Document ID: FAA-2006-23646-0038
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; Air Tractor, Inc. Models AT-400, AT-401, AT-401B, AT-402, AT-402A, and AT-402B Airplanes
Posted Date: 2009-03-31T04:00Z

[Federal Register: March 31, 2009 (Volume 74, Number 60)]
[Rules and Regulations]               
[Page 14465-14471]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr31mr09-6]                         

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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-23646; Directorate Identifier 2006-CE-005-AD; 
Amendment 39-15849; AD 2006-08-08 R1]
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), Department of 
Transportation (DOT).

ACTION: Final rule.

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

SUMMARY: We are adopting a new airworthiness directive (AD) to revise 
AD 2006-08-08, which applies to certain Air Tractor, Inc. (Air Tractor) 
Models AT-400, AT-401, AT-401B, AT-402, AT-402A, and AT-402B airplanes. 
AD 2006-08-08 currently requires you to repetitively eddy current 
inspect the wing lower spar cap in order to reach the safe life and, 
for certain Models AT-402A and AT-402B airplanes and those that 
incorporate or have incorporated Marburger Enterprises, Inc. 
(Marburger) winglets, lowers the safe life for the wing lower spar cap. 
Since we issued AD 2006-08-08, we have received information to update 
inspection intervals for the Models AT-401B, AT-402A, and AT-402B 
airplanes based on a revised damage tolerance analysis. Consequently, 
this AD would not only retain the actions of AD 2006-08-08, but would 
reduce the number of repetitive inspections for all affected Model AT-
401B airplanes and certain Models AT-402A and AT-402B airplanes. 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 becomes effective on May 5, 2009.
    As of April 21, 2006 (71 FR 19986, April 19, 2006), the Director of 
the Federal Register approved the incorporation by reference of Snow 
Engineering Co. 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, listed in this AD.

ADDRESSES: For service information identified in this AD, contact Air 
Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374; telephone: 
(940) 564-5616; facsimile: (940) 564-5612; Internet: http://
www.airtractor.com; 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 AD docket, go to U.S. Department of Transportation, 
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 
New Jersey Avenue, SE., Washington, DC 20590, or on the Internet at 
http://www.regulations.gov. The docket number is FAA-2006-23646; 
Directorate Identifier 2006-CE-005-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:

Discussion

    On December 4, 2008, we issued a proposal to amend part 39 of the 
Federal Aviation Regulations (14 CFR part 39) to include an AD that 
would apply to certain Air Tractor Models AT-400, AT-401, AT-401B, AT-
402, AT-402A, and AT-402B airplanes. This proposal was published in the 
Federal Register as a notice of proposed rulemaking (NPRM) on December 
10, 2008 (73 FR 74999). The NPRM proposed to revise AD 2006-08-08 with 
a new AD that would not only retain the actions of AD 2006-08-08, but 
would reduce the number of repetitive inspections for all affected 
Model AT-401B airplanes and certain Models AT-402A and AT-402B 
airplanes.
    The following table contains AD actions that address the wing spar 
safe life of the Air Tractor airplane fleet:

[[Page 14466]]

                                               Related AD Actions
----------------------------------------------------------------------------------------------------------------
                                           Affected air tractor airplane
                 AD No.                                model                             Issue date
----------------------------------------------------------------------------------------------------------------
2003-07-04..............................  AT-300, AT-400, AT-400A, AT-     March 25, 2003.
                                           401, AT-401B, AT-402, AT-402A,
                                           AT-402B, AT-501, AT-502, and
                                           AT-502B.
2006-08-08..............................  AT-400; AT-401, AT-401B, AT-     April 10, 2006.
                                           402, AT-402A, and AT-402B.
2006-08-09..............................  AT-802 and AT-802A.............  April 10, 2006.
2006-23-09..............................  AT-602.........................  October 26, 2006.
2006-24-10..............................  AT-501, AT-502, AT-502A, AT-     November 22, 2006.
                                           502B, and AT-503A.
2008-09-10..............................  AT-300, AT-301, AT-302, AT-400,  April 18, 2008.
                                           and AT-400A.
----------------------------------------------------------------------------------------------------------------

    You may view these Airworthiness Directives at the following 
Internet Web site addresses: http://rgl.faa.gov or http://
www.gpoaccess.gov/fr/index.html.

Comments

    We provided the public the opportunity to participate in developing 
this AD. The following presents the comment received on the proposal 
and FAA's response to the comment:

Comment Issue: Reduce Applicability

    Mr. David Ligon, Air Tractor, comments that since issuance of AD 
2006-08-08, the 21058-1/-2 lower spar cap is standard on production 
Models 401B, 402A, and 402B airplanes beginning with SN 1183. 
Consequently, he recommends that the applicability of the proposed AD 
end at SN 1182; production airplanes following this SN have installed 
the 21058-1/-2 lower spar cap.
    We agree with the commenter and are changing the AD to reflect the 
installation of the 21058-1/-2 lower spar cap on production Models 
401B, 402A, and 402B airplanes beginning with SN 1183.

Conclusion

    We have carefully reviewed the available data and determined that 
air safety and the public interest require adopting the AD as proposed 
except for the changes previously discussed and minor editorial 
corrections. We have determined that these minor corrections:
     Are consistent with the intent that was proposed in the 
NPRM for correcting the unsafe condition; and
     Do not add any additional burden upon the public than was 
already proposed in the NPRM.

Costs of Compliance

    We estimate that this AD affects 341 airplanes in the U.S. 
registry.
    We estimate the following costs to do the inspection. We have no 
way of determining the number of airplanes that may need repair or 
modification as a result of any inspection:

----------------------------------------------------------------------------------------------------------------
                                                                                            Total cost on U.S.
              Labor cost                      Parts cost        Total cost per airplane         operators
----------------------------------------------------------------------------------------------------------------
* $500 to $800.......................  Not Applicable.........  $500 to $800...........  $170,500 to $272,800.
----------------------------------------------------------------------------------------------------------------
* Eddy current inspections are an estimated flat cost that includes labor and use of equipment.

    We estimate the following costs to do the modification. We have no 
way of determining the number of airplanes that may need this 
modification:

------------------------------------------------------------------------
                                                          Total cost per
              Labor cost                   Parts cost        airplane
------------------------------------------------------------------------
120 work-hours x $80 = $9,600.........         $11,500          $21,100
------------------------------------------------------------------------

    We estimate the following costs to do the replacement. We have no 
way of determining the number of airplanes that may need this 
replacement:

------------------------------------------------------------------------
                                                          Total cost per
              Labor cost                   Parts cost        airplane
------------------------------------------------------------------------
$16,500...............................         $16,500          $33,000
------------------------------------------------------------------------
* The labor costs of the replacement are an estimated flat cost that
  includes labor and use of equipment.

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 AD.

Regulatory Findings

    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

[[Page 14467]]

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 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 ``Docket 
No. FAA-2006-23646; Directorate Identifier 2006-CE-005-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 removing Airworthiness Directive (AD) 
2006-08-08, Amendment 39-14563 (71 FR 19986, April 19, 2006), and 
adding the following new AD:

2006-08-08 R1 Air Tractor, Inc.: Amendment 39-15849; Docket No. FAA-
2006-23646; Directorate Identifier 2006-CE-005-AD.

Effective Date

    (a) This AD becomes effective on May 5, 2009.

Affected ADs

    (b) This AD revises AD 2006-08-08, Amendment 39-14563.

Applicability

    (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 (SNs):

 Table 1--Safe Life for Airplanes That Do Not Incorporate and Never Have
                     Incorporated Marburger Winglets
------------------------------------------------------------------------
                                                            Wing lower
                                                           spar cap safe
             Model                         SNs              life (hours
                                                               TIS)
------------------------------------------------------------------------
AT-400.........................  All beginning with 0416          13,300
AT-401.........................  0662 through 0951......          10,757
AT-401B........................  0952 through 1020,                6,948
                                  except 1015.
AT-401B........................  1015 and 1021 through             7,777
                                  1182.
AT-402.........................  0694 through 0951......           7,440
AT-402A........................  0738 through 0951......           7,440
AT-402A........................  0952 through 1020......           2,000
AT-402A........................  1021 through 1182......           2,300
AT-402B........................  0966 through 1020,                2,000
                                  except 1015.
AT-402B........................  1015 and 1021 through             2,300
                                  1182.
------------------------------------------------------------------------

    (2) If piston-powered aircraft have been converted to turbine 
power, you must use the limits for the corresponding serial number 
(SN) 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 safe life of 9,800 hours TIS. No inspections are 
required to reach this life.
    (i) Airplane SNs beginning with 1183 and those 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 airplane 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 (m)(1) of this AD for a new safe life.
    (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 paragraph (c)(4) of this AD, the wing lower spar cap safe life 
specified in Table 1 of 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 usage
             Model                         SNs                factor
------------------------------------------------------------------------
AT-401.........................  0662 through 0951......             1.6
AT-401B........................  0952 through 1020,                  1.1
                                  except 1015.
AT-401B........................  1015 and 1021 through               1.1
                                  1182.
AT-402.........................  0694 through 0951......             1.6

[[Page 14468]]

AT-402A........................  0738 through 0951......             1.6
AT-402A........................  0952 through 1020......             1.1
AT-402A........................  1021 through 1182......             1.1
AT-402B........................  0966 through 1020,                  1.1
                                  except 1015.
AT-402B........................  1015 and 1021 through               1.1
                                  1182.
------------------------------------------------------------------------

Unsafe Condition

    (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.

Compliance

    (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 this AD, 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 AD 2006-08-08).
    (ii) A person 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 logbook showing compliance with this portion of the AD in 
accordance with 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 April 21, 2006 (the effective date of AD 2006-08-08), 
whichever occurs later. The owner/operator may not do the spar cap 
replacement, unless he/she is a properly certified mechanic.
    (f) Inspection Requirements: For all affected airplanes, except 
Model AT-402A, SNs 0952 through 1182, and except Model AT-402B, SNs 
0966 through 1182, do the initial inspection of the outboard two 
lower spar cap bolt holes using the wing spar lower cap TIS 
schedules listed in Table 3. Follow 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. 
After the initial inspection, perform repetitive inspections at the 
repetitive inspection intervals listed in Table 3. Use the same 
procedure for the repetitive inspections as for the initial 
inspection. 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: Hours listed in the table are in hours TIS and the phrase 
``within the ------ next hours'' refers to ``within the next ------ 
hours after April 21, 2006 (the effective date of AD 2006-08-08).''

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

[[Page 14469]]

AT-401B.........................  1015 and 1021-1124.  Less than or equal   Upon the accumulation            600
                                                        to 1,850.            of 2,350 hours TIS.
AT-401B.........................  1125 through 1182..  Greater than 4,450.  Within the next 50             1,000
                                                                             hours TIS or upon the
                                                                             accumulation of 4,700
                                                                             hours TIS, whichever
                                                                             is later.
AT-401B.........................  1125 through 1182..  Greater than 3,000   Within the next 250            1,000
                                                        but less than or     hours TIS or upon the
                                                        equal to 4,450.      accumulation of 3,500
                                                                             hours TIS, whichever
                                                                             is later.
AT-401B.........................  1125 through 1182..  Greater than 1,850   Within the next 500            1,000
                                                        but less than or     hours TIS.
                                                        equal to 3,000.
AT-401B.........................  1125 through 1182..  Less than or equal   Upon the accumulation          1,000
                                                        to 1,850.            of 2,350 hours TIS.
AT-402/AT-402A..................  0694-0951..........  Greater than 4,250.  Within the next 50               700
                                                                             hours TIS or upon the
                                                                             accumulation of 4,500,
                                                                             whichever is later.
AT-402/AT-402A..................  0694-0951..........  Greater than 2,850   Within the next 250              700
                                                        but less than or     hours TIS or upon the
                                                        equal to 4,250.      accumulation of 3,350
                                                                             hours TIS, whichever
                                                                             is later.
AT-402/AT-402A..................  0694-0951..........  Greater than 1,750   Within the next 500              700
                                                        but less than or     hours TIS.
                                                        equal to 2,850.
AT-402/AT-402A..................  0694-0951..........  Less than or equal   Upon the accumulation            700
                                                        to 1,750.            of 2,250 hours TIS.
----------------------------------------------------------------------------------------------------------------

    (g) For all affected airplanes: Before further flight after the 
inspection in which cracks are found, replace any cracked wing lower 
spar cap following Snow Engineering Drawing Number 21088, dated 
November 3, 2004.
    (h) For Models AT-400, AT-401, AT-401B, and AT-402 airplanes, 
SNs 0952 through 1182: 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 April 21, 2006 (the effective date of AD 2006-08-08), 
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, SNs 0952 through 1182; and 
Model AT-402B airplanes, SNs 0966 through 1182: 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 as specified in the 
alternative method of compliance in AD 2006-08-08, which is approved 
for this AD (see paragraph (o) of this AD for more information).
    (k) For all affected airplanes (those complying with the actions 
in the AD or alternative method of compliance (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
    (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

[[Page 14470]]

[GRAPHIC] [TIFF OMITTED] TR31MR09.000

BILLING CODE 4910-13-C

Special Flight Permit

    (l) Under 14 CFR 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.

Alternative Methods of Compliance (AMOCs)

    (m) The Manager, Fort Worth or Los Angeles Airplane 
Certification Office (ACO), FAA, has the authority to approve AMOCs 
for this AD, if requested using the procedures found in 14 CFR 
39.19. 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. For AMOC approval, send information to ATTN:
    (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, Fort 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;

[[Page 14471]]

telephone: (562) 627-5228; facsimile: (562) 627-5210.
    (n) AMOCs approved for AD 2001-10-04, AD 2001-10-04 R1, or AD 
2002-11-05 for the AT-400 series airplanes are not considered 
approved for this AD.
    (o) AMOCs approved for the repetitive inspection requirements of 
AD 2006-08-08 are approved for this AD until the scheduled 
modification date required by this AD. That AMOC was included in AD 
2006-08-08 and can be found in the docket at: http://
www.regulations.gov/fdmspublic/component/
main?main=DocketDetail&d=FAA-2006-23646.

Material Incorporated by Reference

    (p) You must use Snow Engineering Co. 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, to do the 
actions required by this AD, unless the AD specifies otherwise.
    (1) On April 21, 2006 (71 FR 19986, April 19, 2006) the Director 
of the Federal Register approved the incorporation by reference of 
Snow Engineering Co. 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, under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) For service information identified in this AD, contact Air 
Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374; telephone: 
(940) 564-5616; facsimile: (940) 564-5612; Internet: http://
www.airtractor.com; or Marburger Enterprises, Inc., 1227 Hillcourt, 
Williston, North Dakota 58801; telephone: (800) 893-1420 or (701) 
774-0230; facsimile: (701) 572-2602.
    (3) You may review copies of the service information 
incorporated by reference for this AD at the FAA, Central Region, 
Office of the Regional Counsel, 901 Locust, Kansas City, Missouri 
64106. For information on the availability of this material at the 
Central Region, call (816) 329-3768.
    (4) You may also review copies of the service information 
incorporated by reference for this AD 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.

Appendix 1 to AD 2006-08-08 R1

    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. SA00490LA.
    What if I removed the Marburger winglets prior to further flight 
after April 21, 2006 (the effective date of AD 2006-08-08) or prior 
to April 21, 2006 (the effective date of AD 2006-08-08)?
    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 Marburger STC No. 
SA00490LA. 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, SN 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, SN 
1022 airplane.
    3. Determine the winglet usage factor from paragraph (c)(4) of 
this AD.

    Example: Again, your airplane is a Model AT-401B, SN 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 April 21, 
2006 (the effective date of AD 2006-08-08) 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, SN 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, SN 
1022 airplane.
    3. Determine the winglet usage factor from paragraph (c)(4) of 
this AD.

    Example: Again, your airplane is a Model AT-401B, SN 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. (6,777 hours TIS)- (6,155 hoursTIS) = (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.

    Issued in Kansas City, Missouri, on March 24, 2009.
John Colomy,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E9-7068 Filed 3-30-09; 8:45 am]

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