[Federal Register Volume 68, Number 64 (Thursday, April 3, 2003)]
[Rules and Regulations]
[Pages 16198-16200]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-7747]



[[Page 16198]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-CE-59-AD; Amendment 39-13100; AD 2003-07-04]
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: Final rule.

-----------------------------------------------------------------------

SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
applies 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 AD requires you to repetitively 
inspect the vertical fin front spar fitting for cracks and replace any 
cracked fitting found. This AD also requires you to install a steel 
doubler as a terminating action for the repetitive inspections. This 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 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: This AD becomes effective on May 22, 2003.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in the regulations as of May 
22, 2003.

ADDRESSES: You may get the service information referenced in this AD 
from Air Tractor, Inc., PO Box 485, Olney, Texas 76374. You may view 
this information at the Federal Aviation Administration (FAA), Central 
Region, Office of the Regional Counsel, Attention: Rules Docket No. 
2000-CE-59-AD, 901 Locust, Room 506, Kansas City, Missouri 64106; or at 
the Office of the Federal Register, 800 North Capitol Street, NW., 
suite 700, Washington, DC.

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: 

Discussion

What Events have Caused This 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 Is the Potential Impact if FAA Took No Action?

    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.

Has FAA Taken Any Action to This Point?

    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 
certain 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 
proposal was published in the Federal Register as a notice of proposed 
rulemaking (NPRM) on December 27, 2002 (67 FR 79008). The NPRM proposed 
to require you to repetitively inspect the vertical fin front spar 
fitting for cracks and replace any cracked fitting found. The NPRM also 
proposed to require you to install a steel doubler as a terminating 
action for the repetitive inspections.

Was the Public Invited To Comment?

    The FAA encouraged interested persons to participate in the making 
of this amendment. The following presents the comment received on the 
proposal and FAA's response:

Comment Issue: Change the Serial Number Applicability for Certain 
Affected Airplane Models

What Is the Commenter's Concern?

    The commenter states that the serial number affectivity for Air 
Tractor Models AT-401 and AT-401B should include the notation that 
specifically designates serial numbers that have been converted to 
turbine powerplants as specified in Snow Engineering Co. Service Letter 
155, Revised November 27, 2002.

What Is FAA's Response to the Concern?

    We concur with the commenter and will change the final rule AD 
action to incorporate this change.

FAA's Determination

What Is FAA's Final Determination on This Issue?

    We carefully reviewed all available information related to the 
subject presented above and determined that air safety and the public 
interest require the adoption of the rule as proposed except for the 
changes discussed above and minor editorial corrections. We have 
determined that these changes and minor corrections:
--Provide the intent that was proposed in the NPRM for correcting the 
unsafe condition; and
--Do not add any additional burden upon the public than was already 
proposed in the NPRM.

How Does the Revision to 14 CFR Part 39 Affect This AD?

    On July 10, 2002, FAA 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 special flight 
permits, alternative methods of compliance, and altered products. 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.

[[Page 16199]]

Cost Impact

How Many Airplanes Does This AD Impact?

    We estimate that this AD affects 440 airplanes in the U.S. 
registry.

What Is the Cost Impact of This AD on Owners/Operators of the Affected 
Airplanes?

    We estimate the following costs to accomplish the inspection:

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

    We estimate the following costs to accomplish the modification:

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

Regulatory Impact

Does This AD Impact Various Entities?

    The regulations adopted herein will 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 final rule does not have federalism 
implications under Executive Order 13132.

Does This AD Involve a Significant Rule or Regulatory Action?

    For the reasons discussed above, I certify that this 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) 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 final evaluation prepared for this 
action is contained 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, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the Federal Aviation Administration amends part 39 of the Federal 
Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. FAA amends Sec.  39.13 by adding a new AD to read as follows:

2003-07-04 Air Tractor, Inc.: Amendment 39-13100; 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 Nos.
------------------------------------------------------------------------
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
                                          that have been converted to
                                          turbine powerplants.
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:

[[Page 16200]]



------------------------------------------------------------------------
           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 or spar         27, 2002.
                               fitting next 100
                               hours TIS after May
                               22, 2003 (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 May 22, 2003    Co. Service Letter
                               (the effective date   155,
                               of this AD).          Revised November
                               Installing the        27, 2002.
                               steel doubler is
                               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.
------------------------------------------------------------------------

    (e) Can I comply with this AD in any other way? To use an 
alternative method of compliance or adjust the compliance time, use 
the procedures in 14 CFR 39.19. Send these requests to the Manager, 
Ft. Worth Aircraft Certification Office (ACO). For information on 
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.
    (f) Are any service bulletins incorporated into this AD by 
reference? Actions required by this AD must be done in accordance 
with Snow Engineering Co. Service Letter 155, Revised 
November 27, 2002. The Director of the Federal Register approved 
this incorporation by reference under 5 U.S.C. 552(a) and 1 CFR part 
51. You may get copies from Air Tractor, Inc., P.O. Box 485, Olney, 
Texas 76374. You may view copies at the FAA, Central Region, Office 
of the Regional Counsel, 901 Locust, Room 506, Kansas City, 
Missouri, or at the Office of the Federal Register, 800 North 
Capitol Street, NW., suite 700, Washington, DC.
    (g) When does this amendment become effective? This amendment 
becomes effective on May 22, 2003.

    Issued in Kansas City, Missouri, on March 25, 2003.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 03-7747 Filed 4-2-03; 8:45 am]
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