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 supersedes AD 2005-15-05, amendment 39-14194 (70 FR 42267, July 22, 2005). The existing AD applies to certain Airbus Model A300-600 series airplanes. That NPRM was published in the Federal Register on June 21, 2006 (71 FR 35575). That NPRM proposed to require an inspection for evidence of chafing between the hydraulic flexible hose and the ram air turbine (RAT) hub, and related investigative and corrective actions if necessary.
Comments
We provided the public the opportunity to participate in the development of this AD. We have considered the comments that have been received on the NPRM.
Request To Provide Chafe Limits in the AD
Air Transport Association (ATA) of America, on behalf of its member, FedEx, requests that we provide the chafe limits for the RAT hub cover in the AD to ensure clarity for compliance purposes. FedEx points out that Airbus Service Bulletin A300-29-6054, Revision 02, dated January 12, 2006 (the appropriate source of service information for accomplishing the required actions), specifies evaluating any damage to the hub cover in accordance with Hamilton Sundstrand Component Maintenance Manual (CMM) 29-21-21. FedEx reviewed CMM 29-21-21 and did not find any discussion of chafing damage. FedEx points out that the CMM addresses only dent limits and scratches. FedEx also points out that, for scratches, the CMM gives repair instructions for those under 0.005 inch in depthor requires replacement, but the CMM gives no serviceable limit. FedEx would like to know if it can assume, since chafing is not specifically addressed in the CMM, that the RAT must be removed immediately and replaced, or if the scratch damage criteria apply. FedEx queried both Hamilton Sundstrand and Airbus for clarification, but states that no publications have yet been revised to provide a reasonable amount of clarity.
Since we issued the NPRM, Hamilton Sundstrand incorporated into CMM 29-21-21, dated March 6, 2006, values that clarify the damage limits for the RAT hub cover, as follows:
Check criteria, page 505 (check number 35); and
Repair, page 601 (repair number 16).
CMM 29-21-21 and Airbus Service Bulletin A300-29-6054, Revision 02, state that all external scores, smooth dents, and abrasions that do not include cracks, and that meet the requirement of Flag 1 and Flag 2 of CMM 29-21-21, Figure 818, are acceptable and do not require further action. If damage exceeds the limits provided in Figure 818 of the CMM, the CMM specifies that the cover should be repaired in accordance with CMM 29-21-21, repair number 13. Otherwise, the CMM specifies that the RAT be replaced. Both the CMM and paragraph (f) of the NPRM specify that repair and replacement must be done before further flight. However, operators may request approval of an alternative method of compliance (AMOC) by following the procedures in paragraph (h) of this AD. Since the CMM is secondary reference material, no change to the final rule is needed.
Request To Change Compliance Time
ATA, on behalf of its member, FedEx, requests that the time allotted for operators to accomplish the inspections be increased from 2,500 flight hours to 3,500 flight hours after the effective date of this AD. FedEx states that its A300 maintenance program currently requires heavy maintenance (C-check) to be performed at the earlier of every 3,500 flight hours or 30 months. FedEx states that, since thisRAT inspection has the potential for component replacement that cannot be performed at most line maintenance stations because of test equipment requirements, the longer compliance time would help FedEx to align the work with currently scheduled heavy maintenance checks. This longer compliance time would allow FedEx an additional 200 days (according to its utilization rate) to do the inspection in a heavy maintenance environment. FedEx notes that it began doing the inspections specified in the NPRM in June 2006, but has yet to experience any chafing problems.
We do not agree with the commenter's request to change the compliance time. In developing an appropriate compliance time for this action, we considered the urgency associated with the subject unsafe condition, the availability of required parts, and the practical aspect of accomplishing the required modification within a period of time that corresponds to the normal scheduled maintenance for most affected operators. However,operators may request approval of an alternative method of compliance (AMOC) by following the procedures in paragraph (h) of this AD to request a different compliance time if the request includes data that prove that the new compliance time would provide an acceptable level of safety. We have not changed the final rule in this regard.
Conclusion
We have carefully reviewed the available data, including the comments that have been submitted, and determined that air safety and the public interest require adopting the AD as proposed.
Costs of Compliance
The following table provides the estimated costs for U.S. operators to comply with this AD.
Estimated Costs
Action
Work hours
Average labor rate per hour
Cost per airplane
Number of U.S.-registered airplanes
Fleet cost
Inspection
1
$80
$80
120
$9,600
Rework binding
1
$80
$80
120
$9,600
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 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 39as 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 removing amendment 39-14194 (70 FR 42267, July 22, 2005) and by adding the following new airworthiness directive (AD):