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

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 737-200, -300, -400, and -500 series airplanes. This proposal would require replacement of existing door handle mounting hub assemblies with new, improved hub assemblies. This proposal is prompted by reports of cracked or broken mounting hub assemblies for the interior door handles on the cabin doors. The actions specified by the proposed AD are intended to prevent cracking or breaking of the door handle mounting hub, which could result in the interior door handle breaking off while the door is being opened. In an emergency situation, this could impede evacuation of the airplane.

DATES:

Comments must be received by June 26, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-103-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.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, 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, Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2780; fax (425) 227-1181.

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 notice may be changed in light of the comments received.

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 notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-103-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. 2000-NM-103-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received reports indicating that cracked or broken mounting hub assemblies for the interior door handles on the cabin doors have been found on certain Boeing Model 737-200, -300, -400, and -500 series airplanes. The primary use of the interior door handle is to be turned to latch the door after the door is shut using the assist handles. If the interior door handle is also used to close the door, the moment arm of the door handle puts too much force on the existing aluminum door handle mounting hub, which causes the mounting hub to crack or break. This condition, if not corrected, could result in the interior door handle breaking off while the door is being opened. In an emergency situation, this could impede evacuation of the airplane.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Service Bulletin 737-25-1322, Revision 2, dated February 19, 1998. That service bulletin describes procedures for replacement of existing door handle mounting hub assemblies in the forward and aft entry doors, forward galley door, and aft service door, with new, improved hub assemblies. The new mounting hub assemblies are made of stainless steel and are stronger than the existing aluminum mounting hub assemblies. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

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 require accomplishment of the actions specified in the service bulletin described previously, except as discussed below.

Differences Between the Proposed Rule and the Service Information

Operators should note that the proposed AD would require replacement of existing door handle mounting hub assemblies with new, improved hub assemblies within 18 months after the effective date of this AD. The service bulletin recommends that the mounting hub in the forward entry door be replaced at the next “A” check, and the mounting hub assemblies in the aft entry door, forward galley door, and aft service door be replaced at the next “C” check. In developing an appropriate compliance time for this proposed AD, the FAA considered not only the manufacturer's recommendation, but the degree of urgency associated with addressing the subject unsafe condition, the average utilization of the affected fleet, and the time necessary to replace the mounting hub assemblies (approximately 3 work hours per door). In light of all of these factors, the FAA finds an 18-month compliance time for initiating the proposed actions to be warranted, in that it represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety.

Cost Impact

There are approximately 1,575 airplanes of the affected design in the worldwide fleet. The FAA estimates that 632 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 12 work hours per airplane (3 work hours per door) to accomplish the proposed replacement, and that the average labor rate is $60 per work hour. Required parts would cost approximately $2,150 per airplane. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $1,813,840, or $2,870 per airplane.

The cost impact figure discussed above is 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 AD were not adopted.

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.