AD 98-04-39

On November 7, 1996, the Federal Aviation Administration (FAA) issued airworthiness directive (AD) 96-23-14, Amendment 39-9820 (61 FR 63707, December 2, 1996), which supersedes ADs 87-11-07 R1 and 95-08-15, to require repetitive eddy current, fluorescent penetrant, fluorescent magnetic particle, or visual inspections for cracks in the rear flange, and ultrasonic, fluorescent penetrant, or fluorescent magnetic particle inspections for cracks in the PS4 boss, and drain bosses of the combustion chamber outer case (CCOC); and an additional inspection of the CCOC rear flange for intergranular cracking. In addition, AD 96-23-14 reduces the rear flange inspection interval for CCOCs when only the aft face of the rear flange has been inspected, and introduces an improved ultrasonic probe assembly. Also, AD 96-23-14 introduces a rotating eddy current probe for shop inspections in which the case is removed from the engine. Finally, AD 96-23-14 eliminates fluorescentpenetrant inspection (FPI), fluorescent magnetic particle inspection (FMPI), and visual inspections from hot section disassembly level inspection procedures. That action was prompted by reports of crack origins in the forward face of the rear flange that could not be detected by the inspection methods for installed CCOCs that were mandated in the superseded ADs 87-11-07 R1 and 95-08-15. That condition, if not corrected, could result in uncontained engine failure, inflight engine shutdown, engine cowl release, and airframe damage. Since the issuance of AD 96-23-14, the FAA has received reports of 13 defective ultrasonic inspection probes used to accomplish the ultrasonic inspections required by AD 96-23-14. Those 13 defective probes have been identified and removed from the field, but the engines inspected with the defective probes must be reinspected. Other ultrasonic inspection probes were either overhauled, repaired, or otherwise altered since original manufacture and were not subsequently functionally checked to insure that they met the necessary inspection sensitivity requirements. The calibration check contained in the ultrasonic inspection procedure does not serve as an adequate check to insure that the probe meets inspection sensitivity requirements. Currently, only PW has the capability to perform the necessary functional check to the proper standard. The FAA has reviewed and approved the technical contents of PW Alert Service Bulletin (ASB) No. A6202, Revision 1, dated January 4, 1996, that describes procedures for a borescope inspection of the CCOC rear flange for cracks. This ASB identifies applicability to engines installed on McDonnell Douglas DC-9 and Boeing 737 series engines only; however, the inspection requirements of paragraph 2.A.(5) of PW ASB No. A6202, Revision 1, dated January 4, 1996, are applicable to engines installed on Boeing 727 series aircraft as well. Since an unsafe condition has been identified that is likely to exist or develop on other engines of the same type design, this AD is being issued to prevent an uncontained engine failure. This AD requires a borescope inspection of engines, identified by serial number (S/N) that were ultrasonically inspected in accordance with AD 96-23-14 with defective probes. In addition, this AD requires a functional check at PW of all ultrasonic inspection probes that were overhauled, repaired, or otherwise altered since original manufacture and not subsequently functionally checked. The borescope inspection is required to be accomplished in accordance with the ASB 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 safetyand, 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 aspects of 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 98-ANE-04-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 regulationis 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) asfollows: 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: