Skip to Content

Proposed Rule

Airworthiness Directives; Boeing Model 737-300, -400, -500, -600, -700, -700C, -800, and -900, and 747-400 Series Airplanes; and Model 757, 767, and 777 Airplanes

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Supplemental notice of proposed rulemaking; reopening of comment period.

SUMMARY:

This document revises an earlier proposed airworthiness directive (AD), applicable to certain Boeing Model 737-300, -400, -500, -600, -700, -700C, -800, and -900, and 747-400 series airplanes; and Model 757, 767, and 777 airplanes. The original NPRM would have required modifying the static inverter by relocating resistor R170 of the static inverter bridge assembly. This new action revises the original NPRM by adding a new requirement for modifying the static inverter by replacing resistor R170 with a new resistor and relocating the new resistor. The actions proposed by this supplemental NPRM are intended to prevent a standby static inverter from overheating, which could result in smoke in the flight deck and cabin and loss of the electrical standby power system. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by June 20, 2006.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-12-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 (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2002-NM-12-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 or 2000 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.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Binh V. Tran, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6485; fax (425) 917-6590.

End Further Info End Preamble Start Supplemental Information

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 Start Printed Page 30332and 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 2002-NM-12-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. 2002-NM-12-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) with a notice of proposed rulemaking (NPRM) to add an AD (the “original NPRM”), applicable to certain Boeing Model 737-300, -400, -500, -600, -700, -700C, -800, and -900; 747-400; 757; 767; and 777 series airplanes. The original NPRM was published in the Federal Register on May 17, 2002 (67 FR 35057). The original NPRM would have required modifying the static inverter by relocating resistor R170 of the static inverter bridge assembly. The original NPRM was prompted by reports that static inverters had overheated on several Boeing airplanes. That condition, if not corrected, could result in smoke in the flight deck and cabin and loss of the electrical standby power system.

Actions Since Issuance of Previous Proposal

Since the issuance of the original NPRM, recent in-service experience has shown that simply relocating the carbon composition-style resistor, which was installed in production until late 1999, did not prevent the overheat condition. Further evaluation of the carbon resistor has shown a failure mode that can cause the resistor to ignite, involving adjacent capacitors as well.

Explanation of New Service Information

Boeing has released the following service bulletins:

ActionBoeing service bulletin/revision level/dateAirplane model/series
Modification737-24-1165, Revision 1, dated October 20, 2005 737-24A1166, Revision 1, dated October 20, 2005737-600, -700, -700C, -800, -900. 737-300, -400, -500.
Modification747-24-2254, dated July 21, 2005747-400, -400D, -400F.
Modification757-24-0110, dated April 28, 2005 757-24-0111, dated April 28, 2005757-200, -200CB, -200PF. 757-300.
Modification767-24-0160, dated June 30, 2005 767-24-0161, dated June 30, 2005767-200, -300, -300F. 767-400ER.
Modification777-24-0095, dated June 30, 2005777-200, -300, -300ER.

The modification includes inspecting to verify whether the part number of the affected static inverter is identified in the applicable service bulletin, removing any affected resistor R170 from the logic control card assembly and replacing it with a new resistor, and relocating the new resistor to the solder side of the printed circuit board.

The service bulletins refer to Avionic Instruments Inc. Service Bulletin 1-002-0102-1000-24-28, Revision A, dated June 22, 2005, as an additional source of service information for modifying the static inverter. The modification includes removing resistor R170 from the logic control card assembly, replacing it with a new resistor and relocating the new resistor to the solder side of the printed circuit board, and installing a Nomex pad on the opposing bracket support plate to avoid contact between the resistor body and the support bracket.

Comments on Original NPRM

Due consideration has been given to the comments received in response to the original NPRM.

Request To Change Static Inverter Part Number (P/N) Instead of Mod Letter

Condor Airlines, British Airways (BA), and the Air Transport Association (ATA), request that the static inverter's p/n instead of the mod letter be changed. They indicate that the inventory control systems track parts only by part numbers.

We acknowledge and agree with the comments provided. The Avionic Instruments Inc. Service Bulletin 1-002-0102-1000-24-24 (specified in the original NPRM) has been superseded by Service Bulletin 1-002-0102-1000-24-28, Revision A, to incorporate the part number changes as stated above. We have made no change to the supplemental NPRM in this regard.

Request for Clarification of Table 1

Condor Airlines, BA, and the ATA also request clarification of which listing is correct: Table 1 of the NPRM or the Boeing service letters. They point out that Table 1 of the NPRM is different from the parts listing contained in the Boeing service letter.

We agree that Table 1 of the original NPRM, as published, is misleading. Boeing service letters have been superseded by the Boeing service bulletins identified in the above section titled “Explanation of New Service Information.” This supplemental NPRM is now based on those service bulletins. Hence, Table 1 of the original NPRM has been revised in this supplemental NPRM.

Request for Component AD

Aloha Airlines states that the original NPRM does not specify serial numbers, and this should be a component AD. Aloha Airlines did not provide any justification for the request.

We disagree because this supplemental NPRM is based on the Boeing service bulletins and the Avionic Instruments Inc. service bulletin specified in the “Explanation of Relevant Service Information” section. Therefore, we have chosen an airplane-specific AD rather than a component AD as the appropriate method to correct the problem. We have made no change to the supplemental NPRM in this regard.

Request To Withdraw AD or Extend Compliance Time

Northwest Airlines (NWA) requests that the original NPRM be withdrawn, or at a minimum, that the compliance time be extended to 4 years. NWA states that the root cause of the resistor's overheat condition may not be Start Printed Page 30333accurately addressed. NWA also states that the manufacturer was concerned that more recent evidence indicates that a liquid substance may have leaked onto the resistor and contributed to the R170 resistor overheating condition. NWA requests that the overheating condition of R170 resistor be confirmed to determine if the cause of the excessive overheat condition is due to a liquid spill/leak.

Southwest Airlines (SWA), BA, the ATA, on behalf of its member, American Airlines (AA), and Boeing also request that the compliance time be extended from 18 months to a range between 24 and 48 months. Boeing requests 42 months. The commenters indicate that this is necessary due to the manufacturer's capacity and the volume of components requiring modification.

We partially agree. We disagree that the original NPRM should be withdrawn because we have received no information or evidence to indicate that a liquid substance may have leaked onto the R170 resistor and contributed to the overheating condition. We agree that the compliance time may be extended. We have determined that the compliance time may be extended from 18 to 42 months. We consider a 42-month compliance time will provide an acceptable level of safety, yet will allow operators sufficient time to process unmodified static inverters through the manufacturer's modification program without undue disruption of airline operation. We have changed paragraph (a) of this supplemental NPRM accordingly.

Request for Clarification of Part Number

NWA requests clarification of whether P/N 1-001-0102-0265 requires the resistor modification. NWA indicates that, per the manufacturer, this part also requires the resistor modification.

We do not agree. The number 1-001-0102-0265 is not a P/N and therefore is not identified in the applicability table. However, this supplemental NPRM overrides the original NPRM based on the service information. The affected static inverter part numbers are now listed in those service bulletins. We have made no change to the supplemental NPRM in this regard.

Request To Use Unmodified Spares

SWA and Boeing request that operators be allowed to use unmodified spares during the modification period. The commenters note the volume of units requiring modification versus the repair capabilities of the manufacturer.

We agree that unmodified spares may be used during the modification period. Therefore, we have not included paragraph (b) of the original NPRM in this supplemental NPRM, and we have reidentified subsequent paragraphs accordingly.

Request for Clarification of FAA-Approved Service Letters

Boeing points out that under “Explanation of Relevant Service Information,” the original NPRM reads as follows: “The FAA has reviewed and approved Boeing Service Letters 737-SL-24-165, 747-SL-24-058 * * *” and requests to verify whether the FAA approved those Boeing service letters. Boeing indicated that the FAA typically does not approve Boeing service letters, and Boeing has not been able to locate any such approval.

We agree. We typically do not approve service letters; however, that statement was inadvertently included in the original NPRM. That section is not restated in the supplemental NPRM; therefore, we have made no change in this regard.

Request To Change Cost Impact Section

NWA and Avionic Instruments Inc. request that the original NPRM be revised to identify the recertification cost. The manufacturer has informed the commenters that they will be responsible for recertification and freight charges for returned units.

The ATA points out that the NPRM preamble states that “warranty remedies are available for the cost of modified replacement parts and labor associated with accomplishing the action specified by the original NPRM. Therefore, the economic cost impact of the original NPRM on U.S. operators may be minimal.” The ATA requests that the original NPRM be revised to address cases where warranty remedies are not available. The ATA indicates that the removal and replacement of the inverter will require 2 elapsed hours per airplane, and the proposed modification will require 6 work hours per inverter.

We agree that the cost section of the supplemental NPRM should be changed to incorporate cases where warranty remedies are not available. Additionally, the cost information specified in the original NPRM contained warranty information that is no longer used in ADs. Therefore, the cost information, below, has been revised to remove the warranty information.

Explanation of Change to Costs of Compliance

After the original NPRM was issued, we reviewed the figures we have used over the past several years to calculate AD costs to operators. To account for various inflationary costs in the airline industry, we find it necessary to increase the labor rate used in these calculations from $65 per work hour to $80 per work hour. The cost impact information, below, reflects this increase in the specified hourly labor rate.

Explanation of Change to Applicability

We have revised the applicability of the original NPRM to identify model designations as published in the most recent type certificate data sheet for the affected models.

Clarification of Alternative Method of Compliance (AMOC) Paragraph

We have revised the “Alternative Methods of Compliance (AMOCs)” paragraph in this AD to clarify the appropriate procedure for notifying the principal inspector before using any approved AMOC on any airplane to which the AMOC applies.

Conclusion

Since a certain change expands the scope of the originally proposed rule, we have determined that it is necessary to reopen the comment period to provide additional opportunity for public comment.

Changes to 14 CFR Part 39/Effect on the Proposed 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 (AMOCs). These changes are reflected in this supplemental NPRM.

Cost Impact

There are approximately 3,832 airplanes of the affected design in the worldwide fleet. We estimate that 1,882 airplanes of U.S. registry would be affected by this supplemental NPRM. The following table provides the estimated costs for U.S. operators to comply with this supplemental NPRM. Start Printed Page 30334

Estimated Costs

ActionWork hoursAverage labor rate per hourPartsCost per airplaneNumber of U.S.-registered airplanesFleet cost
ModificationUp to 2 hours, depending on airplane configuration$80$0Between $80 and $1601,882Up to $301,120.

The cost impact figures discussed in ADs are based on assumptions that no operator has yet accomplished any of the proposed requirements, and that no operator would accomplish those actions in the future if the supplemental NPRM 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.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in subtitle VII, part A, subpart III, section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

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.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End List of Subjects

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:

Start Part

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Start Authority

Authority: 49 U.S.C. 106(g), 40113, 44701.

End Authority
[Amended]

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

Boeing: Docket 2002-NM-12-AD.

Applicability: This AD applies to the following airplanes, certificated in any category, as identified in the applicable service bulletin specified in Table 1 of this AD:

Table 1.—Applicability

Airplane model/seriesBoeing service bulletin/revision level/date
737-600, -700, -700C, -800, -900737-24-1165, Revision 1, dated October 20, 2005.
737-300, -400, -500737-24A1166, Revision 1, dated October 20, 2005.
747-400, -400D, -400F747-24-2254, dated July 21, 2005.
757-200, -200CB, -200PF757-24-0110, dated April 28, 2005.
757-300757-24-0111, dated April 28, 2005.
767-200, -300, -300F767-24-0160, dated June 30, 2005.
767-400ER767-24-0161, dated June 30, 2005.
777-200, -300, -300ER777-24-0095, dated June 30, 2005.

Compliance: Required as indicated, unless accomplished previously.

To prevent a standby static inverter from overheating, which could result in smoke in the flight deck and cabin and loss of the electrical standby power system, accomplish the following:

Modification

(a) Within 42 months after the effective date of this AD: Modify the static inverter by removing resistor R170 from the logic control card assembly and replacing it with a new resistor, and relocating the new resistor to the solder side of the printed circuit board, in accordance with the Accomplishment Instructions of the applicable service bulletin specified in Table 1 of this AD.

Note 1:

The Boeing service bulletins specified in Table 1 of this AD refer to Avionic Instruments Inc. Service Bulletin 1-002-0102-1000-24-28, Revision A, dated June 22, 2005, as an additional source of service information for the modification required by paragraph (a) of this AD.

Alternative Methods of Compliance

(b)(1) 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 Start Printed Page 30335Inspector, who may add comments and then send it to the Manager, Seattle ACO.

(2) Before using any AMOC approved in accordance with 14 CFR 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office.

Start Signature

Issued in Renton, Washington, on May 15, 2006.

Kevin M. Mullin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

End Signature End Part End Supplemental Information

[FR Doc. E6-8115 Filed 5-25-06; 8:45 am]

BILLING CODE 4910-13-P