04-9593. Airworthiness Directives; Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Proposed rule; withdrawal.

SUMMARY:

This action withdraws a supplemental notice of proposed rulemaking (NPRM) that proposed a new airworthiness directive (AD), applicable to all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. That action would have superseded an existing AD that currently requires repetitive inspections to find cracks, fractures, or corrosion of each carriage spindle of the left and right outboard mid-flaps; and corrective action, if necessary. That action would also have mandated the previously optional overhaul or replacement of the carriage spindles, which would have ended the repetitive inspections required by the existing AD. Since the issuance of the supplemental NPRM, the Federal Aviation Administration (FAA) has issued another AD that adequately addresses the identified unsafe condition. Accordingly, the proposed rule is withdrawn.

FOR FURTHER INFORMATION CONTACT:

Robert Hardwick, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; 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 all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, was published as a supplemental notice of proposed rulemaking (NPRM) in the Federal Register on November 4, 2003 (68 FR 62409). The proposed rule would have superseded an existing AD that currently requires repetitive inspections to find cracks, fractures, or corrosion of each carriage spindle of the left and right outboard mid-flaps; and corrective action, if necessary. The proposed rule would also have mandated the previously optional overhaul or replacement of the carriage spindles, which would have ended the repetitive inspections required by the existing AD. That action was prompted by the FAA's determination to mandate the previously optional actions. The proposed actions were intended to prevent severe flap asymmetry due to fractures of the carriage spindles on an outboard mid-flap, which could result in reduced control or loss of controllability of the airplane.

Actions That Occurred Since the Supplemental NPRM Was Issued

Since the issuance of that supplemental NPRM, the FAA received a report of an in-service incident, which involved a dual failure that had been considered extremely improbable when the supplemental NPRM was drafted. To address the immediate safety concerns of this dual failure, we issued airworthiness directive (AD) 2003-24-08, amendment 39-13377 (68 FR 67027, December 1, 2003), applicable to all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, to require repetitive inspections to find cracks, fractures, or corrosion of each carriage spindle of the left and right outboard mid-flaps; and corrective action, if necessary. That AD also provides for an optional action of overhaul or replacement of the carriage spindles, which would extend the repetitive inspection interval.

We are currently considering superseding AD 2003-24-08 to mandate the optional overhaul or replacement of the carriage spindles and to add a maximum flight cycle life of carriage spindles, in addition to continuing the repetitive inspections.

FAA's Conclusions

Upon further consideration, the FAA has determined that the requirements of AD 2003-24-08 adequately addresses the identified unsafe condition specified in the supplemental NPRM. Accordingly, the supplemental NPRM is hereby withdrawn.

Withdrawal of this supplemental 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 supplemental NPRM, 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 supplemental notice of proposed rulemaking, Docket 2002-NM-219-AD, published in the Federal Register on November 4, 2003 (68 FR 62409), is withdrawn.

Issued in Renton, Washington, on April 20, 2004.

Ali Bahrami,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.