[Federal Register Volume 71, Number 101 (Thursday, May 25, 2006)]
[Proposed Rules]
[Pages 30090-30094]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-8006]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-24865; Directorate Identifier 2005-NM-194-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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[[Page 30091]]

SUMMARY: The FAA proposes to supersede an existing airworthiness 
directive (AD) that applies to certain Boeing Model 747 airplanes. The 
existing AD currently requires inspections to detect disbonding, 
corrosion, and cracking at the longitudinal rows of fasteners in the 
bonded skin panels in section 41 of the fuselage, and repair, if 
necessary. This proposed AD would add airplanes to the applicability, 
and require new inspections of airplanes that may have Alodine-coated 
rivets installed. This proposed AD results from a report of cracking 
discovered in a skin lap joint that was previously inspected using the 
eddy current method. We are proposing this AD to prevent rapid 
decompression of the airplane due to disbonding and subsequent cracking 
of the skin panels.

DATES: We must receive comments on this proposed AD by July 10, 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.
     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.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for service information identified in this 
proposed 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:

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 in the ADDRESSES section. Include the docket number ``Docket No. 
FAA-2006-24865; Directorate Identifier 2005-NM-194-AD'' at the 
beginning 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 received 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 may review the DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or may 
can visit http://dms.dot.gov.

Examining the Docket

    You may 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 
receives them.

Discussion

    On October 28, 1996, we issued AD 96-23-02, amendment 39-9807 (61 
FR 57994, November 12, 1996), for certain Boeing Model 747 airplanes. 
That AD requires inspections to detect disbonding, corrosion, and 
cracking at the longitudinal rows of fasteners in the bonded skin 
panels in section 41 of the fuselage, and repair, if necessary. That AD 
resulted from a report of skin cracking due to disbonding of the 
internal doubler of the cracked skin panels. We issued that AD to 
prevent rapid decompression of the airplane due to disbonding and 
subsequent cracking of the skin panels.

Actions Since Existing AD Was Issued

    Since 1985 Boeing has incorporated rivets coated with Alodine into 
production fuselage aluminum skins and post-production skin 
modification kits. Alodine coating on rivets provides a protective 
chemical conversion coating, but also increases electrical 
conductivity. Certain non-destructive inspection (NDI) methods rely on 
disruptions in the electromagnetic field around cracks in metallic 
structures to detect cracking. One such NDI method is the sliding probe 
eddy current inspection, which was one inspection method required by AD 
96-23-02. Conductivity of the Alodine-coated rivet could be strong 
enough to mask cracking in the fastener hole during eddy current 
inspections.
    Since we issued AD 96-23-02, cracking was discovered in a skin lap 
joint that was previously inspected using the eddy current method. 
Further investigation showed that the crack was not detected due to 
masking from Alodine rivets. The crack was discovered during a full-
scale fatigue test on a Model 737 fuselage.
    The manufacturer has accomplished a comprehensive study of the 
effect of Alodine-coated rivets on all Boeing Airplane models. Based on 
the critical nature of the sliding probe eddy current inspection 
method, this study indicates that two existing ADs, AD 96-23-02 and AD 
90-26-10, require further rulemaking. We are proposing this NPRM to 
supersede AD 96-23-02, and Docket No. FAA-2006-24877 to supersede AD 
90-26-10. In addition, based on this study, the FAA does not propose to 
issue other ADs related to Alodine-coated rivets.
    Since we issued AD 96-23-02, we have also received reports of new 
crack findings on Model 747 airplanes that were not originally included 
in the applicability of AD 96-23-02.

Other Relevant Rulemaking

    On December 3, 1990, we issued AD 90-26-10, amendment 39-6836 (55 
FR 51401, December 14, 1990). That AD requires repetitive inspections 
to detect cracks at certain stringer fastener locations; and repair, if 
necessary. For certain airplanes, AD 90-26-10 requires a modification 
in certain areas where reports indicate that cracking was prevalent. 
This modification terminates the repetitive inspections only for those 
areas, and is also an option for other airplanes. Skin panels replaced 
in accordance with AD 90-26-10 are not susceptible to the disbonding 
and cracking that is the unsafe condition addressed by this proposed 
AD. That AD resulted from reports of multiple longitudinal skin cracks. 
We issued that AD to prevent rapid decompression of the airplane.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 747-53A2409, 
Revision 5, dated August 18, 2005 (the original issue of Boeing Alert 
Service Bulletin 747-53A2409, dated September 26,

[[Page 30092]]

1996, was referenced as the appropriate source of service information 
for accomplishing the required actions in AD 96-23-02). Operators 
should note Revision 5 of the alert service bulletin revises the 
airplane group numbers that were referenced in AD 96-23-02.
    Boeing Alert Service Bulletin 747-53A2409, Revision 5, describes 
procedures for initial inspections to detect disbonding, corrosion, and 
cracking of the longitudinal rows of fasteners in the bonded skin 
panels in section 41 of the fuselage, and repair if necessary. The 
alert service bulletin also describes procedures for related 
investigative actions if any discrepancy is found. These actions depend 
on the inspected area and the discrepancy and can include additional 
inspections using one of the methods described below.
    The alert service bulletin identifies four affected skin areas:
     Area 1: The flat skin panel aft of the cockpit windows 
from body station (BS) 340 to BS 520 between S-6 and S-14.
     Area 2: The flat skin panels below the cockpit windows.
     Area 3: The large-radius skin panels in the main deck area 
(excluding Area 4).
     Area 4: The section of the large-radius skin panel aft of 
door 1 from BS 488 to BS 500 between S-16 and S-26.
    The alert service bulletin also specifies four methods of 
inspection, with related corrective actions:
     Method 1: One-time external ultrasonic inspections of the 
skin for disbonded doublers; and an external inspection of the skin for 
cracks, and repair, if necessary;
     Method 2: One-time internal detailed inspections of the 
skin for disbonded doublers, corrosion, or cracks; and repair, or an 
external inspection of the skin for cracks, if necessary;
     Method 3: Repetitive external detailed inspections of the 
skin for cracks, and repair, if necessary; and
     Method 4: Repetitive external high frequency eddy current 
(HFEC) inspections of the skin for cracks, and repair, if necessary.
    Figures 1, 2, 3, 17, 18, 19, 20, 21, and 22 of the alert service 
bulletin provide the compliance times for all inspections. The 
compliance times for doing the initial and repetitive inspections 
depend on previous installation of rivets coated with Alodine, and on 
previous inspections, modifications, and repairs. The thresholds for 
initial inspections are the latest of 150 flight cycles after the date 
of the service bulletin or 3,000 flight cycles after a previous 
inspection. The repetitive intervals also depend on certain previous 
repairs and range from 150 flight cycles to 3,000 flight cycles. The 
compliance time for all applicable repairs is before further flight.
    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 develop on airplanes of the same 
type design. For this reason, we are proposing this AD, which would 
supersede AD 96-23-02 and would retain the requirements of the existing 
AD. This proposed AD would also require accomplishing the actions 
specified in the alert service bulletin described previously, except as 
discussed under ``Differences Between the Proposed AD and the Alert 
Service Bulletin.''

Differences Between the Proposed AD and the Alert Service Bulletin

    Operators should note that, although the referenced alert service 
bulletin describes procedures for submitting an inspection report to 
the manufacturer, this proposed AD would not require that action.
    The alert service bulletin specifies compliance times relative to 
the date of issuance or receipt of the service bulletin; however, this 
proposed AD would require compliance before the specified compliance 
time after the effective date of this AD or another applicable AD, as 
specified.
    While the alert service bulletin describes procedures for 
inspections of four particular areas of the airplane, this proposed AD 
would require inspections of only two of those areas.
    The service bulletin specifies to contact the manufacturer for 
instructions on how to repair certain conditions or do certain actions, 
but this proposed AD would require repairing those conditions or doing 
those actions 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.
    The service bulletin specifies that it is not necessary to count 
flight cycles at 2.0 psi or less cabin differential pressure. We find 
that insufficient data exist to support this adjustment to flight 
cycles. Consequently, this AD does not allow for this adjustment 
factor.
    These differences have been coordinated with Boeing.

Clarification of Alternative Method of Compliance (AMOC) Paragraph

    We have revised this action to clarify the appropriate procedure 
for notifying the principal inspector before using any approved AMOC on 
any airplane to which the AMOC applies.

Explanation of Change in Applicability

    We have revised the applicability of the AD to identify the model 
designations as published in the most recent type certificate data 
sheet for the affected model.

Costs of Compliance

    There are about 623 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. The average labor rate 
is $80 per work hour.

                                                 Estimated Costs
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                                                           Cost per
                                                         airplane, per       U.S.-           Fleet cost, per
                Action                    Work hours      inspection      registered        inspection cycle
                                                             cycle         airplanes
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Inspections (required by AD 96-23-02,              308         $24,640              79  $1,946,460.
 and continued in this proposed AD).
New inspections (for airplanes with                 42           3,360              96  Up to $322,560.
 alodine-coated rivets).
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[[Page 30093]]

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 39-9807 (61 FR 57994, November 12, 1996) and adding 
the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2006-24865; Directorate Identifier 2005-NM-
194-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by July 10, 
2006.

Affected ADs

    (b) This AD supersedes AD 96-23-02.

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-
53A2409, Revision 5, dated August 18, 2005.

Unsafe Condition

    (d) This AD results from a report of cracking discovered in a 
skin lap joint that was previously inspected using the eddy current 
method. We are issuing this AD to prevent rapid decompression of the 
airplane due to disbonding and subsequent cracking of the skin 
panels.

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.

Requirements of AD 96-23-02

Actions for Groups 1 Through 10, and 17 Through 36, as Specified in 
Boeing Alert Service Bulletin 747-53A2409, Revision 5

    (f) For airplanes identified as Groups 1 through 10 inclusive, 
and 17 through 36 inclusive, in Boeing Alert Service Bulletin 747-
53A2409, Revision 5, dated August 18, 2005: Do the inspections in 
paragraphs (f)(1); and do the corrective action in paragraph (f)(2) 
of this AD as applicable. Except as provided by paragraph (i) of 
this AD, do all actions in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-53A2409, dated 
September 26, 1996; or Revision 5, dated August 18, 2005. After the 
effective date of this AD, only Revision 5 may be used.
    (1) At the applicable time in Figures 1, 2, 18, and 20 of 
Revision 5 of the service bulletin, do initial and repetitive 
inspections of Areas 1 and 4, as applicable, to detect disbonding, 
corrosion, and cracking of the skin; except any inspection using 
Method 1 or 2 must not be accomplished before the latest of the 
following, as applicable: Before the accumulation of 2,000 total 
flight cycles; 2,000 flight cycles since modification to the 
stretched upper deck (SUD) configuration; or 2,000 flight cycles 
since skin panel replacement in accordance with AD 90-26-10, 
amendment 6836 (55 FR 51401, December 14, 1990). If inspection 
Method 1 or 2 is used and no disbonded doubler is found, no further 
action is required by this AD.
    (2) If any corrosion or cracking is found during any inspection 
required by paragraph (f)(1) of this AD: Before further flight, 
except as provided by paragraph (i) of this AD, repair and do any 
applicable related investigative actions in accordance with the 
Accomplishment Instructions of the service bulletin.

New Requirements of This AD

Actions for Groups 11 Through 16 as Specified in Boeing Alert 
Service Bulletin 747-53A2409, Revision 5 (Airplanes Added To the 
Applicability of This AD)

    (g) For airplanes identified as Groups 11 through 16 inclusive 
in Boeing Alert Service Bulletin 747-53A2409, Revision 5, dated 
August 18, 2005: Do the inspections in paragraph (g)(1); and do the 
corrective action in paragraph (g)(2) of this AD as applicable. 
Except as provided by paragraph (i) of this AD, do all actions in 
accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 747-53A2409, Revision 5, dated August 18, 2005.
    (1) At the applicable time in Figures 18 and 20 of the service 
bulletin, do initial inspections of Area 4 and repetitive 
inspections, as applicable, to detect disbonding, corrosion, and 
cracking of the skin; except any inspection using Method 1 or 2 must 
not be accomplished before the latest of the following, as 
applicable: Before the accumulation of 2,000 total flight cycles; 
2,000 flight cycles since modification to the SUD configuration; or 
2,000 flight cycles since skin panel replacement in accordance with 
AD 90-26-10, amendment 6836 (55 FR 51401, December 14, 1990). If 
inspection Method 1 or 2 is used and no disbonded doubler is found, 
no further action is required by this AD.
    (2) If any corrosion, disbonding, or cracking is found during 
any inspection required by paragraph (g)(1) of this AD, before 
further flight: Repair and do any applicable related investigative 
actions in accordance with the Accomplishment Instructions of the 
service bulletin.

Actions for Airplanes With Alodine-Coated Rivets for Groups 1 
Through 10, and 17 Through 36 as Specified in Boeing Alert Service 
Bulletin 747-53A2409, Revision 5

    (h) For airplanes identified as Groups 1 through 10 inclusive, 
and 17 through 36 inclusive, in Boeing Alert Service Bulletin 747-
53A2409, Revision 5, dated August 18, 2005: Do the inspections in 
paragraph (h)(1); and do the corrective action in paragraph (h)(2) 
of this AD if necessary. Except as provided by paragraph (i) of this 
AD, do all actions in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-53A2409, Revision 
5, dated August 18, 2005.
    (1) At the applicable time in Figures 21 and 22 of the service 
bulletin: Do initial and repetitive inspections of Areas 1 and 4, as 
applicable, to detect cracking of the skin.
    (2) If any cracking is found during any inspection required by 
paragraph (h)(1) of

[[Page 30094]]

this AD, before further flight: Repair in accordance with the 
Accomplishment Instructions of the service bulletin.

Exceptions

    (i) Do all actions in accordance with the applicable service 
bulletin except as provided by paragraphs (i)(1), (i)(2), (i)(3), 
(i)(4), and (i)(5) of this AD.
    (1) For the action in paragraph (f)(1) of this AD: Where Boeing 
Alert Service Bulletin 747-53A2409, dated September 26, 1996; and 
Boeing Alert Service Bulletin 747-53A2409, Revision 5, dated August 
18, 2005; specify a compliance time after the issuance of any 
revision of the service bulletin, this paragraph requires compliance 
before the specified compliance time after November 27, 1996, the 
effective date of AD 96-23-02.
    (2) For the actions in paragraphs (g)(1) and (h)(1) of this AD: 
Where Boeing Alert Service Bulletin 747-53A2409, Revision 5, dated 
August 18, 2005, specifies a compliance time after the issuance or 
receipt of any revision of the service bulletin, this paragraph 
requires a compliance time after the effective date of this AD.
    (3) For any repair or any inspection where Boeing Alert Service 
Bulletin 747-53A2409, Revision 5, dated August 18, 2005, specifies 
to contact the manufacturer for further instructions: Before further 
flight, repair or inspect using a method approved in accordance with 
the procedures specified in paragraph (k) of this AD.
    (4) If corrosion is found during any inspection required by this 
AD, before further flight: Repair in accordance with an FAA-approved 
method.
    (5) Where Boeing Alert Service Bulletin 747-53A2409, Revision 5, 
dated August 18, 2005, specifies that it is not necessary to count 
flight cycles at 2.0 psi or less cabin differential pressure, this 
AD does not allow for that adjustment factor.

Credit for Actions Accomplished Previously

    (j) Actions done before the effective date of this AD in 
accordance with the service bulletins specified in Table 1 of this 
AD are acceptable for compliance with the corresponding requirements 
of paragraphs (f) and (g) of this AD.

                   Table 1.--Credit Service Bulletins
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      Service bulletin        Revision level             Date
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Boeing Alert Service                       1  May 29, 1997.
 Bulletin 747-53A2409.
Boeing Alert Service                       2  August 6, 1998.
 Bulletin 747-53A2409.
Boeing Alert Service                       3  October 22, 1998.
 Bulletin 747-53A2409.
Boeing Alert Service                       4  February 17, 2000.
 Bulletin 747-53A2409.
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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) 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.
    (3) AMOCs approved previously in accordance with AD 96-23-02, 
amendment 39-9807, are approved as AMOCs for the corresponding 
provisions of paragraph (f) of this AD, except AMOCs for terminating 
action based upon inspection results using a sliding probe low 
frequency eddy current (LFEC), sliding probe high frequency eddy 
current (HFEC), or mid frequency surface eddy current (MFEC) 
inspection methods; and provided that any alternative method for 
future inspections did not incorporate a sliding probe LFEC, sliding 
probe HFEC, or MFEC inspection methods.
    (4) 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.

    Issued in Renton, Washington, on May 16, 2006.
Kevin M. Mullin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E6-8006 Filed 5-24-06; 8:45 am]
BILLING CODE 4910-13-P