The FAA proposed to amend 14 CFR part 39 with a proposed AD. The proposed AD applies to GE CF6-45/-50 series turbofan engines. We published the proposed AD in the Federal Register on December 12, 2005 (70 FR 73391). That action proposed to require inspecting and refurbishing the side links of the five-link forward mount assembly at every exposure of the side link. That action also proposed to require the same actions on certain part number side links installed on CF6-80A turbofan engines.
Examining the AD Docket
You may examine the AD Docket (including any comments and service information), by appointment, between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. See ADDRESSES for the location.
Comments
We provided the public the opportunity to participate in the development of this AD. We have considered the comments received.
Definition of Exposure
One commenter proposes that the definition of exposure be revised as follows: " * * * removal of one or more bolts attaching the side links to the fan frame front HPC case or removal of the bolt attaching the side link to the mount platform while the engine is not installed." This commenter believes that the definition of exposure used in the proposed AD will create an undue burden on line maintenance operations, and will eliminate any on-wing maintenance on the link and associated hardware. They also believe the proposed definition will force operators to replace the link assembly even for bolt removal to facilitate other maintenance and unrelated minor discrepancies. We do not agree that the definition of exposure should be relaxed to facilitate on-wing maintenance. The opportunity for coating distress of the links occurs each time a bolt is removed, regardless of where or when the removal occurs. This definition of exposure protects against coating distress that can lead to stress corrosion cracking of the links. We did not change the AD.
Threshold Since Last Refurbishment
One commenter requests that a threshold since the last refurbishment be allowed and that exposure be further defined to allow for staggering of serviceable assemblies within a prescribed threshold since last refurbishment. This commenter believes that there may be instances where an operator staggers a serviceable mount assembly from one engine to another, without that assembly going into the shop. We do not agree that a threshold since the last refurbishment should be allowed to facilitate staggering of serviceable assemblies. The opportunity for coating distress occurs each time a side link bolt is removed, regardless of when the last refurbishment may have occurred. As noted above, this definition of exposure protects against coating distress that can lead to stress corrosion cracking of the links. We did not change the AD.
Clarification of Previous On-wing Inspection Requirement
One commenter requests clarification of the previous on-wing inspection requirement. This commenter notes that the original AD required an on-wing visual inspection and the proposed rule does not. They asked if this was intentional or an oversight. Although the proposed rule did not clearly state that the previous on-wing inspection requirement was being replaced by a shop-level inspection, the FAA's actions are intentional. The accomplishment instructions in the referenced service bulletins include fluorescent particle inspection or magnetic particle inspection as part of the refurbishment process required at each exposure. Experience proves that these in-shop inspections are more effective in detecting distress in the links than the previous on-wing visual inspection requirement. The requirement for refurbishment at each exposure in this final rule will prevent stress corrosion cracking of the links. We did not change the AD.
Conclusion
We have carefully reviewed the available data, including the comments received, and determinedthat air safety and the public interest require adopting the AD as proposed.
Costs of Compliance
We estimate that this AD will affect 195 engines installed on U.S. registered airplanes per year. We also estimate that it will take 8.0 workhours per engine to perform the actions, and that the average labor rate is $65 per workhour. This AD does not require parts. Based on these figures, we estimate the total cost of this AD to U.S. operators to be $101,400 per year.
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 summary of the costs to comply with this AD 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 No. 95-ANE-10-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
0 Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration 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 removing Amendment 39-9346 (60 FR 46758, September 8, 1995) and by adding a new airworthiness directive, Amendment 39-14650, to read as follows: