[Federal Register Volume 71, Number 75 (Wednesday, April 19, 2006)]
[Rules and Regulations]
[Pages 19986-19994]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-3617]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-23646; Directorate Identifier 2006-CE-05-AD; 
Amendment 39-14563; AD 2006-08-08]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

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

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain Air Tractor, Inc. (Air Tractor) Models AT-400, AT-401, AT-401B, 
AT-402, AT-402A, and AT-402B airplanes. This AD requires you to lower 
the safe life for the wing lower spar cap for certain Models AT-402A 
and AT-402B airplanes and those that incorporate or have incorporated 
Marburger Enterprises, Inc. (Marburger) winglets. For Models AT-400, 
AT-401, AT-401B, AT-402, and certain AT-402A, airplanes, this AD 
requires you to repetitively inspect the wing lower spar cap in order 
to reach the safe life. We also developed an alternative method of 
compliance (AMOC) to the requirements of this Ad for certain Models AT-
402A and AT-402B airplanes. The AMOC includes repetitive eddy current 
inspections, modification of the center splice connection, and lower 
spar cap replacement. This AD is the result of reports of cracks in the 
\3/8\-inch bolt hole of the wing lower spar cap before reaching the 
approved safe life. 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 wing separation and 
loss of control of the airplane.

DATES: This AD effective on April 21, 2006.
    As of April 21, 2006, the Director of the Federal Register 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.
     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; US 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, Inc., P.O. Box 485, Olney, Texas 76374; telephone: (940) 564-
5616; facsimile: (940) 564-5612; 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-2006-23646; Directorate Identifier 2006-CE-05;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 
Enterprises, Inc. 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.

SUPPLEMENTARY INFORMATION: 

    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

[[Page 19987]]

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 recalculation the fatigue life of 
the wing lower spar cap on Air Tractor AT-400, AT-500, and 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 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 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 fir 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 2001-04 R1, we received a comment 
from the National Transportation Safety Board (NTSE) 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 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 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 airplanes 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 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.
    Is there service information that applies to this subject? Snow 
Engineering Co. has issued Process Specification 197, page 1, 
revised June 4, 2002, pages 2 through 4, dated February 23, 2001, and 
page 5, dated May 3, 2002; Drawing Number 21088, dated November 3, 
2004; and Service Letter 202, page 3, dated October 16, 2000.
    Snow Engineering Co. has a licensing agreement with Air Tractor 
that allows them to produce technical data to use for Air Tractor 
products.
    What are the provisions of this service information? The process 
specification and drawing include procedures for doing the eddy-current 
inspection and replacing the spar caps and associated hardware. The 
service letter provides information for installing access panels, if 
not already installed.

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 is likely to exist 
or develop on other Air Tractor Models AT-400, AT-401, AT-401B, AT-402, 
AT-402A, and AT-402B airplanes of the same type design. 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 wing separation and loss of control of the 
airplane. The FAA is also issuing a similar AD on the AT-800 series 
airplanes and revising AD 2002-11-05 to retain the applicability of the 
Model AT-501 airplanes.
    What does this AD require? This AD requires you to:
     Lower the safe life for the wing lower spar cap for 
certain Models AT-402A and AT-402B airplanes and those that incorporate 
or have incorporated Marburger winglets;

[[Page 19988]]

     Eddy-current inspect the wing lower spar cap at specified 
thresholds and intervals for Models AT-400, AT-401, AT-401B, AT-402, 
and certain AT-402A airplanes in order to reach the safe life;
     Eddy-current inspect the wing lower spar cap immediately 
before doing the modification for certain Models AT-402A and AT-402B 
airplanes to detect and correct any crack in a bolt hole; and
     Report the results of this inspection to the FAA if any 
cracks are found.
    We also included an alternative method of compliance to the 
requirements of this AD for certain Models AT-402A and AT-402B 
airplanes.
    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-2006-23646; 
Directorate Identifier 2006-CE-05-AD'' in the subject line of your 
comments. If your 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 contract 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 206 
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. It 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-2006-23646; Directorate Identifier 2006-CE-05-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. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

2006-08-08 Air Tractor, Inc.: Amendment 39-14563; Docket No. FAA-
2006-23646; Directorate Identifier 2006-CE-05-AD.

When Does This AD Become Effective?

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

What Other ADs Are Affected by This Action?

    (b) As of the issuance of this action, AD 2002-11-05 applies to 
Models AT-400, AT-401, AT-401B, AT-402, AT-402A, AT-402B, AT-501, 
AT-802, and AT-802A airplanes. The FAA is revising AD 2002-11-05 to 
remove the AT-400 series and AT-800 series airplanes from the 
applicability. The FAA is also issuing another similar AD on the AT-
800 airplanes.

What Airplanes Are Affected by This AD?

    (c) This AD applies to certain Models AT-400, AT-401, AT-401B, 
AT-402, AT-402A, and AT-402B airplanes that are certificated in any 
category. Use paragraph (c)(1) of this AD for affected airplanes 
that do not incorporate and never have incorporated Marburger 
winglets. Use paragraph (c)(3) of this AD for airplanes that have 
been modified to install lower spar caps, part number (P/N) 21058-1, 
and P/N 21058-2. Use paragraph (c)(4) of this AD for certain Models 
AT-401, AT-401B, AT-402, AT-402A, and AT-402B 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 19989]]



Table 1.--Safe Life for Airplanes That Do Not Incorporate and Never Have
                     Incorporated Marburger Winglets
------------------------------------------------------------------------
                                                     Wing lower spar cap
            Model                  Serial Nos.            safe life
------------------------------------------------------------------------
AT-400......................  All beginning with    13,300 hours TIS.
                               0416.
AT-401......................  0662 through 0951...  10,757 hours TIS.
AT-401B.....................  0952 through 1020,    6,948 hours TIS.
                               except 1015.
AT-401B.....................  1015 and all          7,777 hours TIS.
                               beginning with 1021.
AT-402......................  0694 through 0951...  7,440 hours TIS.
AT-402A.....................  0738 through 0951...  7,440 hours TIS.
AT-402A.....................  0952 through 1020...  2,000 hours TIS.
AT-402A.....................  All beginning with    2,300 hours TIS.
                               1021.
AT-402B.....................  0966 through 1020,    2,000 hours TIS.
                               except 1015.
AT-402B.....................  1015 and all          2,300 hours TIS.
                               beginning with 1021.
------------------------------------------------------------------------

    (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) If you have an aircraft that has been modified by installing 
lower spar caps, P/N 21058-1 and P/N 21058-2, you must use a wing 
lower spar cap life of 9,800 hours TIS. No inspections are required 
to reach this life.
    (i) Airplanes that have been modified with replacement spar 
caps, P/N 21058-1 and P/N 21058-2, are not eligible to have 
Supplemental Type Certificate (STC) No. SA00490LA, Marburger 
winglets, installed.
    (ii) If your airplanes currently has spar caps, P/N 21058-1 and 
P/N 21058-2, and winglets installed, then you must remove the 
winglets before further flight and you must contact the FAA at the 
address in paragraph (l)(1) of this AD for a new safe life.
    (iii) Installation of Marburger winglets on airplanes that have 
been modified with replacement spar caps, P/N 21058-1 and P/N 21058-
2, will require additional fatigue-data substantiating an 
appropriate safe life. If you have replacement spar caps and wish to 
install winglets, you must contact the FAA at the address in 
paragraph (l)(1) of this AD for additional information.
    (4) The following table applies to airplanes that incorporate or 
have incorporated Marburger winglets. These winglets are installed 
following STC No. SA00490LA. Use the winglet usage factor in Table 2 
of this paragraph, the wing lower spar cap 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
------------------------------------------------------------------------
            Model                  Serial Nos.      Winglet usage factor
------------------------------------------------------------------------
AT-401......................  0662 through 0951...  1.6
AT-401B.....................  0952 through 1020,    1.1
                               except 1015.
AT-401B.....................  1015 and all          1.1
                               beginning with 1021.
AT-402......................  0694 through 0951...  1.6
AT-402A.....................  0738 through 0951...  1.6
AT-402A.....................  0952 through 1020...  1.1
AT-402A.....................  All beginning with    1.1
                               1021.
AT-402B.....................  0966 through 1020,    1.1
                               except 1015.
AT-402B.....................  1015 and all          1.1
                               beginning with 1021.
------------------------------------------------------------------------

What Is the Unsafe Condition Presented in This AD?

    (d) This AD is the result of fatigue cracking of the wing main 
spar lower cap at the center splice joint outboard fastener hole. 
The actions specified in this AD are intended to detect and correct 
cracks in the wing main spar lower cap, which 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) Safe Life Record: For all affected airplanes, modify the 
applicable aircraft records (logbook) as follows to show the safe 
life for the wing lower spar cap listed in this AD (use the 
information from paragraph (c) of this AD and Appendix 1 to this AD, 
as applicable).
    (1) Incorporate the following into the Aircraft Logbook: 
``Following AD 2006-08-08 the wing lower spar cap is life limited to 
---- hours time-in-service (TIS).'' Insert the applicable safe life 
number from the applicable tables in paragraph (c) of this AD and 
Appendix 1 to this AD.
    (i) Do the logbook entry within the next 10 hours TIS after 
April 21, 2006 (the effective date of this AD).
    (ii) The owner/operator holding at least a private pilot 
certificate as authorized by section 43.7 of the Federal Aviation 
Regulations (14 CFR 43.7) may modify the aircraft records. Make an 
entry into the aircraft records showing compliance with this portion 
of the AD following section 43.9 of the Federal Aviation Regulations 
(14 CFR 43.9).
    (2) Wing Spar Replacement: For all affected airplanes, replace 
the wing lower spar cap following Snow Engineering Drawing Number 
21088, dated November 3, 2004. Replace upon accumulating the safe 
life used in paragraph (e)(1) of this AD or within the next 50 hours 
TIS after [date] (the effective date of this AD), whichever occurs 
later. The owner/operator may not do the spar cap replacement, 
unless he/she holds the proper mechanic's authorization.
    (f) Inspection Requirements: For all affected airplanes, except 
Model AT-402A, all serial numbers beginning with 0952, and except 
Model AT-402B, all serial numbers beginning with 0966: Do the 
initial inspection of the outboard two lower spar cap bolt holes 
following Snow Engineering Co. Process Specification 197, 
page 1, revised June 4, 2002, pages 2 through 4, dated February 23, 
2001, and page 5, dated May 3, 2002; and using the wing spar lower 
cap TIS schedules listed in the following table. After the initial 
inspection, perform repetitive inspections using the same procedure 
as the initial inspection at the repetitive inspection intervals 
listed in the following table. If not already done, install access 
panels at the time of the first inspection following Snow 
Engineering Service Letter 202, page 3, dated October 16, 
2000.

    Note 1:  Hours listed in the table are in hours TIS and the 
phrase ``within ---- hours'' refers to ``within ---- hours after 
[date] (the effective date of this AD).''


[[Page 19990]]



                                           Table 3.--Inspection Times
----------------------------------------------------------------------------------------------------------------
                                                       Current wing spar                          Repetitive
              Model                   Serial Nos.        lower cap TIS    Initial inspection      inspection
                                                             hours                                 interval
----------------------------------------------------------------------------------------------------------------
AT-400..........................  All beginning with  Greater than 7,750  Within 50 hours or  900 hours.
                                   0416.                                   upon the
                                                                           accumulation of
                                                                           8,000 hours,
                                                                           whichever is
                                                                           later.
AT-401..........................  0662-0951.........  Greater than 6,250  Within 50 hours or  700 hours.
                                                                           upon the
                                                                           accumulation of
                                                                           6,500 hours,
                                                                           whichever is
                                                                           later.
AT-401..........................  0662-0951.........  Greater than 4,350  Within 250 hours    700 hours.
                                                       but less than or    or upon the
                                                       equal to 6,250.     accumulation of
                                                                           4,850 hours,
                                                                           whichever is
                                                                           later.
AT-401..........................  0662-0951.........  Greater than 2,750  Within 500 hours..  700 hours.
                                                       but less than or
                                                       equal to 4,350.
AT-401..........................  0662-0951.........  Less than or equal  Upon the            700 hours.
                                                       to 2,750.           accumulation of
                                                                           3,250.
AT-401B.........................  0952-1020 except    Greater than 3,950  Within 50 hours or  600 hours.
                                   1015.                                   upon the
                                                                           accumulation of
                                                                           4,200 hours,
                                                                           whichever is
                                                                           later.
AT-401B.........................  0952-1020 except    Greater than 2,650  Within 250 hours    600 hours.
                                   1015.               but less than or    or upon the
                                                       equal to 3,950.     accumulation of
                                                                           3,150 hours,
                                                                           whichever is
                                                                           later.
AT-401B.........................  0952-1020 except    Greater than 1,600  Within 500 hours..  600 hours.
                                   1015.               but less than or
                                                       equal to 2,650.
AT-401B.........................  0952-1020 except    Less than or equal  Upon the            600 hours.
                                   1015.               to 1,600.           accumulation of
                                                                           2,100 hours.
AT-401B.........................  1015 and 1021-1124  Greater than 4,450  Within 50 hours or  400 hours.
                                                                           upon the
                                                                           accumulation of
                                                                           4,700, whichever
                                                                           is later.
AT-401B.........................  1015 and 1021-1124  Greater than 3,000  Within 250 hours    400 hours.
                                                       but less than or    or upon the
                                                       equal to 4,450.     accumulation of
                                                                           3,500 hours,
                                                                           whichever is
                                                                           later.
AT-401B.........................  1015 and 1021-1124  Greater than 1,850  Within 500 hours..  400 hours.
                                                       but less than or
                                                       equal to 3,000.
AT-401B.........................  1015 and 1021-1124  Less than or equal  Upon the            400 hours.
                                                       to 1,850.           accumulation of
                                                                           2,350.
AT-401B.........................  All beginning with  Greater than 4,450  Within 50 hours or  1,000 hours.
                                   1125.                                   upon the
                                                                           accumulation of
                                                                           4,700 hours,
                                                                           whichever is
                                                                           later.
AT-401B.........................  All beginning with  Greater than 3,000  Within 250 hours    1,000 hours.
                                   1125.               but less than or    or upon the
                                                       equal to 4,450.     accumulation of
                                                                           3,500 hours,
                                                                           whichever is
                                                                           later.
AT-401B.........................  All beginning with  Greater than 1,850  Within 500 hours..  1,000 hours.
                                   1125.               but less than or
                                                       equal to 3,000.
AT-401B.........................  All beginning with  Less than or equal  Upon the            1,000 hours.
                                   1125.               to 1,850.           accumulation of
                                                                           2,350.
AT-402/4 02A....................  0694-0951.........  Greater than 4,250  Within 50 hours or  700 hours.
                                                                           upon the
                                                                           accumulation of
                                                                           4,500, whichever
                                                                           is later.
AT-402/4 02A....................  0694-0951.........  Greater than 2,850  Within 250 hours    700 hours.
                                                       but less than or    or upon the
                                                       equal to 4,250.     accumulation of
                                                                           3,350, whichever
                                                                           is later.
AT-402/4 02A....................  0694-0951.........  Greater than 1,750  Within 500 hours..  700 hours.
                                                       but less than or
                                                       equal to 2,850.
AT-402/4 02A....................  0694-0951.........  Less than or equal  Upon the            700 hours.
                                                       to 1,750.           accumulation of
                                                                           2,250.
----------------------------------------------------------------------------------------------------------------

    (g) For all affected airplanes: Replace any cracked wing lower 
spar cap following Snow Engineering Drawing Number 21088, dated 
November 3, 2004, before further flight after the inspection in 
which cracks are found.
    (h) For all affected airplanes, except Model AT-402A, all serial 
numbers beginning with 0952, and except Model AT-402B, all serial 
numbers beginning with 0966: Report to the FAA any cracks detected 
as the result of each inspection required by paragraph (f) of this 
AD on the form in Figure 1 of this AD.
    (1) Only if cracks are found, send the report within 10 days 
after the inspection required in paragraph (f) of this AD.
    (2) The Office of Management and Budget (OMB) approved the 
information collection requirements contained in this regulation 
under the provisions of the Paperwork Reduction Act and assigned OMB 
Control Number 2120-0056.
    (i) For all affected airplanes: Upon the accumulation of the 
life used in paragraph (e)(1) of this AD or within the next 50 hours 
TIS after [date] (the effective date of this AD), whichever occurs 
later, you must replace your wing lower spar cap before further 
flight following Snow Engineering Drawing Number 21088, dated 
November 3, 2004.
    (j) For Model AT-402A airplanes, all serial numbers beginning 
with 0952; and Model AT-402B airplanes, all serial numbers beginning 
with 0966: In lieu of the safe life used in paragraph (e)(1) of this 
AD, you may eddy-current inspect and modify the wing lower spar cap. 
The inspection schedule and modification procedures are included in 
Appendix 2 to this AD.
    (k) For all affected airplanes (those complying with the actions 
in the AD or AMOC): One of the following must do the inspection:
    (1) A level 2 or 3 inspector certified in eddy current 
inspection using the guidelines established by the American Society 
for Nondestructive Testing or MIL-STD-410; or

[[Page 19991]]

    (2) A person authorized to perform AD work and who has completed 
and passed the Air Tractor, Inc. training course on Eddy Current 
Inspection on wing lower spar caps.
BILLING CODE 4910-13-P
[GRAPHIC] [TIFF OMITTED] TR19AP06.000

BILLING CODE 4910-13-C

[[Page 19992]]

May I Request an Alternative Method of Compliance?

    (1) The Manager, Fort Worth or Los Angeles Airplane 
Certification Office (ACO), as applicable, FAA, has the authority to 
approve alternative methods of compliance (AMOCs) for this AD, if 
requested using the procedures found in 14 CFR 39.19. For 
information on any already approved alternative methods of 
compliance, contact:
    (1) 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, Forth Worth, Texas 76193-0150; telephone: (817) 222-5102; 
facsimile: (817) 222-5960.
    (2) 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: (502) 627-5228; facsimile: 
(562) 627-5210.
    (m) AMOCs approved for AD 2001-10-04, AD 2001-10 R1, or AD 2002-
11-05 for the AT-400 series airplanes are not considered approved 
for this AD.

Special Flight Permit

    (n) 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?

    (o) You must do the actions required by this AD following the 
instructions in Snow Engineering Drawing 21088, dated November 3, 
2004; Snow Engineering Co. Process Specification 197, page 
1, revised June 4, 2002, pages 2 through 4, dated February 23, 2001, 
and page 5, dated May 3, 2002; and Snow Engineering Co. Service 
Letter 202, page 3, dated October 16, 2000. The Director of 
the Federal Register approved the incorporation by reference of this 
service information following 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; telephone: (940) 
564-5616; facsimile: (940) 564-5612; 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; US 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-2006-23646; 
Directorate Identifier 2006-CE-05-AD.

Appendix 1 To AD 2006-08-08

    The following provides procedures for determining the safe life 
for those Models AT-401, AT-401B, AT-402, AT-402A, and AT-402B 
airplanes that incorporate or have incorporated Marburger winglets. 
These winglets are installed following Supplemental Type Certificate 
(STC) No. SA009490LA.

What if I removed the Marburger winglets prior to further flight after 
the effective date of this AD or prior to the effective date of this 
AD?

    1. Review your airplane's logbook to determine your airplane's 
time in service (TIS) with winglets installed per Marburger STC No. 
SA00940LA. 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 future winglet installation will be 
subject to a reduced safe life per these instructions.
    2. Determine your airplane's unmodified safe life from paragraph 
(c)(1) of this AD.

    Example: Your airplane is a Model AT-401B, serial number 1022. 
From paragraph (c)(1) of this AD, the unmodified safe life of your 
airplane is 7,777 hours TIS.

    All examples from hereon will be based on the Model AT-401B, 
serial number 1022 airplane.
    3. Determine the winglet usage factor from paragraph (c)(4) of 
this AD.

    Example: Again, your airplane is a Model AT-401B, serial number 
1022. From paragraph (c)(4) of this AD, your winglet usage factor is 
1.1.

    4. Adjust the winglet TIS to account for the winglet usage 
factor. Multiply the winglet TIS (result of Step 1 above) by the 
winglet usage factor (result of Step 3 above).

    Example: Winglet TIS is 500 hours X a winglet usage factor of 
1.1. The adjusted winglet TIS is 550 hours.

    5. Calculate the winglet usage penalty. Subtract the winglet TIS 
(result of Step 1 above) from the adjusted winglet TIS (result of 
Step 4 above).

    Example: 
    Adjusted winglet TIS-the winglet TIS-winglet usage penalty.
    (550 hours)-(500 hours TIS) = (50 hours TIS).

    6. Adjust the safe life of your airplane to account for winglet 
usage. Subtract the winglet usage penalty (result of Step 5 above) 
result from the unmodified safe life from paragraph (c)(1) of this 
AD (result of Step 2 above.).
    Example: 
    Unmodified safe life-winglet usage penalty = adjusted safe life.
    (7,777 hours TIS)-(50 hours TIS) = (7,727 hours TIS).

    7. If you remove the winglets from your airplane before further 
flight or no longer have the winglets installed on your airplane, 
the safe life of your airplane is the adjusted safe life (result of 
Step 6 above). Enter this number in paragraph (e)(1) of this AD and 
the airplane logbook.

What if I have the Marburger winglet installed as of the effective date 
of this AD and plan to operate my airplane without removing the 
winglet?

    1. Review your airplane's logbook to determine your airplane's 
TIS without the winglets installed.

    Example: A review of your airplane's logbook shows that you have 
accumulated 1,500 hours TIS, including 500 hours with the Marburger 
winglets installed. Therefore, your airplane's TIS without the 
winglets installed is 1,000 hours.

    2. Determine your airplane's unmodified safe life from paragraph 
(c)(1) of this AD.

    Example: Your airplane is a Model AT-401B, serial number 1022. 
From paragraph (c)(1) of this AD, the unmodified safe life of your 
airplane is 7,777 hours TIS.

    All examples from hereon will be based on the Model AT-401B, 
serial number 1022 airplane.
    3. Determine the winglet usage factor from paragraph (c)(4) of 
this AD.

    Example: Again, your airplane is a Model AT-401B, serial number 
1022. From paragraph (c)(4) of this AD, your winglet usage factor is 
1.1.

    4. Determine the potential winglet TIS. Subtract the TIS without 
the winglets installed (result of Step 1 above) from the unmodified 
safe life (result of Step 2 above).

    Example: 
    Unmodified safe life-TIS without winglets = Potential winglet 
TIS.
    (7,777 hours TIS)-(1,000 hours TIS) = (6,777 hours TIS).

    5. Adjust the potential winglet TIS to account for the winglet 
usage factor. Divide the potential winglet TIS (result of Step 4 
above) by the winglet usage factor (result of Step 3 above).

    Example: 
    Potential winglet TIS / Winglet usage factor = Adjusted 
potential winglet TIS.
    (6,777 hours TIS) / (1.1) = (6,155 hours TIS).

    6. Calculate the winglet usage penalty. Subtract the adjusted 
potential winglet TIS (result of Step 5 above) from the potential 
winglet TIS (result of Step 4 above).

    Example: 
    Potential winglet TIS-Adjusted potential winglet TIS = Winglet 
usage penalty.

[[Page 19993]]

    (6,777 hours TIS)-(6,155 hours TIS = (622 hours TIS).

    7. Adjust the safe life of your airplane to account for the 
winglet installation. Subtract the winglet usage penalty (result of 
Step 6 above) from the unmodified safe life from paragraph (c)(1) of 
this AD (the result of Step 2 above).

    Example: 
    Unmodified safe life-Winglet usage penalty = Adjusted safe life.
    (7,777 hours TIS)-(622 hours TIS) = (7,155 hours TIS).

    8. Enter the adjusted safe life (result of Step 7 above) in 
paragraph (e)(1) of this AD and the airplane logbook.

What if I install or remove the Marburger winglet from my airplane in 
the future?

    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 to determine the airplane's safe life.

Appendix 2--Alternative Method of Compliance (AMOC) To AD 2006-08-08

Optional Inspection Program

    For Model AT-402A airplanes, all serial numbers (S/Ns) beginning 
with 0952, and Model AT-402B airplanes, all S/Ns beginning with 
0966, that do not incorporate and never have incorporated Marburger 
winglets installed following STC No. SA00490LA; you may begin a 
repetitive inspection interval program as an alternative to the safe 
life requirement of this AD with the following provisions:
    1. Upon accumulating 1,600 hours time-in-service (TIS) or within 
the next 50 hours TIS after April 21, 2006 (the effective date of AD 
2006-08-08), whichever occurs later, eddy-current inspect the 
outboard two lower spar cap bolt holes following Snow Engineering 
Process Specification 197, page 1, revised June 4, 2002; 
pages 2 through 4, dated February 23, 2001; and page 5, dated May 3, 
2002. The inspection must be done by one of the following:
    a. A Level 2 or Level 3 inspector that is certified for eddy-
current inspection using the guidelines established by the American 
Society for Nondestructive Testing or MIL-STD-410; or
    b. A person authorized to do AD work and who has completed and 
passed the Air Tractor, Inc. training course on Eddy Current 
Inspection on wing lower spar caps.
    2. Repeat these inspections at intervals of (as applicable):
    a. 400 hours TIS:
    i. Model AT-402A, S/Ns 1021 through 1124
    ii. Model AT-402B, S/Ns 1015, and 1021 through 1124
    b. 600 hours TIS:
    i. Model AT-402A, S/Ns 0952 through 1020
    ii. Model AT-402B, S/Ns 0966 through 1020, except 1015
    c. 1,000 hours TIS:
    i. Model AT-402A, all S/Ns beginning with 1125
    ii. Model AT-402B, all S/Ns beginning with 1125
    d. If the outboard two lower spar cap bolt holes have been cold 
worked following Snow Engineering Service Letter 238 or 
239, both dated September 30, 2004, then you may double the 
inspection intervals listed in a., b., and c. above (800 hours TIS, 
1,200 hours TIS, or 2,000 hours TIS, as applicable) (See Step 8.-re: 
mid cycle cold work).
    e. Your logbook entry must include the work done and the 
inspection intervals that are upcoming, as follows:

    ``Following AD 2006-08-08, at XXXX (insert hours TIS of the 
initial pre-modification inspection) hours TIS an eddy-current 
inspection has been performed. As of now, the safe life listed in 
the AD no longer applies to this airplane. This airplane must be 
eddy-current inspected at intervals not to exceed (400/600/800/
1,000/1,200/2,000, as applicable) hours TIS. The first of these 
inspections is due at (insert the total number of hours TIS the 
first of these inspections is due) hours TIS.''

    3. If at any time a crack is found, and:
    a. If the crack indication goes away by doing the initial steps 
of the modification following the applicable sheet of Snow 
Engineering Co. Drawing Number 20992, then you may continue to 
modify your wing. After modification, proceed to Step 5.
    b. If the crack indication does not go away by doing the initial 
steps of the modification following the applicable sheet of Snow 
Engineering Co. Drawing Number 20992, then you must replace all 
parts and hardware listed in Step 7.
    c. Report to the FAA any cracks found using the form in Figure 1 
of this AD.
    4. Upon accumulating 4,000 hours TIS, you must:
    a. Modify your center splice connection following the applicable 
sheet of Snow Engineering Co. Drawing Number 20992, unless already 
done. Before doing the modification, do an eddy-current inspection 
following Snow Engineering Process Specification 197, page 
1, revised June 4, 2002; pages 2 through 4, dated February 23, 2001; 
and page 5, dated May 3, 2002. (See Step 9). If, as of April 21, 
2006 (the effective date of AD 2006-08-08), your airplane is over or 
within 50 hours of reaching the 4,000-hour TIS modification 
requirement, then you must perform the modification within 50 hours 
TIS.
    b. Your logbook entry must include the work done and the 
inspection intervals that are upcoming, as follows:

    ``Following AD 2006-08-08, at XXXX (insert hours TIS of the 
modification) hours TIS an eddy-current inspection has been 
performed. As of now, the safe life listed in the AD no longer 
applies to this airplane. This airplane must be eddy-current 
inspected at (insert the number of hours TIS at modification plus 
1,600 hours TIS) hours TIS.

    5. Upon accumulating 1,600 hours TIS after modification, inspect 
the left-hand and right-hand outboard two lower spar cap bolt holes 
following Snow Engineering Process Specification 197, page 
1, revised June 4, 2002; pages 2 through 4, dated February 23, 2001; 
and page 5, dated May 3, 2002.
    6. Repeat the inspection at intervals of:
    a. 1,000 hours TIS; or
    b. 2,000 hours TIS if the outboard two lower spar cap bolt holes 
have been cold worked following Snow Engineering Service Letter 
239, dated September 30, 2004 (See Step 8.).
    c. Your logbook entry must include the work done and the post-
modification inspection intervals that are upcoming, as follows:

``Following AD 2006-08-08, at XXXX (insert hours TIS of the initial 
post-modification inspection) hours TIS an eddy-current inspection 
has been performed. As of now, the safe life listed in the AD no 
longer applies to this airplane. This airplane must be eddy-current 
inspected at intervals not to exceed (1,000/2,000, as applicable) 
hours TIS. The first of these inspections is due at (insert the 
total number of hours TIS the first of these inspections is due) 
hours TIS.''

    d. If at any time a crack is found, then before further flight 
you must replace the lower spar caps, splice blocks, and wing attach 
angles and hardware. You must also notify the FAA using the form in 
Figure 1 of this AD.
    7. Upon accumulating 8,000 hours TIS, before further flight you 
must replace the lower spar caps, splice blocks, and wing attach 
angles (P/N 20693-1) and associated hardware. No additional time 
will be authorized for airplanes that are at over 8,000 hours TIS 
(See Step 9.).
    8. If you decide to cold work your bolt holes following Snow 
Engineering Service Letter 238 or 239, both dated 
September 30, 2004, at a TIS that does not coincide with a scheduled 
inspection following this AD, then eddy-current inspect at the time 
of cold working and then begin the 800/1,200/2000 hour TIS 
inspection intervals (2 times the intervals listed in Steps 2.a., 
2.b., 2.c., and 6.a listed above).
    9. If you have modified your airplane before accumulating 4,000 
hours TIS, then you may continue to fly your airplane past 
(modification + 4,000 hours TIS) provided you cut your inspection 
intervals in half. Make a logbook entry following Step 6.c. to 
reflect these reduced inspection intervals. Upon accumulating 8,000 
hours TIS, you must comply with Step 7 above. See example:

    Example: An AT-402B had the two-part modification installed at 
3,000 hours TIS and the bolt holes have not been cold worked.
    The first inspection would occur at 4,600 hours TIS. From Step 
5, this is modification plus 1,600 hours.
    Inspections would follow at 5,600 and 6,600 hours TIS. From Step 
6a, this is 1,000-hour TIS inspection intervals.
    There is another inspection at 7,000 hours TIS (modification 
plus 4,000 hours TIS). This relates to the 8,000-hour TIS inspection 
from Step 7, which is modification plus 4,000 hours TIS, except in 
this example the modification took place at 3,000 hours TIS instead 
of 4,000 hours TIS listed in Step 4.
    This airplane may continue to fly if inspected again at 7,500 
hours TIS, which is 500 hours TIS. This 500-hour time corresponds to 
Step 9 where you cut your inspection interval from Step 6a in half.

[[Page 19994]]

    Upon accumulating 8,000 hours TIS (this is the same as Step 7), 
you must replace the parts listed in Step 7 above.

    For Model AT-402A airplanes, al S/N's beginning with 0952, and 
Model AT-402B airplanes, all S/Ns beginning with 0966, that 
incorporate or have incorporated Marburger winglets installed 
following STC No. SA00490LA; you may begin a repetitive inspection 
interval program as an alternative to the safe life requirement of 
this AD following the steps above with the following provisions:
    If you have removed the winglets, then calculate new, reduced 
hours for Steps 1, 4, 5, and 7 above, as applicable, based on the 
winglet usage factor listed in paragraph (c)(4) and Appendix 2 of 
this AD.
    You may repetitively inspect at the same intervals list in Step 
2 above provided that you do not re-install the winglets.

    Example: An AT-402B airplane, S/N 1020, had winglets installed 
at 200 hours TIS and removed at 800 hours TIS.
    The winglet usage factor is: 1.1.
    Calculate equivalent hours: 600 hours TIS with winglets x 1.1 = 
660 hours TIS.
    Winglet usage penalty = 660-600 = 60.
    New Step 1 Pre-Modification Initial Inspection time = 1,600-60 = 
1,540 hours TIS.
    Retained Step 2 Pre-Modification Inspection interval: Since the 
winglets are removed, the Pre-Modification Inspection interval 
remains at 600 hours TIS.
    New Step 4 Modification time = 4,000-60 = 3,940 hours TIS.
    New Step 5 Post-Modification Initial Inspection time = 3,940 + 
1,600 = 5,540 hours TIS.
    Retained Step 6 Post-Modification Inspection interval: Since the 
winglets are removed the Post-Modification Inspection interval 
remains at 1,000/2,000 hours TIS.
    New Step 7 Replacement time = 8,000-60 = 7,940 hours TIS.

    Use the Retained Step 2 interval, the New Step 5 time, and the 
Retained Step 6 interval to make appropriate logbook entries for the 
pre- and post-modification intervals, using the format presented in 
Steps 2.e., 4.b., and 6.c.
    If you have not removed the winglets, then calculate new, 
reduced hours for Steps 1, 2, 4, 5, 6, and 7 above, as applicable, 
based on the winglet usage factor listed in paragraph (c)(4) and 
Appendix 2 of this AD.
    Repetitively inspect at the appropriate interval listed in the 
step above divided by the winglet usage factor.

    Example: An AT-402B, S/N 1,000 has had winglets on since new.
    The winglet usage factor is: 1.1.
    New Step 1 Pre-Modification Initial Inspection time: 1,600 / 1.1 
= 1,455 hours TIS.
    New Step 2 Pre-Modification Inspection interval: 600 / 1.1 = 545 
hours TIS.
    New Step 4 Modification time: 4,000 / 1.1 = 3,636 hours TIS.
    New Step 5 Post-Modification Initial Inspection time: 3,636 + 
(1,600 / 1.1) = 5,090 hours TIS.
    New Step 6 Post-Modification Inspection interval: 1,000 / 1.1 = 
909 hours TIS.
    New Step 7 Replacement time: 8,000 / 1.1 = 7,273 hours TIS.

    Use the reduced hours you calculate in New Step 2, New Step 5, 
and New Step 6 to make appropriate logbook entries for the pre- and 
post-modification inspection intervals, using the format presented 
in Steps 2.e., 4.b., and 6.c.

    Issued in Kansas City, Missouri, on April 10, 2006.
David R. Showers,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 06-3617 Filed 4-18-06; 8:45 am]
BILLING CODE 4910-13-M