AD 98-22-06

This amendment adopts a new airworthiness directive (AD) that is applicable to General Electric Company CF6-6, -45, -50, -80A, and -80C2 series turbofan engines. This action requires, prior to further flight, an ultrasonic immersion inspection for cracks in stage 1 fan disks, and, if necessary, replacement with serviceable parts. This amendment is prompted by reports of cracked fan disks found during routine shop inspections on fan disks manufactured between late 1984/early 1985. The actions specified in this AD are intended to prevent fan disk failure due to cracks, which could result in an uncontained engine failure and damage to the aircraft.

Final rule; request for comments.

98-22-06 General Electric Company: Amendment 39-10853. Docket 98-ANE-52 -AD.

Applicability: General Electric Company (GE) CF6-6, -45, -50, -80A, and -80C2 series turbofan engines, with stage 1 fan disks installed, identified by serial numbers (S/Ns) in the following GE Alert Service Bulletins (ASBs): CF6-6 ASB 72-A996, Revision 4, dated June 9, 1998; CF6-50 ASB 72-A988, Revision 6, dated August 25, 1998; CF6-80A ASB 72-A565, Revision 5, dated June 9, 1998; and CF6-80C2 ASB 72-A478, Revision 4, dated June 9, 1998. These engines are installed on but not limited to Boeing 747 and 767, Airbus A300 and A310, McDonnell Douglas DC-10 and McDonnell Douglas MD-11 series aircraft.

Note 1: This airworthiness directive (AD) applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so thatthe performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (b) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent fan disk failure due to cracks, which could result in an uncontained engine failure and damage to the aircraft, accomplish the following:

(a) Prior to further flight, perform an ultrasonic immersion inspection for cracks of affected stage 1 fan disks, and, if necessary, replace with serviceable parts, as follows:

(1) For GE CF6-6 series engines, in accordance with GE CF6-6 ASB 72-A996, Revision 4, dated June 9, 1998.

(2) For GE CF6-45 and -50 series engines, in accordance with GE CF6-50 ASB 72-A988, Revision 6, dated August 25, 1998.

(3) For GE CF6-80A series engines, in accordance with CF6-80A ASB 72-A565, Revision 5, dated June 9, 1998.

(4) For GE CF6-80C2 series engines, in accordance with CF6-80C2 ASB 72-A478, Revision 4, dated June 9, 1998.

(5) Remove from service cracked fan disks and replace with serviceable parts.

(b) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Engine Certification Office. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Engine Certification Office.

Note 2: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Engine Certification Office.

(c) Specialflight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the requirements of this AD can be accomplished.

(d) The actions required by this AD shall be done in accordance with the following GE ASBs:

Document No.
Pages
Revision
Date
CF6-6 ASB 72-A996
1-13
4
June 9, 1998
Total pages: 13.

CF6-50 ASB 72-A988
1-13
6
August 25, 1998
Total pages: 13.

CF6-80A ASB 72-A565
1-13
5
June 9, 1998
Total pages: 13.

CF6-80C2 ASB 72-A478
1-13
4
June 9, 1998
Total pages: 13.

This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from General Electric Company via Lockheed Martin Technology Services, 10525 Chester Road, Suite C, Cincinnati, OH 45215; telephone (513) 672-8400, fax (513) 672-8422. Copies may be inspected at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(e) This amendment becomes effective on November 23, 1998.

The Federal Aviation Administration (FAA) has received reports of three stage 1 fan disks installed on General Electric Company (GE) CF6 series turbofan engines found cracked during routine shop inspections. The investigation revealed that these fan disks contained titanium impurities including hard alpha or other high density inclusions that can be introduced during the manufacturing process. Fatigue cracks can originate in the area of inclusions and propagate in service to disk failure. These fan disks were manufactured from "older material," defined as triple melt titanium alloys made prior to late 1984/early 1985, when significant titanium melting, forging, and inspection process improvements were introduced. Approximately 90 fan disks manufactured from the older material remain unaccounted for at this time and may be introduced into service or be in service. Previous recommendations for immersion ultrasonic inspection by the manufacturer to theoperators (via service bulletins, wires, etc.) have failed to identify the location or status of these disks. This condition, if not corrected, could result in fan disk failure due to cracks, which could result in an uncontained engine failure and damage to the aircraft.

The FAA has reviewed and approved the technical contents of the following GE Alert Service Bulletins (ASBs), that describe procedures for ultrasonic immersion inspection for cracks: CF6-6 ASB 72-A996, Revision 4, dated June 9, 1998, CF6-50 ASB 72-A988, Revision 6, dated August 25, 1998, CF6-80A ASB 72-A565, Revision 5, dated June 9, 1998, and CF6-80C2 ASB 72-A478, Revision 4, dated June 9, 1998.

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 fan disk failure. This AD requires, prior to further flight, an ultrasonic immersion inspection for cracks in stage 1 fan disks, and, if necessary, replacement with serviceable parts. The actions are required to be accomplished in accordance with the ASBs 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 thisrule 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-52-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: