AD 99-26-06

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to Pratt & Whitney (PW) JT8D-209, -217, -217A, -217C, and -219 series turbofan engines was published in the Federal Register on September 23, 1999 (64 FR 51483). That action proposed to require initial and repetitive fluorescent magnetic particle inspections or fluorescent penetrant inspections of the combustion chamber outer case (CCOC) for cracks, and, if necessary, replacement with serviceable parts. Also, that AD proposed to require a one-time boss material verification, and, if necessary, replacement with serviceable parts. Finally, that AD proposed to require replacement of CCOCs with welded-on bosses with improved, one-piece CCOCs. Installation of the one-piece CCOC would constitute terminating action to the inspection requirements of the AD. That action was prompted by a report of an uncontained engine failure caused by fatigue cracks originating at the weld joining the drain boss to the CCOC. That condition, if not corrected, could result in CCOC cracks, which could result in an uncontained engine failure and damage to the airplane. Comments Received Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. Understated Financial Impact One commenter states that the Federal Aviation Administration (FAA) has understated the financial impact the AD by not including the ancillary costs of removing a cracked CCOC. The FAA does not concur. The indirect costs associated with this AD are not directly related to this rule, and, therefore, are not addressed in the economic analysis for this rule. A full cost analysis for each AD, including such indirect costs, is not necessary since the FAA has already performed a cost benefit analysis when adopting the airworthiness requirements towhich these engines were originally certificated. A finding that an AD is warranted means that the original design no longer achieves the level of safety specified by those airworthiness requirements, and that other required actions are necessary, such as inspections of existing CCOCs and replacement with a one-piece CCOC. Because the original level of safety was already determined to be cost beneficial, these additional requirements needed to return the engine to that level of safety do not add any additional regulatory burden, and, therefore, a full cost analysis would be redundant and unnecessary. SB Publication Date vs. Effective Date of this AD The same commenter expresses confusion as to how to compute the compliance intervals of this AD; specifically, if the effective date of the AD should be used vs. the publication date of the SB for a compliance baseline. The FAA concurs. For the purpose of this AD, all baseline compliance times should be calculated based upon the effective date of this AD. The FAA has added an explanatory paragraph (c) to this final rule to explicitly address this issue. On-Wing Rejection of CCOC and Replacement of CCOC The same commenter states that there is no clear direction as to the time interval between an on-wing rejection and the subsequent removal of the CCOC. The FAA concurs. After an on-wing rejection, the CCOC must be removed prior to further flight. The FAA has added explicit phrasing to each inspection paragraph of this final rule to indicate that there is no operating interval between an on-wing rejection and the subsequent removal of the CCOC. Concurrence One commenter supports the rule as proposed. New Revision to Service Bulletin (SB) Since publication of the NPRM, PW has issued Revision 2 to SB No. 6291, dated August 27, 1999. The original version of PW SB No. 6291, dated May 20, 1997, Revision 1, dated July 9, 1997, or Revision 2, dated August 27,1999, are all acceptable for performing the terminating action of installing a one-piece machined CCOC assembly, part number (P/N) 815556, as stated in paragraph (d) of this final rule. Conclusion 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 as 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 2,624 engines of the affected design in the worldwide fleet. The FAA estimates that 1,280 engines installed on aircraft of US registry will be affected by this proposed AD, that it will take approximately 2.5 work hours per engine to accomplish the proposed inspections and that the average labor rate is $60 per work hour. Required parts will cost approximately $42,320 per engine. Based on these figures, the total cost impact of the AD on US operators is estimated to $54,361,600. Regulatory Impact The regulations adopted herein 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order (E.O.) 13132. For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under E.O. 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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from 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 the following new airworthiness directive: