[Federal Register Volume 71, Number 73 (Monday, April 17, 2006)]
[Rules and Regulations]
[Pages 19628-19633]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-3614]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-23647; Directorate Identifier 2006-CE-06-AD; 
Amendment 39-14564; AD 2002-11-05 R1]
RIN 2120-AA64


Airworthiness Directives; Air Tractor, Inc. Model AT-501 
Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

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

SUMMARY: The FAA is adopting a new airworthiness directive (AD) to 
revise AD 2002-11-05, which applies to certain Air Tractor, Inc. (Air 
Tractor) AT-400 series and Models AT-501, AT-802, and AT-802A 
airplanes. AD 2002-11-05 establishes a safe life for the wing lower 
spar cap. Since we issued AD 2002-11-05, we have received reports of 
cracks found prior to the established safe life on AT-400 series 
airplanes and on Model AT-802A airplanes. We are issuing separate AD 
actions for AT-400 series and Models AT-802 and AT-802A airplanes to 
address the unsafe condition of those airplanes. This AD retains the 
actions required in AD 2002-11-05 for Model AT-501 airplanes and 
removes AT-400 series and Models AT-802 and AT-802A airplanes from the 
applicability of AD 2002-11-05.

DATES: This AD becomes effective on April 21, 2006.
    On June 8, 2001 (66 FR 27014, May 16, 2001), the Director of the 
Federal Register previously approved the incorporation by reference of 
certain publications listed in the regulation.
    We must receive any comments on this AD by June 2, 2006.

ADDRESSES: Use one of the following to submit comments on this AD:

[[Page 19629]]

     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 20590-001.
     Fax: 1-202-493-2251.
     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.
    To get the service information identified in this AD, contact Air 
Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374; or Marburger 
Enterprises, Inc., 1227 Hillcourt, Williston, North Dakota 58801; 
telephone: (800) 893-1420 or (701) 774-0230; facsimile: (701) 572-2602.
    To view the comments to this AD, go to http://dms.dot.gov. The 
docket number is FAA-2006-23647; Directorate Identifier 2006-CE-06-AD.

FOR FURTHER INFORMATION CONTACT: Direct all questions to:

--For airplanes that do not incorporate and never have incorporated 
Marburger winglets: Rob Romero, Aerospace Engineer, FAA, Fort Worth 
Airplane Certification Office, 2601 Meacham Boulevard, Fort Worth, 
Texas 76193-0150; telephone: (817) 222-5102; facsimile: (817) 222-5960; 
and
--For airplanes that incorporate or have incorporated Marburger 
winglets: John Cecil, Aerospace Engineer, Los Angeles Aircraft 
Certificate Office, FAA, 3960 Paramount Boulevard, Lakewood, California 
90712; telephone: (562) 627-5228; facsimile: (562) 627-5210.

SUPPLEMENTARY INFORMATION:

Discussion

    What is the background of the subject matter? There have been five 
previous airworthiness directives (ADs) issued related to the wing spar 
inspection and safe life on Air Tractor airplanes:
     AD 2000-14-51, Amendment 39-11837 (65 FR 46567, July 31, 
2000).
     AD 2001-10-04, Amendment 39-12230 (66 FR 27014, May 16, 
2001).
     AD 2001-10-04, R1, Amendment 39-12247 (66 FR 2990, June 4, 
2001).
     AD 2002-11-05, Amendment 39-12766 (67 FR 37967, May 31, 
2002).
     AD 2002-26-05, Amendment 39-12991 (68 FR 18, January 2, 
2003).
    AD 2000-14-51. An Air Tractor Model AT-502A experienced an in-
flight wing separation. As a result, the FAA issued AD 2000-14-51 as an 
emergency AD. This AD required the inspection of the wing lower spar 
cap for cracks on Air Tractor Models AT-501, AT-502, and AT-502A 
airplanes and modification or replacement of any cracked wing lower 
spar cap. Following the release of this AD, the manufacturer evaluated 
the AT-400 and AT-800 series lower spar cap fatigue life.
    AD 2001-10-04: The manufacturer recalculated the fatigue life of 
the wing lower spar cap on Air Tractor AT-400, and AT-500, and AT-800 
series airplanes. The manufacturer also received reports of in-service 
cracks on airplanes with hours time-in-service (TIS) less than the 
published safe life. The cracks originated in the wing main spar lower 
cap at the center splice joint outboard \3/8\-inch bolt hole. To 
address this condition, we issued AD 2001-10-04 to lower the safe life 
for the wing lower spar cap on Air Tractor AT-400, AT-500, and AT-800 
series airplanes. The safe life for the wing lower spar cap ranged from 
a low of 3,000 hours TIS to a high of 13,300 hours TIS depending upon 
model and serial number. This AD superseded AD 2000-14-51 and allowed 
for inspection (using eddy-current methods) of the wing lower spar cap 
for airplanes that were at or over the lower safe life and for which 
parts were not available. Operation of the airplane was not allowed if 
you found cracks or you reached TIS limit.
    AD 2001-10-04 R1: We inadvertently included those AT-800 series 
airplanes in the applicability of AD 2001-10-04 that were equipped with 
the factory-supplied computerized fire gate (part number 80540) and 
engaged in full-time firefighting. Consequently, we revised the AD to 
clarify that those airplanes were not affected.
    AD 2002-11-05: In response to AD 2001-10-04 R1, we received a 
comment from the National Transportation Safety Board (NTSB) to 
recommend an eddy-current inspection requirement immediately before 
doing the two-part modification described in Snow Engineering Service 
Letter 202, revised March 26, 2001. Doing the eddy-current 
inspection before the modification makes the crack easier to detect and 
gives the mechanic an area to concentrate on during any post-
modification inspections. We issued AD 2002-11-05 to minimize the 
possibility that a crack existing in a bolt hole before doing the 
modification was still present after doing the modification. Additional 
analysis by the manufacturer also indicated the need to further reduce 
the safe life for certain AT-400 series airplanes and certain AT-500 
series airplanes that either incorporate or have incorporated Marburger 
winglets. These winglets were installed following Supplemental Type 
Certificate (STC) No. SA00490LA. We developed criteria for determining 
what the new safe life would be for airplanes that either incorporate 
or have incorporated these winglets. The safe life was reduced for 
airplanes that either incorporate or have incorporated these winglets 
by a usage factor reduction that is applied to the basic safe life. We 
used this information and issued AD 2002-11-05 to supersede AD 2001-10-
04 R1 and require eddy-current inspections of the wing lower spar cap 
immediately before doing the replacement/modification to detect and 
correct any crack in a bolt hole before it extends to the modified 
center section of the wing. This AD further reduced the safe life for 
certain Models AT-401, AT-401B, AT-402, AT-402A, AT-402B, and AT-501 
airplanes that incorporate or have incorporated Marburger winglets and 
removed the Models AT-502, AT-502A, AT-502B, and AT-503A airplanes from 
the applicability.
    AD 2002-26-05: To address the Models AT-502, AT-502A, AT-502B, and 
AT-503A airplanes that were removed from AD applicability by AD 2002-
11-05, we issued AD 2002-26-05. This AD is still in effect and lowers 
the safe life and requires the eddy-current inspections of the wing 
lower spar cap immediately before doing the replacement/modification. 
This would allow you to detect and correct any crack in a bolt hole 
before it extends to the modified center section of the wing.
    What has happened to initiate this AD action? The FAA received 
reports of fatigue cracking found on three AT-400 series airplanes and 
on three Model AT-802A airplanes that were below the reduced safe life 
established in AD 2002-11-05. One of the AT-400 series airplanes had 
Marburger winglets and the other incident airplanes did not. 
Specifically:
     One AT-400 series airplane equipped with winglets cracked 
at 5,340 hours TIS where the reduced safe life was 5,380 hours TIS. A 
second AT-400 series airplane cracked at 3,359 hours TIS where the 
reduced safe life was 4,589 hours TIS. A third AT-400 series airplane 
cracked at 4,176 hours TIS where the reduced safe life was 4,589 hours 
TIS, and the cracks were severe enough to not allow modification and 
required immediate wing spar replacement; and
     One AT-802A airplane cracked at 2,378 hours TIS where the 
reduced safe

[[Page 19630]]

life was 4,531 hours TIS. A second AT-802A airplane cracked at 3,809 
hours TIS where the reduced safe life was 4,531 hours TIS. A third AT-
802A airplane cracked at 4,479 hours TIS where the reduced safe life 
was 4,531 hours TIS.
    Further analysis shows the continued operation of these airplanes 
without inspection and/or modification could severely jeopardize the 
safety of the fleet.
    What is the potential impact if the FAA took no action? This 
condition could result in fatigue cracks 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 wing 
separation and loss of control of the airplane.

The FAA's Determination and Requirements of the AD

    What has the FAA decided? We have evaluated all pertinent 
information and identified an unsafe condition that continues to exist 
or develop on type design Air Tractor Model AT-501 airplanes. 
Therefore, we are issuing this AD to prevent fatigue cracks from 
occurring in the wing lower spar cap before the originally 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 of the airplane.
    What does this AD require? This AD revises AD 2002-11-05, Amendment 
39-12766 (67 FR 37967, May 31, 2002), with a new AD that retains the 
actions required in AD 2002-11-05 for Model AT-501 and removes the AT-
400 series and Models AT-802 and AT-802A airplanes from the 
applicability.
    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.

Comments Invited

    Will I have the opportunity to comment before you issue the rule? 
This AD is a final rule that involves requirements affecting flight 
safety and was not preceded by notice and an opportunity for public 
comment; however, we invite you to submit any written relevant data, 
views, or arguments regarding this AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2006-23647; 
Directorate Identifier 2006-CE-06-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. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify it. If a person contacts us through a 
nonwritten communication, and that contact relates to a substantive 
part of this 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 the AD in light of those comments.

Authority for This Rulemaking

    What authority does the FAA have for issuing this rulemaking 
action? 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 AD.

Regulatory Findings

    Will this AD impact various entities? We have 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.
    Will this AD involve a significant rule or regulatory action? 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 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 AD (and 
other information as included in the Regulatory Evaluation) 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 FAA-2006-23647; Directorate Identifier 2006-CE-06-AD'' in your 
request.

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 removing Airworthiness Directive (AD) 
2002-11-05, Amendment 39-12766 (67 FR 37967, May 31, 2002), and by 
adding a new AD to read as follows:

2002-11-05-R1 Air Tractor, Inc.: Amendment 39-14564; Docket No. FAA-
2006-23647; Directorate Identifier 2006-CE-06-AD.

When Does This AD Become Effective?

    (a) This AD becomes effective on April 21, 2006.

Are Any Other ADs Affected by This Action?

    (b) This AD revises AD 2002-11-05, Amendment 39-12766.

What Airplanes Are Affected by This AD?

    (c) This AD applies to Model AT-501 airplanes that are 
certificated in any category. Use Table 1 in paragraph (c)(1) of 
this AD for AT-501 airplanes that do not incorporate and never have 
incorporated Marburger winglets and use Table 2 in paragraph (c)(3) 
of this AD for AT-501 airplanes that incorporate or have 
incorporated Marburger winglets.
    (1) The following table applies to airplanes that do not 
incorporate and never have incorporated Marburger winglets along 
with the safe life (presented in hours time-in-service (TIS)) of the 
wing lower spar cap for all affected airplane models and serial 
numbers:

[[Page 19631]]



    Table 1.--Safe Life for Airplanes That Do Not Incorporate and Never Have Incorporated Marburger Winglets
----------------------------------------------------------------------------------------------------------------
                  Model                             Serial Nos.                Wing lower spar cap safe line
----------------------------------------------------------------------------------------------------------------
AT-501..................................  0002 through 0061..............  4,531 hours TIS.
AT-501..................................  All beginning with 0062........  7,693 hours TIS.
----------------------------------------------------------------------------------------------------------------

    (2) If piston-powered aircraft have been converted to turbine 
power, you must use the limits for the corresponding serial number 
turbine-powered aircraft.
    (3) The following table applies to airplanes that incorporate or 
have incorporated Marburger winglets. These winglets are installed 
in accordance with Supplemental Type Certificate (STC) No. 
SA00490LA. Use the winglet usage factor in Table 2 of this 
paragraph, the safe life specified in Table 1 in paragraph (c)(1) of 
this Ad, and the instructions included in Appendix 1 to this AD to 
determine the new safe life of airplanes that incorporate or have 
incorporated Marburger winglets:

 Table 2.--Winglet Usage Factor To Determine the Safe Life for Airplanes
  That Incorporate or Have Incorporated Marburger Winglets Per STC No.
                                SA00490LA
------------------------------------------------------------------------
                                                                 Winglet
            Model                        Serial Nos.              usage
                                                                 factor
------------------------------------------------------------------------
AT-501......................  0002 through 0061...............       1.6
AT-501......................  all serial numbers beginning           1.6
                               with 0062.
------------------------------------------------------------------------

What Is the Unsafe Condition Presented in This AD?

    (d) This AD is the result of service reports and analysis done 
on wing lower spar caps of Air Tractor airplanes. The actions 
specified in 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 of the airplane.

What Must I Do To Address This Problem?

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

                                     Table 3.--Actions/Compliance/Procedures
----------------------------------------------------------------------------------------------------------------
               Actions                             Compliance                            Procedures
----------------------------------------------------------------------------------------------------------------
(1) Modify the applicable aircraft    Do the logbook entry within the next  The owner/operator holding at least
 records as follows to show the        10 hours TIS after July 12, 2002      a private pilot certificate as
 reduced safe life for the wing        (the effective date of AD 2002-11-    authorized by section 43.7 of the
 lower spar cap (use the information   05), unless already done. The         Federal Aviation Regulations (14
 from table in paragraph (c)(1) of     logbook language is referenced as     CFR 43.7) may modify the aircraft
 this AD and utilize the information   AD 2002-11-05 instead of AD 2002-     records as specified in paragraphs
 in paragraph (c)(3) of this AD and    2002-11-05 R1 to maintain             (e)(1) of this AD. Make an entry
 the Appendix to this AD, as           continuity and to assure that no      into the aircraft records showing
 applicable).                          additional action is necessary.       compliance with this portion of the
(i) Incorporate the following into                                           following section 43.9 of the
 the Aircraft Logbook ``In                                                   Federal Aviation Regulations (14
 accordance with AD 2002-11-05, the                                          CFR 43.9). Do the replacement when
 wing lower spar cap is life limited                                         the safe life is reached following
 to ------.'' Insert the applicable                                          Snow Engineering Service Letters
 safe life number from the                                                   197 or 205, both
 applicable tables in paragraphs                                             revised March 26, 2001, as
 (c)(1) and (c)(3) of this AD and                                            applicable. The owner/operator may
 the Appendix of this AD.                                                    not do the replacement unless he/
(ii) If, as of the time of the                                               she holds the proper mechanic
 logbook entry requirement of                                                authorization.
 paragraph (e)(1) of this AD, your
 airplane is over or within 10 hours
 of the safe life, an additional 10
 hours TIS after July 12, 2002 (the
 effective date of this AD) is
 allowed to do the replacement.

[[Page 19632]]

 
(2) If you have ordered parts from    Inspect before further flight after   Following the procedures in Snow
 the factory when it is time to        ordering the parts and thereafter     Engineering Service Letter 197, pages 1 and 2, revised March
 required when you reach the           hours TIS until one of the criteria   26, 2001, and page 3, dated June
 established safe life), but the       in paragraphs (e)(2)(i),              13, 2000; and Snow Engineering
 parts are not available, you may      (e)(2)(ii), and (e)(2)(iii) of this   Service Letter 205, pages
 eddy-current inspect the wing lower   AD is met.                            1, 2, and 4, revised March 26,
 spar cap. These inspections are                                             2001, and page 3, dated October 25,
 allowed until one of the following                                          2000 as applicable.
 occurs, at which time the
 replacement must be done:
(i) Crack(s) is/are found;
(ii) Parts become available from the
 manufacturer; or
(iii) Not more than three
 inspections or 1,200 hours TIS go
 by: the first inspection would have
 to be done upon accumulating the
 safe life; the second inspection
 would have to be done within 400
 hours TIS after accumulating the
 safe life; the third inspection
 would have to be done 400 hours TIS
 after the second inspection; and
 the replacement would have to be
 done within 400 hours TIS after the
 third inspection (maximum elapsed
 time would be 1,200 hours TIS).
(3) Eddy-current inspect the wing     Immediately before the replacement/   Following the procedures in Snow
 lower spar cap in order to detect     modification required when you        Engineering Service Letter 197, pages 1 and 2, revised March
 modified center section of the wing   airplanes that had this replacement   26, 2001, and page 3, dated June
 and repair that crack or replace      done in accordance with either AD     13, 2000; and Snow Engineering
 the wing section. The inspection      2001-10-04 or AD 2001-10-04 R1, do    Service Letter 205, pages
 must be done by one of the            this inspection and any necessary     1, 2, and 4, revised March 26,
 following:                            corrective action within the next     2001, and page 3, dated October 25,
(i) a Level 2 or Level 3 inspector     400 hours TIS after July 12, 2002     2000, as applicable.
 that is certified for eddy-current    (the effective date of AD 2002-11-
 inspection using the guidelines       05), unless already done (have the
 established by the American Society   mechanic who did the work mark the
 for Nondestructive Testing or MIL-    logbook accordingly).
 STD-410; or
(ii) A person authorized to perform
 AD work who has completed and
 passed the Air Tractor, Inc.
 training course on Eddy Current
 Inspection on wing lower spar caps.
----------------------------------------------------------------------------------------------------------------

May I Request an Alternative Method of Compliance (AMOC)?

    (f) The Manager, Fort Worth or Los Angeles Airplane 
Certification Office (ACO), as applicable, FAA, has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19.
    (1) For information on any already approved AMOCs or for 
information pertaining to this AD, contact:
    (i) For the airplanes that do not incorporate and never have 
incorporated Marburger winglets: Rob Romero, Aerospace Engineer, 
FAA, Fort Worth Airplane Certification Office, 2601 Meacham 
Boulevard, Fort Worth, Texas 76193-0150; telephone: (817) 222-5102; 
facsimile: (817) 222-5960; and
    (ii) For airplanes that incorporate or have incorporated 
Marburger winglets: John Cecil, Aerospace Engineer, Los Angeles 
Aircraft Certification Office, FAA, 3960 Paramount Boulevard, 
Lakewood, California 90712; telephone: (562) 627-5228; facsimile: 
(562) 627-5210.
    (2) AMOCs approved for AD 2001-10-04 and/or AD 2000-14-51 are 
not considered approved for this AD.
    (3) AMOCs approved for AD 2001-10-04 R1 for the Model AT-501 
airplanes are considered approved for this AD.
    (4) AMOCs approved for AD 2002-11-05 for the Model AT-501 
airplanes are considered approved for this AD.

Are There Any Additional AMOCs Being Considered for This AD?

    (g) The FAA may approve, as an AMOC, inspection of the wing 
lower spar cap. You must submit the request in accordance with the 
procedures in paragraph (f) of this AD and adhere to the following:
    (1) If you are over or within 10 hours TIS of reaching the safe 
life used in paragraph (e)(1) of this AD for the wing lower spar cap 
and you have ordered parts and scheduled a date for the replacement, 
but having the replacement done on this date grounds the airplane, 
do the following:
    (i) Inspect the wing lower spar cap within 10 hours TIS after 
approval of the AMOC;
    (ii) re-inspect thereafter at intervals not to exceed 400 hours 
TIS until either cracks are found, the date of the scheduled 
replacement occurs, or 1,200 hours TIS after the initial inspection 
are accumulated, whichever occurs first; and
    (iii) do the inspections following the procedures in Snow 
Engineering Service Letter 197, pages 1 and 2, revised 
March 26, 2001, and page 3, dated June 13, 2000; and Snow 
Engineering Service Letter 205, pages 1, 2, and 4, revised 
March 26, 2001, and page 3, dated October 25, 2000, as applicable.
    (2) Submit the following to the Fort Worth or Los Angeles ACO, 
as applicable, using the procedures described in paragraph (f) of 
this AD:
    (i) The airplane model serial number designation, and airplane 
registration number (N-number);
    (ii) the number of hours TIS on the airplane;
    (iii) the scheduled date for the replacement; and
    (iv) the name and location of the authorized repair shop.
    (3) For more information about this issue, contact:
    (i) For the airplanes that do not incorporate and never have 
incorporated Marburger winglets: Rob Romero, Aerospace Engineer, 
FAA, Fort Worth Airplane Certification

[[Page 19633]]

Office, 2601 Meacham Boulevard, Fort Worth, Texas 76193-0150; 
telephone: (817) 222-5102; facsimile: (817) 222-5960; and
    (ii) For the airplanes that incorporate or have incorporated 
winglets: John Cecil, Aerospace Engineer, Los Angeles Aircraft 
Certification Office, FAA, 3960 Paramount Boulevard, Lakewood, 
California 90712; telephone: (562) 627-5228; facsimile: (562) 627-
5210.

Special Flight Permit

    (h) Under 14 CFR part 39.23, we are allowing special flight 
permits for the purpose of compliance with this AD under the 
following conditions:
    (1) Only operate 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.

Does This AD Incorporate Any Material by Reference?

    (i) You must do the actions required by this AD following the 
instructions in Snow Engineering Service Letter 197, pages 
1 and 2, revised March 26, 2001, and page 3, dated June 13, 2000; 
and Snow Engineering Service Letter 205, pages 1, 2, and 4, 
revised March 26, 2001, and page 3, dated October 25, 2000. On June 
8, 2001 (66 FR 27014, May 16, 2001), the Director of the Federal 
Register previously approved this incorporation by reference under 5 
U.S.C. 552(a) and 1 CFR part 51. To get a copy of this service 
information, contact Air Tractor, Incorporated, P.O. Box 485, Olney, 
Texas 76374; or Marburger Enterprises, Inc., 1227 Hillcourt, 
Williston, North Dakota 58801; telephone: (800) 893-1420 or (701) 
774-0230; facsimile: (701) 572-2602. To review copies of this 
service information, go to the National Archives and Records 
Administration (NARA). For information on the availability of this 
material at NARA, go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html or call (202) 
741-6030. 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 20590-001 or on 
the Internet at http://dms.dot.gov. The docket number is FAA-2006-
23647; Directorate Identifier 2006-CE-06-AD.

Appendix to AD 2002-11-05 R1

    The following provides procedures for determining the safe life 
for those Model AT-501 airplanes that incorporate or have 
incorporated Marburger winglets. These winglets are installed in 
accordance with Supplemental Type Certificate (STC) No. SA00490LA.
    1. Review your airplane's logbook to determine your airplane's 
time in service (TIS) with winglets installed per Marburger STC No. 
SA00490LA. This includes all time spent with the winglets currently 
installed and any previous installations where the winglet was 
installed and later removed.
    Example: A review of your airplane's logbook shows that you have 
accumulated 350 hours TIS since incorporating the Marburger STC. 
Further review of the airplane's logbook shows that a previous owner 
had installed the STC and later removed the winglets after 
accumulating 150 hours TIS. Therefore, your airplane's TIS with the 
winglets installed is 500 hours.
    If you determine that the winglet STC has never been 
incorporated on your airplane, then your safe life is presented in 
paragraph (c)(1) of this AD. Any further winglet installation would 
be subject to a reduced safe life per these instructions.
    2. Determine you airplane's unmodified safe life from paragraph 
(c)(1) of this AD.
    Example: Your airplane is a Model AT-501, serial number 0100. 
From paragraph (c)(1) of this AD, the unmodified safe-life of your 
airplane is 7,693 hours TIS. All examples from hereon will be based 
on the Model AT-501, serial number 0100 airplane.
    3. Determine the winglet usage factor from paragraph (c)(3) of 
this AD.
    Example: Again, your airplane is a Model AT-501, serial number 
0100. From paragraph (c)(3) of this AD, your winglet usage factor is 
1.6.
    4. Adjust the winglet TIS to account for the winglet usage 
factor. Multiply the winglet TIS (result of 1.) by the winglet usage 
factor (result of 3.).
    Example: Winglet TIS is 500 hours X a winglet usage factor of 
1.6. The adjusted winglet TIS is 800 hours.

Appendix to AD 2002-11-05 R1

    5. Calculate the winglet usage penalty. Subtract the winglet TIS 
(result of 1.) from the adjusted winglet TIS (result of 4.).
    Example: Adjusted winglet TIS is 800 hours - the winglet TIS of 
500 hours. The winglet usage penalty is 300 hours TIS.
    6. Adjust the safe life of your airplane to account for winglet 
usage. Subtract the winglet usage penalty (result of 5.) result from 
the unmodified safe life from paragraph (c)(1) of this AD (the 
result of 2.).
    Example: The unmodified safe life is 7,693 hours TIS - the 300 
hours TIS usage penalty = 7,393 hours TIS adjusted safe life.
    7. If your remove the winglets from your airplane before further 
flight or nor longer have the winglets installed on your airplane, 
the safe life of your airplane is the adjusted safe life (result of 
6.). Enter this number in paragraph (e)(1) of this AD and the 
airplane logbook.
    8. If you keep the current winglet installation on your 
airplane, you must further reduce the safe life by dividing the 
adjusted safe life (result of 6.) by the winglet usage factor 
(result of 3.). Record this result in your airplane's logbook.
    Example: Adjusted safe life is 7,393 hours / winglet usage 
factor of 1.6 = 4,621 hours TIS.
    9. If, at anytime in the future, you install or remove the 
Marburger winglet STC from your airplane, you must repeat the 
procedures in this Appendix.

    Issued in Kansas City, Missouri, on April 10, 2006.
David R. Showers,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 06-3614 Filed 4-14-06; 8:45 am]
BILLING CODE 4910-13-M