02-842. Airworthiness Directives; Boeing Model 737 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM); Extension of the comment period.

SUMMARY:

This document extends the period for public comment on the above-referenced NPRM that proposes the supersedure of two existing airworthiness directives (AD), applicable to certain Boeing Model 737 series airplanes. The NPRM proposes to require installation of a new rudder control system and changes to the adjacent systems to accommodate that new rudder control system. This proposal is prompted by FAA determinations that the existing system design architecture is unsafe due to inherent failure modes, including single-jam modes and certain latent failures or jams, which, when combined with a second failure or jam, could cause an uncommanded rudder hardover event and consequent loss of control of the airplane. Additionally, the current rudder operational procedure is not effective throughout the entire flight envelope. This extension of the comment period is necessary to assure that all interested persons have ample opportunity to present their views on the proposed requirements of the NPRM.

DATES:

Comments must be received by February 14, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-251-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2001-NM-251-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

FOR FURTHER INFORMATION CONTACT:

Kenneth W. Frey, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2001-NM-251-AD.” The postcard will be date stamped and returned to the commenter.

Events Leading to This Extension of the Comment Period

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to certain Boeing Model 737 series airplanes was published as a notice of proposed rulemaking (NPRM) in the Federal Register on November 6, 2001(66 FR 56783). The NPRM proposed to require installation of a new rudder control system and changes to the adjacent systems to accommodate that new rudder control system.

The FAA has received a request from the manufacturer, Boeing, to extend the comment period of the NPRM by 30 days. Boeing requests the extension because the NPRM would encompass holidays during November and December, which would significantly decrease the number of working days necessary to develop responses to the comments. Further, during a Boeing Critical Design Review (CDR), held on December 4, 2001, the CDR team provided information to the operators to enable them to assess the impact of the NPRM on their operations. Because the CDR was held after the NPRM was issued, operators have less time to assess the requirements of the proposed rule. In addition, Boeing states that the proposed action of the NPRM is a complex retrofit requirement with many aspects to consider.

The FAA's Determination

The FAA has considered Boeing's request and finds it appropriate to extend the comment period to give all interested persons additional time to examine the proposed requirements of the NPRM and submit comments. After evaluating the comments provided in Boeing Letter B-H210-01-0400, dated November 30, 2001, we have determined that extending the comment period by 30 days will not compromise the safety of these airplanes.

The Extension

The comment period for Docket No. 2001-NM-251-AD is hereby extended to February 14, 2002.

Since no portion of the NPRM or other regulatory information has been changed, the entire NPRM is not being republished.

Issued in Renton, Washington, on January 8, 2002.

Vi L. Lipski,

Manager, Transport Airplane Directorate,Aircraft Certification Service.