AD 2008-08-07

We are adopting a new airworthiness directive (AD) for the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

A crack has been found in an axle adaptor during fatigue testing. It was found that the internal edges of the dowel holes did not have the correct radius and the crack had developed from the edge of one of the dowel holes.
A crack in the axle adaptor can cause the axle adaptor to fail and ultimately lead to loss of [the] wheels and total loss of brake capability.

We are issuing this AD to require actions to correct the unsafe condition on these products.

Final rule.

2008-08-07 Saab Aircraft AB: Amendment 39-15459. Docket No. FAA- 2007-29331; Directorate Identifier 2007-NM-136-AD.

Effective Date

(a) This airworthiness directive (AD) becomes effective May 19, 2008.

Affected ADs

(b) None.

Applicability

(c) This AD applies to the airplanes listed in paragraphs (c)(1) and (c)(2) of this AD, certificated in any category, unless equipped with main landing gear (MLG) shock struts modified in accordance with APPH Service Bulletin AIR83064-32-12 or AIR83022-32-32.
(1) Saab Model SAAB-Fairchild SF340A (SAAB/SF340A) airplanes, serial numbers (S/Ns) SF340A-004 through -159.
(2) Saab Model SAAB 340B airplanes, S/Ns 340B-160 through -459.

Subject

(d) Air Transport Association (ATA) of America Code 32: Landing Gear.

Reason

(e) The mandatory continuing airworthiness information (MCAI) states:

A crack has been found in an axle adaptor during fatigue testing. It was found that the internal edges of the dowelholes did not have the correct radius and the crack had developed from the edge of one of the dowel holes.
A crack in the axle adaptor can cause the axle adaptor to fail and ultimately lead to loss of [the] wheels and total loss of brake capability.

The corrective action includes doing repetitive ultrasonic inspections to detect cracking in the axle adaptor; replacing the axle adaptor if necessary; and ultimately doing the terminating action of inspecting and modifying the main landing gear (MLG) shock strut and axle adaptors. The inspection is a crack test. The modification includes measuring the dowel hole and corrective actions if necessary (replacing the axle adaptor, repairing the dowel hole), and, when accomplished, terminates the repetitive inspection requirements.

Actions and Compliance

(f) Unless already done, do the following actions.
(1) Within 8,000 flight cycles since the last MLG overhaul, or within 1,500 flight cycles, or 6 months after the effectivedate of this AD, whichever occurs latest: Inspect the MLG in accordance with the Accomplishment Instructions of Saab Service Bulletin 340-32-133, Revision 01, dated May 3, 2006. If any crack is found, before further flight: Replace the axle adaptor in accordance with the Accomplishment Instructions of Saab Service Bulletin 340-32-133, Revision 01, dated May 3, 2006.
(2) Repeat the inspection required by paragraph (f)(1) of this AD thereafter at intervals not to exceed 2,000 flight cycles until the terminating action required by paragraph (f)(3) of this AD is accomplished.
(3) Within 12,000 flight cycles after the effective date of this AD, or at the next MLG overhaul, whichever occurs earlier: Inspect and modify the MLG shock strut and axle adaptors in accordance with the Accomplishment Instructions of APPH Service Bulletin AIR83064- 32-12, Revision 3, dated April 26, 2006; or AIR83022-32-32, Revision 3, dated April 26, 2006; as applicable.
(4) Actions done before the effective date of this AD in accordance with the service bulletins listed in paragraphs (f)(4)(i), (f)(4)(ii), and (f)(4)(iii) of this AD, as applicable, are acceptable for compliance with the corresponding actions in this AD.
(i) Saab Service Bulletin 340-32-133, dated April 19, 2006.
(ii) APPH Service Bulletin AIR83064-32-12, dated January 2006; Revision 1, dated January 23, 2006; and Revision 2, dated March 30, 2006.
(iii) APPH Service Bulletin AIR83022-32-32, dated January 2006; Revision 1, dated January 23, 2006; and Revision 2, dated March 30, 2006.
(5) As of the effective date of this AD, no person may install an MLG shock strut having part number (P/N) AIR83022 or AIR83064, or axle adaptor having P/N AIR127308, AIR390226, or AIR130238, unless it has been inspected and modified in accordance with APPH Service Bulletin AIR83022-32-32 or AIR83064-32-12, as specified in paragraph (f)(3), (f)(4)(ii), or (f)(4)(iii) of this AD, as applicable.

FAA AD Differences

Note: This AD differs from the MCAI and/or service information as follows: No differences.

Other FAA AD Provisions

(g) The following provisions also apply to this AD:
(1) Alternative Methods of Compliance (AMOCs): The Manager, ANM- 116, International Branch, Transport Airplane Directorate, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to ATTN: Mike Borfitz, Aerospace Engineer, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 227-2677; fax (425) 227-1149. 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.
(2) Airworthy Product: For any requirement in this AD to obtain corrective actions from a manufacturer or other source, use these actions if they are FAA-approved. Corrective actions are considered FAA-approved if they are approved by the State of Design Authority (or their delegated agent). You are required to assure the product is airworthy before it is returned to service.
(3) Reporting Requirements: For any reporting requirement in this AD, under the provisions of the Paperwork Reduction Act, the Office of Management and Budget (OMB) has approved the information collection requirements and has assigned OMB Control Number 2120- 0056.

Related Information

(h) Refer to MCAI EASA Airworthiness Directive 2006-0263, dated August 29, 2006; Saab Service Bulletin 340-32-133, Revision 01, dated May 3, 2006; APPH Service Bulletin AIR83064-32-12, Revision 3, dated April 26, 2006; and APPH Service Bulletin AIR83022-32-32, Revision 3, dated April 26, 2006; for related information.

Material Incorporated by Reference

(i) You must use the service information specified in Table 1 of this AD to do the actions required by this AD, unless the AD specifies otherwise.
(1) The Director of the Federal Register approved the incorporation by reference of this service information under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) For service information identified in this AD, contact Saab Aircraft AB, SAAB Aircraft Product Support, S-581.88, Link[ouml]ping, Sweden.
(3) You may review copies at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or 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/cfr/ibr- locations.html.

Table 1.--Material Incorporated by Reference

Service Bulletin
Revision
Date
APPH Service Bulletin AIR83022-32-32
3
April 26, 2006
APPH Service Bulletin AIR83064-32-12
3
April 26, 2006
Saab Service Bulletin 340-32-133
01
May 3, 2006

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to the specified products. That NPRM was published in the Federal Register on September 28, 2007 (72 FR 55116). That NPRM proposed to correct an unsafe condition for the specified products. The MCAI states:

A crack has been found in an axle adaptor during fatigue testing. It was found that the internal edges of the dowel holes did not have the correct radius and the crack had developed from the edge of one of the dowel holes.
A crack in the axle adaptor can cause the axle adaptor to fail and ultimately lead to loss of [the] wheels and total loss of brake capability.

The corrective action includes doing repetitive ultrasonic inspections to detect cracking in the axle adaptor; replacing the axle adaptor if necessary; and ultimately doing the terminating action of inspecting and modifying the main landing gear (MLG) shock strut and axle adaptors. The inspection is a crack test. The modification includes measuring the dowel hole, and corrective actions if necessary (replacing the axle adaptor, repairing the dowel hole) and, when accomplished, terminates the repetitive inspection requirements. You may obtain further information by examining the MCAI in the AD docket.

Comments

We gave the public the opportunity to participate in developing this AD. We received no comments on the NPRM or on the determination of the cost to the public.

Clarification of Service Bulletin Revisions

We have revised paragraph (f)(5) of the final rule to clarify the applicable service bulletin revisions for the parts installation.

Conclusion

We reviewed the available data and determined that air safety and the public interest require adopting the AD with the change described previously. We determined that this change will not increase the economic burden on any operator or increase the scope of the AD.Differences Between This AD and the MCAI or Service Information

We have reviewed the MCAI and related service information and, in general, agree with their substance. But we might have found it necessary to use different words from those in the MCAI to ensure the AD is clear for U.S. operators and is enforceable. In making these changes, we do not intend to differ substantively from the information provided in the MCAI and related service information.
We might also have required different actions in this AD from those in the MCAI in order to follow our FAA policies. Any such differences are highlighted in a NOTE within the AD.

Costs of Compliance

We estimate that this AD will affect about 220 products of U.S. registry. We also estimate that it will take about 9 work-hours per product to comply with the basic requirements of this AD. The average labor rate is $80 per work-hour. Required parts cost would be negligible. Where the service information lists required partscosts that are covered under warranty, we have assumed that there will be no charge for these parts. As we do not control warranty coverage for affected parties, some parties may incur costs higher than estimated here. Based on these figures, we estimate the cost of this AD to the U.S. operators to be $158,400, or $720 per product.

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 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.
For the reasons discussed above, I certify 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 regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket.

Examining the AD Docket

You may examine the AD docket on the Internet at http:// www.regulations.gov; or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains the NPRM, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone (800) 647-5527) is 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.

Adoption of the Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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 AD: