
[Federal Register: April 14, 2008 (Volume 73, Number 72)]
[Rules and Regulations]               
[Page 19993-19995]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr14ap08-15]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-0339; Directorate Identifier 2007-NM-182-AD; 
Amendment 39-15464; AD 2008-08-12]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 757 Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for all 
Boeing Model 757 airplanes. This AD requires repetitive inspections of 
the anchor tab of the bulkhead seal assemblies of the wing thermal 
anti-ice (TAI) system for cracks at certain outboard stations of the 
left and right wings, and corrective action if necessary. This AD also 
provides optional terminating action for the repetitive inspections. 
This AD results from reports of cracks found at the anchor tab of the 
bulkhead seal assemblies of the wing TAI system. In one incident, the 
anchor tab and bulkhead seal assembly had separated because of the 
cracks. We are issuing this AD to prevent failure of the anchor tab of 
the bulkhead seal assembly, which in icing conditions could result in 
insufficient airflow to the wing TAI system, subsequent ice on the 
wings, and consequent reduced controllability of the airplane.

DATES: This AD is effective May 19, 2008.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in this AD as of May 19, 2008.

ADDRESSES: For service information identified in this AD, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-
2207.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this AD, the regulatory evaluation, 
any comments received, and other information. The address for the 
Docket Office (telephone 800-647-5527) is the Document Management 
Facility, U.S. Department of Transportation, Docket Operations, M-30, 
West Building, Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., 
Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Barbara Mudrovich, Aerospace Engineer, 
Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98057-3356; telephone (425) 917-6477; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to include an airworthiness directive (AD) that would apply to 
all Boeing Model 757 airplanes. That NPRM was published in the Federal 
Register on December 17, 2007 (72 FR 71275). That NPRM proposed to 
require repetitive inspections of the anchor tab of the bulkhead seal 
assemblies of the wing thermal anti-ice (TAI) system for cracks at 
certain outboard stations of the left and right wings, and corrective 
action if necessary. That NPRM also proposed to provide for optional

[[Page 19994]]

terminating action for the repetitive inspections.

Comments

    We gave the public the opportunity to participate in developing 
this AD. We considered the comments received.

Support for the NPRM

    Boeing concurs with the contents of the NPRM.

Request To Extend Compliance Time

    Northwest Airlines (NWA) asks that the repetitive inspection 
intervals specified in the NPRM be changed from 6,000 flight hours to 
24 months. NWA states that because the NPRM already allows up to 36 
months after the airplane has accumulated 20,000 total flight hours to 
accomplish the initial check, an acceptable level of safety would be 
maintained if repetitive intervals coincide with operator-scheduled 
heavy check intervals not to exceed 24 months. NWA adds that if 
repetitive inspections are at the proposed 6,000-flight-hour intervals, 
the inspections would need to be accomplished in a line environment. 
NWA asks that we allow the repetitive inspections to be done during 
heavy maintenance checks where specialized personnel are available in a 
controlled environment more conducive to performing the work.
    We do not agree to extend the compliance time for the repetitive 
inspections. Based on data from the manufacturer, we find that a 6,000-
flight-hour interval is appropriate. We do not currently have data or 
analysis, nor did NWA provide any, that can support such an extension 
of the compliance time. We have determined that the 6,000-flight-hour 
compliance time is appropriate given the probability of crack 
initiation, crack growth characteristics, and the ability of operators 
to integrate the required actions into established maintenance 
practices. However, according to the provisions of paragraph (i) of 
this AD, we may approve requests to adjust the compliance time if the 
request includes data that prove that the new compliance time would 
provide an acceptable level of safety. We have made no change to the AD 
in this regard.

Request To Increase Work Hour Estimate

    NWA also states that the work-hour estimate specified in the Costs 
of Compliance section of the NPRM is underestimated. NWA states that 
the 2-hour estimate for the inspections is well below the estimate 
provided by Boeing Special Attention Service Bulletins 757-30-0021 and 
757-30-0022, both Revision 1, both dated June 13, 2007, as referenced 
in the NPRM. NWA adds that an accurate estimate for accomplishing the 
inspections is 8 work hours (2 work hours per support) when access is 
provided at a heavy maintenance check.
    From this comment, we infer that NWA would like us to increase the 
work-hour estimate given in the NPRM. We do not agree. The cost 
information below describes only the direct costs of the specific 
actions required by this AD. Based on the best data available, the 
manufacturer provided the number of work hours (2) necessary to do the 
required inspections, as specified in the service bulletins. This 
number represents the time necessary to perform only the actions 
actually required by this AD. We recognize that, in doing the actions 
required by an AD, operators might incur incidental costs in addition 
to the direct costs. The cost analysis in AD rulemaking actions, 
however, typically does not include incidental costs such as the time 
required to gain access and close up, time necessary for planning, or 
time necessitated by other administrative actions. Those incidental 
costs, which might vary significantly among operators, are almost 
impossible to calculate. We have made no change to the AD in this 
regard.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
the AD as proposed.

Costs of Compliance

    There are about 929 airplanes of the affected design in the 
worldwide fleet. This AD affects about 530 airplanes of U.S. registry. 
The inspection takes about 2 work hours per airplane, at an average 
labor rate of $80 per work hour. Based on these figures, the estimated 
cost of the AD for U.S. operators is $84,800, or $160 per airplane, per 
inspection cycle.

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 Findings

    This AD will not have federalism implications under Executive Order 
13132. This AD 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.
    For the reasons discussed above, I certify that this AD:
    (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.
    You can find our regulatory evaluation and the estimated costs of 
compliance in the AD Docket.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 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. The FAA amends Sec.  39.13 by adding the following new AD:

2008-08-12 Boeing: Amendment 39-15464. Docket No. FAA-2007-0339; 
Directorate Identifier 2007-NM-182-AD.

Effective Date

    (a) This airworthiness directive (AD) is effective May 19, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all Boeing Model 757-200, -200PF, -200CB, 
and -300 series airplanes, certificated in any category.

[[Page 19995]]

Unsafe Condition

    (d) This AD results from reports of cracks found at the anchor 
tab of the bulkhead seal assemblies of the wing thermal anti-ice 
(TAI) system. In one incident, the anchor tab and bulkhead seal 
assembly had separated because of the cracks. We are issuing this AD 
to prevent failure of the anchor tab of the bulkhead seal assembly, 
which in icing conditions could result in insufficient airflow to 
the wing TAI system, subsequent ice on the wings, and consequent 
reduced controllability of the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Repetitive Inspections/Corrective Action

    (f) At the applicable times specified in paragraph 1.E., 
``Compliance,'' of Boeing Special Attention Service Bulletin 757-30-
0021 or 757-30-0022, both Revision 1, both dated June 13, 2007, as 
applicable; except where the service bulletins specify starting the 
compliance time `` * * * from the date on this service bulletin,'' 
this AD requires starting the compliance time from the effective 
date of this AD: Perform detailed inspections for cracks of the 
anchor tab of the bulkhead seal assemblies of the wing TAI system at 
certain outboard stations of the left and right wings by doing all 
the actions, including all applicable corrective actions, in 
accordance with the Accomplishment Instructions of the applicable 
service bulletin. Do all applicable corrective actions before 
further flight.

Optional Terminating Action

    (g) Installing a new duct anchor support bracket adjacent to the 
bulkhead seal assemblies in accordance with Part 2 of the 
Accomplishment Instructions of Boeing Special Attention Service 
Bulletin 757-30-0021 or 757-30-0022, both Revision 1, both dated 
June 13, 2007, as applicable, ends the repetitive inspections 
required by paragraph (f) of this AD.

Credit for Actions Done According to Previous Issue of Service 
Information

    (h) Actions accomplished before the effective date of this AD in 
accordance with Boeing Special Attention Service Bulletins 757-30-
0021 and 757-30-0022, both dated August 15, 2006, are considered 
acceptable for compliance with the corresponding actions specified 
in this AD.

Alternative Methods of Compliance (AMOCs)

    (i)(1) The Manager, Seattle Aircraft Certification Office, FAA, 
has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.

Material Incorporated by Reference

    (j) You must use Boeing Special Attention Service Bulletin 757-
30-0021, Revision 1, dated June 13, 2007; or Boeing Special 
Attention Service Bulletin 757-30-0022, Revision 1, dated June 13, 
2007; as applicable; to do the actions required by this AD, unless 
the AD specifies otherwise.
    (1) The Director of the Federal Register approved the 
incorporation by reference of this service information under 5 
U.S.C. 552(a) and 1 CFR part 51.
    (2) For service information identified in this AD, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 
98124-2207.
    (3) You may review copies of the service information 
incorporated by reference 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.

    Issued in Renton, Washington, on April 3, 2008.
Dionne Palermo,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E8-7662 Filed 4-11-08; 8:45 am]

BILLING CODE 4910-13-P
