Airworthiness Directives; Boeing Model 737-300, -400, and -500 Series Airplanes Equipped With Air Cruisers Evacuation Slides

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 95-NM-138-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-103, Attention: Rules Docket No. 95-NM-138-AD, 1601 Lind Avenue SW., Renton, Washington 98055-4056.

Discussion

On March 21, 1988, the FAA issued AD 88-07-07, amendment 39-5884 (53 FR 9864, March 28, 1988), applicable to certain Boeing Model 737- 300 series airplanes, to require modification of the packing and slide containers of the escape slide. (This modification has been accomplished on Model 737-400 and -500 series airplanes during production, in accordance with Production Revision Report 34388.) That action was prompted by reports of slide girt material interfering with the girt bar stowage brackets during door opening, arresting the door opening motion. The requirements of that AD are intended to prevent failure or interference of opening of the forward doors during an emergency evacuation. On October 31, 1991, the FAA issued AD 91-24-04, amendment 39-8090 (56 FR 57588, November 13, 1991), applicable to certain Boeing Model 737-300, -400, and -500 series airplanes, equipped with certain Air Cruisers forward door escape slides that had been modified in accordance with AD 88-07-07. That AD requires repetitive inspections of the velcro girt retaining straps at the forward door escape slides. That action was prompted by reports of incorrectly routed and unserviceable slides or jammed doors during an emergency evacuation. The requirements of that AD are intended to prevent a jammed door or an escape slide deployed in an unusable position during an emergency evacuation. Since the issuance of those AD's, the FAA has reviewed and approved Air Cruisers Company Service Bulletin S.B. 103-25-19, dated March 25, 1992, which describes procedures for modification of the escape slide girts. This modification involves removing the existing girt; bonding on the girt attachments; installing a detachable girt; rigging a painter/mooring line; and bonding a placard to slide assembly and reidentifying it. This modification will improve the operation of the escape slide of the forward entry and service doors. Accomplishment of this modification eliminates the need for the repetitive inspections of the velcro girt retaining straps at the forward door escape slides (currently required by AD 91-24-04). Further, the FAA finds that accomplishment of this modification will positively address the unsafe condition addressed by the two existing AD's. 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 supersede AD 88-07-07 to continue to require modification of the escape slide packing and slide containers. The proposed AD would also supersede AD 91-24-04 to continue to require repetitive inspections of the velcro girt retaining straps at the forward door of the escape slides. Additionally, the proposed AD would require modification of the escape slide girts, which would constitute terminating action for the repetitive inspection requirements. The FAA has determined that long term continued operational safety will be better assured by modification or design change to remove the source of the problem, rather than by repetitive inspections. Long term inspections may not be providing the degree of safety assurance necessary for the transport airplane fleet. This, coupled with a better understanding of the human factors associated with numerous repetitive inspections, has led the FAA to consider placing less emphasis on special procedures and more emphasis on design improvements. The proposed modification requirement is in consonance with these considerations. There are approximately 1,572 Model 737-300, -400, and -500 series airplanes, equipped with Air Cruisers forward door escape slide of the affected design in the worldwide fleet. The FAA estimates that 663 airplanes of U.S. registry would be affected by this proposed AD.

The actions that are currently required by AD 88-07-07 take approximately 9 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts cost approximately $76 per airplane. Based on these figures, the cost impact on U.S. operators (175 airplanes) of the actions currently required is estimated to be $107,800, or $616 per airplane. The actions that are currently required by AD 91-24-04 take approximately 1 work hour per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact on U.S. operators (439 airplanes) of the actions currently required is estimated to be $26,340, or $60 per airplane, per inspection cycle. The modification that is proposed in this new AD action would take approximately 6 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts would cost approximately $1,800 per airplane. Based on these figures, the cost impact on U.S. operators of the new proposed modification requirements of this AD is estimated to be $1,432,080, or $2,160 per airplane. The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the current or proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The regulations proposed herein would not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. 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 USC 106(g), 40101, 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing amendments 39-5884 (53 FR 9864, March 28, 1988) and 39-8090 (56 FR 57588, November 13, 1991), and by adding a new airworthiness directive (AD), to read as follows:

Boeing: Docket 95-NM-138-AD. Supersedes AD 88-07-07, amendment 39- 5884; and AD 91-24-04, amendment 39-8090. Applicability: Model 737-300, -400, and -500 series airplanes, line numbers up to and including 2211; equipped with Air Cruisers forward door escape slides as listed in Air Cruisers Company Service Bulletin S.B. 103-25-19, dated March 25, 1992; certificated in any category.

Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must use the authority provided in paragraph (d) of this AD to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD.

Compliance: Required as indicated, unless accomplished previously. To prevent failure or interference of opening of the forward doors, which could delay or impede the evacuation of passengers during an emergency, accomplish the following: (a) Within 30 days after December 17, 1991 (the effective date of 91-24-04, amendment 39-8090), establish operating procedures, approved by the FAA Principal Maintenance Inspector (PMI), for the forward doors to include the requirements specified in paragraphs (a)(1), (a)(2), and (a)(3) of this AD; and thereafter, comply with those procedures until the modification required by paragraph (c) of this AD is accomplished. The procedures required by paragraphs (a)(1) and (a)(2) of this AD must be accomplished by qualified and trained mechanics. The procedures required by paragraph (a)(3) may be accomplished by qualified and trained members of the flightcrew or cabin crew. The training program to implement the procedures required by this paragraph must be approved by the FAA PMI. Methods for documentation of compliance with the following procedures must be approved by the FAA PMI. (1) Prior to the next flight after December 17, 1991 (the effective date of AD 91-24-04, amendment 39-8090), and thereafter at intervals not to exceed 200 flight hours, inspect the condition of the girt retaining straps at the forward doors. (2) Prior to further flight after December 17, 1991 (the effective date of 91-24-04, amendment 39-8090), replace worn or aged velcro whose grip strength will no longer hold the girt retaining straps in position. (3) Prior to the next flight after December 17, 1991 (the effective date of 91-24-04, amendment 39-8090), and thereafter prior to each flight, inspect the routing of the girt retaining straps at the forward doors, and reroute straps that are found not to be routed in accordance with the placarded instructions installed in accordance with AD 88-07-07, amendment 39-5885, on the inboard face of the slide compartment. (b) For Model 737-300 series airplanes: Within 6 months after May 9, 1988 (the effective date of AD 88-07-07, amendment 39-5885), modify the escape slide packing and slide containers in accordance with Boeing Alert Service Bulletin 737-25A1221, dated December 17, 1987, or Revision 1, dated June 2, 1988. This modification must be accomplished prior to or in conjunction with accomplishment of the requirements of paragraph (c) of this AD. (c) Within 36 months after the effective date of this AD, modify the escape slide girts in accordance with Air Cruisers Company Service Bulletin S.B. 103-25-19, dated March 25, 1992. Accomplishment of the modification constitutes terminating action for the repetitive inspections required by paragraph (a) of this AD. (d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

(e) Special flight permits may be issued in accordance with sections 21.197 and 21.199

of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. Issued in Renton, Washington, on January 5, 1996. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 96-474 Filed 1-18-96; 8:45 am] BILLING CODE 4910-13-U