AD 2006-08-09

The FAA is adopting a new airworthiness directive (AD) for all Air Tractor, Inc. (Air Tractor) Models AT-802 and AT-802A airplanes. This AD requires you to repetitively inspect (using the eddy current method) the two outboard fastener holes in both of the wing main spar lower caps at the center splice joint for cracks and repair or replace any cracked spar cap. This AD results from in-service fatigue cracking of the wing main spar lower cap at the center splice joint outboard fastener hole at hours time-in-service below the safe life limit established for these airplanes in AD 2002-11-05. We are issuing this AD to detect and correct cracks in the wing main spar lower cap at the center splice joint, which could result in failure of the spar cap and lead to wing separation and loss of control of the airplane.

Final rule; request for comments.

2006-08-09 Air Tractor, Inc.: Amendment 39-14565; Docket No. FAA- 2005-20591; Directorate Identifier 2005-CE-14-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- 400 series airplanes.

What Airplanes Are Affected by This AD?

(c) This AD affects Model AT-802 and AT-802A airplanes, all serial numbers beginning with 802-0001, that are:

(1) Certificated in any category;

(2) Engaged in agricultural dispersal operations including those airplanes that have been converted between fire fighting and agricultural dispersal;

(3) Not equipped with thefactory-supplied computerized fire gate (part number 80540); and

(4) Not engaged in full-time fighting only.

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 Service Information Must I Use To Do the Actions Required by This AD?

(e) You must use the following Snow Engineering Co. service information to do the actions required by this AD:

(1) Process Specification 197, page 1, revised June 4, 2002; pages 2 through 4, dated February 23, 2001; and page 5, dated May 3, 2002;

(2) Process Specification 204, Rev. C, dated November 16, 2004;

(3) Service Letter 215, page 5, titled "802 Spar Inspection Holes and Vent Tube Mod," dated November 19, 2003;
(4) Service Letter 240, dated September 30, 2004;

(5) Service Letter 244, dated April 25, 2005;

(6) Drawing Number 20975, Sheet 2, Rev. A, dated September 1, 2004;

(7) Drawing Number 20975, Sheet 3, dated January 6, 2005; and

(8) Drawing Number 20995, Sheet 2, Rev. C., dated September 28, 2004.

What Must I Do To Address This Problem?

(f) At the initial inspection time specified in paragraph (f)(2) of this AD, do the following:

(1) For the affected airplanes listed in Table 1 in paragraph (f)(2) of this AD, gain access for the required inspection listed below by installing cover plates following Service Letter 215, page 5, titled "802 Spar Inspection Holes and Vent tube mod," dated November 19, 2003.

(2) For the following airplanes, eddy current inspect the center splice joint outboard two fastener holes in both the right and left wing main spar lower caps for cracks following Process Specification 197.For these airplanes, use the following wing spar lower cap hours time-in-service (TIS) schedule to do the initial and repetitive inspections:

Table 1.--Inspection Times

Serial No.
Condition
Initially inspect:
Repetitively inspect thereafter at intervals not to exceed:

(i) 802 0001 through 802 0091.
As manufactured
Upon accumulating 1,700 hours TIS or within 50 hours TIS after April 21, 2006 (the effective date of this AD), whichever occurs later.
850 hours TIS.

(ii) 802 0001 through 802
0091.
Modified with cold-worked fastener holes following Service Letter #244.
If performing the cold-working procedure in Service Letter #244, it includes the eddy current inspection.
1,700 hours TIS.

(3) One of the following must do the inspection:

(i) 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

(ii) 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.

(g) For all affected airplanes listed in paragraphs (f)(2)(i) and (f)(2)(ii) of this AD as terminating action for the inspection requirements, you may modify your wing by installing part number (P/ N) 20997-2 web plate and P/N 20985-1 and 20985-2 extended 8-bolt splice blocks following Drawing 20995, Sheet 2, and cold-working the outboard two fastener holes in both the left and right hand lower spar caps at the center splice joint following Service Letter 240.

(h) For all affected airplanes listed in paragraphs (f)(2)(i) and (f)(2)(ii) of this AD, repair or replace any cracked spar cap before further flight after the inspection in which cracks are found. For repair or replacement, do whichever of the following that applies:

(1) For cracks that can be repaired by incorporating the terminating action specified in paragraph (g) of this AD, do the actions in paragraph (g) of this AD before further flight after the inspection in which cracks are found.

(2) For cracks that cannot be repaired by incorporating the terminating action specified in paragraph (g) of this AD, replace the lower spar caps and associated parts listed in paragraph (i) of this AD before further flight after the inspection in which cracks are found.

(i) For all AT-802 and AT-802A airplanes, upon accumulating the hours TIS on the wing spar lower caps listed in paragraph (i)(3) of this AD or within 50 hours TIS after April 21, 2006 (the effective date of this AD), whichever occurs later, replace the wing main spar lower spar caps, the center joint splice blocks and hardware, the wing attach angles and hardware, and install the steel web splice plate (P/N 21106-1 for serial numbers 0001 through -0091, and P/N 20094-2 for all serial numbers beginning with 0092), unless already done. Replace as follows:

(1) For airplane serial numbers 802-0001 through 802-0091, follow Drawing Number 20975, Sheet 3, and Process Specification 204.

(2) For airplane serial numbers beginning with 802-0092, follow Drawing Number 20975, Sheet 2, and Process Specification 204.

(3) The following presents the safe life and replacements times as required in paragraph (i) of this AD:

Table 2.--Safe Life and Replacement Times

Serial No.
Wing spar lower cap safe-life
AT 802 0001 through AT 802 0059
4,132 hours TIS.
AT 802 0060 through AT 802 0091
4,188 hours TIS.
All begining with AT 802 0092
8,163 hours TIS.
AT 802A 0001 through AT 802A 0059
4,969 hours TIS.
AT 802A 0060 through AT 802 0091
4,531 hours TIS.
All beginning with AT 802A 0092
8,648 hours TIS.

(j) After replacing the wing spar lower caps and hardware, installing the web splice plate, and cold working the fastener holes by following Drawing Number 20975, Sheet 3 (serial numbers 802-0001 through 802-0091), or Sheet 2 (all serial numbers beginning with 802-0092), and Process Specification 204, the new safe-life for wing spar lower caps is as follows:

Table 3.--New Safe Life for Wing Spar Lower Caps

Serial No.
Wing spar lower cap safe-life
All beginning with AT 802 0001
8,163 hours TIS.
All beginning with AT 802A 0001
8,648 hours TIS.

(k) Report any cracks you find within 10 days after the cracks are found or within 10 days after April 21, 2006 (the effective date of this AD), whichever occurs later.

(1) Include in your report the aircraft serial number, aircraft TIS, wing spar cap TIS, crack location and size, corrective action taken, and a point of contact name and phone number. Send your report to Andrew McAnaul, Aerospace Engineer, ASW-150 (c/o MIDO-43), 10100 Reunion Place, Suite 650, San Antonio, Texas 78216; telephone: (210) 308-3365; fascimile: (210) 308-3370.

(2) The Office of Management and Budget (OMB) approved the information collection requirements contained in ths regulation under the provisions of the Paperwork Reduction Act and assigned OMB Control Number 2120-0056.

May I Request an Alternative Method of Compliance?

(l) The Manager, Fort Worth Airplane Certification Office, FAA, has the authority to aprove alternative methods of compliance for this AD, if requested using the procedures found in 14 CFR 39.19. For information on any already approved alternative methods of compliance or for information pertaining to this AD, contact Andrew McAnual, Aerospace Engineer, ASW-150 (c/o MIDO-43), 10100 Reunion Place, suite 650, San Antonio, Texas 78216; telephone: (210) 308- 3365; facsimile: (210) 308-3370.

(m) AMOCs approved for AD 2001-10-04, AD 2001-10-04 R1, or AD 2002-11-05 for the Models AT-802 and AT-802A 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 References?

(o) You must do the actions required by this AD following the instructions in 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; Snow Engineering Co. Process Specification 204, Rev. C, dated November 16, 2004; Snow Engineering Co. Service Letter 215, page 5, titled "802 Spar Inspection Holes and Vent Tube Mod," dated November 19, 2003; Snow Engineering Co. Service 240, dated September 30, 2004; Snow Engineering Co. Service Letter 244, dated April 25, 2005; Snow Engineering Co. Drawing Number 20975, Sheet 2, Rev. A, datedSeptember 1, 2004; Snow Engineering Co. Drawing Number 20975, Sheet 3, dated January 6, 2005; and Snow Engineering Co. Drawing Number 20995, Sheet 2, Rev. C., dated September 28, 2004. The Director of the Federal Register approved the incorporation by reference of this service information in accordance with 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. 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 20590-0001 or on the Internet at http://dms.dot.gov. The docket number FAA-2005-20591; Directorate Identifier 2005-20591; Directorate Identifier 2005-CE-14-AD.

What is the background of the subject matter?

There have been five previous airworthiness directives (ADs) issued related to the wing spar inspection and safe life on Air Tractor airplanes:

AD 2000-14-51, Amendment 39-11837 (65 FR 46567, July 31, 2000).

AD 2001-10-04, Amendment 39-12230 (66 FR 27014, May 16, 2001).

AD 2001-10-04 R1, Amendment 39-12247 (66 FR 2990, June 4, 2001).

AD 2002-11-05, Amendment 39-12766 (67 FR 37967, May 31, 2002).

AD 2002-26-05, Amendment 39-12991 (68 FR 18, January 2, 2003).

AD 2000-14-51: An Air Tractor Model AT-502A experienced an in- flight wing separation. As a result, the FAA issued AD 2000-14-51 as an emergency AD. This AD required the inspection of the wing lower spar cap for cracks on Air Tractor Models AT-501, AT-502, and AT-502A airplanes and modification or replacement of any cracked wing lower spar cap. Following the release of this AD, the manufacturer evaluated the AT-400 and AT-800 series lower spar cap fatigue life.

AD 2001-10-04: The manufacturer recalculated the fatigue life of the wing lower spar cap on Air Tractor AT-400, AT-500, and AT-800 series airplanes. The manufacturer also received reports of in-service cracks on airplanes with hours time-in-service (TIS) less than the published safe life. The cracks originated in the wing main spar lower cap at the center splice joint outboard \3/8\-inch bolt hole. To address this condition, we issued AD 2001-10-04 to lower the safe life for the wing lower spar cap on Air Tractor AT-400, AT-500, and AT-800 series airplanes. The safe life for the wing lower spar cap ranged from a low of 3,000 hours TIS to a high of 13,300 hours TIS depending upon model and serial number. This AD superseded AT 2000-14-51 and allowed for inspection (using eddy current methods) of the wing lower spar cap for airplanes that were at or over the lower safe life and for which parts were not available. Operation of the airplane was not allowed if you found cracks or you reached TIS limit.

AD 2001-10-04 R1: We inadvertently included those AT-800 series airplanes in the applicability of AD 2001-10-04 that were equipped with the factory-supplied computerized fire gate (part number 80540) and engaged in full-time firefighting. Consequently, we revised the AD to clarify that those airplanes were not affected.

AD 2002-11-05: In response to AD 2001-10-04 R1, we received a comment from the National Transportation Safety Board (NTSB) to recommend an eddy-current inspection requirement immediately before doing the two-part modification described in Snow Engineering Service letter 202, revised March 26, 2001. Doing the eddy current inspection before the modification makes the crack easier to detect and gives the mechanic an area to concentrate on during any post- modification inspections. We issued AD 2002-11-05 to minimize the possibility that a crack existing in a bolt hole before doing the modification was stillpresent after doing the modification. Additional analysis by the manufacturer also indicated the need to further reduce the safe life for certain AT-400 series airplanes and certain AT-500 series airplanes that either incorporate or have incorporated Marburger winglets. These winglets were installed following Supplemental Type Certificate (STC) No. SA00490LA. We developed criteria for determining what the new safe life would be for airplanes that either incorporate or have incorporated these winglets. The safe life was reduced for airplanes that either incorporate or have incorporated these winglets by a usage factor reduction that is applied to the basic safe life. We used this information and issued AD 2002-11-05 to supersede AD 2001-10- 04 R1 and require eddy-current inspections of the wing lower spar cap immediately before doing the replacement/modification to detect and correct any crack in a bolt hole before it extends to the modified center section of the wing. This AD furtherreduced the safe life for certain Models AT-401, AT-401B, AT-402, AT-402A, AT-402B, and AT-501 airplanes that incorporate or have incorporated Marburger winglets and removed the Models AT-502, AT-502A, AT-502B, and AT-503A airplanes from the applicability.

AD 2002-26-05: To address the Models AT-502, AT-502A, AT-502B, and AT-503A airplanes that were removed from AD applicability by AD 2002- 11-05, we issued AD 2002-26-05. This AD is still in effect and lowers the safe life and requires the eddy-current inspections of the wing lower spar cap immediately before doing the replacement/modification. This would allow you to detect and correct any crack in a bolt hole before it extends to the modified center section of the wing.

What has happened to initiate this AD action?

The FAA received reports of fatigue cracking found on three AT-400 series airplanes and on three Model AT-802A airplanes that were below the reduced safe life established in AD 2002-11-05. One of the AT-400 series airplanes had Marburger winglets and the other incident airplanes did not. Specifically:

One AT-400 series airplane equipped with winglets cracked at 5,340 hours TIS where the reduced safe life was 5,380 hours TIS. A second AT-400 series airplane cracked at 3,359 hours TIS where the reduced safe life was 4,589 hours TIS. A third AT-400 series airplane cracked at 4,176 hours TIS where the reduced safe life was 4,589 hours TIS, and the cracks were severe enough to not allow modification and required immediate wing spar replacement; and

One AT-802A airplane cracked at 2,378 hours TIS where the reduced safe 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; Process Specification 204, Rev. C, dated November 16, 2004; Service Letter 215, page 5, titled "802 Spar Inspection Holes and Vent Tube Mod," dated November 19, 2003; Service Letter 240, dated September 30, 2004; Service letter 244, dated April 25, 2005; Drawing Number 20975, Sheet 2, Rev. A, dated September 1, 2004; Drawing Number 20975, Sheet 3, dated January 6, 2005; and Drawing Number 20995, Sheet 2, Rev. C., dated September 28, 2004.

Snow Engineering Co. has a licensing agreement with Air Tractor that allows them to produce technical data to be used for Air Tractor products.

What are the provisions of this service information?

The service letters, process specifications, and drawings include procedures for:

Preparing the airplane and the eddy current machine for inspection of the lower wing spar caps;

Inspecting the lower wing spar caps for cracks;

Verifying suspected cracks for steel lower wing spar caps;

Installing a web plate and 8-bolt splice block to repair cracks and as terminating action for inspections; and

Replacing the spar caps and associated hardware.

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 Model AT-802 and AT-802A 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-400 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 incorporate the actions in the previously referenced service information. This AD requires you to use the service information described previously to perform these actions.

This AD changes the inspection interval to address the additional cracking found and base the inspection intervals on damage tolerance analysis. It also provides a terminating action to the inspection requirement and adds serial numbers produced after we issued AD 2002- 11-05. It also retains the safe life for the AT-800series airplanes currently addressed in AD 2002-11-05.

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-2005-20591; Directorate Identifier 2005-CE-14-AD" in the subject line of your comments. If you want us to acknowledge receipt of your mailed comments, send us a self-addressed, stamped postcard with the docket number written on it; we will date-stamp your postcard and mail it back

to you. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify it. If a person contacts us through a non- written communication, and that contact relates to a substantive part of this AD, we will summarize the contact and place the summary in the docket. We will consider all comments received by the closing date and may amend the AD in light of those comments.

Authority for This Rulemaking

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

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, Section 106 describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the agency's authority.

We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, "General requirements." Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this AD.

Regulatory Findings

Will this AD impact various entities?

We have determined that this AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.

Will this AD involve a significant rule or regulatory action?

For the reasons discussed above, I certify that this AD:

1. Is not a "significant regulatory action" under Executive Order 12866;

2. Is not a "significant rule" under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and

3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

We prepared a summary of the costs to comply with this AD (and other information as included in the Regulatory Evaluation) and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include "AD Docket FAA-2005-20591; Directorate Identifier 2005-CE-14-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

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

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 adding the following new airworthiness directive (AD):