[Federal Register Volume 71, Number 49 (Tuesday, March 14, 2006)]
[Proposed Rules]
[Pages 13055-13058]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-3559]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-24119; Directorate Identifier 2005-NM-100-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 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 certain Boeing Model 747 airplanes. This proposed AD would require 
repetitive mid- and low-frequency eddy current inspections for cracks 
in the overlapped skin panels in the fuselage skin lap joints in 
sections 41, 42, 44, and 46, and corrective actions if necessary. This 
proposed AD is prompted by a report indicating that an operator found 
multiple small cracks in the overlapped skin panels in the fuselage 
skin lap joints. We are proposing this AD to detect and correct cracks 
in the overlapped skin panels, which could join together and result in 
reduced structural capability in the skin and consequent rapid 
decompression of the airplane.

DATES: We must receive comments on this proposed AD by April 28, 2006.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, 
Washington, DC 20590.
     By fax: (202) 493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this proposed AD, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-
2207.
    You can examine the contents of this AD docket on the Internet at 
http://dms.dot.gov, or in person at the Docket Management Facility, 
U.S. Department of Transportation, 400 Seventh Street, SW., room PL-
401, on the plaza level of the Nassif Building, Washington, DC. This 
docket number is FAA-2006-24119; the directorate identifier for this 
docket is 2005-NM-100-AD.

FOR FURTHER INFORMATION CONTACT: Nicholas Kusz, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
917-6432; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

[[Page 13056]]

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2006-24119; 
Directorate Identifier 2005-NM-100-AD'' in the subject line of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments submitted by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of 
that Web site, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You can review DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
can visit http://dms.dot.gov.

Examining the Docket

    You can examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Management Facility office (telephone (800) 647-
5227) is located on the plaza level of the Nassif Building at the DOT 
street address stated in the ADDRESSES section. Comments will be 
available in the AD docket shortly after the Docket Management System 
(DMS) receives them.

Discussion

    We have received a report indicating that an operator found 
multiple small cracks in the overlapped skin panels in the fuselage 
skin lap joints at stringer (S)-44L between station (STA) 440 and 460, 
and at S-12R between STA 1870 and STA 1910, on a Boeing Model 747SR 
series airplane. The operator trimmed out the cracked skins and 
repaired them in accordance with the structural repair manual. The 
manufacturer analyzed the trimmed-out skins and found that the cracks 
were caused by fatigue from cyclic pressurization, flight loads, and 
ground handling loads. Multiple cracks in the overlapped skin panels 
could join together. This condition, if not corrected, could result in 
reduced structural capability in the skin and consequent rapid 
decompression of the airplane.
    The subject area on certain Model 747-100, 747-100B, 747-100B SUD, 
747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, and 
747SP series airplanes is almost identical to that on the affected 
Model 747SR series airplanes. Therefore, those airplanes may be subject 
to the unsafe condition revealed on the Model 747SR series airplane.

Other Relevant Rulemaking

    We have previously issued AD 2004-13-02, amendment 39-13682 (69 FR 
35237, June 24, 2004). That AD applies to certain Boeing Model 747-100, 
-200B, and -200F series airplanes. That AD requires initial and 
repetitive inspections to find discrepancies in the upper and lower 
skins of the fuselage lap joints, and repair if necessary. 
Accomplishing the actions in AD 2004-13-02 terminates certain 
inspections in this proposed AD for those airplanes.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 747-53A2501, dated 
March 24, 2005. The service bulletin describes procedures for doing 
inspections for cracks in the overlapped skin panels in the fuselage 
skin lap joints in sections 41, 42, 44, and 46. For all airplanes, at 
most affected lap joint locations, the service bulletin describes 
procedures for doing repetitive mid-frequency eddy current inspections 
of the internal surface at the overlapped skin around the bottom row of 
fasteners in the lap joint.
    For airplanes having line numbers 201 and after, the service 
bulletin describes procedures for doing additional repetitive external 
surface low-frequency eddy current inspections of the overlapped skin 
around the bottom row of fasteners at any section 41 lap joint with 
four rows of fasteners. If cracks are found, the service bulletin 
states that operators should repair them before further flight. The 
service bulletin recommends that operators repair the cracks in 
accordance with the structural repair manual, or get repair data from 
Boeing. In addition, if the damaged area is more than certain specified 
limits, the service bulletin recommends that operators write to Boeing 
for repair instructions, and that the letter include sketches, 
photographs, and information about any corrosion damage.
    For airplanes identified in the service bulletin as Groups 1, 2, 4, 
and 11 that have line numbers 1 through 200 inclusive, the service 
bulletin states that the procedures apply only to airplanes that have 
accumulated between 25,000 and 30,000 total flight cycles. When the 
airplane has accumulated 30,000 total flight cycles, the service 
bulletin states that the airplane is subject to the inspection 
requirements of AD 2004-13-02. The service bulletin recommends that 
operators of these airplanes that have accumulated 29,000 total flight 
cycles as of the effective date of the service bulletin do the 
inspections in accordance with AD 2004-13-02 rather than the 
inspections in this service bulletin.
    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. Therefore, we are proposing this AD, which 
would require accomplishing the actions specified in the service 
information described previously, except as discussed under 
``Differences Between the Proposed AD and the Service Bulletin.''

Differences Between the Proposed AD and the Service Bulletin

    Although the service bulletin referenced in this proposed AD 
specifies to submit certain information to the manufacturer, this 
proposed AD does not include that requirement.
    The service bulletin specifies that you may contact the 
manufacturer for instructions on how to repair certain conditions, but 
this proposed AD would require you to repair 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.
    These differences have been coordinated with Boeing.

Costs of Compliance

    There are about 1,081 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD.

[[Page 13057]]



                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                 Number of U.S.-
            Action               Work hours     Average labor      Cost per        registered       Fleet cost
                                                rate per hour      airplane         airplanes
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Inspection for Model 747SP                 48             $80  $3,840, per                   10  $38,400, per
 series airplanes.                                              inspection                        inspection
                                                                cycle.                            cycle.
Inspection for all other                   68              80  $5,440, per                  196  $1,066,240, per
 Model 747 series airplanes.                                    inspection                        inspection
                                                                cycle.                            cycle.
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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. 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 FAA amends Sec.  39.13 by adding the following new 
airworthiness directive (AD):

Boeing: Docket No. FAA-2006-24119; Directorate Identifier 2005-NM-
100-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by April 28, 2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to 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; as identified in Boeing Alert Service Bulletin 747-
53A2501, dated March 24, 2005.

Unsafe Condition

    (d) This AD was prompted by a report indicating that an operator 
found multiple small cracks in the overlapped skin panels in the 
fuselage skin lap joints. We are issuing this AD to detect and 
correct cracks in the overlapped skin panels, which could join 
together and result in reduced structural capability in the skin and 
consequent rapid decompression 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.

Inspections and Corrective Actions: For Airplanes With Line Numbers 1 
Through 200 Inclusive

    (f) For airplanes with line numbers 1 through 200 inclusive, at 
the applicable time in paragraph (f)(1) or (f)(2) of this AD: Do the 
applicable eddy current inspection or inspections for cracks in the 
overlapped skin panels in the fuselage skin lap joints in sections 
41, 42, 44, and 46; and do any applicable corrective actions before 
further flight. Except as provided by paragraph (f)(1)(ii) of this 
AD, repeat the applicable inspection or inspections thereafter at 
intervals not to exceed 3,000 flight cycles. Except as provided by 
paragraph (h) of this AD, do all actions in accordance with the 
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
53A2501, dated March 24, 2005.
    (1) Except as provided by paragraph (f)(2) of this AD, do the 
applicable action in paragraph (f)(1)(i) or (f)(1)(ii) of this AD.
    (i) For airplanes that have accumulated fewer than 29,000 total 
flight cycles as of the effective date of this AD: Before the 
accumulation of 25,000 total flight cycles, or within 1,000 flight 
cycles after the effective date of this AD, whichever occurs later, 
do a mid-frequency eddy current inspection for cracks of the 
internal surface at the overlapped skin around the bottom row of 
fasteners in the lap joint.
    (ii) For airplanes that have accumulated 29,000 or more total 
flight cycles, do the inspections in accordance with the 
requirements of AD 2004-13-02, amendment 39-13682, at the applicable 
threshold and intervals in that AD. Doing the repeat inspections in 
accordance with AD 2004-13-02, terminates the repetitive inspection 
requirements of this AD only for airplanes with line numbers 1 
through 200 inclusive.
    (2) For airplanes that have had skin panels replaced: Do the 
eddy current inspections of the replaced overlapped panel prior to 
the accumulation of 25,000 total flight cycles since panel 
replacement, or within 1,000 flight cycles after the effective date 
of this AD, whichever occurs later. Skin panel replacement, along 
with ongoing inspections in accordance with paragraph (f) of this AD 
terminates the requirements of paragraphs (a) and (d) of AD 2004-13-
02, only for the skin lap sections where the overlapped panel has 
been replaced.

Inspections and Corrective Actions: For Airplanes With Line Numbers 201 
and After

    (g) For airplanes with line numbers 201 and after: Before the 
accumulation of 25,000 total flight cycles, within 1,000 flight 
cycles after the effective date of this AD, or within 25,000 flight 
cycles after the time when the overlapped skin was replaced, 
whichever occurs later, do the applicable inspection in paragraphs 
(g)(1) and (g)(2) of this AD for cracks in the overlapped skin 
panels in the fuselage skin lap joints in sections 41, 42, 44, and 
46; and do any applicable corrective actions before further flight. 
Repeat the applicable inspection thereafter at intervals

[[Page 13058]]

not to exceed 3,000 flight cycles. Except as provided by paragraph 
(h) of this AD, do all actions in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-53A2501, dated 
March 24, 2005.
    (1) Do a mid-frequency eddy current inspection for cracks of the 
internal surface at the overlapped skin around the bottom row of 
fasteners in the lap joint.
    (2) Do a low-frequency eddy current inspection for cracks of the 
overlapped skin around the bottom row of fasteners at the Section 41 
lap joints with four rows of fasteners.

Repair Instructions

    (h) If any crack is found during any inspection required by this 
AD, and the bulletin specifies to contact Boeing for appropriate 
action: Before further flight, repair the crack using a method 
approved in accordance with the procedures specified in paragraph 
(j) of this AD.

No Reporting Required

    (i) Although Boeing Alert Service Bulletin 747-53A2501, dated 
March 24, 2005, specifies to submit certain information to the 
manufacturer, this AD does not include that requirement.

Alternative Methods of Compliance (AMOCs)

    (j)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) 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, and the approval must specifically refer to this 
AD.
    (3) Before using any AMOC approved in accordance with Sec.  
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 March 3, 2006.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E6-3559 Filed 3-13-06; 8:45 am]
BILLING CODE 4910-13-P