[Federal Register Volume 70, Number 21 (Wednesday, February 2, 2005)]
[Rules and Regulations]
[Pages 5366-5370]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-1722]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2003-NM-221-AD; Amendment 39-13958; AD 2005-03-02]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-300, -400, and -500 
Series Airplanes; and Model 757-200 and -200CB Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 737-300, -400, and -500 series 
airplanes; and Model 757-200 and -200CB series airplanes, that requires 
inspection of the applicable body station frames for open body station 
frames and related investigative/corrective actions; and installation 
of lanyard hook brackets and lanyard assemblies under the air 
conditioning overhead ducts, as applicable. This action is necessary to 
prevent loosened or disconnected overhead ducts from causing ceiling 
panels to drop below the minimum height of the evacuation zone for the 
passenger cabin, which could result in inadequate height for safe exit 
in the event of an emergency evacuation. This action is intended to 
address the identified unsafe condition.

DATES: Effective March 9, 2005.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 9, 2005.

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 FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington. 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 (202) 741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

FOR FURTHER INFORMATION CONTACT: Keith Ladderud, Aerospace Engineer, 
Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 917-6435; fax (425) 917-6590.

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 737-300, -
400, and -500 series airplanes; and Model 757-200 and -200CB series 
airplanes was published in the Federal Register on May 11, 2004 (69 FR 
26054). That action proposed to require inspection of the applicable 
body station frames for open body station frames and related 
investigative/corrective actions; and installation of lanyard hook 
brackets and lanyard assemblies under the air conditioning overhead 
ducts, as applicable.

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.

Request for an Optional Terminating Action

    Two commenters request that we add Boeing Service Letter 757-SL-21-
057-A, including Attachments I and II, dated March 24, 2004, as an 
alternative method of compliance (AMOC) for the installation of 
lanyards on Boeing Model 757 series airplanes. As justification, one 
commenter states that the duct manufacturer has created replacement 
overhead ducts with nearly 50 percent greater ultimate strength than 
the ducts delivered on the affected airplanes. The commenter also 
asserts that, because of the reduced duct dimensions and air loads, 
there has not been any tension failure of ducts forward of station 550 
or aft of station 1389 on Model 757-200 series airplanes.
    The other commenter states that the new, improved overhead ducts

[[Page 5368]]

eliminate the need to install lanyards, since they are more robust and 
resistant to de-coupling, delamination, moisture ingress, and breakaway 
at attach points. The commenter also points out that the FAA has 
approved these ducts through the parts manufacturer approval process.
    We agree with the commenters. Since issuance of the proposed AD, we 
have reviewed Boeing Service Letter 757-SL-21-057-A, including 
Attachments I and II, dated March 24, 2004. For certain Model 757 
series airplanes, the Boeing service letter describes procedures for 
replacing the original design foam ducts with new, improved foam ducts. 
We find that this optional replacement adequately addresses the unsafe 
condition in this AD on certain Model 757-200 and -200CB series 
airplanes. The optional replacement would eliminate the need for the 
general visual inspection and corrective actions, if applicable, 
required by paragraph (c) of this AD. Therefore, we have inserted a new 
paragraph (d) into this final rule and relettered the subsequent 
paragraphs accordingly.

Request To Extend Compliance Time

    One commenter requests that we extend the compliance time for 
installing lanyards from 60 months to at least 63 months, so affected 
operators can perform the installation during a scheduled heavy 
maintenance interval. The commenter states the 60-month interval does 
not correspond with any maintenance interval for Boeing Model 757 
series airplanes or with the Maintenance Review Board (MRB) heavy 
maintenance visit (4C), which is scheduled at a 72-month interval. The 
commenter also asserts that airplane downtime would be significant if 
the proposed installation is scheduled outside of a heavy maintenance 
visit. As justification for the request, the commenter says that 
failure of the ducts is evident by the appearance of the ceiling 
panels, which could be discovered and corrected during the MRB zonal 
inspection of the main cabin that occurs every 18 months (at 1C). In 
its experience, the commenter believes this interval is sufficient. The 
commenter also states ``* * * a 63-month compliance time would leave 
one interval at no more than (allowing for prior yield loss) 12 months 
which would be less than the 1C interval.''
    We agree with the commenter's request to extend the compliance 
time. We intended to require the inspection and installation of 
lanyards at intervals that would coincide with regularly scheduled 
maintenance visits for the majority of the affected fleet, when the 
airplanes would be located at a base where special equipment and 
trained personnel would be readily available, if necessary. Based on 
the information supplied by the commenters, we now recognize that 72 
months corresponds more closely to the interval representative of most 
of the affected operators' normal maintenance schedules. We have 
revised paragraphs (b)(1), (b)(2), and (c) of the final rule to require 
a compliance time of 72 months. We do not consider that this extension 
will adversely affect safety.

Request To Withdraw Proposed AD

    One commenter objects to requiring an AD to address the unsafe 
condition in Boeing Special Attention Service Bulletin 737-21-1131, 
Revision 2, dated April 18, 2002, because of the large expense of 
complying with the proposed AD. For its 67 affected airplanes, the 
commenter states that it would cost $1,500,000, and that the 
manufacturer would not offer any reimbursement for this expense. The 
commenter also states that the price of the modification kit increased 
40 percent after issuance of the proposed AD. We infer that the 
commenter is asking us to withdraw the proposed AD.
    We do not agree with the inferred request, since the installation 
of lanyards is necessary to prevent loosened or disconnected overhead 
ducts from causing ceiling panels to drop below the minimum height of 
the evacuation zone for the passenger cabin. This condition could 
result in inadequate height for safe exit in the event of an emergency 
evacuation. While we acknowledge the concern of the commenter, we 
cannot control the cost of the manufacturer's modification kit or get 
involved in any discussion related to reimbursement from the 
manufacturer. The cost impact of this AD is based on the best data 
available provided to us by the manufacturer. No change to this AD is 
necessary in this regard.

Request To Allow Repetitive Inspections and Optional Terminating Action

    Two commenters request that, as an alternate method of compliance, 
we allow repetitive inspections of the overhead ducts and replacement 
of deteriorating ducts before they fail. One commenter requests 
specifically that the repetitive inspections are done at every C-check, 
and that the replacement is done in accordance with Boeing Service 
Letter 757-SL-21-057-A, including Attachments I and II, dated March 24, 
2004. The commenter states that this service letter provides procedures 
for installing improved overhead ducts, which substantially increases 
the structural support for the ducts and ceiling panels. The commenter 
provides no justification for the repetitive inspections.
    The other commenter believes that regular inspections of the 
overhead ducts for air leakage and the addition of repetitive 
inspections of the duct holding clamps/brackets and ceiling supports to 
the regular inspection of the overhead duct assembly by borescope 
method would sufficiently address the unsafe condition in the proposed 
AD. The commenter asserts that these inspections would allow early and 
proper action to prevent the unsafe condition. The commenter states 
that its proposed AMOC is adequate, since it has never discovered the 
unsafe condition addressed by the proposed AD on any of its own or its 
customer's affected airplanes.
    We do not agree with the commenters' request to allow repetitive 
inspections of the overhead ducts. However, as stated in our response 
to a previous comment, we agree that replacement of the overhead ducts 
in accordance with Boeing Service Letter 757-SL-21-057-A adequately 
addresses the unsafe condition in this AD for certain Model 757-200 and 
-200CB series airplanes and eliminates the need for the actions 
required by paragraph (c) of this AD.
    We have investigated the potential for repetitive inspections of 
the overhead ducts, either by borescope or other methods, as an 
alternative to installing lanyards and have determined that an 
inspection program is impracticable due to the nature of the duct 
design and failure mode. It has been shown that, over time, the 
overhead ducts will deteriorate. In addition, operators have reported 
overhead ducts with air leakage, moisture ingress, delamination, broken 
isolator mounts, and support mounts that have pulled through the duct. 
Furthermore, the manufacturer has told us that it cannot identify the 
specific damage to the air ducts, which would indicate where failure 
(the ceiling panels dropping into the passenger evacuation zone) is 
imminent.
    While there have been very few reported instances where the 
overhead duct failed and consequently allowed the panels to fall into 
the passenger cabin, such a failure has been encountered. This failure 
has been linked to a deficiency in the design of the affected airplanes 
and could cause the inboard edge of the ceiling panel to be in the 
passenger evacuation zone. This situation will impede egress in the 
event of an emergency evacuation.

[[Page 5369]]

Request To Revise Cost Impact

    One commenter questions our estimate of 27 work hours for 
installing lanyards in the proposed AD, where the service bulletin 
estimates 39 work hours, which includes time to gain access to the 
area. The commenter states that installing the attach brackets for the 
lanyards involves significant problems in gaining access and working in 
a confined space. The commenter also states that a review of the work 
required for its fleet of Model 757 series airplanes indicated that the 
estimate in the service bulletin is already very conservative. We infer 
that the commenter requests that we revise the Cost Impact for this AD.
    We do not agree with the inferred request because the purpose of 
the Cost Impact section is only to estimate the costs of compliance 
with the AD. As stated in this and the proposed AD, 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. Therefore, no change to 
this AD 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 2,187 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 984 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. The average 
labor rate is $65 per work hour. The estimated maximum total cost for 
all airplanes affected by this AD is $10,607,648.

                                               Table.--Cost Impact
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                                    U.S.                         Labor cost
             Model               registered    Work hours per       per        Parts cost per      Total cost
                                 airplanes        airplane        airplane        airplane
----------------------------------------------------------------------------------------------------------------
737-300, -400, and -500 series          665  28 (Identify the        $1,820  $6,925 to $9,650   $5,815,425 to
 airplanes.                                   body frames,                    (Depending on      $7,627,550
                                              install support                 overhead duct      (Depending on
                                              brackets; rework                installation       overhead duct
                                              and install                     configuration).    installation
                                              insulation;                                        configuration),
                                              install lanyard                                    or $8,745 to
                                              and hook                                           $11,470 per
                                              brackets).                                         airplane.
757-200 and -200CB series               319  27 (Examine              1,755  7,587............  $2,980,098, or
 airplanes.                                   station frame,                                     $9,342 per
                                              install bracket,                                   airplane.
                                              lanyard, and
                                              insulation).
----------------------------------------------------------------------------------------------------------------

    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 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

    The FAA's authority to issue rules regarding aviation safety is 
found in Title 49 of the United States Code. 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.
    This rulemaking is promulgated 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 AD.

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

0
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

0
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]

0
2. Section 39.13 is amended by adding the following new airworthiness 
directive:

2005-03-02 Boeing: Amendment 39-13958. Docket 2003-NM-221-AD.


[[Page 5370]]


    Applicability: This AD applies to the airplanes listed in Table 
1 of this AD, certificated in any category:

                         Table 1.--Applicability
------------------------------------------------------------------------
               Boeing model                         As listed in
------------------------------------------------------------------------
Model 737-300, -400, and -500 series        Boeing Special Attention
 airplanes.                                  Service Bulletin 737-21-
                                             1131, Revision 2, dated
                                             April 18, 2002.
Model 757-200 and -200CB series airplanes.  Boeing Special Attention
                                             Service Bulletin 757-21-
                                             0088, dated April 18, 2002.
------------------------------------------------------------------------

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent loosened or disconnected overhead ducts from causing 
ceiling panels to drop below the minimum height of the evacuation 
zone for the passenger cabin, which could result in inadequate 
height for safe exit in the event of an emergency evacuation, 
accomplish the following:

Service Bulletin References

    (a) The term ``service bulletin,'' as used in this AD, means the 
applicable service bulletins listed in Table 1 of this AD.

Inspection and Related Investigative/Corrective Actions

    (b) For Model 737-300, -400, and -500 series airplanes, do the 
actions required in paragraphs (b)(1) and (b)(2) of this AD at the 
specified compliance times, in accordance with the Accomplishment 
Instructions of the service bulletin.
    (1) Within 72 months after the effective date of this AD, do a 
general visual inspection at the applicable body station frames for 
open body station frames; and, before further flight, do all the 
related investigative/corrective actions, as applicable; by 
accomplishing all of the actions in paragraph 3.B. of the service 
bulletin.

    Note 1: 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.''

    (2) Within 72 months after the effective date of this AD, do the 
actions required in paragraph (b)(2)(i) or (b)(2)(ii) of this AD, as 
applicable.
    (i) For Groups 1 and 3 airplanes identified in the service 
bulletin: Install the lanyard hook brackets and each lanyard 
assembly under the air conditioning (AC) overhead ducts in 
accordance with paragraph 3.C. of the service bulletin.
    (ii) For Group 2 airplanes identified in the service bulletin: 
Install the lanyard hook brackets and the lanyard assemblies under 
the AC overhead ducts by accomplishing all of the actions in 
paragraph 3.D. of the service bulletin.
    (c) For Model 757-200 and -200CB series airplanes: Within 72 
months after the effective date of this AD, do a general visual 
inspection of the applicable body station frames for open body 
station frames; and, before further flight, do all the corrective 
actions, as applicable; by accomplishing all of the actions in the 
Accomplishment Instructions of the service bulletin.

Optional Terminating Action

    (d) For Model 757-200 and -200CB series airplanes: Accomplishing 
the replacement of the original design foam ducts with Saint-Gobain 
design foam ducts by doing all of the actions in Attachments I and 
II of Boeing Service Letter 757-SL-21-057-A, dated March 24, 2004, 
terminates the actions required by paragraph (c) of this AD.

Credit for Actions Accomplished Per Previous Service Bulletins

    (e) Actions accomplished before the effective date of this AD 
per Boeing Special Attention Service Bulletin 737-21-1131, original 
release, dated December 20, 2001; or Revision 1, dated January 25, 
2002; are acceptable for compliance with the requirements of 
paragraph (b) of this AD.

Alternative Methods of Compliance

    (f) In accordance with 14 CFR 39.19, the Manager, Seattle 
Aircraft Certification Office, FAA, is authorized to approve 
alternative methods of compliance (AMOCs) for this AD.

Incorporation by Reference

    (g) Unless otherwise specified by this AD, the actions shall be 
done in accordance with Boeing Special Attention Service Bulletin 
737-21-1131, Revision 2, dated April 18, 2002; and Boeing Special 
Attention Service Bulletin 757-21-0088, dated April 18, 2002; as 
applicable. The optional terminating action, if accomplished, shall 
be done in accordance with Boeing Service Letter 757-SL-21-057-A, 
including Attachements I and II, dated March 24, 2004. 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 Airplanes, 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 (202) 741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

Effective Date

    (h) This amendment becomes effective on March 9, 2005.

    Issued in Renton, Washington, on January 18, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-1722 Filed 2-1-05; 8:45 am]
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