------------------------------------------------------------------
1 workhour x $65 per hour = $65.......  No parts required........             $65  $65 x 1,194 = $77,610.
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    We estimate the following costs to accomplish any necessary 
replacements that would be required based on the results of the 
proposed inspection(s). We have no way of determining the number of 
airplanes that may need this replacement:

------------------------------------------------------------------------
                                                       Total cost per
         Labor cost                Parts cost             airplane
------------------------------------------------------------------------
27 workhours x $65 per hour   For AT-400, AT-500,   For AT-400, AT-500,
 = $1,755.                     and AT-600 series     and AT-600 series
                               airplanes: $35.       airplanes: $1,755 +
                                                     $35 = $1,790.
                              For AT-800 series     For AT-800 series
                               airplanes: $45.       airplanes: $1,755 +
                                                     $45 = $1,800.
------------------------------------------------------------------------

    What is the difference between the cost impact of this proposed AD 
and the cost impact of AD 2002-19-10? The difference is the addition of 
certain Model AT-501, AT-502, AT-502A, AT-502B, and AT-503A airplanes 
to the applicability section of this proposed AD and the cost of 
replacing any cracked upper aft longeron. There is no difference in 
cost to perform the proposed inspection.

Regulatory Findings

    Would this proposed AD impact various entities? 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.
    Would this proposed AD involve a significant rule or regulatory 
action? For the reasons discussed above, I certify that this proposed 
AD:
    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 summary of the costs to comply with this proposed AD 
and placed it in the AD Docket. You may get a copy of this summary by 
sending a request to us at the address listed under ADDRESSES. Include 
``AD Docket No. 2004-CE-05-AD'' in your request.

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 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.

[[Page 18850]]

Sec.  39.13  [Amended]

    2. The FAA amends Sec.  39.13 by removing Airworthiness Directive 
(AD) 2002-19-10, Amendment 39-12890 (67 FR 61481, October 1, 2002), and 
by adding a new AD to read as follows:

Air Tractor, Inc.: Docket No. 2004-CE-05-AD.

When Is the Last Date I Can Submit Comments on This Proposed AD?

    (a) We must receive comments on this proposed airworthiness 
directive (AD) by June 7, 2004.

What Other ADs Are Affected by This Action?

    (b) This AD supersedes AD 2002-19-10.

What Airplanes Are Affected by This AD?

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

------------------------------------------------------------------------
                   Model                             Serial Nos.
------------------------------------------------------------------------
AT-401, AT-401B, AT-402, AT-402A, and AT-   0716 through 1144.
 402B.
AT-501, AT-502, AT-502A, AT-502B, and AT-   0037 through 0658.
 503A.
AT-602....................................  0337 through 0664.
AT-802 and AT-802A........................  0001 through 0139.
------------------------------------------------------------------------

What Is the Unsafe Condition Presented in This AD?

    (d) This AD is the result of reports of cracks in the aft 
fuselage upper longeron, originally detected as excessive movement 
in the empennage due to the loss of fuselage torsional rigidity. The 
actions specified in this AD are intended to detect and correct 
cracks in the upper aft longeron, which could cause the fuselage to 
fail. Such failure could result in loss of control of the airplane.

What Must I Do To Address This Problem?

    (e) To address this problem, you must 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 at 
the times specified below. You must also replace and modify any 
cracked upper and diagonal longerons found during any inspection 
required by this AD before further flight after the inspection in 
which cracks are found.

----------------------------------------------------------------------------------------------------------------
 Affected models and serial numbers        Inspection compliance times                   Procedures
----------------------------------------------------------------------------------------------------------------
(1) AT-401, AT-401B, AT-402, AT-      Initially inspect upon the            Inspect following Snow Engineering
 402A, and AT-402B: serial numbers     accumulation of 1,250 total hours     Co. Service Letter 218A,
 (S/Ns) 0716 through 1144.             time-in-service (TIS) or within the   dated November 10, 2003, as
                                       next 100 hours TIS after the          specified in Snow Engineer Co.
                                       effective date of this AD,            Service Letter 195,
                                       whichever occurs later.               reissued November 10, 2003.
                                      Repetitively inspect thereafter at    Replace and modify following Snow
                                       intervals not to exceed 100 hours     Engineering Co. Service Letter
                                       TIS until the upper and diagonal      218B, dated November 10,
                                       longerons are replaced and            2003.
                                       modified.
                                      Replacing and modifying the upper
                                       and diagonal longerons is the
                                       terminating action for the
                                       repetitive inspection requirement
                                       in this AD.
(2) AT-501, AT-502, AT-502B, and AT-  Initially inspect upon the            Inspect following Snow Engineering
 503A, S/Ns 0037 through 0658.         accumulation of 4,800 total hours     Co. Service Letter 218A,
                                       TIS or within the next 100 hours      dated November 10, 2003, as
                                       TIS after the effective date of       specified in Snow Engineer Co.
                                       this AD, whichever occurs later.      Service Letter 195,
                                      Repetitively inspect thereafter at     reissued November 10, 2003.
                                       intervals not to exceed 100 hours    Replace and modify following Snow
                                       TIS until the upper and diagonal      Engineering Co. Service Letter
                                       longerons are replaced and            195A, revised November 10,
                                       modified.                             2003.
                                      Replacing and modifying the upper
                                       and diagonal longerons is the
                                       terminating action for the
                                       repetitive inspection requirement
                                       in this AD.
(3) AT-502A, S/Ns 0037 through 0658.  Initially inspect upon the            Inspect following Snow Engineering
                                       accumulation of 2,800 total hours     Co. Service Letter 195B,
                                       TIS or within the next 100 hours      dated November 10, 2003, as
                                       TIS after the effective date of       specified in Snow Engineer Co.
                                       this AD, whichever occurs later.      Service Letter 195,
                                      Repetitively inspect thereafter at     reissued November 10, 2003.
                                       intervals not to exceed 100 hours    Replace and modify following Snow
                                       TIS until the upper and diagonal      Engineering Co. Service Letter
                                       longerons are replaced and            195A, revised November 10,
                                       modified.                             2003.
                                      Replacing and modifying the upper
                                       and diagonal longerons is the
                                       terminating action for the
                                       repetitive inspection requirement
                                       in this AD.
(4) AT-602, S/Ns 0337 through 0661.   Initially inspect upon the            Inspect following Snow Engineering
                                       accumulation of 700 total hours TIS   Co. Service Letter 213A,
                                       or within the next 100 hours TIS      dated November 10, 2003, as
                                       after the last inspection required    specified in Snow Engineer Co.
                                       by AD 2002-19-10, whichever occurs    Service Letter 195,
                                       later.                                reissued November 10, 2003.
                                      Repetitively inspect thereafter at    Replace and modify following Snow
                                       intervals not to exceed 100 hours     Engineering Co. Service Letter
                                       TIS until the upper and diagonal      218B, dated November 10,
                                       longerons are replaced and            2003.
                                       modified.
                                      Replacing and modifying the upper
                                       and diagonal longerons is the
                                       terminating action for the
                                       repetitive inspection requirement
                                       in this AD.

[[Page 18851]]

 
(5) AT-602, S/Ns 0662 through 0664.   Initially inspect upon the            Inspect following Snow Engineering
                                       accumulation of 1,750 total hours     Co. Service Letter 213A,
                                       TIS or within the next 100 hours      dated November 10, 2003, as
                                       TIS after the last inspection         specified in Snow Engineer Co.
                                       required by AD 2002-19-10,            Service Letter 195,
                                       whichever occurs later.               reissued November 10, 2003.
                                      Repetitively inspect thereafter at    Replace and modify following Snow
                                       intervals not to exceed 100 hours     Engineering Co. Service Letter
                                       TIS until the upper and diagonal      213B, revised November 10,
                                       longerons are replaced and            2003.
                                       modified.
                                      Replacing and modifying the upper
                                       and diagonal longerons is the
                                       terminating action for the
                                       repetitive inspection requirement
                                       in this AD.
(6) AT-802 and AT-802A, S/Ns 0001     Initially inspect upon the            Inspect following Snow Engineering
 through 0004 and 0012 through 0118.   accumulation of 250 total hours TIS   Co. Service Letter 217A,
                                       or within the next 100 hours TIS      dated November 10, 2003, as
                                       after the last inspection required    specified in Snow Engineer Co.
                                       by AD 2002-19-10, whichever occurs    Service Letter 195,
                                       later.                                reissued November 10, 2003.
                                      Repetitively inspect thereafter at    Replace and modify following Snow
                                       intervals not to exceed 100 hours     Engineering Co. Service Letter
                                       TIS until the upper and diagonal      217B, revised November 10,
                                       longerons are replaced and            2003.
                                       modified.
                                      Replacing and modifying the upper
                                       and diagonal longerons is the
                                       terminating action for the
                                       repetitive inspection requirement
                                       in this AD.
(7) AT-802 and AT-802A, S/Ns 0005     Initially inspect upon the            Inspect following Snow Engineering
 through 0011.                         accumulation of 900 total hours TIS   Co. Service Letter 217A,
                                       or within the next 100 hours TIS      dated November 10, 2003, as
                                       after the last inspection required    specified in Snow Engineer Co.
                                       by AD 2002-19-10, whichever occurs    Service Letter 195,
                                       later.                                reissued November 10, 2003.
                                      Repetitively inspect thereafter at    Replace and modify following Snow
                                       intervals not to exceed 100 hours     Engineering Co. Service Letter
                                       TIS until the upper and diagonal      217B, dated November 10,
                                       longerons are replaced and            2003.
                                       modified.
                                      Replacing and modifying the upper
                                       and diagonal longerons is the
                                       terminating action for the
                                       repetitive inspection requirement
                                       in this AD.
(8) AT-802 and AT-802A, S/Ns 0119     Initially inspect upon the            Inspect following Snow Engineering
 through 0139.                         accumulation of 1,750 total hours     Co. Service Letter 217A,
                                       TIS or within the next 100 hours      dated November 10, 2003, as
                                       TIS after the last inspection         specified in Snow Engineer Co.
                                       required by AD 2002-19-10,            Service Letter 195,
                                       whichever occurs later.               reissued November 10, 2003.
                                      Repetitively inspect thereafter at    Replace and modify following Snow
                                       intervals not to exceed 100 hours     Engineering Co. Service Letter
                                       TIS until the upper and diagonal      217B, revised November 10,
                                       longerons are replaced and            2003.
                                       modified.
                                      Replacing and modifying the upper
                                       and diagonal longerons is the
                                       terminating action for the
                                       repetitive inspection requirement
                                       in this AD.
----------------------------------------------------------------------------------------------------------------

    (f) You may replace and modify the upper and diagonal longeron 
at any time as a terminating action for the repetitive inspection 
requirement in this AD. However, you must replace and modify the 
upper and diagonal longeron before further flight after any 
inspection in which cracks are found.

May I Request an Alternative Method of Compliance?

    (g) You may request a different method of compliance or a 
different compliance time for this AD by following the procedures in 
14 CFR 39.19. Unless FAA authorizes otherwise, send your request to 
your principal inspector. The principal inspector may add comments 
and will send your request to the Manager, Fort Worth Aircraft 
Certification Office (ACO), FAA. For information on any already 
approved alternative methods of compliance, contact Andrew D. 
McAnaul, Aerospace Engineer, FAA, Fort Worth ACO, 2601 Meacham 
Boulevard, Fort Worth, Texas 76193-0150. Current duty station: San 
Antonio Manufacturing Inspection District Office (MIDO), 10100 
Reunion Place, Suite 650, San Antonio, Texas 78216; telephone: (210) 
308-3365; facsimile: (210) 308-3370.

May I Get Copies of the Documents Referenced in This AD?

    (h) 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 April 1, 2004.
David R. Showers,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-8056 Filed 4-8-04; 8:45 am]
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