04-6503. Airworthiness Directives; Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes to revise an existing airworthiness directive (AD), applicable to certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, that currently requires replacing existing screw, nut, and washers that attach the latch cable assembly to the latch block assembly of the door mounted escape slides, with new, improved screw, nut, and washers. The actions specified by that AD are intended to prevent the latch cable assembly from disconnecting from the latch block assembly of the door mounted escape slide, which could result in an escape slide not deploying in an emergency situation. This action would revise the parts installation paragraph to allow certain nuts to be installed and is intended to address the identified unsafe condition.

DATES:

Comments must be received by May 10, 2004.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2004-NM-29-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. 2004-NM-29-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 or 2000 or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Keith Ladderud, Aerospace Engineer, Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; 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 2004-NM-29-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2004-NM-29-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On February 5, 2004, the FAA issued AD 2004-03-34, amendment 39-13478 (69 FR 7553, February 18, 2004), applicable to certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, to require replacing existing screw, nut, and washers that attach the latch cable assembly to the latch block assembly of the door mounted escape slides, with new, improved screw, nut, and washers. That action was prompted by a report that the cable on a door mounted escape slide had disconnected from the latch block assembly on a Boeing Model 737 series airplane. The requirements of that AD are intended to prevent the latch cable assembly from disconnecting from the latch block assembly of the door mounted escape slide, which could result in an escape slide not deploying in an emergency situation.

Actions Since Issuance of Previous Rule

Since the issuance of AD 2004-03-34, the FAA has recognized that paragraph (b) of that AD does not allow any nut, part number (P/N) BACN10R10L, to be installed “on the latch block assembly of any airplane.” It is not our intention to prevent nut, P/N BACN10R10L, from being installed on the latch block assembly. We do however want to prevent any nuts, P/N BACN10R10LH, that were removed from any airplane, from being installed on the latch block assembly. While the notice of proposed rulemaking (NPRM) for AD 2004-03-34 states “no person may install a nut, part number (P/N) BACN10R10L, that was removed from any airplane,” the text “that was removed from any airplane,” was inadvertently removed from paragraph (b) of the final rule. We have revised paragraph (b) of this proposed AD to state, “* * * no person may install a nut, part number (P/N) BACN10R10L, that was removed from any airplane.”

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would revise AD 2004-03-34 to continue to require replacing the existing screw, nut, and washers that attach the latch cable assembly to the latch block assembly of the door mounted escape slides, with new, improved screw, nut, and washers. In addition, the proposed AD would allow nuts, P/N BACN10R10L, that were not removed from the airplane, to be installed on the latch block assembly.

Cost Impact

The proposed changes in this action add no additional economic burden. The current costs for this proposed AD are repeated for the convenience of affected operators, as follows:

There are approximately 2,919 airplanes of the affected design in the worldwide fleet. The FAA estimates that 1,129 airplanes of U.S. registry would be affected by this proposed AD. The FAA estimates that it would take approximately 2 work hours for each airplane specified as Group 1 in the referenced service bulletin, and approximately 1 work hour for each airplane specified as Group 2 in the referenced service bulletin, to accomplish the proposed actions; the average labor rate is estimated to be $65 per work hour. Parts and materials are standard and are to be supplied by the operator. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $130 per Group 1 airplane, and $65 per Group 2 airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. The manufacturer may cover the cost of replacement parts associated with this proposed AD, subject to warranty conditions. Manufacturer warranty remedies may also be available for labor costs associated with this proposed AD. As a result, the costs attributable to the proposed AD may be less than stated above.

Regulatory Impact

The regulations proposed herein would not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13

[Amended]

2. Section 39.13 is amended by removing amendment 39-13478 (69 FR 7553, February 18, 2004), and by adding a new airworthiness directive (AD), to read as follows:

2004-03-34 R1 Boeing: Docket 2004-NM-29-AD. Revises AD 2004-03-34, Amendment 39-13478.

Applicability: Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, as listed in Boeing Special Attention Service Bulletin 737-25-1434, dated March 22, 2001; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent the latch cable assembly from disconnecting from the latch block assembly of the door mounted escape slide, which could result in an escape slide not deploying in an emergency situation, accomplish the following:

Replacement

(a) Within 36 months after the effective date of this AD, replace existing screw, nut, and washers that attach the latch cable assembly to the latch block assembly of the door mounted escape slides, with new, improved screw, nut, and washers; per the Work Instructions of Boeing Special Attention Service Bulletin 737-25-1434, dated March 22, 2001.

Parts Installation

(b) As of the effective date of this AD, no person may install either of the parts specified in paragraphs (b)(1) and (b)(2) of this AD on the latch block assembly of any airplane.

(1) A nut, part number (P/N) BACN10R10L, that has been removed from any airplane.

(2) A screw, P/N NAS623-3-8.

Alternative Methods of Compliance

(c)(1) In accordance with 14 CFR 39.19, the Manager, Seattle Aircraft Certification Office (ACO), FAA, is authorized to approve alternative methods of compliance (AMOC) for this AD.

(2) An AMOC that provides an acceptable level of safety may be used for repair of the latch cable assembly and the latch block assembly for the door mounted escape slide, if it is approved by a Boeing Company Designated Engineering Representative (DER) who has been authorized by the Manager, Seattle ACO, to make such findings.

Issued in Renton, Washington, on March 15, 2004.

Kevin M. Mullin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.