A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that is applicable to Pratt & Whitney (PW) JT8D-200 series turbofan engines was published in the Federal Register on July 10, 2002 (67 FR 45680). That action proposed to require the installation of stops on the fan exit guide vane case in accordance with Pratt & Whitney (PW) service bulletin No. 6100, Revision 2, dated December 9, 1998.
Comments
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.
Exemption of Stops for Improved Fan Blade Incorporations
One commenter states that the fan exit guide vane case stops should not be required for engines that incorporate the improved fan blades required by AD 99-10-11. The commenter states that the installation of the improved fan blades prevents fan blade failures which cause fan case failures; therefore, the stops should not be required once the improved fan blades are incorporated.
The FAA does not agree. It is true that the fan blade modification mandated by AD 99-10-11 greatly improves the durability of the fan blades. However, the modifications cannot guarantee that a fan blade will never be released for any cause. Further, airworthiness standards for engines require that the design and construction of engines be such that failure of the most critical fan blade does not lead to an unsafe condition. Separation of the fan exit guide vane case from the fan duct assembly can lead to a number of unsafe conditions that hazard the aircraft. The intent of this AD is to return the engine to the level of safety prescribed by the airworthiness standards in the Code of Federal Regulations.
Change Definition of Shop Visit
Two commenters state that the definition of shop visit should be changed to exclude line-maintenance type shop visits.
The FAA agrees. The shop visit definition has been changed in this final rule.
Increased Operational Costs
One commenter states that the installation of the stops will add additional weight that will increase the operational costs associated with increased annual fuel requirements and therefore this AD should not be issued.
The FAA does not agree. While the annual fuel burn requirements may increase due to additional weight, the FAA has determined that this potential cost increase is outweighed by the increase in safety that will result from the lower risk of aircraft damage after the installation of the stops.
Applicability Clarification
One commenter states that the applicability section needs clarification to indicate which case and duct part numbers the stops must be installed on.
The FAA agrees. The applicability has been changed to state the part numbers for the cases and the ducts that will require the installation of the stops in the AD.
Allow Additional Options for RubberStrips
One commenter states that the AD should allow additional options for rubber strips on the forward ID of each stop to prevent vibration instead of using silicone and allow bolt hole clocking options for the stops. The commenter states that the silicone is cumbersome to apply and difficult to remove, and the clocking options are requested to prevent interference with brackets or case repairs.
The FAA does not agree. The FAA is not familiar with the details of the design changes being requested, however, we will evaluate them as an alternate method of compliance if submitted in accordance with paragraph (d) of this AD.
Previous SB Compliance To Constitute AD Compliance
One commenter requests that compliance with the previous SB's PW ASB 6100, Original and Revision 1, constitute compliance with the AD. Many of the commenter's engines have already complied to the earlier SB's.
The FAA agrees. Credit for compliance to earlier revisions of PW ASB 6100 has beenadded to this final rule.
Agreement With Proposal as Written
The National Transportation Safety Board agrees with the proposal as written.
After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes described previously. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.
Economic Analysis
There are approximately 1,346 PW JT8D-200 series engines of the affected design in the worldwide fleet. The FAA estimates that 821 engines installed on airplanes of U.S. registry would be affected by this AD. The FAA also estimates that it would take approximately 1.5 work hours per engine to perform the actions, and that the average labor rate is $60 per work hour. Required parts would cost approximately $5,200 per engine. Based on these figures, the total cost of the AD to U.S. operators is estimated to be $4,343,090.
Regulatory Analysis
This final rule does not have federalism implications, as defined in Executive Order 13132, because it would 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. Accordingly, the FAA has not consulted with state authorities prior to publication of this final rule.
For the reasons discussed above, I certify that this action (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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to 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.
39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive to read as follows: