
[Federal Register: July 2, 2008 (Volume 73, Number 128)]
[Proposed Rules]               
[Page 37900-37903]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr02jy08-46]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0731; Directorate Identifier 2008-NM-058-AD]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-
100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 
747-400F, 747SR, and 747SP Series 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 supersede an existing airworthiness 
directive (AD) that applies to all Boeing Model 747 series airplanes. 
The existing AD currently requires repetitive detailed inspections of 
the aft pressure bulkhead for indications of ``oil cans'' and previous 
oil can repairs, and corrective actions, if necessary. An oil can is an 
area on a pressure dome web that moves when pushed from the forward 
side. This proposed AD would reduce the compliance time for the initial 
detailed inspection and clarify the applicability. This proposed AD 
results from a report that cracks in oil-canned areas were found during 
an inspection of the aft pressure bulkhead. We are proposing this AD to 
detect and correct the propagation of fatigue cracks in the vicinity of 
oil cans on the web of the aft pressure bulkhead, which could result in 
rapid decompression of the airplane and overpressurization of the tail 
section, and consequent loss of control of the airplane.

DATES: We must receive comments on this proposed AD by August 18, 2008.

[[Page 37901]]


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: Ivan Li, Aerospace Engineer, Airframe 
Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind 
Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6437; 
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-2008-0731; 
Directorate Identifier 2008-NM-058-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

    On July 30, 2004, we issued AD 2004-16-09, amendment 39-13765 (69 
FR 48133, August 9, 2004), for all Boeing Model 747 series airplanes. 
That AD requires repetitive detailed inspections of the aft pressure 
bulkhead for indications of ``oil cans'' and previous oil can repairs, 
and corrective actions, if necessary. An oil can is an area on a 
pressure dome web that moves when pushed from the forward side. That AD 
resulted from a report indicating that a 2.1-inch long crack in the web 
of the aft pressure bulkhead at the perimeter of an ``oil can'' was 
found on a Model 747SR series airplane. We issued that AD to detect and 
correct the propagation of fatigue cracks in the vicinity of oil cans 
on the web of the aft pressure bulkhead, which could result in rapid 
decompression of the airplane and overpressurization of the tail 
section, and consequent loss of control of the airplane.

Actions Since Existing AD Was Issued

    Since we issued AD 2004-16-09, we received a report that 9 cracks 
(up to 0.4-inch long in 2 oil-canned areas) were found during an 
inspection on the aft pressure bulkhead of a Model 747-200F series 
airplane with about 21,000 total flight cycles. Boeing recommends 
reducing the initial inspection threshold (required in paragraph (b) of 
AD 2004-16-09) from 30,000 total flight cycles to 20,000 total flight 
cycles.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 747-53A2482, 
Revision 1, dated February 21, 2008. The service bulletin describes 
procedures that are the same as in Boeing Alert Service Bulletin 747-
53A2482, dated October 3, 2002, except for a reduction in a compliance 
time and some editorial changes. Revision 1 of the service bulletin 
also specifies contacting Boeing for repair data if any crack is found 
during a detailed inspection of any previous ``oil can'' repair.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to develop on other airplanes of the 
same type design. For this reason, we are proposing this AD, which 
would supersede AD 2004-16-09 and would retain the requirements of the 
existing AD. This proposed AD would also require accomplishing the 
actions specified in the service bulletin described previously at a 
reduced threshold, except as discussed under ``Differences Between the 
Proposed AD and Revision 1 of the Service Bulletin.''

Differences Between the Proposed AD and Revision 1 of the Service 
Bulletin

    The service bulletin specifies to contact the manufacturer for 
instructions on how to repair certain conditions, but this proposed AD 
would require repairing those conditions in one of the following ways:
     Using a method that we approve; or
     Using data that meet the certification basis of the 
airplane, and that have been approved by an Authorized Representative 
for the Boeing Commercial Airplanes Delegation Option Authorization 
Organization whom we have authorized to make those findings.
    We have revised paragraph (g) of AD 2004-16-09 to allow repairs in 
accordance with data that conforms to an airplane's type certificate 
and that are approved by an Authorized Representative for the Boeing 
Commercial Airplanes Delegation Option Authorization Organization whom 
we have authorized to make such findings.

Change to Existing AD

    This proposed AD would retain all requirements of AD 2004-16-09. 
Since AD 2004-16-09 was issued, the AD format has been revised, and 
certain paragraphs have been rearranged. As a result, the corresponding 
paragraph identifiers have changed in this proposed AD, as listed in 
the following table:

                      Revised Paragraph Identifiers
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                                            Corresponding requirement in
       Requirement in AD 2004-16-09               this proposed AD
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paragraph (a).............................  paragraph (f).
paragraph (b).............................  paragraph (g).
paragraph (c).............................  paragraph (h).
paragraph (d).............................  paragraph (i).
paragraph (e).............................  paragraph (j).
paragraph (f).............................  paragraph (k).
paragraph (g).............................  paragraph (l).
------------------------------------------------------------------------

    The cost information specified in AD 2004-16-09 inadvertently 
contained information on on-condition inspections. The cost 
information, below, has been revised to state only the work hours 
necessary for the initial and repetitive inspections specified in 
paragraph (g) of this proposed AD.

Costs of Compliance

    There are about 917 airplanes of the affected design in the 
worldwide fleet.

[[Page 37902]]

This proposed AD would affect about 165 airplanes of U.S. registry.
    The actions that are required by AD 2004-16-09 and retained in this 
proposed AD 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 currently required actions to the U.S. operators is $26,400, 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

    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 
removing amendment 39-13765 (69 FR 48133, August 9, 2004) and adding 
the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2008-0731; Directorate Identifier 2008-NM-
058-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by August 
18, 2008.

Affected ADs

    (b) This AD supersedes AD 2004-16-09.

Applicability

    (c) This AD applies to all Boeing Model 747-100, 747-100B, 747-
100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 
747-400F, 747SR, and 747SP series airplanes, certificated in any 
category.

Unsafe Condition

    (d) This AD results from a report that cracks in oil-canned 
areas were found during an inspection of the aft pressure bulkhead. 
We are issuing this AD to detect and correct the propagation of 
fatigue cracks in the vicinity of oil cans on the web of the aft 
pressure bulkhead, which could result in rapid decompression of the 
airplane and overpressurization of the tail section, and consequent 
loss of control 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.

    Note 1: This AD refers to certain portions of a Boeing service 
bulletin for inspections and repair information. In addition, this 
AD specifies requirements beyond those included in the service 
bulletin. Where the AD and the service bulletin differ, the AD 
prevails.

Service Bulletin References

    (f) The term ``service bulletin,'' as used in this AD, means the 
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
53A2482, dated October 3, 2002; or Boeing Alert Service Bulletin 
747-53A2482, Revision 1, dated February 21, 2008. After the 
effective date of this AD, Revision 1 must be used.

Requirements of AD 2004-16-09, With Reduced Threshold

Initial and Repetitive Inspections

    (g) At the earlier of the times specified in paragraphs (g)(1) 
and (g)(2) of this AD, perform a detailed inspection of the aft 
pressure bulkhead for indications of oil cans and previous oil can 
repairs, in accordance with the service bulletin.
    (1) Prior to the accumulation of 30,000 total flight cycles, or 
within 1,000 flight cycles after September 13, 2004 (the effective 
date of AD 2004-16-09), whichever is later.
    (2) Prior to the accumulation of 20,000 total flight cycles, or 
within 1,000 flight cycles after the effective date of this AD, 
whichever occurs later.

    Note 2: For the purposes of this AD, a detailed inspection is 
``an intensive examination of a specific item, installation, or 
assembly to detect damage, failure, or irregularity. Available 
lighting is normally supplemented with a direct source of good 
lighting at an intensity deemed appropriate. Inspection aids such as 
mirrors, magnifying lenses, etc. may be necessary. Surface cleaning 
and elaborate procedures may be required.''

    (h) If no indication of an oil can is found and no indication of 
a previous oil can repair is found during the detailed inspection 
required by paragraph (g) of this AD, repeat the detailed inspection 
thereafter at intervals not to exceed 2,000 flight cycles.

Indication of Oil Can

    (i) If any indication of an oil can is found during the detailed 
inspection required by paragraph (g) or (h) of this AD, before 
further flight, perform an eddy current inspection of the web around 
the periphery of the oil can indication for cracks, as shown in 
Figure 3 of the service bulletin.
    (j) If no crack is found during the eddy current inspection 
required by paragraph (i) of this AD, do the actions specified in 
paragraph (j)(1) or (j)(2) of this AD, as applicable.
    (1) For the oil can that meets the allowable limits specified in 
the service bulletin: Repeat the eddy current inspection specified 
in paragraph (i) of this AD thereafter at intervals not to exceed 
1,000 flight cycles. As an option, repair the oil can in accordance 
with paragraph (j)(2) of this AD.
    (2) For the oil can that does not meet the allowable limits 
specified in the service bulletin: Before further flight, repair the 
oil can in accordance with the service bulletin. If the repair 
eliminates the oil can, accomplishment of this repair constitutes 
terminating action for the repetitive eddy current inspection 
requirements of paragraph (j)(1) of this AD for that location only. 
However, the repetitive detailed inspection required by paragraph 
(h) of this AD is still required. If any oil can remains after the 
repair, repeat the eddy current inspection specified in paragraph 
(i) of this AD thereafter at intervals not to exceed 1,000 flight 
cycles.

[[Page 37903]]

Indication of Previous Oil Can Repairs

    (k) If any previous oil can repair is found during the detailed 
inspection required by paragraph (g) or (h) of this AD, before 
further flight, do a detailed inspection of the web for cracks and 
oil cans, as shown in Figure 4 or Figure 5 of the service bulletin, 
as applicable.
    (1) If no crack and no oil can are found, repeat the detailed 
inspection in accordance with paragraph (h) of this AD.
    (2) If any oil can is found, before further flight, do the eddy 
current inspection for cracks, as shown in Figure 3 of the service 
bulletin. If no crack is found during the eddy current inspection 
required by this paragraph, do the actions specified in paragraph 
(j)(1) or (j)(2) of this AD, as applicable, at the time specified in 
the applicable paragraph.

Repair of Cracks

    (l) If any crack is found during any inspection required by this 
AD, before further flight, repair in accordance with the service 
bulletin. If any crack or damage exceeds limits specified in the 
service bulletin and the service bulletin specifies to contact 
Boeing for appropriate action: Before further flight, repair per a 
method approved by the Manager, Seattle Aircraft Certification 
Office (ACO), FAA; or per data meeting the type certification basis 
of the airplane approved by a Boeing Company Designated Engineering 
Representative who has been authorized by the Manager, Seattle ACO, 
to make such findings; or using a method approved in accordance with 
the procedures specified in paragraph (n) of this AD. For a repair 
method to be approved, the approval must specifically reference this 
AD.

New Requirements of This AD

    (m) As of the effective date of this AD, if any crack or damage 
is found during any inspection required by this AD, and Boeing Alert 
Service Bulletin 747-53A2482, Revision 1, dated February 21, 2008, 
specifies to contact Boeing for appropriate action (repair data): 
Before further flight, repair the crack or damage using a method 
approved in accordance with the procedures specified in paragraph 
(n) of this AD.

Alternative Methods of Compliance (AMOCs)

    (n)(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.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair required by this AD, if it is approved by an 
Authorized Representative for the Boeing Commercial Airplanes 
Delegation Option Authorization Organization who has been authorized 
by the Manager, Seattle ACO, to make those findings. For a repair 
method to be approved, the repair must meet the certification basis 
of the airplane.
    (4) AMOCs approved previously in accordance with AD 2004-16-09 
are not approved as AMOCs for the corresponding provisions of 
paragraph (g) of this AD. They are approved as AMOCs for the 
corresponding provisions of paragraphs (h), (i), (j), (k), (l), and 
(m) of this AD.

    Issued in Renton, Washington, on June 24, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E8-14974 Filed 7-1-08; 8:45 am]

BILLING CODE 4910-13-P
