AD 97-22-14

This amendment adopts a new airworthiness directive (AD) that is applicable to General Electric Company (GE) CF6-50 and -80C2 series turbofan engines. This action requires removal from service of defective high pressure compressor rotor (HPCR) stage 3-9 spools, and replacement with serviceable parts. This amendment is prompted by a report of an uncontained failure of an HPCR stage 3-9 spool installed on a GE model CF6-80C2 turbofan engine. The actions specified in this AD are intended to prevent failure of the HPCR stage 3-9 spool, which can result in an uncontained engine failure and damage to the aircraft.

Final rule; request for comments.

97-22-14 General Electric Company: Amendment 39-10186. Docket 97-ANE-52-AD.
Applicability: General Electric Company (GE) CF6-50 and -80C2 series turbofan engine, installed on but not limited to Boeing 767 and 747 series, McDonnell Douglas DC-10 and MD-11, and Airbus Industries A300 and A310 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 that the 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 failure of the high pressure compressor rotor (HPCR) 3-9 spool, which can result in an uncontained engine failure and damage to the aircraft, accomplish the following:
(a) Within 30 days after the effective date of this AD, remove from service HPCR 3-9 spools identified by serial number in the applicable service bulletin (SB), and replace with serviceable parts, as follows:
(1) For GE CF6-50 series turbofan engines, remove and replace in accordance with GE CF6-50 SB 72-A1139, dated October 17, 1997.
(2) For GE CF6-80C series turbofan engines, remove and replace in accordance with GE CF6-80C2 SB 72-A906, dated October 17, 1997.
(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) Special flight 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 SBs:

Document No.
Pages
Date
CF6-50 SB 72-A1139
1-7
October 17, 1997
Total pages: 7.

CF6-80C2 SB 72-A906
1-7
October 17, 1997
Total pages: 7.

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 Technical Services, Attention: Leader for distribution/microfilm, 10525 Chester Road, Cincinnati, OH 45215; telephone (513) 672-8400 Ext. 114, fax (513) 672-8422. Copies may be inspected at the FAA, New England Region, Office of the Assistant Chief 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 17, 1997.

The Federal Aviation Administration (FAA) has received a report of an uncontained failure of a high pressure compressor rotor (HPCR) stage 3-9 spool installed on a GE model CF6-80C2 turbofan engine. The investigation revealed that a crack initiated in the HPCR stage 3-9 spool and propagated in low cycle fatigue to rapid fracture and disk rupture. The crack initiated from an oxygen stabilized alpha region located in the area of the stage 3 dovetail blade slot and propagated radially inward to the disk bore. The FAA has determined that HPCR stage 3-9 spools produced from the same melt of material may also be affected. The investigation is continuing and pending the results of the investigation the requirements of this AD may be changed. This condition, if not corrected, could result in failure of the HPCR stage 3-9 spool, which can result in an uncontained engine failure and damage to the aircraft.
The FAA has reviewed and approved the technical contents of GE CF6-50 Service Bulletin (SB) 72-A1139, dated October 17, 1997, and GE CF6-80C2 SB 72-A906, dated October 17, 1997, that describe procedures for removal from service of defective HPCR 3-9 spools, and replacement with serviceable parts.
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 failure of the HPCR 3-9 spool. This AD requires, within 30 days after the effective date of this AD, removal from service of defective HPCR 3-9 spools, and replacement with serviceable parts. This calendar end-date was determined based upon risk analysis. The actions are required to be accomplished in accordance with the SBs 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-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: