02-10946. Airworthiness Standards: Aircraft Engines; Fuel and Induction Systems

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) that proposed to require fail-safe design features in the fuel control systems used on reciprocating aircraft engines. The proposal would have required the fuel-air mixture control device and the throttle control device to move automatically to an acceptable position for continued safe operation if the linkage to these devices becomes disconnected. Based upon comments and after further analysis of the issue, we are withdrawing Notice No. 92-14 because existing regulations adequately cover the issues contained in the NPRM, and Advisory Circular No. 20-143, Installation, Inspection, and Maintenance of Controls for General Aviation Reciprocating Aircraft Engines, issued on June 6, 2000, provides additional guidance on maintenance procedures.

FOR FURTHER INFORMATION CONTACT:

Bonnie Fritts, ARM-28, Office of Rulemaking, Federal Aviation Administration, 800 Independence Avenue, SW, Washington, DC 20591; telephone [phone]; e-mail [e-mail].

SUPPLEMENTARY INFORMATION

Background

The FAA published an Advance Notice of Proposed Rulemaking (ANPRM) (51 FR 7224, Notice No. 86-2) on February 28, 1986, as a result of analysis of accidents attributed to mixture control failure. Accidents involving mixture and throttle control failures had resulted in serious injuries and a fatality. The National Transportation Safety Board (NTSB) analyzed 54 aircraft accidents and concluded that in most cases, failure of the mixture control linkage mechanism resulted in the mixture control moving to the idle cut-off position. Concerns of commenters to the ANPRM included inadequate maintenance, inclusion of a similar proposal on the throttle linkage, and that the full-rich mixture may not be the needed mixture position after linkage disconnect. The NTSB had also recommended a similar requirement for the throttle linkage.

As a result of the information gathered from the ANPRM responses, the FAA published a Notice of Proposed Rulemaking (NPRM) (57 FR 47934, Notice No. 92-14) on October 20, 1992. Notice No. 86-2 had addressed mixture control failures. Notice No. 92-14 addressed both mixture and throttle control failures. The NPRM would have also removed the requirement that full-rich is the only acceptable mixture position following mixture control failure. The comment period of the NPRM closed February 17, 1993.

After issuance of the NPRM, further investigations revealed the accidents were not a result of design problems, but were a result of inconsistent maintenance procedures involving throttle and mixture control cables. The FAA has determined that existing regulations adequately address the concerns of Notice No. 92-14, but to provide additional means of compliance, we have also issued an advisory circular to address maintenance procedures. We issued Advisory Circular No. 20-143, Installation, Inspection, and Maintenance of Controls for General Aviation Reciprocating Aircraft Engines, on June 6, 2000.

Discussion of Comments

Twelve commenters responded to the NPRM. Concerns of commenters included maintenance techniques, editorial corrections to the NPRM, harmonization with Joint Aviation Authorities, and application of the proposed rulemaking to multi-engine aircraft.

The National Transportation Safety Board concurred with the need to define and require fail-safe provisions at the engine certification level.

The Air Line Pilots Association expressed support for the proposed rulemaking without further comment.

The Joint Aviation Authorities (JAA) expressed concern that the proposed rulemaking creates new differences between the Joint Aviation Regulations and the Code of Federal Regulations. They also stated their position that an engine requirement is not the appropriate solution to the problem, as well as pointed out some editorial errors in the NPRM. They concluded that the FAA should cancel the NPRM or harmonize the issues with the JAA.

Three aviation industry associations responded, two of which expressed concern that the proposal should not be mandatory for multi-engine aircraft. One association suggested a review of maintenance techniques and withdrawal of the proposal, stating that the proposal increases opportunity for disaster.

Two aviation industry manufacturers also cited maintenance procedures as a focus for further scrutiny. Of five individuals responding, one concerned about maintenance stated that “given good maintenance, this problem should not exist.” Another individual wanted the proposal to be made effective for new production engines after a specified date. Another supported the proposal but emphasized the need to keep requirements simple. Others suggested editorial changes to the proposed rule language and requested a detailed study of the problem.

The greater number of commenters were concerned about effective maintenance procedures, which prompted further analysis of those procedures. Analysis revealed the issues contained in the NPRM to be largely a product of inconsistent maintenance practices involving throttle and mixture control cables. Based on the comments and further analysis of the issues, we provided additional guidance on maintenance procedures to complement existing regulations.

Reason for Withdrawal

Existing regulations adequately cover the concerns of Notice No. 92-14, but to provide additional means of compliance with the regulations, we have issued an advisory circular on maintenance issues. Analysis revealed the issues addressed in the NPRM were largely a product of inconsistent maintenance practices. The FAA determined that issuance of an advisory circular was the proper method of dealing with the maintenance issues, and that a rule was not necessary. Advisory Circular No. 20-143, Installation, Inspection, and Maintenance of Controls for General Aviation Reciprocating Aircraft Engines, issued on June 6, 2000, addresses the issues contained in the NPRM. Therefore, we withdraw Notice No. 92-14, published October 20, 1992 at 57 FR 47934.

Issued in Washington, DC, on April 26, 2002.

John Hickey,

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