[Federal Register Volume 73, Number 21 (Thursday, January 31, 2008)]
[Proposed Rules]
[Pages 5768-5770]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-1703]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0107; Directorate Identifier 2007-NM-087-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain Boeing Model 747 airplanes. This proposed AD would require 
inspections for scribe lines in affected lap and butt splices, wing-to-
body fairing locations, and external repair and cutout reinforcement 
areas; and related investigative and corrective actions if necessary. 
This proposed AD results from reports of scribe lines found at lap 
joints and butt joints, around external doublers and antennas, and at 
locations where external decals had been cut. We are proposing this AD 
to detect and correct scribe lines, which can develop into fatigue 
cracks in the skin and cause sudden decompression of the airplane.

DATES: We must receive comments on this proposed AD by March 17, 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: Wayne Lockett, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
917-6447; 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-2008-0107; 
Directorate Identifier 2007-NM-087-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 a report indicating that scribe lines have been 
found by 8 operators on 15 Model 747 airplanes. Scribe lines were found 
at lap joints and butt joints, around external doublers and antennas, 
and at locations where external decals had been cut. Many of the scribe 
lines appear to have been made when sealant was removed as part of 
preparation of the airplane for repainting. Although fatigue cracks can 
develop in the skin at scribe line locations--and have been found on 
some airplane models, no such cracking has been found on Model 747 
airplanes. Such fatigue cracks, if not corrected, could grow large and 
cause sudden decompression of the airplane.

Related ADs

    This proposed AD is similar to two existing ADs. AD 2006-07-12, 
amendment 39-14539 (71 FR 16211, March 31, 2006), applies to all Boeing 
Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. AD 
2007-19-07, amendment 39-15198 (72 FR 60244, October 24, 2007), applies 
to all Boeing Model 757-200, -200PF, and -200CB series airplanes. Those 
ADs require inspections to detect scribe lines in the fuselage skin at 
certain lap joints, butt joints, external repair doublers, and other 
areas; and related investigative/corrective actions if necessary. Those 
actions resulted from reports of fuselage skin cracks adjacent to the 
skin lap joints on airplanes that had scribe lines.

Relevant Service Information

    We have reviewed Boeing Service Bulletin 747-53A2563, Revision 2, 
dated January 3, 2008. The service bulletin describes procedures for 
exploratory detailed inspections to detect scribe lines in affected lap 
and butt splices, wing-to-body fairing locations, and external repair 
and cutout reinforcement areas. The service bulletin specifies removing 
paint and sealant from affected areas before the initial exploratory 
inspection. The compliance time for the exploratory inspections is 
15,000 or 25,000 total flight cycles (depending on the inspection 
location), with a grace period between 500 and 1,500 flight cycles 
depending on the age of the airplane and the location of the 
inspection.
    The service bulletin specifies conditional actions, depending on 
the size, depth, and location of the damage. These actions include 
performing eddy current or ultrasonic inspections of the scribe lines 
to detect cracks, and either repairing scribe lines and cracks or 
contacting Boeing for repair instructions.
    The service bulletin specifies repairing scribe lines before 
further flight, except when a limited return to service (LRTS) program 
for qualifying scribe lines would allow return to service for a limited 
period before scribe lines are repaired. The LRTS program includes 
repetitive inspections to detect cracks where scribe lines are found. 
To

[[Page 5769]]

qualify for an LRTS program, scribe lines must meet certain criteria 
based on their depth and location. The service bulletin specifies 
contacting Boeing for final repair instructions, which would eliminate 
the need for the repetitive inspections of the LRTS program. The 
repetitive intervals for the LRTS program range from 250 to 10,000 
flight cycles, depending on the depth and location of the scribe lines 
and the configuration of the airplane.
    The service bulletin notes that certain inspections would not be 
required under the following conditions:
     The airplane had never been stripped or repainted.
     The wing-to-body fairings had never been removed.
     The airplane had never been stripped or repainted under 
the wing-to-body fairings.
     For each repair, the airplane had never been stripped or 
repainted since the repair was installed.
     No sealant had been removed except in accordance with the 
specified sealant removal processes as given in Appendix A of the 
service bulletin.
    The service bulletin specifies submitting the initial inspection 
results to Boeing. The service bulletin also provides procedures for 
addressing scribe lines detected before the initial inspection 
threshold.

FAA's Determination and Requirements of This Proposed AD

    We are proposing this AD because we evaluated all relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the(se) same type 
design(s). This proposed AD would require accomplishing the actions 
specified in the service information described previously, except as 
discussed below. This proposed AD would also require sending the 
results of the exploratory inspections to Boeing.

Difference Between the Proposed AD and 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.

Clarification of Proposed Requirements Beyond Specified Inspection 
Areas and Threshold

    Although the service bulletin provides procedures for addressing 
scribe lines that are found outside the inspection areas and before the 
initial inspection threshold, this proposed AD would not include such 
requirements.

Interim Action

    This proposed AD is considered to be interim action. The inspection 
reports that would be required by this proposed AD will enable the 
manufacturer to obtain better insight into the nature, cause, and 
extent of the cracking, and eventually to develop final action to 
address the unsafe condition. Once final action has been identified, we 
may consider further rulemaking.

Costs of Compliance

    There are about 1,038 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.

                                                                     Estimated Costs
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                                                                                                            Number of U.S.-
              Action                       Work hours          Average labor       Cost per  airplane         registered             Fleet cost
                                                               rate per hour                                   airplanes
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Exploratory inspections..........  1,020 to 1,140...........             $80  $81,600 to $91,200..........             219  $17,870,400 to $19,972,800.
Report...........................  1........................              80  $80.........................             219  $17,520.
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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 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 this 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.
    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, 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 AD:


[[Page 5770]]


Boeing: Docket No. FAA-2008-0107; Directorate Identifier 2007-NM-
087-AD.

Comments Due Date

    (a) We must receive comments by March 17, 2008.

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, 747SP, and 747SR series airplanes, certificated in any 
category; as identified in Boeing Service Bulletin 747-53A2563, 
Revision 2, dated January 3, 2008.

Unsafe Condition

    (d) This AD results from reports of scribe lines found at lap 
joints and butt joints, around external doublers and antennas, and 
at locations where external decals had been cut. We are issuing this 
AD to detect and correct scribe lines, which can develop into 
fatigue cracks in the skin and cause sudden 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.

Inspection

    (f) At the applicable times specified in paragraph 1.E., 
``Compliance,'' of Boeing Service Bulletin 747-53A2563, Revision 2, 
dated January 3, 2008, except as provided in paragraph (g) of this 
AD, do detailed exploratory inspections for scribe lines of affected 
lap and butt splices, wing-to-body fairing locations, and external 
repair and cutout reinforcement areas, and do all applicable related 
investigative and corrective actions, by accomplishing all actions 
specified in the Accomplishment Instructions of the service 
bulletin, except as provided by paragraph (h) of this AD.

    Note 1: The inspection exemptions noted in paragraph 1.E. of 
Boeing Service Bulletin 747-53A2563, Revision 2, dated January 3, 
2008, apply to this AD.

Exceptions to Service Bulletin Specifications

    (g) Where Boeing Service Bulletin 747-53A2563, Revision 2, dated 
January 3, 2008, specifies a compliance time after the date on the 
service bulletin, this AD requires compliance within the specified 
compliance time after the effective date of this AD.
    (h) Where Boeing Service Bulletin 747-53A2563, Revision 2, dated 
January 3, 2008, specifies to contact Boeing for appropriate action, 
accomplish applicable actions before further flight using a method 
approved in accordance with the procedures specified in paragraph 
(k) of this AD.

Report

    (i) At the applicable time specified in paragraph (i)(1) or 
(i)(2) of this AD: Submit a report of the findings (both positive 
and negative) of the inspections required by paragraph (f)(1) of 
this AD. One approved method for reporting is Appendixes B and C as 
applicable of Boeing Service Bulletin 747-53A2563, Revision 2, dated 
January 3, 2008. Send the report to Boeing Commercial Airplanes, 
P.O. Box 3707, Seattle, Washington 98124-2207. The report must 
contain, at a minimum, the inspection results, a description of any 
discrepancies found, the airplane serial number, and the number of 
flight cycles and flight hours on the airplane. Under the provisions 
of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.), the Office 
of Management and Budget (OMB) has approved the information 
collection requirements contained in this AD and has assigned OMB 
Control Number 2120-0056.
    (1) If the inspection was done after the effective date of this 
AD: Submit the report within 30 days after the inspection.
    (2) If the inspection was done before the effective date of this 
AD: Submit the report within 30 days after the effective date of 
this AD.

Actions Accomplished According to Previous Issue of Service Bulletin

    (j) Actions accomplished before the effective date of this AD 
according to Boeing Alert Service Bulletin 747-53A2563, dated March 
29, 2007, are considered acceptable for compliance with the 
corresponding actions specified in this AD.

Alternative Methods of Compliance (AMOCs)

    (k)(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.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair or limited return to service (LRTS) plan 
specified in this AD, if the repair or LRTS plan 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. To be approved, 
the repair and LRTS plan must meet the certification basis of the 
airplane, and the approval must specifically refer to this AD.

    Issued in Renton, Washington, on January 18, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E8-1703 Filed 1-30-08; 8:45 am]
BILLING CODE 4910-13-P