02-32659. Airworthiness Directives; General Electric Company CF6-50 Series Turbofan Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The Federal Aviation Administration (FAA) proposes to adopt a new airworthiness directive (AD) that is applicable to General Electric Company (GE) CF6-50 series turbofan engines. This proposal would require removal from service of eight serial number (SN) low pressure turbine (LPT) stage 1 disks, part number (P/N) 9061M21P03, at the next engine shop visit. This proposal is prompted by a report of the potential for iron-rich inclusions introduced during manufacture in the affected disks. The actions specified by the proposed AD are intended to prevent LPT stage 1 disk cracking, due to iron-rich inclusions introduced during manufacture, leading to uncontained disk failure.

DATES:

Comments must be received by February 25, 2003.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2002-NE-35-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may be inspected at this location, by appointment, between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. Comments may also be sent via the Internet using the following address: “[e-mail]”. Comments sent via the Internet must contain the docket number in the subject line.

FOR FURTHER INFORMATION CONTACT:

Karen Curtis, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone: [phone], fax: [phone].

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 action 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 action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2002-NE-35-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRM's

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. 2002-NE-35-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

In November of 2000, the FAA became aware that a CF6-80C2 engine high pressure turbine disk was rejected at inspection because it was cracked. GE and the disk supplier investigated and determined that the crack resulted from the presence of an iron-rich inclusion that was inadvertently introduced into the lot of INCO 718 disk material during the manufacturing melt process. GE and the disk supplier have since identified another lot that potentially had iron-rich inclusions introduced during the manufacturing melt process. That lot was used to manufacture eight CF6-50 engine LPT stage 1 disks. GE and the disk supplier have since coordinated and implemented corrective actions to prevent inclusions from being introduced in the manufacturing melt process.

On November 30, 2001, GE issued service bulletin (SB) SB 72-1225, requesting that operators remove the eight suspect disks from service at the next engine shop visit. On January 7, 2002, GE issued All Operators Wire No. 02.CF6/002, again informing the operators of the above SB, recommending removal of the suspect disks from service, and requesting report back of the disk removal date to GE. Currently, not all of the eight disks have been reported as having been removed or scheduled for removal. This condition, if not corrected, could result in LPT stage 1 disk cracking, leading to uncontained disk failure.

FAA's Determination of an Unsafe Condition and Proposed Actions

Since an unsafe condition has been identified that is likely to exist or develop on other CF6 series turbofan engines of a similar type design and manufacturing sequence, the proposed AD would require removal from service of CF6-50 LPT stage 1 disks, P/N 9061M21P03, SN's SNL17693, SNL17694, SNL44200, SNL47624, SNL47625, SNL47626, SNL47627, and SNL47628 at the next engine shop visit after the effective date of the AD.

Economic Analysis

There are approximately 2,101 CF6-50 series turbofan engines of the affected design in the worldwide fleet. The FAA estimates that no more than eight of the 469 engines installed on airplanes of U.S. registry would be affected by this proposed AD. The FAA also estimates that it would take approximately 32 work hours per engine to perform the proposed actions, and that the average labor rate is $60 per work hour. Required parts would cost approximately $75,490 per engine. Based on these figures, the total cost of the proposed AD to eight U.S. operators is estimated to be $619,280.

Regulatory Analysis

This proposed rule does not have federalism implications, as defined in Executive Order 13132, because it would not have a substantial direct effect 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. Accordingly, the FAA has not consulted with state authorities prior to publication of this proposed rule.

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.

39.13

[Amended]

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

General Electric Company: Docket No. 2002-NE-35-AD.

Applicability

This airworthiness directive (AD) is applicable to General Electric Company CF6-50 series turbofan engines with low pressure turbine (LPT) stage 1 disks, part number (P/N) 9061M21P03, serial numbers (SN's) SNL17693, SNL17694, SNL44200, SNL47624, SNL47625, SNL47626, SNL47627, and SNL47628 installed. These engines are installed on, but not limited to Airbus Industrie A300, Boeing 747, and McDonnell Douglas DC-10 airplanes.

Note 1:

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 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

Compliance with this AD is required as indicated, unless already done.

To prevent LPT stage 1 disk cracking due to the potential for iron-rich inclusions introduced during manufacture, leading to uncontained disk failure, do the following:

(a) Remove from service LPT stage 1 disks P/N 9061M21P03, SN's SNL17693, SNL17694, SNL44200, SNL47624, SNL47625, SNL47626, SNL47627, and SNL47628 at the next engine shop visit.

(b) After the effective date of this AD, do not install any of the LPT stage 1 disks listed in paragraph (a) of this AD into any engine.

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

Special Flight Permits

(d) Special flight permits may be issued in accordance with §§ 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 done.

Issued in Burlington, Massachusetts, on December 20, 2002.

Jay J. Pardee,

Manager, Engine and Propeller Directorate, Aircraft Certification Service.