AD 2006-06-12

The FAA is adopting a new airworthiness directive (AD) for certain Aerospatiale Model ATR72 airplanes. This AD requires a one-time general visual inspection for contamination of the surface of the upper arms of the main landing gear (MLG) secondary side brace assemblies; and repetitive eddy current inspections for cracking of the upper arms, and related specified and corrective actions if necessary. This AD also mandates eventual replacement of aluminum upper arms with steel upper arms, which would end the repetitive inspections. This AD results from two reports of rupture of the upper arm of the MLG secondary side brace due to fatigue cracking. We are issuing this AD to prevent cracking of the upper arms of the secondary side brace assemblies of the MLG, which could result in collapse of the MLG during takeoff or landing, damage to the airplane, and possible injury to the flightcrew and passengers.

Final rule.

2006-06-12 Aerospatiale: Amendment 39-14521. Docket No. FAA-2005- 21909; Directorate Identifier 2005-NM-059-AD.

Effective Date

(a) This AD becomes effective May 1, 2006.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Aerospatiale Model ATR72-101, -102, -201, -202, -211, -212, and -212A airplanes, certificated in any category; except airplanes that have received ATR Modification 5522 in production.

Unsafe Condition

(d) This AD was prompted by two reports of rupture of the upper arm of the main landing gear (MLG) secondary side brace assembly due to fatigue cracking. We are issuing this AD to prevent cracking of the upper arms of the secondary side brace assemblies of the MLG, which could result in collapse of the MLG during takeoff or landing, damage to the airplane, and possible injury to the flightcrew and passengers.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliancetimes specified, unless the actions have already been done.

Inspections

(f) At the latest of the times specified in paragraphs (f)(1), (f)(2), and (f)(3) of this AD: Accomplish a general visual inspection for contamination of the surface of the upper arms of the MLG secondary side brace assemblies, and an eddy current inspection for cracking of the upper arms by doing all the actions specified in Parts A and B of the Accomplishment Instructions of Messier-Dowty Special Inspection Service Bulletin 631-32-178, Revision 1, dated September 30, 2004. Repeat the eddy current inspection at intervals not to exceed 800 flight cycles until accomplishment of paragraph (h) of this AD.

(1) Before the accumulation of 4,000 total flight cycles on the secondary side brace.

(2) Before the accumulation of 800 flight cycles on the secondary side brace since overhauled.

(3) Within 200 flight cycles after the effective date of this AD.

Note 1: For the purposes of this AD, a general visual inspection is: "A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.''

Related Specified and Corrective Actions

(g) If any cracking is found during any inspection required by paragraph (f) of this AD: Before further flight, replace the affected upper arm of the MLG secondary side brace assembly as specified in paragraph (g)(1) or (g)(2) of this AD.

(1) Replace the aluminum upper arm of the MLG secondary side brace assembly with a steel upper arm by doing the applicable actions specified in the Accomplishment Instructions of Messier- Dowty Service Bulletin 631-32-183, dated October 6, 2004. This replacement ends the repetitive inspections required by paragraph (f) of this AD for that side brace only.

(2) Replace the aluminum upper arm of the MLG secondary side brace assembly with a new or serviceable aluminum upper arm in accordance with a method approved by either the Manager, International Branch, ANM-116, Transport Airplane Directorate, FAA; or the Direction Generale de l'Aviation Civile (or its delegated agent). ATR Component Maintenance Manual, Chapter 32-18- 41, Revision 3, dated September 30, 2002, is one approved method. Accomplish a general visual inspection for contamination of the surface of the upper arm before the accumulation of 4,000 total flight cycles on the replacement aluminum upper arm, and if cracks are found, before further flight, replace the aluminum upper arm with a steel upper arm as required by paragraph (g)(1) of this AD. If no cracks are found, repeat the eddy current inspection thereafter at intervals not to exceed 800 flight cycles until accomplishment of paragraph (h) of this AD.

Terminating Action

(h) Replace all aluminum upper arms of the MLG secondary side brace assembly with steel upper arms by doing all the applicable actions in accordance with the Accomplishment Instructions of Messier-Dowty Service Bulletin 631-32-183, dated October 6, 2004; at the applicable time specified in paragraph (h)(1), (h)(2), (h)(3), or (h)(4) of this AD. Accomplishing this replacement ends the repetitive inspections required by paragraph (f) of this AD.

(1) For airplanes on which any upper arm has been overhauled before the effective date of this AD and on which Messier-Bugatti Service Bulletin 631-32-085, dated August 21, 1992, has not been accomplished, as of the effective date of this AD: Within 15,000 flight cycles or 96 months, whichever is first, since overhaul on the affected upper arm.

(2) For airplanes on which any upper arm has been overhauled before the effective date of this AD and on which Messier-Bugatti Service Bulletin 631-32-085, dated August 21, 1992, has been accomplished, as of the effective date of this AD: Within 18,000 flight cycles or 96 months, whichever is first, since overhaul on the affected upper arm.

(3) For airplanes on which any upper arm has not been overhauled and on which Messier-Bugatti Service Bulletin 631-32-085, dated August 21, 1992, has not been accomplished, as of the effective date of this AD: Before the accumulation of 15,000 total flight cycles on an upper arm since new, or within 96 months on an upper arm since new, whichever is first.

(4) For airplanes on which any upper arm has not been overhauled and on which Messier-Bugatti Service Bulletin 631-32-085, dated August 21, 1992, has been accomplished, as of the effective date of this AD: Before the accumulation of 18,000 total flight cycles on an upper arm since new, or within 96 months on an upper arm since new, whichever is first.

No Report Required

(i) Messier-Dowty Special Inspection Service Bulletin 631-32- 178, Revision 1, dated September 30, 2004, recommends sending an inspection report to Messier-Dowty, but this AD does not contain that requirement.

Parts Installation

(j) As of the effective date of this AD, no person may install, on any airplane, an aluminum upper arm of the MLG secondary side brace assembly, unless the applicable requirements specified in paragraphs (f) and (g) of this AD have been accomplished.

Alternative Methods of Compliance (AMOCs)

(k)(1) The Manager, International Branch, ANM-116, Transport Airplane Directorate, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(2) Before using any AMOC approved in accordance with 14 CFR 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office.

Related Information

(l) French airworthiness directive F-2004-164, dated October 13, 2004, also addresses the subject of this AD.

Material Incorporated by Reference

(m) You must use Messier-Dowty Special Inspection Service Bulletin 631-32-178, Revision 1, dated September 30, 2004; and Messier-Dowty Service Bulletin 631-32-183, dated October 6, 2004; as applicable; to perform the actions that are required by this AD, unless the AD specifies otherwise. Messier-Dowty Special Inspection Service Bulletin 631-32-178, Revision 1, dated September 30, 2004, contains the following effective pages:

Page No.
Revision level shown on page
Date shown on page
1 3, 5 9 .......
1 ..............
Sept. 30, 2004.
4 ...................
Original ....
May 3, 2004.

The Director of the Federal Register approved the incorporation by referenceof these documents in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Contact Aerospatiale, 316 Route de Bayonne, 31060 Toulouse, Cedex 03, France, for a copy of this service information. You may review copies at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., Room PL-401, Nassif Building, Washington, DC; on the Internet at http://dms.dot.gov ; or at the National Archives and Records Administration (NARA). For information on the availability of this material at the NARA, call (202) 741-6030, or go to http://www. archives.gov/federal-- register/code --of--federal-- regulations/ibr -- locations. html.

Examining the Docket

You may examine the airworthiness directive (AD) docket on the Internet at http://dms.dot.gov or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the street address stated in the ADDRESSES section.

Discussion

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to certain Aerospatiale Model ATR72 airplanes. That NPRM was published in the Federal Register on July 21, 2005 (70 FR 42003). That NPRM proposed to require a one- time general visual inspection for contamination of the surface of the upper arms of the main landing gear (MLG) secondary side brace assemblies; and repetitive eddy current inspections for cracking of the upper arms, and related specified and corrective actions if necessary. That NPRM also proposed to mandate eventual replacement of aluminum upper arms with steel upper arms, which would end the repetitive inspections.

Comments

We provided the public the opportunity to participate in the development of this AD. We have considered the comment received from one commenter.

Request To Change Number of U.S.-Registered Airplanes in Cost Section

American Airlines asks that we change the estimated number of U.S.- registered airplanes listed in the "Costs of Compliance'' section of the NPRM, which specifies that there are about 18 airplanes of U.S. registry affected by the AD. American Airlines states that this number is incorrect because his airline operates 29 Model ATR72-212 airplanes and 12 Model ATR72-212A airplanes in the U.S. American Airlines suggests that the figure for airplanes of U.S. registry be changed to add these airplanes.

We agree to change the estimated number of U.S. airplanes listed in the "Costsof Compliance'' section of the AD. The purpose of that section is only to `estimate' the number of airplanes affected by the AD. When an NPRM is written, we obtain the total number of U.S- registered airplanes from the Air Claims database, and that number frequently changes. The total number of U.S-registered airplanes is currently 53. We have changed the "Costs of Compliance'' section accordingly.

For clarification, the AD applies to Aerospatiale Model ATR72-101, -102, -201, -202, -211, -212, and -212A airplanes, certificated in any category; except airplanes that have received ATR Modification 5522 in production. We have made no change to the applicability specified in this AD.

Clarification of AMOC Paragraph

We have revised paragraph (k) of this AD to clarify the appropriate procedure for notifying the principal inspector before using any approved AMOC on any airplane to which the AMOC applies.

Conclusion

We have carefully reviewed the available data, including the comment that has been received, and determined that air safety and the public interest require adopting the AD with the changes described previously. These changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

This AD affects about 53 airplanes of U.S. registry.

The initial and repetitive inspections take about 1 work hour per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of the inspections for U.S. operators is $3,445, or $65 per airplane, per inspection cycle.

The replacement takes about 4 work hours per airplane (2 work hours per upper arm), at an average labor rate of $65 per work hour. Required parts cost about $4,948 per airplane ($2,474 per upper arm). Based on these figures, the estimated cost of the replacement for U.S. operators is $276,024, or $5,208 per airplane.

Authority for This Rulemaking

Title 49 of the United StatesCode 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 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 that this AD:

(1) Is not a "significant regulatory action'' under Executive Order 12866;

(2) Is not a "significant rule'' under 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. See the ADDRESSES section for a location to examine the regulatory evaluation.

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 Federal Aviation Administration (FAA) amends Sec. 39.13 by adding the following new airworthiness directive (AD):