[Federal Register Volume 71, Number 102 (Friday, May 26, 2006)]
[Proposed Rules]
[Pages 30331-30335]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-8115]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NM-12-AD]
RIN 2120-AA64


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

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: 
[email protected]. 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.

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.

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

[[Page 30332]]

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 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:

----------------------------------------------------------------------------------------------------------------
                                      Boeing service bulletin/
              Action                    revision level/date                   Airplane model/series
----------------------------------------------------------------------------------------------------------------
Modification......................  737-24-1165, Revision 1,     737-600, -700, -700C, -800, -900.
                                     dated October 20, 2005.     737-300, -400, -500.
                                    737-24A1166, Revision 1,
                                     dated October 20, 2005.
Modification......................  747-24-2254, dated July 21,  747-400, -400D, -400F.
                                     2005.
Modification......................  757-24-0110, dated April     757-200, -200CB, -200PF.
                                     28, 2005.                   757-300.
                                    757-24-0111, dated April
                                     28, 2005.
Modification......................  767-24-0160, dated June 30,  767-200, -300, -300F.
                                     2005.                       767-400ER.
                                     767-24-0161, dated June
                                     30, 2005.
Modification......................  777-24-0095, dated June 30,  777-200, -300, -300ER.
                                     2005.
----------------------------------------------------------------------------------------------------------------

    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

[[Page 30333]]

accurately 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.

[[Page 30334]]



                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                 Number of U.S.-
             Action                      Work hours          Average labor       Parts       Cost per airplane     registered           Fleet cost
                                                             rate per hour                                          airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Modification....................  Up to 2 hours, depending             $80              $0  Between $80 and               1,882  Up to $301,120.
                                   on airplane                                               $160.
                                   configuration.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    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.

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.


Sec.  39.13  [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/series                         Boeing service bulletin/revision level/date
----------------------------------------------------------------------------------------------------------------
737-600, -700, -700C, -800, -900....  737-24-1165, Revision 1, dated October 20, 2005.
737-300, -400, -500.................  737-24A1166, Revision 1, dated October 20, 2005.
747-400, -400D, -400F...............  747-24-2254, dated July 21, 2005.
757-200, -200CB, -200PF.............  757-24-0110, dated April 28, 2005.
757-300.............................  757-24-0111, dated April 28, 2005.
767-200, -300, -300F................  767-24-0160, dated June 30, 2005.
767-400ER...........................  767-24-0161, dated June 30, 2005.
777-200, -300, -300ER...............  777-24-0095, 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

[[Page 30335]]

Inspector, 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.

    Issued in Renton, Washington, on May 15, 2006.
Kevin M. Mullin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E6-8115 Filed 5-25-06; 8:45 am]
BILLING CODE 4910-13-P