AD 98-20-18

Effective November 30, 1998, to all persons except those persons to whom it was made immediately effective by priority letter AD 98-20-18, issued on September 14, 1998, which contained the requirements of this amendment.

Comments for inclusion in the Rules Docket must be received on or before January 12, 1999.

Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Assistant Chief Counsel, Attention: Rules Docket No. 98-ANE-67-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: ``9-ad-[email protected]''. Comments sent via the Internet must contain the docket number in the subject line.

Diane Cook, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7133, fax (781) 238-7199.

On September 14, 1998, the Federal Aviation Administration (FAA) issued priority letter airworthiness directive (AD) 98-20-18, applicable to International Aero Engines (IAE) V2500-A1 series turbofan engines, which requires, prior to further flight, removal from service of affected high pressure turbine (HPT) disks, identified by part number and serial number in the applicability paragraph of this AD, and replacement with a serviceable part. That action was prompted by a report of an uncontained HPT disk failure on an IAE V2500-A1 series turbofan engine installed on an Airbus A320 series aircraft. Preliminary investigation of the recovered HPT stage 1 disk fracture surface indicates that the fracture initiated from a subsurface location in the disk bore area. The fractured part has been returned to IAE to continue the investigation. A review of manufacturing records has identified 6 additional HPT disks that were produced from the same or related material lot. There exists a possibility that these 6 disks produced from the same material lot could be similarly affected as the failed HPT disk. Therefore, the FAA has determined that these 6 disks must be immediately removed from service prior to further flight. This condition, if not corrected, could result in an HPT disk fracture, an uncontained engine failure, and damage to the aircraft.

Since the unsafe condition described is likely to exist or develop on other engines of the same type design, the FAA issued priority letter AD 98-20-18 to prevent HPT disk fracture. The AD requires, prior to further flight, removal from service of affected HPT disks, identified by part number and serial number in the applicability paragraph of this AD, and replacement with a serviceable part.

Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual letters issued on September 14, 1998, to all known U.S. owners and operators of IAE V2500-A1 series turbofan engines. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to Section 39.13 of part 39 of the Federal Aviation Regulations (14 CFR part 39) to make it effective to all persons.

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 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-67-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.

Air transportation, Aircraft, Aviation safety, Safety.

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:

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.