AD 95-8444

[Federal Register Volume 60, Number 66 (Thursday, April 6, 1995)] [Proposed Rules] [Pages 17487-17489] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 95-8444]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-ANE-10]

Airworthiness Directives; General Electric Company CF6 Series Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to General Electric Company (GE) CF6- 45/-50 series turbofan engines. This proposal would require an initial and repetitive on-wing visual inspection of the side links of the five- link forward mount assembly for cracks, and replacement of the side links and pylon attachment bolts, and inspection of the fail-safe bolt and platform lug, if the side links are found cracked. This proposal would also require a shop-level refurbishment of the side links as a terminating action to the on-wing inspection program. This proposal is prompted by four reports of cracked side links detected during routine engine shop visits. The actions specified by the proposed AD are intended to prevent a side link fracture, which could result in the failure of the second side link, or the forward engine mount pylon attachment bolts, and possible separation of the engine from the aircraft.

DATES: Comments must be received by May 8, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Assistant Chief Counsel, Attention: Rules Docket No. 95-ANE-10, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may be inspected at this location between 8:00 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. The service information referenced in the proposed rule may be obtained from General Electric Aircraft Engines, CF6 Distribution Clerk, Room 132, 111 Merchant Street, Cincinnati, OH 45246. This information may be examined at the FAA, New England Region, Office of the Assistant Chief Counsel, 12 New England Executive Park, Burlington MA.

FOR FURTHER INFORMATION CONTACT: Robert J. Ganley, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (617) 238-7138; fax (617) 238-7199.

SUPPLEMENTARY INFORMATION:

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 in triplicate 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 95-ANE-10.'' 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 [[Page 17488]] Assistant Chief Counsel, Attention: Rules Docket No. 95-ANE-10, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

This proposed airworthiness directive (AD) is applicable to the General Electric Company (GE) CF6-45/-50 series turbofan engines. The Federal Aviation Administration (FAA) has received four reports of cracked side links of the five-link forward mount assembly. These cracks were detected during routine engine shop visits. Metallurgical analysis performed on the fractured side links indicate that the cracking is the result of stress corrosion. Stress corrosion cracking occurs when the protective coating is locally missing, allowing corrosive materials to come in contact with the base material of the side link. Preliminary analysis conducted with a simulated side link failure indicates that the second side link, or the pylon attachment bolts depending on the type of aircraft, may not be capable of withstanding the resulting loads in this configuration. A shop-level refurbishment procedure exists which enhances the durability of the side links' protective coating, therefore reducing the chance of cracks due to stress corrosion. This condition, if not corrected, could result in a side link fracture, which could result in the failure of the second side link or the forward engine mount pylon attachment bolts, and possible separation of the engine from the aircraft. The requirements of this AD have been reviewed by the Transport Airplane Directorate. The FAA has reviewed and approved the technical contents of GE Aircraft Engines CF6-50 Service Bulletin No. 72-1092, dated November 18, 1994, that describes procedures for the initial and repetitive on- wing visual inspection and side link refurbishment. 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 require an initial and repetitive on-wing visual inspection of the side links of the five-link forward mount assembly for cracks, replacement of the side links and pylon attachment bolts, and inspection of the fail-safe bolt and platform lug, if side links are found cracked. This proposal would also require a shop-level refurbishment of the side links as a terminating action to the on-wing inspection program. The FAA estimates that 220 engines installed on aircraft of U.S. registry would be affected by this proposed AD, that it would take approximately 7.5 work hours per engine to accomplish the proposed actions, and that the average labor rate is $60 per work hour. The FAA has estimated that only a small percentage of parts will actually require replacement as a result of this AD, and therefore, has determined the parts cost to be negligible. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $99,000.

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 14 CFR 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

General Electric Company: Docket No. 95-ANE-10.

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

Note: This 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 use the authority provided in paragraph (d) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition, or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any engine from the applicability of this AD.

Compliance: Required as indicated, unless accomplished previously. To prevent a side link fracture, which could result in failure of the second side link, or the forward engine mount pylon attachment bolts, and possible separation of the engine from the aircraft, accomplish the following: (a) Inspect left-hand side links, Part Numbers (P/N) 9204M94P01, 9204M94P03, and 9346M99P01, and right-hand side links, P/N's 9204M94P02, 9204M94P04, and 9346M99P02, that have not had the side link refurbishment done in accordance with GE CF6-50 Task Numbered Shop Manual, GEK 50481, Chapter 72-23-11, including Temporary Revision No. 72-0821 and 72-0822, both dated November 1, 1994, as follows: (1) For side links that have not been previously inspected in accordance with GE Aircraft Engines (GEAE) CF6-50 Service Bulletin (SB) No. 72-1092, dated November 18, 1994, inspect in accordance with paragraph 2.A of GEAE CF6-50 SB No. 72-1092, dated November 18, 1994, prior to accumulating 350 cycles in service (CIS), or 750 hours time in service (TIS), after the effective date of this AD, whichever occurs earlier. (2) For side links that have been previously inspected in accordance with GEAE CF6-50 SB No. 72-1092, dated November 18, 1994, inspect in accordance with paragraph 2.A of GEAE CF6-50 SB No. 72- 1092, dated November 18, 1994, prior to accumulating 350 CIS, or 750 hours TIS since inspected in accordance with GEAE CF6-50 SB No. 72- 1092, dated November 18, 1994, whichever occurs earlier. (3) Thereafter, inspect in accordance with paragraph 2.A of GEAE CF6-50 SB No. 72-1092, dated November 18, 1994, at intervals [[Page 17489]] not to exceed 350 CIS, or 750 hours TIS since the last inspection, whichever occurs earlier. (4) If side links are found cracked, replace the cracked side links and pylon attachment bolts with serviceable parts, and inspect the fail-safe bolt and platform lug in accordance with paragraph 2.B of GEAE CF6-50 SB No. 72-1092, dated November 18, 1994, prior to further flight. (b) Refurbish the left-hand and right-hand side links identified in paragraph (a) of this AD at the next engine shop visit after the effective date of this AD in accordance with paragraph 2.C of GEAE CF6-50 SB No. 72-1092, dated November 18, 1994. Refurbishment of side links in accordance with this paragraph constitutes terminating action to the on-wing inspection requirements of paragraph (a) of this AD. (c) For the purpose of this AD, an engine shop visit is defined as the induction of an engine into a shop for maintenance involving the separation of the fan and core modules. (d) 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. The request should be forwarded through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Engine Certification Office.

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

Issued in Burlington, Massachusetts, on March 22, 1995. James C. Jones, Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service. [FR Doc. 95-8444 Filed 4-3-95; 1:31 pm] BILLING CODE 4910-13-P