

[Federal Register: December 17, 2007 (Volume 72, Number 241)]
[Proposed Rules]               
[Page 71275-71277]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr17de07-18]                         

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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]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 757 Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for all Boeing Model 757 airplanes. This proposed AD would require 
repetitive inspections of the anchor tab of the bulkhead seal 
assemblies of the wing thermal anti-ice (TAI) system for cracks

[[Page 71276]]

at certain outboard stations of the left and right wings, and 
corrective action if necessary. This proposed AD also provides optional 
terminating action for the repetitive inspections. This proposed 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 
proposing 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: We must receive comments on this proposed AD by January 31, 
2008.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov.
 Follow the instructions for submitting comments.

     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building, Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building, Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    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 proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (telephone 800-647-5527) is in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

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:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2007-0339; 
Directorate Identifier 2007-NM-182-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov
, including any personal information you provide. We 

will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    We have received reports of cracks found at the anchor tab of the 
bulkhead seal assemblies of the wing thermal anti-ice (TAI) system on 
Boeing Model 757 airplanes. In one incident the anchor tab and bulkhead 
seal assembly had separated because of the cracks. The anchor tab of 
the bulkhead seal assembly was held in position with a bolt. If the 
anchor tab fails, the TAI spray tube disconnects from the TAI duct, and 
it could not supply sufficient airflow for the wing TAI system. If the 
flight is in icing conditions and there is insufficient airflow, it 
could cause ice to form on the wings. These conditions, if not 
corrected, could result in reduced controllability of the airplane.

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletins 757-30-
0021 and 757-30-0022, both Revision 1, both dated June 13, 2007. The 
service bulletins describe procedures for repetitive 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, and corrective action before further flight if 
necessary. The compliance time specified in the service bulletin for 
the initial inspection is before the accumulation of 20,000 total 
flight hours or within 36 months from the effective date on the service 
bulletin, whichever occurs later.
    The corrective action includes replacing the bulkhead seal assembly 
or installing new duct anchor support brackets if cracks are found. If 
the bulkhead seal assembly is replaced, but new support brackets are 
not installed, the inspections must be repeated until the existing 
brackets are replaced. Replacing the support brackets eliminates the 
need for the repetitive inspections. The compliance time for the 
repetitive inspections is at intervals not to exceed 6,000 flight 
hours; for airplanes on which the bulkhead seal assemblies are 
replaced, the inspection is repeated within 20,000 flight hours after 
the replacement, and thereafter at intervals not to exceed 6,000 flight 
hours.
    Accomplishing the actions specified in the service information is 
intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other airplanes 
of this same type design. For this reason, we are proposing this AD, 
which would require accomplishing the actions specified in the service 
information described previously.

Costs of Compliance

    There are about 929 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 530 airplanes of 
U.S. registry. The proposed inspection would take 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 proposed 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.

[[Page 71277]]

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD 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.
    For the reasons discussed above, I certify that the 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. 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD and placed it in the AD docket. See the 
ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-0339; Directorate Identifier 2007-NM-
182-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by January 
31, 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.

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 Issues 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 (ACO), 
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.

    Issued in Renton, Washington, on December 10, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-24329 Filed 12-14-07; 8:45 am]

BILLING CODE 4910-13-P
