[Federal Register Volume 67, Number 249 (Friday, December 27, 2002)]
[Proposed Rules]
[Pages 79008-79011]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-32685]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-CE-59-AD]
RIN 2120-AA64


Airworthiness Directives; Air Tractor, Inc. Models AT-300, AT-
400, AT-400A, AT-401, AT-401B, AT-402, AT-402A, AT-402B, AT-501, AT-
502, and AT-502B Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to adopt a new airworthiness directive 
(AD) that would apply to certain Air Tractor, Inc. (Air Tractor) Models 
AT-300, AT-400, AT-400A, AT-401, AT-401B, AT-402, AT-402A, AT-402B, AT-
501, AT-502, and AT-502B airplanes. This proposed AD would require you 
to repetitively inspect the vertical fin front spar fitting for cracks 
and replace any cracked fitting found. This proposed AD would also 
require you to install a steel doubler as a terminating action for the 
repetitive inspections. This proposed AD is the result of a report of 
failure of a 1/4-inch thick vertical fin front spar fitting. The 
actions specified by this proposed AD are intended to prevent failure 
of the vertical fin front spar fitting, which could result in failure 
of the rear spar fitting. Such failures could lead to loss of 
directional control of the airplane.

DATES: The Federal Aviation Administration (FAA) must receive any 
comments on this proposed rule on or before February 28, 2003.

ADDRESSES: Submit comments to FAA, Central Region, Office of the 
Regional Counsel, Attention: Rules Docket No. 2000-CE-59-AD, 901 
Locust, Room 506, Kansas City, Missouri 64106. You may view any 
comments at this location

[[Page 79009]]

between 8 a.m. and 4 p.m., Monday through Friday, except Federal 
holidays. You may also send comments electronically to the following 
address: [email protected]. Comments sent electronically must 
contain ``Docket No. 2000-CE-59-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 text.
    You may get service information that applies to this proposed AD 
from Air Tractor, Inc., 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: Andy McAnaul, Aerospace Engineer, FAA, 
Fort Worth Airplane Certification Office, 2601 Meacham Boulevard, Fort 
Worth, Texas 76193-0150; telephone: (817) 222-5156; facsimile: (817) 
222-5960.

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 mailed comments, 
you must include a self-addressed, stamped postcard. On the postcard, 
write ``Comments to Docket No. 2000-CE-59-AD.'' We will date stamp and 
mail the postcard back to you.

Discussion

What Events Have Caused This Proposed AD?

    The FAA received reports of two incidents, one in 1994 and one in 
1995, in which the vertical fin front spar fitting and rear spar 
fitting failed, while in flight, on an Air Tractor Model AT-402 and a 
Model AT-502 airplane. Failure of the vertical fin front spar fitting 
causes the rear spar fitting to fail. These failures result in the 
vertical tail lying over against the elevator creating difficulty in 
controlling the airplane.
    These vertical fin front spar fittings were made of \3/16\-inch 
thick aluminum. Investigation revealed that Air Tractor models with the 
\3/16\-inch front spar attach plates installed were subject to fatigue 
failure.
    This unsafe condition was addressed in AD 95-20-06, Amendment 39-
9384. AD 95-20-06 applied to airplanes with \3/16\-inch thick and \1/
4\-inch thick aluminum fin front spar fittings installed.
    In 1997, we issued AD 97-14-05, Amendment 39-10063, that supersedes 
AD 95-20-06. Further investigation revealed that only Air Tractor 
models with a \3/16\-inch thick fin front spar fitting installed were 
developing cracks. Therefore, we issued AD 97-14-05 to remove Air 
Tractor models with a \1/4\-inch thick fin front spar fitting installed 
from the applicability.
    Recently, a Model AT-502 airplane was found with a cracked \1/4\-
inch thick fin front spar fitting. The crack was found during a routine 
inspection. The rear spar had not yet failed. This recent finding 
demonstrates that Air Tractor models with a \1/4\-inch thick fin front 
spar fitting are subject to fatigue failure.

What Are the Consequences if the Condition Is Not Corrected?

    This condition, if not detected and corrected, could result in 
structural failure of the vertical fin front spar fitting and 
eventually the rear spar fitting. Such failure could result in loss of 
directional control of the airplane.

Is There Service Information That Applies to This Subject?

    Snow Engineering Company has issued Service Letter  155, 
Revised November 27, 2002.

What Are the Provisions of This Service Information?

    The service letter includes procedures for:

--Repetitively inspecting the vertical fin front spar fitting cracks;
--Replacing any cracked fitting found; and
--Installing a steel doubler as a terminating action for the repetitive 
inspections.

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 Models AT-300, AT-400, AT-400A, AT-401, 
AT-401B, AT-402, AT-402A, AT-402B, AT-501, AT-502, and AT-502B 
airplanes of the same type design;
--The actions specified in the previously-referenced service 
information should be accomplished on the affected airplanes; and
--AD action should be taken in order to correct this unsafe condition.

What Would This Proposed AD Require?

    This proposed AD would require you to incorporate the actions in 
the previously-referenced service bulletin.

Cost Impact

How Many Airplanes Would This Proposed AD Impact?

    We estimate that this proposed AD affects 440 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:

----------------------------------------------------------------------------------------------------------------
                                                                      Total cost per      Total cost on U.S.
               Labor cost                         Parts cost             airplane              operators
----------------------------------------------------------------------------------------------------------------
4 workhours x $60 = $240................  No parts required.........            $240  $240 x 440 = $105,600.
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[[Page 79010]]

    We estimate the following costs to accomplish the proposed 
modification:

------------------------------------------------------------------------
                                                            Total cost
           Labor cost                   Parts cost         per airplane
------------------------------------------------------------------------
7 workhours x $60 = $420.......  Parts will be provided             $420
                                  by Air Tractor at no
                                  charge to the customer.
------------------------------------------------------------------------

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.


Sec.  39.13  [Amended]

    2. FAA amends Sec.  39.13 by adding a new airworthiness directive 
(AD) to read as follows:

Air Tractor, Inc.: Docket No. 2000-CE-59-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 numbers
------------------------------------------------------------------------
AT-300, AT-400, and AT-400A.......  All serial numbers with a turbine
                                     powerplant and is retrofitted with
                                     a 1/4-inch thick aluminum vertical
                                     fin front spar fitting and an all-
                                     metal rudder.
AT-401 and AT-401B................  401-0737 through 401-1015 and 401B-
                                     0737 through 401B-1015.
AT-402, AT-402A, and AT-402B......  402-0737 through 402B-1015.
AT-501............................  501-0031 and subsequent that have
                                     been converted to turbine
                                     powerplants.
AT-502 and AT-502B................  502-0031 through 502B-0398.
------------------------------------------------------------------------

    (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 vertical fin front 
spar fittings, which could result in failure of the rear spar 
fitting. Such failures could lead to loss of directional 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 vertical fin  Upon the              In accordance with
 front spar fitting for        accumulation of       Snow Engineering
 cracks.                       2,000 hours time-in-  Co. Service Letter
                               service (TIS) on      155,
                               the vertical fin      Revised November
                               front spar fitting    27, 2002.
                               or within the next
                               100 hours TIS after
                               the effective date
                               of this AD,
                               whichever occurs
                               later. If no cracks
                               are found,
                               repetitively
                               inspect thereafter
                               at intervals not to
                               exceed 100 hours
                               TIS.
(2) If cracks are found       Prior to further      In accordance with
 during any inspection         flight after the      Snow Engineering
 required in paragraph         crack is found.       Co. Service Letter
 (d)(1) of this AD, replace    Continue with the     155,
 the vertical fin front spar   repetitive            Revised November
 fitting.                      inspection            27, 2002.
                               requirements in
                               paragraph (d)(1) of
                               this AD until the
                               terminating action
                               is accomplished.
(3) Modify the vertical fin   Within the next       In accordance with
 front spar fitting by         2,000 hours TIS       Snow Engineering
 installing a steel doubler.   after the effective   Co. Service Letter
                               date of this AD.      155,
                               Installing the        Revised November
                               steel doubler is      27, 2002.
                               considered
                               terminating action
                               for the repetitive
                               inspection
                               requirements of
                               this AD. The
                               installation may be
                               accomplished at any
                               time provided the
                               vertical fin front
                               spar fitting is
                               crack free.
------------------------------------------------------------------------


[[Page 79011]]

    (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, Ft. 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, Ft. 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 Andy McAnaul, Aerospace 
Engineer, FAA, Fort Worth Airplane Certification Office, 2601 
Meacham Boulevard, Fort Worth, Texas 76193-0150; telephone: (817) 
222-5156; facsimile: (817) 222-5960.
    (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, Inc., 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 December 20, 2002.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 02-32685 Filed 12-26-02; 8:45 am]
BILLING CODE 4910-13-P