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Proposed Rule

Airworthiness Directives; Pratt & Whitney JT9D-7R4 Series Turbofan Engines

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

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AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Proposed rule; withdrawal.

SUMMARY:

This action withdraws a supplemental notice of proposed rulemaking (SNPRM) that proposed a new airworthiness directive (AD) applicable to Pratt & Whitney (PW) JT9D-7R4 series turbofan engines. That action would have required the addition of initial and repetitive on-wing eddy current inspections (ECI) of affected diffuser case assembly bosses for cracks, and replacement of cracked bosses with serviceable parts. In addition, that action would have revised the initial accomplishment time for the previously proposed actions. Finally, that action would have added further etches, fluorescent penetrant inspections (FPIs), x-ray inspections, and shotpeening to the shop requirements, and would have provided an optional terminating action in the form of a redesigned diffuser case. The actions specified by the SNPRM were intended to prevent diffuser case assembly rupture, which could result in an uncontained engine failure, engine fire, and damage to the airplane. Since the issuance of the SNPRM, the FAA has reevaluated the safety risk to the fleet using the most recent fleet data , including the status of how much of the fleet has already undergone the modifications and inspections included in the proposed actions.. The drawdown period of the fleet management program that was originally proposed has been completed. All case assemblies continue to be inspected on-wing as part of normal maintenance actions. Therefore, the safety risk has been considerably reduced. As a result, the FAA has determined that an AD is no longer required, and the proposed rule is withdrawn.

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FOR FURTHER INFORMATION CONTACT:

Tara Goodman, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone: (781) 238-7130, fax: (781) 238-7199.

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SUPPLEMENTARY INFORMATION:

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add a new AD, applicable to PW JT9D-7R4 series turbofan engines, was published in the Federal Register on August 23, 1995 (60 FR 43730). That proposal would have required the removal of material from certain bosses on the diffuser case assembly, inspection of the reworked area using Flourscent Penetrant and x-ray methods, and shotpeening of the reworked area. That action was prompted by reports of cracks at the aft corners of bosses on the diffuser case assemblies.

The FAA received comment on the proposed rule, and in response to those comments and further analysis of the unsafe condition published a Supplemental Notice of Proposed Rulemaking (SNPRM) on December 8, 1997 (62 FR 64523). As supplemented the proposed rule would have required the addition of initial and repetitive on-wing eddy current inspection (ECI) of affected diffuser case assembly bosses for cracks, and replacement, if necessary, with serviceable parts. The proposed rule as supplemented also would have revised the initial accomplishment time for the previously proposed actions. Finally, the supplemented proposed rule would have added further etches, FPIs, x-ray inspections, and shotpeening to the shop requirements and would have provided an optional terminating action in the form of a redesigned diffuser case. The proposed actions were intended to prevent diffuser case assembly rupture, which could result in an uncontained engine failure, engine fire, and damage to the airplane.

Since the issuance of that SNPRM, the FAA has reevaluated the safety risk to the fleet using the most recent fleet data, including the status of how much of the fleet has already undergone the modifications and inspections included in the proposed actions. The drawdown period of the fleet management program that was originally proposed, which corresponds to the actions in the service bulletins, has been completed. All case assemblies continue to be inspected on-wing as part of normal maintenance actions. Therefore, the safety risk has been considerably reduced.

Upon further consideration, the FAA has determined that the unsafe condition no longer exists. Accordingly, the proposed rule is hereby withdrawn.

Withdrawal of this supplemental notice of proposed rulemaking constitutes only such action, and does not preclude the agency from issuing another notice in the future, nor does it commit the agency to any course of action in the future.

Since this action only withdraws a supplemental notice of proposed rulemaking, it is neither a proposed nor a final rule and therefore, is not covered under Executive Order 12866, the Regulatory Flexibility Act, or DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979).

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List of Subjects in 14 CFR Part 39

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The Withdrawal

Accordingly, the supplemental notice of proposed rulemaking, Docket 95-ANE-38, published in the Federal Register on December 8, 1997 (62 FR 64523), is withdrawn.

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Issued in Burlington, Massachusetts, on July 21, 2000.

Robert Guyotte,

Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.

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[FR Doc. 00-19074 Filed 7-27-00; 8:45 am]

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