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

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule.

SUMMARY:

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, that 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. This action is necessary 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 is intended to address the identified unsafe condition.

DATES:

Effective March 24, 2004.

The incorporation by reference of a certain publication listed in the regulations is approved by the Director of the Federal Register as of March 24, 2004.

ADDRESSES:

The service information referenced in this AD may be obtained from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., Suite 700, Washington, DC.

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 (425) 917-6435; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes was published in the Federal Register on September 18, 2003 (68 FR 54684). That action proposed 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 the new, improved screw, nut, and washers.

Comments

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Generally Agree With the Proposed AD

Two commenters generally agree with this proposed AD and have no additional comments.

Extend Compliance Time

Three commenters request that the proposed compliance time for the replacement be extended from 18 months to 36 months. The commenters state that the extended compliance time would allow for the replacement to be accomplished concurrently with the modification of the escape slide compartment hinge assembly required by AD 2004-02-08, amendment 39-13443 (69 FR 4452, January 30, 2004). In addition, a compliance time of 36 months will allow operators to perform the replacement during the typical overhaul period for escape slides.

The FAA agrees with the commenters' request to extend the compliance time for the replacement. Extending the compliance time by 18 months will not adversely affect safety and will allow the replacement to be performed during regularly scheduled maintenance visits. Paragraph (a) of the AD has been revised to specify a compliance time of 36 months.

Clarify Applicability of Parts Installation Paragraph

Four commenters request that paragraph (b) of the proposed AD be revised to state specifically that the nut, part number (P/N) BACN10R10L, and screw, P/N NAS623-3-8, cannot be installed in the latch assembly. The commenters state that the intent of the proposed AD is to identify nuts, P/N BACN10R10L, and screws, P/N NAS623-3-8, that are not to be installed on the latch assembly. These parts are used elsewhere throughout the airplane and are not exclusive to the latch assembly.

We agree with the commenters that the intent of the proposed AD is to prevent nuts, P/N BACN10R10L, and screws, P/N NAS623-3-8, from being installed on the latch assembly. We have revised paragraph (b) of the AD to limit the use of nuts, P/N BACN10R10L, and screws, P/N NAS623-3-8, on the latch block assembly. In addition, we removed the phrase “that was removed from any airplane” to clarify that any nut, P/N BACN10R10L, may not be installed on the latch block assembly of any airplane.

Conclusion

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Cost Impact

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 will be affected by this AD. The FAA estimates that it will 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 required 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 AD on U.S. operators is estimated to be $130 per Group 1 airplane, and $65 per Group 2 airplane.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this 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 AD, subject to warranty conditions. Manufacturer warranty remedies may also be available for labor costs associated with this AD. As a result, the costs attributable to the AD may be less than stated above.

Regulatory Impact

The regulations adopted herein will 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 final rule does not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this action (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• Safety

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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.

2. Section 39.13 is amended by adding the following new airworthiness directive:

2004-03-34 Boeing: Amendment 39-13478. Docket 2001-NM-156-AD.

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 slides, 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 a nut, part number (P/N) BACN10R10L; or install a screw, P/N NAS623-3-8; on the latch block assembly of any airplane.

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.

Incorporation by Reference

(d) Unless otherwise specified by this AD, the actions shall be done in accordance with Boeing Special Attention Service Bulletin 737-25-1434, dated March 22, 2001. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., Suite 700, Washington, DC.

Effective Date

(e) This amendment becomes effective on March 24, 2004.