Airworthiness Directives: Air Tractor, Inc. Models AT-400, AT-401, AT-401B, AT-402, AT-402A, and AT-402B Airplanes
Federal Register: December 10, 2008 (Volume 73, Number 238)
Proposed Rules
Page 74999-75007
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
DOCID:fr10de08-16
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration 14 CFR Part 39
Docket No. FAA-2006-23646; Directorate Identifier 2006-CE-005-AD
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: Notice of proposed rulemaking (NPRM).
SUMMARY: We propose to revise Airworthiness Directive (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 proposed 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 proposing 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: We must receive comments on this proposed AD by February 9, 2009.
ADDRESSES: Use one of the following addresses to comment on this proposed AD:
Federal eRulemaking Portal: Go to http:// www.regulations.gov. Follow the instructions for submitting comments.
Fax: (202) 493-2251.
Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue, SE., Washington, DC 20590.
Hand Delivery: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.
For service information identified in this proposed AD, contact Air
Tractor, Inc., 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.
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:
Comments Invited
We invite you to send any written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include the docket number, ``FAA- 2006-23646; Directorate Identifier 2006-CE-005-AD'' at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed
AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.
We will post all comments we receive, without change, to http:// www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive concerning this proposed AD.
Discussion
An Air Tractor Model AT-502A experienced an in-flight wing separation. As a result, the FAA issued AD 2000-14-51 as an emergency
AD. That 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. Since the release of that AD, the manufacturer has evaluated the AT-400, AT- 500, AT-600, and AT-800 series lower spar cap fatigue life.
AD 2006-08-08 currently requires you to repetitively eddy current inspect the wing lower spar cap for fatigue cracks 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 winglets, lowers the safe life for the wing lower spar cap.
Since we issued AD 2006-08-08, we have received updated inspection intervals for fatigue cracks for the Models AT-401B, AT-402A, and AT- 402B airplanes based on a revised damage tolerance analysis. Any occurrence of 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 following table contains AD actions that address the wing spar safe life of the Air Tractor airplane fleet:
Page 75000
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.
Relevant Service Information
We have reviewed this Snow Engineering Co. service information:
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.
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.
FAA's Determination and Requirements of the Proposed AD
We are proposing this AD because we evaluated all information and determined the unsafe condition described previously is likely to exist or develop on other products of the same type design. This proposed AD would revise AD 2006-08-08 with a new AD that would not only retain the actions AD 2006-08-8, but would reduce the number of repetitive inspections for:
All affected Model AT-401B airplanes;
Model AT-402A airplanes, all serial numbers beginning with 0952; and
Model AT-402B airplanes, all serial numbers beginning with 0966.
This proposed AD would require you to use the service information described previously to perform these actions.
Costs of Compliance
We estimate that this AD affects 343 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........... $171,500 to
$274,400.
* 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
Labor cost
Parts cost
per 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 rulemaking action.
Regulatory Findings
We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government.
For the reasons discussed above, I certify that the proposed regulation: 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
Page 75001
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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 regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket.
Examining the AD Docket
You may examine the AD docket that contains the proposed AD, the regulatory evaluation, any comments received, and other information on the Internet at http://www.regulations.gov; or in person at the Docket
Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone (800) 647-5527) is located at the street address stated in the ADDRESSES section.
Comments will be available in the AD docket shortly after receipt.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
The Proposed Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:
PART 39--AIRWORTHINESS DIRECTIVES 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] 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:
Air Tractor, Inc.: Docket No. FAA-2006-23646; Directorate Identifier 2006-CE-005-AD.
Comments Due Date
(a) We must receive comments on this AD action by February 9, 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:
Table 1--Safe Life for Airplanes That Do Not Incorporate and Never Have
Incorporated Marburger Winglets
Wing lower spar cap safe
Model
Serial Nos.
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 all beginning
7,777 with 1021.
AT-402......................... 0694 through 0951......
7,440
AT-402A........................ 0738 through 0951......
7,440
AT-402A........................ 0952 through 1020......
2,000
AT-402A........................ All beginning with 1021
2,300
AT-402B........................ 0966 through 1020,
2,000 except 1015.
AT-402B........................ 1015 and all beginning
2,300 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 safe 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 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.
(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 (m)(2) 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 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:
Page 75002
Table 2--Winglet Usage Factor To Determine the Safe Life for Airplanes
That Incorporate or Have Incorporated Marburger Winglets per STC No.
SA00490LA
Winglet
Model
Serial Nos.
usage factor
AT-401........................... 0662 through 0951.......
1.6
AT-401B.......................... 0952 through 1020,
1.1 except 1015.
AT-401B.......................... 1015 and all beginning
1.1 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 1021.
1.1
AT-402B.......................... 0966 through 1020,
1.1 except 1015.
AT-402B.......................... 1015 and all beginning
1.1 with 1021.
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, all serial numbers beginning with 0952, and Model AT- 402B, all serial numbers beginning with 0966, 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
Serial Nos.
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 equal to 6,250.
the 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
700 to 2,750.
accumulation of 3,250 hours TIS.
AT-401B......................... 0952-1020 except 1015 Greater than 3,950.. Within the next 50
600 hours TIS or upon the accumulation of 4,200 hours TIS, whichever is later.
AT-401B......................... 0952-1020 except 1015 Greater than 2,650
Within the next 250
600 but less than or
hours TIS or upon equal to 3,950.
the accumulation of 3,150 hours TIS, whichever is later.
AT-401B......................... 0952-1020 except 1015 Greater than 1,600
Within the next 500
600 but less than or
hours TIS. equal to 2,650.
AT-401B......................... 0952-1020 except 1015 Less than or equal
Upon the
600 to 1,600.
accumulation of 2,100 hours TIS.
Page 75003
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 equal to 4,450.
the 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.
AT-401B......................... 1015 and 1021-1124... Less than or equal
Upon the
600 to 1,850.
accumulation of 2,350 hours TIS.
AT-401B......................... All beginning with
Greater than 4,450.. Within the next 50
1,000 1125.
hours TIS or upon the accumulation of 4,700 hours TIS, whichever is later.
AT-401B......................... All beginning with
Greater than 3,000
Within the next 250
1,000 1125.
but less than or
hours TIS or upon equal to 4,450.
the accumulation of 3,500 hours TIS, whichever is later.
AT-401B......................... All beginning with
Greater than 1,850
Within the next 500
1,000 1125.
but less than or
hours TIS. equal to 3,000.
AT-401B......................... All beginning with
Less than or equal
Upon the
1,000 1125.
to 1,850.
accumulation 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 equal to 4,250.
the 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
700 to 1,750.
accumulation 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 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 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, 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 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 75004
GRAPHIC
TIFF OMITTED TP10DE08.002
BILLING CODE 4910-13-C
Mail report to: Manager, Fort Worth ACO, ASW-150, 2601 Meacham
Blvd., Fort Worth, TX 76193-0150; or fax to (817) 222-5960.
Special Flight Permit
(l) 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.
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.
Page 75005
(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: (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.
Related Information
(p) To get copies of the service information referenced 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.
Appendix 1 to Docket No. FAA-2006-23646
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, 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 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, 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.
(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 any time 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 Docket No. FAA-2006-23646
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
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Tractor, Inc. training course on Eddy Current Inspection on wing lower spar caps. 2. Repeat these inspections at intervals of (as applicable): a. 600 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 1112. 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{time} 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{time} hours TIS. The first of these inspections is due at {insert the total number of hours TIS the first of these inspections is due{time} 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{time} 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{time} 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. Repetitively thereafter inspect at intervals not to exceed: 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{time} 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{time} hours TIS. The first of these inspections is due at {insert the total number of hours TIS the first of these inspections is due{time} 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 or 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.
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, all S/Ns 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 listed 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 thereafter inspect at intervals not to exceed the appropriate interval listed
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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 December 4, 2008.
Kim Smith,
Manager, Small Airplane Directorate, Aircraft Certification Service.
FR Doc. E8-29165 Filed 12-9-08; 8:45 am
BILLING CODE 4910-13-P
