Airworthiness Directives; General Electric Company CF6-6, CF6-45, and CF6-50 Series Turbofan Engines

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with the substance of this proposal 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-41-AD.'' The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the

FAA, New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 98-ANE-41-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

On April 2, 1999, the Federal Aviation Administration (FAA) issued airworthiness directive (AD) 99-08-18, Amendment 39-11124 (64 FR 17958, April 13, 1999), to require revisions to the Time Limits Section of the manufacturer's Instructions for Continued Airworthiness (ICA) for General Electric Company (GE) CF6-6, CF6-45, and CF6-50 series turbofan engines to include required enhanced inspection of selected critical life-limited parts at each piece-part exposure.

New Inspection Procedures

Since the issuance of that AD, GE has developed additional focused inspection procedures. This proposal would add disk bore eddy current inspections (ECI) for the high pressure turbine rotor (HPTR) Stage 1 and 2 disks.

Proposed Actions

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would supersede AD 99-08-18 to add disk bore ECI for the HPTR Stage 1 and 2 disks at each piece-part opportunity.

Economic Analysis

The FAA estimates that 730 engines installed on airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 4 work hours per engine to accomplish the proposed new inspections, and that the average labor rate is $60 per work hour for a total approximate cost of $240 per engine. The FAA estimates that approximately 170 HPTR Stage 1 and 2 disks would be exposed to the piece-part level per year; therefore, the total annual cost for the added bore ECI is estimated to be $40,800.

Regulatory Impact

The regulations proposed herein would 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 proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. For the reasons discussed above, I certify that this proposed regulation (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing Amendment 39-11124 (64 FR 17958, April 13, 1999), and by adding a new airworthiness directive, to read as follows:

General Electric Company: Docket No. 98-ANE-41-AD. Supersedes AD 99- 08-18, Amendment 39-11124.

Applicability: General Electric Company (GE) CF6-6, CF6-45, and CF6-50 series turbofan engines, installed on but not limited to Airbus Industrie A300 series, Boeing 747 series, and McDonnell Douglas DC-10 series airplanes.

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 (c) 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 critical life-limited rotating engine part failure, which could result in an uncontained engine failure and damage to the airplane, accomplish the following:

Inspections

(a) Within the next 30 days after the effective date of this AD, revise the manufacturer's Time Limits Section of the Instructions for Continued Airworthiness (ICA), and for air carrier operations revise the approved continuous airworthiness maintenance program, by adding the following:

``MANDATORY INSPECTIONS

(1) Perform inspections of the following parts at each piece- part opportunity in accordance with the instructions provided in the applicable manual provisions:

------------------------------------------------------------------------ Inspect per engine Part nomenclature Part No. (P/N) shop manual chapter ------------------------------------------------------------------------ For CF6-6 Engines: Disk, Fan Rotor Stage One.. All............ 72-21-03 Paragraph 2.F. or Paragraph 2.A.B. Fluorescent- Penetrant Inspect, and 72-21-03 Paragraph 3 or 3.A. Eddy Current Inspection Disk, HPT Rotor Stage One.. All............ 72-53-03 Paragraph 1. One Fluorescent- Penetrant Inspect, and 72-53-03 Paragraph 4. Eddy Current Inspection of the HPTR Disk Rim Boltholes and 72-53- 03 Paragraph 5. Disk Bore Area Eddy Current Inspection Disk, HPT Rotor Stage Two.. All............ 72-53-04 Paragraph 1. Florescent-Penetrant Inspect, and Paragraph 4. Eddy Current Inspection of the Stage 2 HPTR Disk Rim Boltholes and 72- 53-04 Paragraph 5. Eddy Current Inspection of the Stage 2 Disk Inner Boltholes and 72-53- 04 Paragraph 6. Disk Bore Area Eddy Current Inspection For CF6-45, CF6-50 Engines:

Disk, Fan Rotor Stage One.. All............ Task 72-21-03-230-051 Fluorescent-Penetrant Inspection, and Task 72-21-03-250-002-052 Manual Eddy Current Inspection or 72-21- 03-250-003-053 Automated Eddy Current Inspection Disk, HPT Rotor Stage One.. All............ Task 72-53-03-230-001- 059 Fluorescent- Penetrant Inspect Disk, and Task 72-53- 03-250-052 Eddy Current Inspection of the HPTR Stage 1 Rim Boltholes, and Task 72-53-03-250-054 Disk Bore Area Eddy Current Inspection Disk, HPT Rotor Stage Two.. All............ Task 72-53-04-230-001- 057 Fluorescent- Penetrant Inspect Disk, and Task 72-53- 04-250-053 Eddy Current Inspection of the HPTR Stage 2 Rim and/or Inner Boltholes, and Task 72-53-04-250-056 Disk Bore Area Eddy Current Inspection ------------------------------------------------------------------------

(2) For the purposes of these mandatory inspections, piece-part opportunity means: (i) The part is considered completely disassembled when accomplished in accordance with the disassembly instructions in the manufacturer's engine manual; and (ii) The part has accumulated more than 100 cycles in service since the last piece-part opportunity inspection, provided that the part was not damaged or related to the cause for its removal from the engine.'' (b) Except as provided in paragraph (c) of this AD, and notwithstanding contrary provisions in section 43.16 of the Federal Aviation Regulations (14 CFR 43.16), these mandatory inspections shall be performed only in accordance with the Time Limits Section of the manufacturer's ICA.

Alternative Methods of Compliance

(c) 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 Engine Certification Office (ECO). Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector (PMI), who may add comments and then send it to the ECO.

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

Ferry Flights

(d) 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 airplane to a location where the requirements of this AD can be accomplished.

Continuous Airworthiness Maintenance Program

(e) FAA-certificated air carriers that have an approved continuous airworthiness maintenance program in accordance with the record keeping requirement of Sec. 121.369(c) of the Federal Aviation Regulations [14 CFR 121.369(c)] of this chapter must maintain records of the mandatory inspections that result from revising the Time Limits Section of the Instructions for Continuous Airworthiness (ICA) and the air carrier's continuous airworthiness program. Alternately, certificated air carriers may establish an approved system of record retention that provides a method for preservation and retrieval of the maintenance records that include the inspections resulting from this AD, and include the policy and procedures for implementing this alternate method in the air carrier's maintenance manual required by Sec. 121.369(c) of the Federal Aviation Regulations [14 CFR 121.369(c)]; however, the alternate system must be accepted by the appropriate PMI and require the maintenance records be maintained either indefinitely or until the work is repeated. Records of the piece-part inspections are not required under Sec. 121.380(a)(2)(vi) of the Federal Aviation Regulations [14 CFR 121.380(a)(2) (vi)]. All other Operators must maintain the records of mandatory inspections required by the applicable regulations governing their operations.

Note 3: The requirements of this AD have been met when the engine shop manual changes are made and air carriers have modified their continuous airworthiness maintenance plans to reflect the requirements in the engine shop manuals.

Issued in Burlington, Massachusetts, on September 30, 1999. David A. Downey, Assistant Manager, Engine and Propeller Directorate, Aircraft Certification Service. [FR Doc. 99-26209 Filed 10-6-99; 8:45 am] BILLING CODE 4910-13-P