AD 97-11-51 R1

On May 12, 1997, the Federal Aviation Administration (FAA) issued telegraphic airworthiness directive (AD) T97-11-51, applicable to Pratt & Whitney (PW) PW2000 series turbofan engines, which supersedes AD 97-09-01 by correcting errors in the Serial Number (S/N) tables, and removing the McDonnell Douglas C-17 aircraft from the applicability section, as a different model engine is installed on McDonnell Douglas C-17 aircraft. In addition, that AD clarifies that inspections must be performed prior to rework, and clarifies that new parts do not need to be reworked prior to installation, but must be reworked at the next shop visit. Finally, that AD makes minor editorial changes for clarity without changing meaning or intent. That action was prompted by comments from the manufacturer received in response to AD 97-09-01 that require the FAA to issue immediate changes and corrections to the compliance section prior to initiating the inspection and rework programdescribed in the AD 97-09-01. Airworthiness directive 97-09-01 was prompted by reports of two uncontained disk failures resulting from a fir tree lug fracturing, that subsequently released two blades and a fir tree lug, that penetrated the engine high pressure turbine (HPT) case. That condition, if not corrected, could result in fracture of the first stage HPT disk, resulting in a possible uncontained engine failure and damage to the aircraft. Since the issuance of that telegraphic AD, the FAA has received changes from the manufacturer to the inspection program that would provide relief to operators while maintaining an equivalent level of safety. The FAA has reviewed and approved the technical contents of PW Service Bulletin (SB) No. PW2000 72-588, Revision 1, dated March 31, 1997, and Original, dated February 17, 1997, that describe procedures for inspections for cracks in the forward face of the first stage HPT disk at the base of the fir tree lug at the outer diameter (OD)snap fillet radius where the side plates mate with the disk utilizing an eddy current inspection technique, and PW Alert Service Bulletin (ASB) No. PW2000 A72-592, dated March 18, 1997, that describes procedures for rework to the forward and aft faces of the first stage HPT disk OD snap fillet radii at the base of the fir tree lug. Since an unsafe condition has been identified that is likely to exist or develop on other engines of this same type design, this AD revises telegraphic AD T97-11-51 to relax the compliance intervals for rework and provide relieving requirements by adding an optional double independent eddy current inspection. The actions are required to be accomplished in accordance with the service documents described previously. Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days. Comments Invited Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspectsof the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket. Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 97-ANE-25-AD." The postcard will be date stamped and returned to the commenter. The regulations adopted herein will not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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: