Airworthiness Directives; General Electric Company CT58 Series Turboshaft Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive that would supersede two existing airworthiness directives (AD's), applicable to General Electric Company (GE) CT58 series turboshaft engines. The current AD's revised the counting method for hours in repetitive heavy-lift (RHL) service and reduced the life limit for rotating components. Life-limited rotating components must be removed from service in accordance with the multiplying factors and retirement lives contained in General Electric Alert Service Bulletin (ASB) CT58 A72-162 (CEB-258), dated July 9, 1979. This proposal would require applying an additional multiplying factor to life-limited rotating parts when the engine is used in heavy lifting operations. This proposal is prompted by a review of the current AD's, 69-23-02 and 79-23-04, and a determination that the requirements of those AD's may conflict. This AD would prevent RHL and utility service multiplier factors from being applied incorrectly. The actions specified in the proposed AD are intended to prevent low-cycle fatigue failure of rotating parts that could result in uncontained engine failure and damage to the helicopter.

DATES:

Comments must be received by June 2, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-NE-13-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: “9-ane-adcomment@faa.gov”. Comments sent via the Internet must contain the docket number in the subject line. 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 GE Aircraft Engines, General Electric Company, 1000 Western Avenue, Lynn, MA 01910. This information may be examined at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT:

Kevin Donovan, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7743, fax (781) 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 99-NE-13-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. 99-NE-13-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

On November 4, 1969, the Federal Aviation Administration (FAA) issued airworthiness directive (AD) 69-23-02, Amendment 39-870 (34FR 18296, November 15, 1969), to reduce the life limits for stage 2 compressor rotor disk shafts and to remove from service stage 2 compressor rotor disk shafts before reaching those reduced life limits. That action was prompted by analyses that indicated the need for a reduced life-limit for certain life-limited parts when the engine is used in repetitive heavy lift (RHL) operations. That condition, if not corrected, could result in low-cycle fatigue failure of rotating parts that could result in uncontained engine failure and damage to the helicopter.

On December 13, 1979, the Federal Aviation Administration (FAA) issued airworthiness directive (AD) 79-23-04, Amendment 39-3610 (44 FR 72103, December 13, 1979), to require that the life-limits of certain life-limited rotating parts be revised based on multiplying factors specified in GEAE alert service bulletin (ASB) (CT58) 72-162 CEB 258, dated July 9, 1979, for RHL operations. That action was prompted by the need for lower life limits for life-limited rotating parts that are installed on engines used for RHL operations. That condition, if not corrected, could result in low-cycle fatigue failure of rotating parts that could result in uncontained engine failure and damage to the helicopter.

Events Since the Issuing of AD 69-23-02 and AD 79-23-04

Since the issuance of those AD's, the FAA has determined that some operators may be applying the multiplying factors for RHL operations incorrectly because the requirements of AD 79-23-04 apparently conflict with the requirements of AD 69-23-02. The requirements contained in AD 79-23-04 should have superseded the hourly life limits contained in AD 69-23-02 and should have specified the use of GEAE ASB (CT58) 72-162 CEB 258 for all CT58 series engines.

Service Information

The FAA has reviewed and approved the technical contents of GEAE ASB (CT58) 72-162 CEB 258, revision 9, dated October 6, 1998, that describes procedures for calculating revised cyclic life limits from the hourly life limits based on multiplying factors when the engine is used in RHL and utility service operation.

Requirements of the Proposed AD

Since an unsafe condition has been identified that is likely to exist or develop on other GEAE CT58 series turboshaft engines of the same type design, this AD supersedes AD 69-23-02 and AD 79-23-04 to require calculation of life cycles for life-limited rotating parts based on multipliers for RHL and utility service operation, and replacement of any part that exceeds the revised limits. The actions are required to be accomplished in accordance with the service bulletin described previously.

Economic Impact

There are approximately 380 engines of the affected design in the worldwide fleet. The FAA estimates that 130 engines installed on aircraft of U.S. registry would be affected by this proposed AD, that it would take approximately 0.25 work hour per engine to accomplish the proposed calculations, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $1,950.

Regulatory Impact

This proposed rule does not have federalism implications, as defined in Executive Order (EO) No. 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 EO No. 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.