E7-22329. Airworthiness Directives; Boeing Model 747 Series Airplanes Powered by General Electric (GE) CF6-45/50, Pratt & Whitney (P&W) JT9D-70, or JT9D-7 Series 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 certain Boeing Model 747 series airplanes powered by GE CF6-45/50, P&W JT9D-70, or JT9D-7 series engines. That action would have required repetitive inspections to find cracks and broken fasteners of the inboard and outboard nacelle struts of the rear engine mount bulkhead, and repair, if necessary. For certain airplanes, that action would have provided for an optional terminating modification for the inspections of the outboard nacelle struts. Since the issuance of the NPRM, the Federal Aviation Administration (FAA) has received new data of other issues related to the unsafe condition. The data include many new reports of additional web and frame cracks and sheared attachment fasteners, and reports of cracks on the outboard struts of airplanes not identified in the applicability of the NPRM, in addition to the comments received for the NPRM. We have determined from these data that the corrective actions required by the NPRM are inadequate for addressing the identified unsafe condition. Accordingly, the proposed rule is withdrawn.

FOR FURTHER INFORMATION CONTACT:

Tamara Anderson, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; 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 certain Boeing Model 747 series airplanes powered by General Electric (GE) CF6-45/50, Pratt & Whitney (P&W) JT9D-70, or JT9D-7 series engines, was published as a notice of proposed rulemaking (NPRM) in the Federal Register on January 9, 2002 (67 FR 1167). The proposed rule would have required repetitive inspections to find cracks and broken fasteners of the inboard and outboard nacelle struts of the rear engine mount bulkhead, and repair, if necessary. For certain airplanes, the proposed rule would have provided for an optional terminating modification for the inspections of the outboard nacelle struts. That action was prompted by reports indicating that fatigue cracking of the inboard and outboard nacelle struts of the rear engine mount bulkhead was found. The proposed actions were intended to find and fix cracks and broken fasteners of the inboard and outboard nacelle struts, which could result in possible loss of the bulkhead load path and consequent separation of the engine from the airplane.

Actions That Occurred Since the NPRM Was Issued

Since the issuance of the NPRM, the Federal Aviation Administration (FAA) has received new data of other issues related to the unsafe condition. The data include many new reports of additional web and frame cracks and sheared attachment fasteners, and reports of cracks on the outboard struts of airplanes not identified in the applicability of the NPRM, in addition to the comments received for the NPRM. We have determined from these data that the corrective actions required by the NPRM are inadequate for addressing the identified unsafe condition. Therefore, we are issuing a new rulemaking to adequately address the identified unsafe condition.

FAA's Conclusions

Upon further consideration, the FAA has determined that the corrective actions required by the NPRM are inadequate for addressing the identified unsafe condition. Accordingly, the proposed rule is hereby withdrawn.

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

Regulatory Impact

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 2001-NM-40-AD, published in the Federal Register on January 9, 2002 (67 FR 1167), is withdrawn.

Issued in Renton, Washington, on November 7, 2007.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.