Airworthiness Directives; Boeing Model 727, 737, 757-200, 757-200CB, and 757-300 Series Airplanes

Summary:

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 727, 737, 757-200, 757-200CB, and 757-300 series airplanes. This AD requires modification of the latch assembly of the escape slides. For certain airplanes, this AD also requires 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.

Table of Contents

Table of Figures

Addresses:

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

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 727, 737, 757-200, 757-200CB, and 757-300 series airplanes was published in the Federal Register on February 15, 2001 (66 FR 10384). That action proposed to require modification of the latch assembly of the escape slides. For certain airplanes, that action also proposed to require installation of a cover assembly on the trigger housing of the inflation cylinder on the escape slides.

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.

Support for the Proposed Rule

One commenter supports the proposed rule.

Identify Additional Affected Airplane Model

One commenter requests that the FAA revise the proposed rule to identify an additional affected airplane model. The commenter states that Boeing Model 737-200C airplanes are included in the effectivity listing of Boeing Service Bulletin 737-25-1405, dated May 25, 2000, but points out that these airplanes were not identified in the proposed rule with Model 737-100, -200, -300, -400, and -500 series airplanes.

The FAA concurs with the commenter's request. Though the FAA inadvertently failed to refer to Model 737-200C series airplanes separately from Model 737-200 series airplanes in the proposed rule, these airplanes are affected by this AD. Therefore, the “Cost Impact” section, the applicability statement, and Table 1 of this final rule have been revised to specifically identify Model 737-200C series airplanes along with the other airplane models affected by this AD.

Allow Installation of Unmodified Slide Latch

One commenter requests that the FAA remove paragraph (b) from the proposed AD. (That paragraph, the “Spares” paragraph, would prohibit installation of certain escape slide assemblies or escape latch assemblies after the effective date of this AD.) The commenter states that an operator may replace an escape slide on an airplane at any time due to a maintenance discrepancy or the slide reaching its overhaul threshold. The commenter notes that, on certain fleets, the slide latch is part of the complete escape slide assembly; therefore, the latch is replaced when a new slide is installed. The commenter states that, by not allowing the installation of a non-modified latch prior to the compliance time required by the proposed AD, the operator's entire spares inventory of escape slides would have to be modified according to the proposed AD before the AD becomes effective.

The FAA concurs with the commenter's request. Operators must comply with the requirements of this AD by the specified compliance time. If an operator must install a slide, it is their responsibility to ensure that all affected parts of that slide conform to the requirements of this AD by the compliance deadline. Accordingly, paragraph (b) of the proposed rule has not been included in this final rule. (Operators should note, however, that once an airplane has been modified according to this AD, the airplane cannot be modified in any way that negates accomplishment of the actions in this AD—i.e., a modified latch assembly cannot be replaced with an unmodified assembly.)

Consider Impact of Previously Issued AD

One commenter states that the FAA did not adequately consider AD 90-12-11 R1, amendment 39-6683, when it proposed this AD. The commenter points out that AD 90-12-11 R1 requires repetitive inspections of all Boeing Model 727, 737, and 757 series airplanes with escape slides having release cables installed. Escape slides with such release cables installed do not have the split ring assembly that the proposed AD would require to be replaced on certain airplanes. The commenter further notes that Boeing has issued certain service bulletins that provide instructions for replacing release cables on escape slides with release chains, which eliminates the need for the inspections required by AD 90-12-11 R1. The commenter states that it operates some airplanes that have not been modified according to these service bulletins, so the airplanes are still equipped with escape slides with release cables (and without the split ring assembly). The commenter asks whether the FAA intends to require the installation of escape slides with release chains on all subject airplanes as part of this AD, or if escape slides with release cables are still considered to be acceptable, provided that the airplanes continue to be repetitively inspected according to AD 90-12-11 R1.

The FAA concurs that clarification is necessary with regard to the requirements of AD 90-12-11 R1. The modification of the escape slide latch assembly required by this AD involves two actions for certain airplanes. The first action involves replacement of existing spring pins with new spring pins. While AD 90-12-11 R1 requires repetitive inspections of the slide release latch assembly for frayed or broken cables, that AD does not require inspections for corrosion of the spring pins because the spring pins cannot be properly inspected for corrosion. Therefore, the replacement of the existing spring pins with new spring pins is necessary for all airplanes subject to this AD. The second action that is part of the modification involves replacement of the existing split ring which attaches the chain assembly to the latch block assembly, with a clevis. In response to the commenter's concern, the FAA finds that an operator of an airplane subject to the requirement to replace the split ring with a clevis may not be required to do this replacement if the airplane is equipped with a release cable instead of a release chain. Operators of airplanes equipped with a release cable instead of a release chain may request approval of an alternative method of compliance under the provisions of paragraph (b) of this AD, as long as the airplane is receiving the repetitive inspections required by AD 90-12-11 R1. Operators should note that Note 1 of this AD applies to airplanes modified, altered, or repaired in the area subject to the requirements of this AD. Due to the fact that Note 1 already addresses this circumstance, no change to this AD is necessary in this regard.

Extend Compliance Time for Certain Airplanes

One commenter requests that the FAA extend the compliance time from 18 months to 36 months for the actions required by this AD on Boeing Model 737-600, -700, and -800 series airplanes. The commenter notes that, as the FAA stated in the proposed rule, the 18-month compliance time for these airplanes is based on the degree of urgency associated with installation of a cover assembly on the trigger housing of the inflation cylinder on the escape slides, as specified in Boeing Special Attention Service Bulletin 737-25-1403, dated May 4, 2000. The commenter states that some operators have already accomplished that service bulletin, and other airplanes are not subject to the actions in that service bulletin because they are equipped with different escape slides. The commenter states, for these airplanes, the compliance time for accomplishment of the modification of the slide latch assembly described in Boeing Service Bulletin 737-25-1404, dated May 25, 2000, should be 36 months.

The FAA does not concur with the commenter's request to extend the compliance time. The commenter notes that, for certain airplanes as listed in Boeing Service Bulletin 737-25-1404, that service bulletin specifies accomplishment of Boeing Special Attention Service Bulletin 737-25-1403 as an integral part of the other actions in that service bulletin. For this reason, the FAA finds that it is necessary to mandate accomplishment of Boeing Service Bulletin 737-25-1404 within 18 months after the effective date of this AD, as proposed. However, the FAA notes that operators of airplanes on which Boeing Special Attention Service Bulletin 737-25-1403 has been accomplished may request approval of an alternative method of compliance or adjustment of the compliance time under the provisions of paragraph (b) of this AD. No change to the final rule is necessary in this regard.

Allow Use of Solid Spring Pin

The modification of the escape slide latch assembly for all airplanes subject to this AD involves replacement of existing spring pins with new spring pins made from corrosion-resistant material. One commenter requests that the FAA approve the use of a new, solid spring pin with both ends staked as an alternative to the spring pin of hollow-roll design that is specified in the service bulletins. The commenter states that the spring pin specified in the service bulletins may allow for collection of water in the pin which could lead to corrosion. The commenter states that a solid pin will provide the corrosion prevention needed to ensure the integrity of the pin and operation of the slide latch and will provide a level of safety equivalent to that provided by the pin specified in the service bulletins.

The FAA does not concur with the commenter's request to allow use of a solid pin with staked ends. The FAA notes that the latch assembly housing is a forged part and is made of hard, corrosion-resistant steel. If solid spring pins are installed and staked at both ends, it may be possible for these pins to bend or be insufficiently staked, which could result in an unacceptable latch assembly. Therefore, the FAA finds that the spring pins must be replaced with the new pins specified in the applicable service bulletin. No change to the final rule is necessary in this regard.

Require Replacement of Latch Assemblies With New Assemblies

One commenter states that the escape slide latch assemblies that are subject to this AD should not be reworked as allowed by the proposed rule, but, rather, should be replaced with new latch assemblies. The commenter is concerned about modifying the existing latches due to the critical nature of these latches.

The FAA does not concur with the commenter's request. The FAA does not consider the modifications in the referenced service bulletins technically challenging, and expects that operators should be able to accomplish such modifications. No change to the final rule is necessary in this regard.

Adjust Cost Impact Information

One commenter states that, because the proposed AD results from a design defect, replacement parts for the modification of the escape slide latch assembly should be supplied at no cost to the operators. The commenter makes no specific request for a change to the proposed rule. The FAA acknowledges this comment, but the FAA cannot mandate which party should bear the cost of replacement parts. This issue must be negotiated between the operator and the manufacturer. No change to the final rule is necessary in this regard.

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 5,759 Model 727, 737, 757-200, 757-200CB, and 757-300 airplanes of the affected design in the worldwide fleet. The FAA estimates that 2,906 airplanes of U.S. registry will be affected by this 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 estimated cost impact is as follows:

Models/seriesActionU.S.-registered airplanesWork 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, -200C, -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 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 includeincidental 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 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.

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

2001-15-01Boeing: Amendment 39-12335. Docket 2000-NM-159-AD.

Applicability: The following airplanes, certificated in any category:

ModelAs listed inService bulletindate
727-100 and 727-200 series Boeing Service Bulletin 727-25-0294 May 25, 2000.
737-100, -200, -200C, -300, -400, and -500 series Boeing Service Bulletin 737-25-1405 May 25, 2000.
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 May 25, 2000.
757-300 series Boeing Service Bulletin 757-25-0218 May 25, 2000.

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 (b) 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 modelAs listed inDatedDo these actionsNo 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, -200C, -300, -400, and -500 series Boeing Service Bulletin 737-25-1405 May 25, 2000 Modify the escape slide latch assembly 36 months after the effective date of this AD.
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 18 months after the effective date of this AD.
757-200 and -200CB series Boeing Service Bulletin 757-25-0217 May 25, 2000 Modify the escape slide latch assembly 36 months after the effective date of this AD.
757-300 series Boeing Service Bulletin 757-25-0218 May 25, 2000 Modify the escape slide latch assembly 36 months after the effective date of this AD.

Alternative Methods of Compliance

(b) 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

(c) Special flight permits may be issued in accordance with sections 21.197 and 21.199of 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.

Incorporation by Reference

(d) The actions shall be done in accordance with Boeing Service Bulletin 727-25-0294, dated May 25, 2000; Boeing Special Attention Service Bulletin 737-25-1403, dated May 4, 2000; Boeing Service Bulletin 737-25-1404, dated May 25, 2000; Boeing Service Bulletin 737-25-1405, dated May 25, 2000; Boeing Service Bulletin 757-25-0217, dated May 25, 2000; and Boeing Service Bulletin 757-25-0218, dated May 25, 2000; as applicable. 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 Airplane Group, 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 August 28, 2001.

Issued in Renton, Washington, on July 13, 2001. Donald L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

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