04-25189. Airworthiness Directives; Boeing Model 757-200, -200PF, -200CB, and -300 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule.

SUMMARY:

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 757-200, -200PF, -200CB, and -300 series airplanes, that requires inspection for damage of the W2800 wire bundle insulation, wire conductor, the wire bundle clamp bracket, and the BACC10GU( ) clamp, and repair or replacement with new or serviceable parts, if necessary. This amendment also requires installation of spacers between the clamp and the bracket. This action is necessary to prevent contact between the power feeder wires of the auxiliary power unit (APU) and the clamp bracket aft of the STA 1720 bulkhead due to chafing damage of the Adel clamp and “L” shaped bracket, which could result in electrical arcing and fire, or loss of APU electrical power in the airplane. This action is intended to address the identified unsafe condition.

DATES:

Effective December 21, 2004.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of December 21, 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 National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call [phone], or go to: http://www.archives.gov/​federal_​register/​code_​of_​federal_​regulations/​ibr_​locations.html.

FOR FURTHER INFORMATION CONTACT:

Elias Natsiopoulos, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

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 757-200, -200PF, -200CB, and -300 series airplanes was published in the Federal Register on June 14, 2002 (67 FR 40894). That action proposed to require inspection for damage of the W2800 wire bundle insulation, wire conductor, the wire bundle clamp bracket, and the BACC10GU( ) clamp, and repair or replacement with new or serviceable parts, if necessary. That action also proposed to require installation of spacers between the clamp and the bracket.

Since the Issuance of the Proposed AD

Since the issuance of the proposed AD, Boeing has issued Special Attention Service Bulletins 757-24-0089, Revision 1, and 757-24-0090, Revision 1, both dated February 27, 2003. Except for the addition of an auxiliary power unit (APU) generator system test to be accomplished if damage is found on the W2800 wire bundle, the service bulletins are essentially identical to the original service bulletins, both dated March 15, 2001. The original issue service bulletins were referenced in the proposed AD as the appropriate sources of service information for the required actions.

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 AD

One commenter has no objection to the proposed AD.

Request To Extend the Compliance Time

One commenter requests that the compliance time for the general visual inspections be extended from 15 months to 24 months. The commenter states that it has found no chafing damage to the wire bundle on its airplanes. Therefore, the commenter states the extension of compliance time will allow the inspections to be performed during scheduled heavy maintenance checks, which are scheduled every 24 months.

The FAA agrees that the compliance time for the accomplishment of the general visual inspections may be extended somewhat. We have reassessed the compliance time and considered the manufacturer's recommendation of a compliance time of 18 months for the general visual inspection. In addition, we have determined that, for airplanes on which no damage is found and there is a 0.25-inch minimum clearance between the wire bundles and aft edge of the bracket, the compliance time for accomplishing the follow-on actions (installing the spacers and ensuring the minimum clearance) may be extended from “before further flight” to “24 months after the effective date of this AD” for those follow-on actions. We consider that such an extension of the compliance time for the follow-on actions will not adversely affect the adequate safety of flight of the airplane. The requirements of paragraph (a) of the AD have been revised accordingly.

Request To Remove the Requirement To Install Spacers

One commenter requests that the requirement to install spacers be removed from the proposed AD. The commenter states that it inspected wire bundle W2800 on an airplane in its fleet that did not have spacers, and the inspection revealed that there was at least 1/4-inch clearance between the bracket and wire bundle. The commenter asserts that correct positioning of the wire bundle, without the installation of spacers, will prevent interference between the bundle and bracket.

The FAA does not agree to remove the requirement to install spacers. Installing spacers will ensure that appropriate clearance is maintained between the bracket and wire bundle. However, as discussed in our response above, we have revised paragraph (a) of this AD to extend the compliance time to 24 months for installation of the spacers for certain airplanes.

Request To Allow Damage Where Certain Tolerances Are Not Exceeded

One commenter requests that the proposed AD allow certain damage to exist where certain damage tolerance limits are not exceeded. The commenter states that there should be no requirement to repair or replace a wire bundle or its attaching hardware when it meets acceptable damage tolerances. The commenter points out that, in those cases, only repositioning is necessary, rather than repair or replacement, to prevent further damage.

The FAA partially agrees with the commenter. We have determined that it is unnecessary to “repair or replace” for those cases where damage to the wire bundle is within certain limits. However, there are no acceptable damage limits for the clamp bracket or the BACC10GU( ) clamp. Therefore, the final rule specifies that any damage to the clamp bracket or the BACC10GU( ) clamp requires replacement of the applicable part. We have revised the final rule to specify that the damage tolerance limits for the wire bundle must be approved by the Seattle Aircraft Certification Office (ACO), FAA. Damage limits specified in Chapter 20-10-13 the Boeing Standard Wiring Practices Manual (BSWPM) are also approved as a source to identify specific damage limits.

Request To Permit Interim Repair

One commenter states that the repair for damaged wires as specified in the BSWPM, referenced in the applicable service bulletin, requires replacement or repair by splicing any wire when damage extends to the conductor. The commenter notes that, in this case, the affected area does not allow sufficient distance to install a repair splice. The commenter advises that the only way to repair such a damaged conductor is to install a repair splice inside of the pressurized area and run the other end to the production ALCU splice at B STA 1862. The commenter further states that this procedure will require the removal of a galley and certain cabin panels, which will increase the length of time needed to accomplish the corrective action. Additionally, the commenter recommends the following actions instead of wire replacement with the following limitations:

• In the case of a single damaged conductor (one nicked strand, no broken strands), perform an interim insulation repair per BSWPM Chapter 20-10-13 and repair the clamp per the service bulletin.
• Replace the interim wire repair at the next C check, with a permanent wire splice per BSWPS Chapters 20-10-13 and 20-30-13 at B STA 1640.

The commenter asserts that those actions would provide an equivalent level of safety and allow minimal interruption of service.

We agree that, in the case of a single damaged conductor (one nicked strand, no broken strands), an interim insulation repair may be performed per the BSWPM under the following condition: The interim wire repair is replaced per the BSWPM within 6,000 flight hours from the accomplishment date of the interim repair. We have added new paragraph (c) of the AD to address accomplishment of the interim repair.

Request To Clarify Cost Information

This same commenter notes that the cost impact for accomplishing the repair of a damaged wire by splicing may significantly increase the cost of this AD. The commenter states that it would take approximately 65 work hours per airplane to perform that type of repair.

We acknowledge that if an operator is required to perform an “on-condition” repair, the costs of accomplishing the AD may increase. However, the economic analysis of an AD is limited to the cost of actions that are actually required. The economic analysis does not consider the costs of conditional actions, such as repairing damage detected during a required inspection (“repair, if necessary”), or as in this case, an alternative interim repair. Conditional costs would be required, regardless of AD direction, to correct an unsafe condition identified in an airplane and to ensure that the airplane is operated in an airworthy condition is required by the Federal Aviation Regulations. Therefore, no change to the “Cost Impact” section is required to this AD 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.

Changes to 14 CFR Part 39/Effect on the AD

On July 10, 2002, the FAA issued a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs the FAA's airworthiness directives system. The regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance. However, for clarity and consistency in this final rule, we have retained the language of the NPRM regarding that material.

Cost Impact

There are approximately 934 Boeing Model 757-200, -200PF, -200CB, and -300 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 595 airplanes of U.S. registry will be affected by this AD, that it will take approximately 1 work hour per airplane to accomplish the required actions, and that the average labor rate is $65 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $38,675, or $65 per 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.

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

[Amended]

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

2004-23-06 Boeing: Amendment 39-2004-23-06. Docket 2001-NM-74-AD.

Applicability: Model 757-200, -200PF, -200CB, as listed in Boeing Special Attention Service Bulletin 757-27-0089, Revision 1; and Model 757-300 series airplanes, as listed in Boeing Special Attention Service Bulletin 757-24-0090, Revision 1; both service bulletin revisions dated February 27, 2003; certificated in any category.

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 (d) 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 electrical contact between the power feeder wires of the auxiliary power unit (APU) and the clamp bracket aft of STA 1720 bulkhead due to chafing damage of the Adel clamp and “L” shaped bracket, which could result in electrical arcing and fire or loss of electrical power in the airplane; accomplish the following:

Inspection and Repair

(a) Within 18 months after the effective date of this AD, perform a general visual inspection for damage of the W2800 wire bundle insulation, wire conductor, wire bundle clamp bracket, and the BACC10GU( ) clamp; per Boeing Special Attention Service Bulletin 757-24-0089, Revision 1, dated February 27, 2003 (for Boeing Model 757-200 series airplanes); or Boeing Special Attention Service Bulletin 757-24-0090, Revision 1, dated February 27, 2003 (for Boeing Model 757-300 series airplanes); as applicable.

Note 2:

For the purposes of this AD, a general visual inspection is defined as: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

(1) With the exception of the actions specified in paragraph (c) of this AD: For the conditions specified in paragraph (a)(1)(i), (a)(1)(ii), or (a)(1)(iii) of this AD, and in paragraph (a)(1)(iv) of this AD, within 24 months after the effective date of this AD, install spacers and ensure that there is the minimum clearance between the wire bundle and aft edge of the bracket, per the applicable service bulletin.

(i) No damage is detected to the wire bundle insulation or the wire conductor,

(ii) Damage is detected to the wire bundle insulation or the wire conductor that is within certain limits approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, or

(iii) Damage is detected to the wire bundle insulation or the wire conductor that is within certain limits specified in Chapter 20-10-13 of the BSWPM; and

(iv) There is a 0.25-inch minimum clearance between the wire bundle and aft edge of the bracket.

(2) With the exception of the actions specified in paragraph (c) of this AD: For the conditions specified in paragraphs (a)(2)(i), (a)(2)(ii), or (a)(2)(iii) of this AD, and in paragraph (a)(2)(iv) of this AD, before further flight, install spacers and ensure the minimum clearance between the wire bundle and aft edge of the bracket, per the applicable service bulletin.

(i) No damage is detected to the wire bundle insulation or the wire conductor,

(ii) Damage is detected to the wire bundle insulation or the wire conductor that is within certain limits approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, or

(iii) Damage is detected to the wire bundle insulation or the wire conductor that is within certain limits specified in Chapter 20-10-13 of the BSWPM; and

(iv) There is less than 0.25-inch minimum clearance between the wire bundle and aft edge of the bracket.

(3) If any damage is detected to the wire insulation or wire conductor and the damage is outside the damage limits approved by the Manager, Seattle ACO, or specified in Chapter 20-10-13 of the BSWPM: Before further flight, repair the damage per the applicable service bulletin.

(4) If no damage is detected to the wire bundle clamp bracket or the BACC10GU( ) clamp: Within 24 months after the effective date of this AD, install spacers and ensure that there is 0.25-inch minimum clearance between the wire bundle and aft edge of the bracket; per the applicable service bulletin.

(5) If any damage is detected to the wire bundle clamp bracket or the BACC10GU( ) clamp: Before further flight, replace the clamp bracket and the clamp with new or serviceable parts, install spacers, and ensure that there is 0.25-inch minimum clearance between the wire bundle and aft edge of the bracket; per the applicable service bulletin.

Acceptable Method of Compliance

(b) Accomplishment of the actions specified in Boeing Service Bulletin 757-24-0089, dated March 15, 2001; or Boeing Service Bulletin 757-24-0090, dated March 15, 2001; as applicable, is considered acceptable for compliance with the requirements specified in paragraph (a) of this AD.

Interim Repair

(c) If damage to a wire conductor is detected during any inspection required by paragraph (a) of this AD that only consists of one strand being nicked and no broken strands: Accomplish the actions specified in paragraph (c)(1), (c)(2), and (c)(3) of this AD at the time specified.

(1) Prior to further flight, accomplish an interim repair of the insulation per a method approved by the Manager, Seattle ACO. For an interim repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically refer to this AD. Chapter 20-10-13 of the BSWPM is one approved method for accomplishing an interim repair.

(2) Accomplish the actions at the time specified in either paragraph (a)(4) or (a)(5) of this AD, as applicable.

(3) Within 6,000 flight hours after accomplishing the interim repair of the insulation specified in paragraph (c)(1) of this AD, replace the interim repair with a permanent repair, per a method approved by the Manager, Seattle ACO. For a permanent method to be approved by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically refer to this AD. Accomplishing Chapters 20-10-13 and 20-30-13 of the BSWPM is one approved method for replacement of the interim repair with a permanent repair.

Alternative Methods of Compliance

(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 ACO. 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 3:

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

(e) Special flight permits may be issued in accordance with §§ 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.

Incorporation by Reference

(f) Unless otherwise specified in this AD, the actions shall be done in accordance with Boeing Special Attention Service Bulletin 757-24-0089, Revision 1, dated February 27, 2003; or Boeing Special Attention Service Bulletin 757-24-0090, Revision 1, dated February 27, 2003. 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 National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call [phone], or go to: http://www.archives.gov/​federal_​register/​code_​of_​federal_​regulations/​ibr_​locations.html.

Effective Date

(g) This amendment becomes effective on December 21, 2004.

Issued in Renton, Washington, on November 3, 2004.

Kevin M. Mullin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.