01-12674. Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Proposed rule; withdrawal.

SUMMARY:

This action withdraws a notice of proposed rulemaking (NPRM) that proposed a new airworthiness directive (AD), applicable to Pratt & Whitney (PW) JT8D series turbofan engines. That action would have superseded an existing AD to require initial and repetitive borescope inspections for loss of fuel nozzle nut torque and nozzle support wear, and replacement or modification of the fuel nozzles at the next accessibility of the diffuser build group as terminating action to the inspections. That proposal was prompted by reports of loss of fuel nozzle nut torque and nozzle support wear. Since the issuance of that NPRM, the FAA has reevaluated the likelihood that the unsafe condition will exist or develop on other products of the same type design. Accordingly, the proposed rule is withdrawn.

FOR FURTHER INFORMATION CONTACT:

Tara Goodman, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add a new airworthiness directive (AD), applicable to PW JT8D series turbofan engines, was published in the Federal Register on May 1, 1998 (63 FR 24138). The proposed rule would have required initial and repetitive borescope inspections for loss of fuel nozzle nut torque and nozzle support wear, and replacement or modification of the fuel nozzles at the next accessibility of the diffuser build group as terminating action to the inspections. That action was prompted by reports of loss of fuel nozzle nut torque and nozzle support wear. The proposed actions were intended to prevent loss of fuel nozzle nut torque and nozzle support wear, which could result in a fuel leak and possible engine fire.

Since issuing that NPRM, the FAA has reevaluated the safety concerns that the proposed actions would have addressed using the most recent fleet data. Field experience shows that leaking fuel nozzles, which can lead to burn-through of the diffuser case, was a significant flight safety concern primarily at the number 7 location because of the proximity of oil lines. This is addressed by AD 95-02-16.

To date, there have not been any incidents of diffuser case burn-through due to fuel leakage across the fuel nozzle secondary seal where the fuel nozzle configuration is as prescribed by AD 95-02-16. There has been one incident where the fuel nozzle at the number 7 position has leaked due to loss of nut torque, ignited, and burned through the diffuser case. However, because the oil line fittings had been replaced in accordance with AD 95-02-16, there was no burn-through of the oil fittings and no oil fire. The following requirements of AD 95-02-16, are sufficient to mitigate the safety concern:

• Initial and repetitive inspections of the number 7 fuel nozzle and support assembly, AND
• Replacement of the number 7 fuel nozzle and support assembly with a more leak resistant configuration, AND
• Replacement of aluminum oil pressure and scavenge tube fittings with steel fittings, AND
• Replacement of an aluminum oil scavenge line bolt with a steel bolt.

Upon further consideration, the FAA has determined that there is no longer a likelihood that the unsafe condition will exist or develop on other products of the same type design, and as a result, superseding the existing AD is no longer required. Accordingly, the proposed rule is hereby withdrawn.

Withdrawal of this 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 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).

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Withdrawal

Accordingly, the notice of proposed rulemaking, Docket 97-ANE-59-AD, published in the Federal Register on May 1, 1998, (63 FR 24138), is withdrawn.

Issued in Burlington, Massachusetts, on May 10, 2001.

Francis A. Favara,

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