02-21472. Airplane Engine Cowling Retention

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM); withdrawal.

SUMMARY:

The FAA is withdrawing a previously published Notice of Proposed Rulemaking (NPRM) (54 FR 38610, September 19, 1989) that would provide improved engine cowling retention for transport category airplanes by adding specific design requirements for cowling retention systems. The proposed rule would have promoted design and construction of cowling retention systems to withstand vibration, inertial loads, over-pressure, normal air loads, and thermal conditions of an engine compartment fire after failure or improper fastening of latching devices. We are withdrawing the proposed rule because the proposal has been surpassed by technological advances. The issues will be addressed by future regulatory action based on recommendations from the Aviation Rulemaking Advisory Committee, and will be harmonized with similar regulations in Europe and Transport Canada.

FOR FURTHER INFORMATION CONTACT:

Michael McRae, Propulsion and Mechanical Systems Branch, Federal Aviation Administration, telephone [phone], e-mail [e-mail].

SUPPLEMENTARY INFORMATION

Background

On September 19, 1989, the FAA published Notice of Proposed Rulemaking No. 89-25 (54 FR 38610) to propose an amendment to 14 CFR part 25, and invited public comment on the issue of engine cowling retention. Section 25.1193, Cowling and nacelle skin, addresses the design of engine cowlings, but does not address the single failure of a latch or hinge, or an improperly fastened latch. Several in-flight incidents of engine cowling separation resulted in damage to airplanes and property on the ground, and highlighted the need to re-evaluate the design and maintenance requirements applicable to engine cowlings. Notice No. 89-25 proposes to specify standards for failsafe criteria in the design of engine cowling retention systems, which would enable the systems to withstand the loss of a single latch and easily detect unlocked or improperly closed latches. The comment period for Notice No. 89-25 closed March 19, 1990.

Discussion of Comments

Fifteen commenters responded to the NPRM. In general, most commenters are in favor of the proposed requirement for direct visual inspection of cowling retention systems, and are not in favor of the proposed cockpit visual warning system. A few commenters suggest additional enhancements to the proposal.

Four commenters favor direct visual inspection of the cowling but oppose the cockpit visual warning system. One of these commenters states that the direct visual inspection makes redundant the proposed addition of a cockpit visual warning system. Another opposes the cockpit visual warning system stating that the system would not be justified economically or functionally. Others state that the cockpit visual warning system would be impractical, introduce the potential for false signal indications, add complexity, and increase potential for failures detrimental to safety.

One commenter states that the real problem is inadequate preflight inspections. Another commenter notes concern about the clarity of terms, and the low probability of a double failure condition of an engine fire and an unlatched latch. An additional commenter considers the fundamental problem to be the lack of preload and resulting wear, plus any accidental damage done while opening or closing the latch. In response to commenters' interest in direct visual inspections, the FAA continues to require pilots to determine that an aircraft is in a condition safe for flight and encourage an on-going focus on appropriate preflight inspections to uphold safety standards.

Commenters also express concern about harmonization of any engine cowling requirements. The withdrawal of Notice No. 89-25 will allow the FAA to consider harmonization concerns and address the issues more completely in future regulatory actions in consideration of recommendations developed within ARAC.

ICAO and Harmonization

The International Civil Aviation Organization (ICAO) established the International Standards and Recommended Practices to promote international cooperation towards the highest possible degree of uniformity in regulations and standards. The FAA and the Joint Aviation Authorities (JAA) of Europe came together to standardize their respective codes of regulation and identified a number of significant regulatory differences. Both consider harmonization a high priority. The FAA tasked ARAC with the harmonization effort. In 1999, the FAA and JAA agreed on a Fast Track Harmonization Program to expedite the standardization process. ICAO Resolution A29-3, Global Rule Harmonization, urges States to take positive action to promote global harmonization of national rules for application of ICAO standards. The FAA actively supports ICAO initiatives and programs to achieve a safe and efficient aviation system worldwide.

Reason for Withdrawal

The FAA is involved in eliminating unnecessary differences and harmonizing where practical similar requirements with the JAA and Transport Canada. The FAA finds that including the issues of Notice No. 89-25 within harmonization efforts assigned to ARAC will contribute to a more complete analysis of the issues and will better serve the public interest. We will propose future changes to the Code of Federal Regulations to achieve harmonization through an NPRM with an opportunity for public comment. Therefore, the FAA withdraws Notice No. 89-25, (54 FR 38610) published September 19, 1989.

Issued in Washington, DC, on August 16, 2002.

Ronald T. Wojnar,

Deputy Director, Aircraft Certification Service (AIR-1).