Document ID: FAA-2008-0476-0001
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; Air Tractor, Inc. Models AT-300, AT- 301, AT-302, AT-400, and AT-400A Airplanes
Posted Date: 2008-04-28T04:00Z

[Federal Register: April 28, 2008 (Volume 73, Number 82)]
[Rules and Regulations]               
[Page 22795-22800]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr28ap08-7]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0476; Directorate Identifier 2008-CE-018-AD; 
Amendment 39-15491; AD 2008-09-10]
RIN 2120-AA64

 
Airworthiness Directives; Air Tractor, Inc. Models AT-300, AT-
301, AT-302, AT-400, and AT-400A Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) to 
supersede AD 2003-06-01, which applies to all Air Tractor, Inc. (Air 
Tractor) Models AT-300, AT-301, AT-302, and AT-400A airplanes that have 
aluminum spar caps; certain Air Tractor Models AT-400 airplanes that 
have aluminum spar caps; and all Models AT-300 and AT-301 airplanes 
that have aluminum spar caps and are or have been converted to turbine 
power. AD 2003-06-01 requires replacing the wing spar lower caps at a 
specified safe life limit; allows extending the safe life limit on 
certain airplanes if a wing lower spar cap splice rework is done; 
allows a limited time of continued operation beyond the safe life limit 
provided parts are ordered, the replacement is scheduled, and 
repetitive inspections reveal no cracks; and requires a report of any 
cracks found during any inspection to the FAA. This AD results from a 
recent report of cracks found on a Model AT-301 airplane at hours below 
the modification time specified in AD 2003-06-01. Consequently, this AD 
retains the wing spar lower cap replacement and reporting requirements 
from AD 2003-06-01 and adds a repetitive eddy-current inspection. We 
are issuing this AD to detect and correct cracks in the wing centerline 
splice joint. If not detected and corrected, these cracks could result 
in the wing separating from the airplane during flight.

DATES: This AD becomes effective on May 8, 2008.
    On May 8, 2008, the Director of the Federal Register approved the 
incorporation by reference of Snow Engineering Co. Service Letter 
55, revised October 4, 2004, listed in this AD.
    As of April 4, 2003, (68 FR 13221, March 19, 2003), the Director of 
the Federal Register approved the incorporation by reference of Snow 
Engineering Co. Service Letter 55, revised October 23, 2002, 
and Snow Engineering Co. Process Specification Number 197, revised June 
4, 2002, listed in this AD.
    We must receive any comments on this AD by June 27, 2008.

ADDRESSES: Use one of the following addresses to comment on this 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.
    To get the service information identified in this AD, contact Air 
Tractor, Inc., P.O. Box 485, Olney, Texas 76374; telephone: (940) 564-
5616; facsimile: (940) 564-5612.
    To view the comments to this AD, go to http://www.regulations.gov. 
The docket number is FAA-2008-0476; Directorate Identifier 2008-CE-018-
AD.

FOR FURTHER INFORMATION CONTACT: Rob Romero, Aerospace Engineer, FAA, 
Fort Worth Airplane Certification Office (ACO), 2601 Meacham Boulevard, 
Fort Worth, Texas 76193-0150; telephone: (817) 222-5102; facsimile: 
(817) 222-5960; or Andrew McAnaul, Aerospace Engineer, FAA, Fort Worth 
ACO (c/o MIDO-43), 10100 Reunion Place, Suite 650, San Antonio, Texas 
78216; telephone: (210) 308-3365; facsimile: (210) 308-3370.

SUPPLEMENTARY INFORMATION: 

Discussion

    An incident on an Air Tractor Model AT-400A where the wing 
separated from the airplane caused us to issue AD 2002-13-02, Amendment 
39-12789 (67 FR 44024, July 1, 2002). Investigation revealed that the 
right-hand lower spar cap failed due to fatigue at the \3/8\-inch 
outboard bolt, which is located 6.5 inches outboard of the fuselage 
centerline.

[[Page 22796]]

    The airplanes affected by AD 2002-13-02 have a similar type design 
to that of the accident airplane. AD 2002-13-02 required inspecting 
(one-time) the wing centerline splice joint for cracks and, if any 
crack was found, replacing the affected wing spar lower cap; reporting 
the results of the inspection to the FAA; and replacing the wing spar 
lower caps after a certain amount of usage.
    The inspection reports submitted to the FAA (as required in AD 
2002-13-02) revealed a Model AT-400A airplane with a cracked spar cap. 
The damage was significant enough to require spar cap replacement. 
Based on this damage and the results of the inspection reports, we 
determined that the mandatory replacement time for the wing spar lower 
cap on the affected turbine engine powered airplanes should be reduced.
    This prompted us to issue AD 2003-06-01, Amendment 39-13088 (68 FR 
13221, March 19, 2003) to supersede AD 2002-13-02. AD 2003-06-01 
requires replacing the wing spar lower caps at a specified safe life 
limit; allows extending the safe life limit on certain airplanes if a 
wing lower spar cap splice rework is done; allows a limited time of 
continued operation beyond the safe life limit provided parts are 
ordered, the replacement is scheduled, and repetitive inspections 
reveal no cracks; and requires a report of any cracks found during any 
inspection to the FAA.
    The FAA recently received a report of cracks found on a Model AT-
301 airplane with less hours than the modification time specified in AD 
2003-06-01. Based on this incident, we reevaluated the fatigue 
management plan for the AT-300 and AT-400 series airplanes that have 
aluminum spar caps without part number 20990-1/-2 steel web plate 
installed. We have determined that repetitive eddy-current inspections 
are needed on these airplanes in order to detect any cracks that may 
develop on the wing spar lower cap before reaching the safe life limit.
    This condition, if not corrected, could result in the wing 
separating from the airplane during flight.

Relevant Service Information

    The manufacturer has issued the following service information to 
address this situation:
     Snow Engineering Co. Service Letter 55, revised 
October 23, 2002, which includes procedures and information for doing 
the wing lower spar cap splice joint modification rework on all AT-300 
and AT-301 series airplanes;
     Snow Engineering Co. Service Letter 55, revised 
October 4, 2004, which includes revised procedures and information for 
doing the wing lower spar cap splice joint modification rework on all 
AT-300 and AT-301 series airplanes; and
     Snow Engineering Co. Process Specification Number 197, 
revised June 4, 2002, which provides procedures for accomplishing eddy 
current inspections of the wing lower spar caps.

FAA's Determination and Requirements of This AD

    We are issuing this AD because we evaluated all the information and 
determined the unsafe condition described previously is likely to exist 
or develop on other products of the same type design. This AD 
supersedes AD 2003-06-01 with a new AD that:
     Requires repetitive eddy-current inspections;
     Requires you to replace the wing spar lower caps at 
specified times;
     Allows you to extend the time for replacement on certain 
airplanes if a wing lower spar cap splice rework is done;
     Requires you to inspect the wing lower spar cap 
immediately prior to modification; and
     Requires you to report any cracks found during the 
inspections to the FAA.
    We are not retaining from AD 2003-06-01 the provision to allow a 
limited time of continued operation beyond the safe life limit.
    In preparing this rule, we contacted type clubs and aircraft 
operators to get technical information and information on operational 
and economic impacts. We did not receive any information through these 
contacts. If received, we would have included a discussion of any 
information that may have influenced this action in the rulemaking 
docket.

FAA's Determination of the Effective Date

    Since an unsafe condition exists that requires the immediate 
adoption of this AD, we determined that notice and opportunity for 
public comment before issuing this AD are impracticable, and that good 
cause exists for making this amendment effective in fewer than 30 days.

Comments Invited

    This AD is a final rule that involves requirements affecting flight 
safety, and we did not precede it by notice and an opportunity for 
public comment. We invite you to send any written relevant data, views, 
or arguments regarding this AD. Send your comments to an address listed 
under the ADDRESSES section. Include the docket number ``FAA-2008-0476; 
Directorate Identifier 2008-CE-018-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the AD. We will consider 
all comments received by the closing date and may amend the 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 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.
    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 determined that this AD will not have federalism implications 
under Executive Order 13132. This AD 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.
    For the reasons discussed above, I certify that this AD:
    (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.

[[Page 22797]]

    We prepared a regulatory evaluation of the estimated costs to 
comply with this AD and placed it in the AD docket.

Examining the AD Docket

    You may examine the AD docket that contains the AD, the regulatory 
evaluation, any comments received, and other information on the 
Internet at http://www.regulations.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) 647-5527) 
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, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 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. The FAA amends Sec.  39.13 by removing Airworthiness Directive (AD) 
2003-06-01, Amendment 39-13088 (68 FR 13221, March 19, 2003), and by 
adding a new AD to read as follows:

2008-09-10 Air Tractor, Inc.: Amendment 39-15491; Docket No. FAA-
2008-0476; Directorate Identifier 2008-CE-018-AD.

Effective Date

    (a) This AD becomes effective on May 8, 2008.

Affected ADs

    (b) This AD supersedes AD 2003-06-01, Amendment 39-13088.

Applicability

    (c) This AD applies to the following airplanes that are 
certificated in any category:
    (1) Models AT-300, AT-301, AT-302, and AT-400A airplanes, all 
serial numbers, that have aluminum spar caps;
    (2) Models AT-400 airplanes, serial numbers 400-0244 through 
400-0415, that have aluminum spar caps; and
    (3) Models AT-300 and AT-301 airplanes, all serial numbers that 
have aluminum spar caps and are or have been converted to turbine 
power.

Unsafe Condition

    (d) This AD is the result of service reports and analysis done 
on wing lower spar caps of Air Tractor, Inc. airplanes. The actions 
specified by this AD are intended to prevent fatigue cracks from 
occurring in the wing lower spar cap before the established safe 
life is reached. Fatigue cracks in the wing lower spar cap, if not 
detected and corrected, could result in failure of the spar cap and 
lead to wing separation and loss of control.

Compliance

    (e) To address this problem, you must do the following, unless 
already done:
    (1) For all affected airplanes without steel web plates, part 
numbers (P/N) 20990-1 or 20990-2, or steel spar caps installed, 
eddy-current inspect the left and right wing spar lower cap outboard 
holes for cracks following Snow Engineering Co. Process 
Specification 197, revised June 4, 2002. Do the inspections 
at the following compliance times:

------------------------------------------------------------------------
                               Initial compliance        Repetitive
     Affected airplanes               time             compliance time
------------------------------------------------------------------------
(i) For all airplanes.......  Initially inspect     Repetitively inspect
                               upon reaching 3,500   thereafter at
                               total hours time-in-  intervals not to
                               service (TIS) on      exceed 450 hours
                               the wing spar lower   TIS until the wing
                               cap or within the     spar center splice
                               next 10 hours TIS     joint modification
                               after May 8, 2008     or the required
                               (the effective date   wing spar lower cap
                               of this AD),          replacement. After
                               whichever occurs      each replacement,
                               later.                initially inspect
                                                     upon reaching 3,500
                                                     total hours TIS on
                                                     either wing spar
                                                     lower cap, and
                                                     repetitively
                                                     inspect thereafter
                                                     at intervals not to
                                                     exceed 450 hours
                                                     TIS until the wing
                                                     spar center splice
                                                     joint modification
                                                     or the required
                                                     wing spar lower cap
                                                     replacement.
(ii) Airplanes that have had  You may take credit   Repetitively inspect
 an eddy-current inspection    for that              thereafter at
 done on the wing spar lower   inspection.           intervals not-to-
 cap within the last 450       Continue with the     exceed 450 hours
 hours TIS before the          required repetitive   TIS from the time
 effective date of this AD.    inspection            of the last
                               intervals.            inspection until
                                                     the wing spar
                                                     center splice joint
                                                     modification or the
                                                     required wing spar
                                                     lower cap
                                                     replacement. After
                                                     each replacement,
                                                     initially inspect
                                                     upon reaching 3,500
                                                     total hours TIS on
                                                     either wing spar
                                                     lower cap, and
                                                     repetitively
                                                     inspect thereafter
                                                     at intervals not to
                                                     exceed 450 hours
                                                     TIS until the wing
                                                     spar center splice
                                                     joint modification
                                                     or the required
                                                     wing spar lower cap
                                                     replacement.
------------------------------------------------------------------------

    (2) For all affected Models AT-300 and AT-301 airplanes with 
reciprocating engines, the 450-hour repetitive inspections required 
in this AD are terminated after the wing spar center splice joint 
modification is incorporated in accordance with paragraph (g) of 
this AD or when the wing lower spar caps are replaced. The 
replacement specified in paragraph (f)(2) of this AD is still 
applicable.
    (3) If cracks are found during any inspection required in 
paragraphs (e)(1)(i), (e)(1)(ii), or (g)(2) of this AD, replace the 
wing lower spar cap before further flight.
    (f) Replace each wing lower spar cap in accordance with the 
applicable maintenance manual, as follows:

[[Page 22798]]

------------------------------------------------------------------------
                                                         Repetitive
                               Initial replacement      replacement/
     Affected airplanes          compliance time         inspection
                                                       compliance time
------------------------------------------------------------------------
(1) For all affected Models   Upon reaching 5,000   Replace each time
 AT-300 and AT-301 airplanes   total hours TIS on    the safe life limit
 with reciprocating engines    either wing spar      of 5,000 total
 and that do not incorporate   lower cap or within   hours TIS on either
 the wing spar center splice   the next 25 hours     wing spar lower cap
 joint modification.           TIS after April 4,    is reached. After
                               2003 (the effective   each replacement,
                               date of AD 2003-06-   inspect as
                               01), whichever        specified in
                               occurs later.         paragraph (e)(1) of
                                                     this AD until the
                                                     wing spar center
                                                     splice joint
                                                     modification or the
                                                     required wing spar
                                                     lower cap
                                                     replacement.
(2) For all affected Models   Upon reaching the     Replace each time
 AT-300 and AT-301 airplanes   safe life limit of    the safe life limit
 with reciprocating engines    7,000 total hours     of 7,000 total
 that do incorporate the       TIS on either wing    hours TIS on either
 wing spar center splice       spar lower cap or     wing spar lower cap
 joint modification done in    within the next 25    is reached. After
 accordance paragraph (g) of   hours TIS after       each replacement,
 this AD.                      April 4, 2003 (the    inspect as
                               effective date of     specified in
                               AD 2003-06-01),       paragraph (e)(1) of
                               whichever occurs      this AD until the
                               later.                wing spar center
                                                     splice joint
                                                     modification or the
                                                     required wing spar
                                                     lower cap
                                                     replacement.
(3) For all affected AT-302,  Upon reaching 4,450   Replace each time
 AT-400, and AT-400A           total hours TIS on    the safe life limit
 airplanes with aluminum       either wing spar      of 4,450 total
 spar caps; and all affected   lower cap or within   hours TIS on the
 Models AT-300 and AT-301      the next 25 hours     wing spar lower cap
 airplanes with aluminum       TIS after April 4,    is reached. After
 spar caps that are or have    2003 (the effective   each replacement
 ever been converted to        date of AD 2003-06-   inspect as
 turbine power.                01), whichever        specified in
                               occurs later.         paragraph (e)(1) of
                                                     this AD until the
                                                     required wing spar
                                                     lower cap
                                                     replacement.
------------------------------------------------------------------------

    (g) For airplanes specified in paragraph (f)(1) of this AD, you 
may extend the safe life limit of the wing spar lower cap to 7,000 
hours TIS by incorporating the wing spar center splice joint 
modification following the procedures in Snow Engineering Co. 
Service Letter 55, revised October 23, 2002; or Snow 
Engineering Co. Service Letter 55, revised October 4, 2004, 
with the following requirements:
    (1) This modification must be done no earlier than 4,600 total 
hours TIS on the wing spar lower cap and no later than 5,000 total 
hours TIS on the wing spar lower cap.
    (2) Immediately before incorporating the modification, you must 
do an eddy-current inspection for cracks following Snow Engineering 
Co. Process Specification 197, revised June 4, 2002.
    (3) After each replacement, inspect as specified in paragraph 
(e)(1) of this AD until the wing spar center splice joint 
modification or the required wing spar lower cap replacement.
    (h) Eddy-current inspections required by this AD must be done by 
one of the following:
    (1) A level 2 or 3 inspector certified in eddy-current 
inspection using the guidelines established by the American Society 
for Nondestructive Testing or NAS 410; or
    (2) A person authorized to perform AD maintenance work and who 
has completed and passed the Air Tractor, Inc. training course on 
eddy-current inspection on wing lower spar caps.

    Note 1: We are not retaining from AD 2003-06-01 the provision to 
allow a limited time of continued operation beyond the safe life 
limit provided parts are ordered, the replacement is scheduled, and 
repetitive inspections reveal no cracks. That provision was put in 
AD 2003-06-01 to prevent airplanes from being inadvertently grounded 
if parts were not available. If parts availability were to ever 
become a problem in the future, the owner/operator could request an 
alternative method of compliance following the procedures in 14 CFR 
39.19 and this AD.

    (i) Report the results of any inspection required by this AD 
where cracks are found to the FAA.
    (1) Submit this report within 10 days after the inspection.
    (2) Use the form (Figure 1 of this AD) and submit it to FAA, 
Fort Worth Airplane Certification Office (ACO), 2601 Meacham 
Boulevard, Fort Worth, Texas 76193-0150; telephone: (817) 222-5156; 
facsimile: (817) 222-5960.
    (3) The Office of Management and Budget (OMB) approved the 
information collection requirements contained in this regulation 
under the provisions of the Paperwork Reduction Act of 1980 (44 
U.S.C. 3501 et seq.) and assigned OMB Control Number 2120-0056.
BILLING CODE 4910-13-P

[[Page 22799]]

[GRAPHIC] [TIFF OMITTED] TR28AP08.001

BILLING CODE 4910-13-C

Alternative Methods of Compliance (AMOCs)

    (j) The Manager, Fort Worth ACO, 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: Rob Romero, Aerospace 
Engineer, FAA, Fort Worth ACO, 2601 Meacham Boulevard, Fort Worth, 
Texas 76193-0150; telephone: (817) 222-5102; facsimile: (817) 222-
5960; or Andrew McAnaul, Aerospace Engineer, ASW-150 (c/o MIDO-43), 
10100 Reunion Place, Suite 650, San Antonio, Texas 78216; telephone: 
(210) 308-3365; facsimile: (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.
    (k) AMOCs approved for AD 2003-06-01 are approved for this AD.

[[Page 22800]]

Special Flight Permit

    (l) Under 14 CFR part 39.23, we are limiting the special flight 
permits for this AD by the following conditions:
    (1) Operate only in day visual flight rules (VFR).
    (2) Ensure that the hopper is empty.
    (3) Limit airspeed to 135 miles per hour (mph) indicated 
airspeed (IAS).
    (4) Avoid any unnecessary g-forces.
    (5) Avoid areas of turbulence.
    (6) Plan the flight to follow the most direct route.

Material Incorporated by Reference

    (m) You must use Snow Engineering Co. Service Letter 
55, revised October 23, 2002; Snow Engineering Co. Service 
Letter 55, revised October 4, 2004; and Snow Engineering 
Co. Process Specification Number 197, revised June 4, 2002, to do 
the actions required by this AD, unless the AD specifies otherwise.
    (1) The Director of the Federal Register approved the 
incorporation by reference of Snow Engineering Co. Service Letter 
55, revised October 4, 2004, under 5 U.S.C. 552(a) and 1 
CFR part 51.
    (2) On April 4, 2003, (68 FR 13221, March 19, 2003), the 
Director of the Federal Register approved the incorporation by 
reference of Snow Engineering Co. Service Letter 55, 
revised October 23, 2002, and Snow Engineering Process Specification 
Number 197, revised June 4, 2002.
    (3) For service information identified in this AD, contact 
Tractor, Inc., P.O. Box 485, Olney, Texas 76374.
    (4) You may review copies at the FAA, Central Region, Office of 
the Regional Counsel, 901 Locust, Kansas City, Missouri 64106; or at 
the National Archives and Records Administration (NARA). For 
information on the availability of this material at NARA, call 202-
741-6030, or go to: http://www.archives.gov/federal_register/code_
of_federal_regulations/ibr_locations.html.

    Issued in Kansas City, Missouri, on April 18, 2008.
David R. Showers,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E8-9058 Filed 4-25-08; 8:45 am]

BILLING CODE 4910-13-P