01-3856. Airworthiness Directives; Boeing Model 727, 737, 757-200, 757-200CB, and 757-300 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 727, 737, 757-200, 757-200CB, and 757-300 series airplanes. This proposal would require modification of the latch assembly of the escape slides. For certain airplanes, this proposal would also require installation of a cover assembly on the trigger housing of the inflation cylinder on the escape slides. This action is necessary to prevent failure of an escape slide to deploy or inflate correctly, which could result in the slide being unusable during an emergency evacuation and consequent injury to passengers or airplane crewmembers. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by April 2, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-159-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. 2000-NM-159-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.

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, 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 2000-NM-159-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-159-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received reports indicating that latch assemblies on the emergency escape slides have failed on several Boeing Model 727, 737, 757-200, 757-200CB, and 757-300 series airplanes. Several operators have reported failures due to corrosion of the spring pins in the latch assemblies, while others have reported finding discrepant (e.g., deformed or incorrectly soldered) split rings attaching the chain assembly to the latch block assembly. Failed spring pins or discrepant split rings in the escape slide latch assembly could result in failure of the escape slide latch assembly in service, and consequent failure of the escape slide to deploy.

The FAA has also received reports that, during functional tests of escape slides prior to delivery of Boeing Model 737-600, -700, and -800 series airplanes, the trigger housing of the inflation cylinder of an escape slide caught on the jumper cable of the escape slide compartment. The interference between these two parts caused the escape slide to fail to completely drop from the door before inflating, which resulted in the escape slides failing to inflate correctly.

Failure of an escape slide to deploy or inflate correctly in an emergency situation could result in the slide being unusable during an emergency evacuation and consequent injury to passengers or airplane crewmembers.

Explanation of Relevant Service Information

The FAA has reviewed and approved the following Boeing Service Bulletins:

Service bulletin	Date	For model * * *	Actions
727-25-0294	May 25, 2000	727-100 and 727-200 series	Modification of escape slide latch assembly.
737-25-1405	......do	737-100, -200, -300, -400, and -500 series	Do.
737-25-1403	May 4, 2000	737-600, -700, and -800 series	Installation of a cover assembly on the trigger housing of the inflation cylinder on the escape slides.
737-25-1404	May 25, 2000	737-600, -700, and -800 series	Modification of escape slide latch assembly.
757-25-0217	......do	757-200 and -200CB series	Do.
757-25-0218	......do	757-300 series	Do.

The modification of the escape slide latch assembly for all airplanes involves replacement of existing spring pins with new spring pins made from more corrosion-resistant material. For certain airplanes, the modification also involves replacement of the existing split ring, which attaches the chain assembly to the latch block assembly, with a clevis.

Boeing Service Bulletin 737-25-1403 refers to BF Goodrich Service Bulletin 5A3307-25-309, dated October 29, 1999, as an additional source of service information for the installation of a cover assembly on the trigger housing of the inflation cylinder on the escape slides on Model 737-600, -700, and -800 series airplanes.

Accomplishment of the actions specified in the applicable service bulletins 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 applicable service bulletins described previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletins

Operators should note that, although the service bulletins do not recommend a specific compliance time, the FAA has determined that a specific compliance time is needed to ensure that the identified unsafe condition is addressed in a timely manner. In developing an appropriate compliance time for this proposed AD for these airplanes, the FAA considered not only the manufacturer's recommendation, but the degree of urgency associated with addressing the subject unsafe condition, and the average utilization of the affected fleets.

Considering these factors, the FAA finds a 36-month compliance time for completing the proposed actions on Model 727, 737-100, 737-200, 737-300, 737-400, 737-500, 757-200, 757-200CB, and 757-300 series airplanes to be warranted, in that this represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety.

For Model 737-600, -700, and -800 series airplanes, the FAA finds an 18-month compliance time for completing the proposed actions to be warranted. In developing an appropriate compliance time for this proposed AD for these airplanes, the FAA considered not only the manufacturer's recommendations for installing a cover assembly on the trigger housing of the inflation cylinder on the escape slides, but also the degree of urgency associated with failure of an escape slide to inflate correctly due to interference between the trigger housing of the inflation cylinder and the jumper cable of the escape slide compartment. Considering these factors, and the fact that it will be convenient for affected operators to modify the escape slide latch assembly at the same time they install the cover assembly, the FAA has determined that 18 months represents an appropriate interval for affected airplanes to continue to operate without compromising safety.

Cost Impact

There are approximately 5,759 airplanes of the affected design in the worldwide fleet. The FAA estimates that 2,906 airplanes of U.S. registry would be affected by this proposed AD. The following table shows the estimated cost impact for airplanes affected by this AD. “Action 1” is the modification of the escape slide latch assembly, and “Action 2” is the installation of a cover assembly on the trigger housing of the inflation cylinder on the escape slide. The average labor rate is $60 per work hour. The cost impact is as follows:

Models/series	Action	U.S.- registered airplanes	Work hours per airplane (estimated)	Parts cost (estimated maximum)	Cost per airplane (estimated)	Maximum fleet cost (estimated)
727	1	955	2	$1,068	$1,188	$1,134,540
737-100, -200, -300, -400, -500	1	1,156	2	1,192	1,312	1,516,672
737-600, -700, -800	1	277	2	1,424	1,544	427,688
737-600, -700, -800	2	277	4	Free	240	66,480
757-200, -200CB, -300	1	518	3	1,602	1,782	923,076

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.

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 adding the following new airworthiness directive:

Boeing: Docket 2000-NM-159-AD.

Applicability: The following airplanes, certificated in any category:

Model	As listed in * * *	Service bulletin date
727-100 and 727-200 series	Boeing Service Bulletin 727-25-0294	May 25, 2000.
737-100, -200, -300, -400, and -500 series	Boeing Service Bulletin 737-25-1405	Do.
737-600, -700, and -800 series	Boeing Special Attention Service Bulletin 737-25-1403	Do.
737-600, -700, and -800 series	Boeing Service Bulletin 737-25-1404	Do.
757-200 and -200CB series	Boeing Service Bulletin 757-25-0217	Do.
757-300 series	Boeing Service Bulletin 757-25-0218	Do.

Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been 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 request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of an escape slide to deploy or inflate correctly, which could result in the slide being unusable during an emergency evacuation and consequent injury to passengers or airplane crewmembers, accomplish the following:

Modification

(a) At the schedule specified in the following table, do the actions in the “Do these actions * * * ” column, per the service bulletin specified in the “As listed in * * *” column:

Table 1.—Required Actions

For model * * *	As listed in * * *	Dated * * *	Do these actions * * *	No later than * * *
727-100 and 727-200 series	Boeing Service Bulletin 727-25-0294	May 25, 2000	Modify the escape slide latch assembly	36 months after the effective date of this AD.
737-100, -200, -300, -400, and -500 series	Boeing Service Bulletin 737-25-1405	......do	......do	Do.
737-600, -700, and -800 series	Boeing Special Attention Service Bulletin 737-25-1403	May 4, 2000	Install a cover assembly on the trigger housing of the inflation cylinder on the escape slides	18 months after the effective date of this AD.
737-600, -700, and -800 series	Boeing Service Bulletin 737-25-1404	May 25, 2000	Modify the escape slide latch assembly	Do.
757-200 and -200CB series	Boeing Service Bulletin 757-25-0217	......do	......do	36 months after the effective date of this AD.
757-300 series	Boeing Service Bulletin 757-25-0218	......do	......do	Do.

Spares

(b) After the effective date of this AD, no person may install an escape slide assembly or escape slide latch assembly listed in the “Existing Part Number” column of the table under paragraph 2.E. in the following service bulletins, on any airplane:

Table 2.—Spare Parts

For Models * * *	Listed in * * *	Service bulletin date
727-100 and 727-200 series	Boeing Service Bulletin 727-25-0294	May 25, 2000
737-100, -200, -300, -400, and -500 series	Boeing Service Bulletin 737-25-1405	Do.
737-600, -700, and -800 series	Boeing Special Attention Service Bulletin 737-25-1403	May 4, 2000.
737-600, -700, and -800 series	Boeing Service Bulletin 737-25-1404	May 25, 2000.
757-200 and -200CB series	Boeing Service Bulletin 757-25-0217	Do.
757-300 series	Boeing Service Bulletin 757-25-0218	Do.

Alternative Methods of Compliance

(c) 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. 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.

Special Flight Permits

(d) 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 February 9, 2001.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.