03-22707. Airworthiness Directives; McDonnell Douglas Model MD-11 Series Airplanes

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 McDonnell Douglas Model MD-11 series airplanes. That action would have required an inspection to detect arcing damage of the electrical cables leading to the terminal strips and surrounding structure in the wing areas inboard of the pylons 1 and 3 and the No. 2 engine; and corrective actions, if necessary. That action also would have required revising the cable connection stackup of the terminal strips on the wings and No. 2 engine. Since the issuance of the NPRM, the Federal Aviation Administration (FAA) has received new data indicating that the identified unsafe condition specified in NPRM does not exist on the affected airplanes. Accordingly, the proposed rule is withdrawn.

FOR FURTHER INFORMATION CONTACT:

Brett Portwood, Aerospace Engineer, Systems and Equipment Branch, ANM-130L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712; 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 McDonnell Douglas Model MD-11 series airplanes, was published in the Federal Register as a Notice of Proposed Rulemaking (NPRM) on February 20, 2001 (66 FR 10844). The proposed rule would have required an inspection to detect arcing damage of the electrical cables leading to the terminal strips and surrounding structure in the wing areas inboard of the pylons 1 and 3 and the No. 2 engine; and corrective actions, if necessary. The proposed rule also would have required revising the cable connection stackup of the terminal strips on the wings and No. 2 engine. That action was prompted by an incident in which arcing occurred between the power feeder cables and support bracket of the terminal strips on a McDonnell Douglas Model MD-11 series airplane. The proposed actions were intended to prevent arcing damage to the terminal strips and damage to the adjacent structure in the wing areas inboard of the pylons 1 and 3 and the No. 2 engine, which could result in a fire inboard of the pylons 1 and 3 or the No. 2 engine.

Actions That Occurred Since the NPRM Was Issued

Since the issuance of that NPRM, the results of an FAA analysis have revealed that there is a lack of materials and fuels in the vicinity of the terminal strips and surrounding structure in the wing areas inboard of the pylons 1 and 3 and the No. 2 engine, and that a fire in that area is highly unlikely. The probable result is that a power feed arc in the pylon area would typically damage and pit the feeder line and, perhaps, damage and pit the terminal bracket at the chafing location. As the arc current level increases, the electrical power system differential fault protection would detect this condition and disconnect electrical loads supplied to that particular feeder. In addition, the flightcrew would be alerted to this condition, allowing the operator/owner to correct the problem at the next maintenance interval. On the basis of this analysis, we have determined that the potential arcing on the terminal strips in the wing areas inboard of the pylons 1 and 3 and the No. 2 engine does not constitute an unsafe condition.

FAA's Conclusions

Upon further consideration, we have determined that the identified unsafe condition does not exists on the affected airplanes. 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 2000-NM-192-AD, published in the Federal Register on February 20, 2001 (66 FR 10844), is withdrawn.

Issued in Renton, Washington, on August 29, 2003.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.