

[Federal Register: October 17, 2007 (Volume 72, Number 200)]
[Proposed Rules]               
[Page 58777-58781]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr17oc07-17]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-0043; Directorate Identifier 2007-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, 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 certain Boeing Model 747 series 
airplanes. The existing AD currently requires inspecting to detect 
cracking in certain lower lobe fuselage skin lap joints, doing 
repetitive inspections for cracking at certain fastener locations 
having countersunk fasteners, and replacing countersunk fasteners with 
protruding head fasteners at certain fastener locations. This proposed 
AD would replace a previous high-frequency eddy current (HFEC) 
inspection method with a new HFEC inspection method, add a one-time 
inspection for cracking of certain airplanes, and terminate the 
adjustment factor for the inspection compliance times based on cabin 
differential pressure. This proposed AD also would include inspection 
at an additional lap joint. This proposed AD results from reports of 
fuselage skin cracks found at certain countersunk fastener locations in 
the upper row of lap joints near the wing-to-body fairings, and from a 
report that the presence of alodine-coated rivets could cause faulty 
results during the required inspections using the optional sliding 
probe HFEC inspection method specified in the existing AD. We are 
proposing this AD to prevent reduced structural integrity of the 
fuselage.

DATES: We must receive comments on this proposed AD by December 3, 
2007.

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-2007-0043; 
Directorate Identifier 2007-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 13, 1994, we issued AD 94-15-06, amendment 39-8977 (59 FR 
37659, July 25, 1994), for certain Boeing Model 747 series airplanes. 
That AD requires inspections to detect cracking in certain lower lobe 
fuselage skin lap joints; doing repetitive inspections for cracking at 
certain fastener locations having countersunk fasteners; and replacing 
countersunk fasteners with protruding head fasteners at certain 
fastener locations. That AD resulted from reports of cracking of the 
fuselage skin in certain areas and findings of additional countersunk 
fasteners. We issued that AD to prevent reduced structural integrity of 
the fuselage.

Actions Since Existing AD Was Issued

    In 1985, Boeing started installing aluminum rivets coated with 
alodine in fuselage skins during production and supplied them to 
operators in modification kits. Alodine coating on aluminum rivets 
increases the rivet/skin 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 high frequency eddy 
current (HFEC) inspection, which was an optional inspection method 
specified by AD 94-15-06. The effects of these increases in rivet/skin 
electricity conductivity could be strong enough to mask a crack 
indication during the required inspections using the optional sliding 
probe HFEC inspection method specified in AD 94-15-06.
    Boeing has informed us that airplanes with line numbers 630 through 
814 inclusive could have alodine-coated aluminum rivets installed in 
the fastener holes that were required to be inspected in accordance 
with AD 94-15-06. The presence of these rivets could cause faulty 
results when performing the required inspections using the optional 
sliding probe HFEC skin inspection method. Consequently, Boeing has 
issued Boeing Alert Service Bulletin 747-53A2312, Revision 3, dated 
February 8, 2007. (In AD 94-15-06, we referred to Boeing Service 
Bulletin 747-53A2312, Revision 2, dated October 8, 1992, as the 
appropriate source of service information for doing the required 
actions.) Revision 3 of the alert service bulletin updates the sliding 
probe HFEC skin inspection method, and includes a one-time special HFEC 
or detailed inspection of the affected fastener holes for airplanes on 
which the modification required by AD 94-15-06 has not been

[[Page 58778]]

accomplished and on which the optional sliding probe HFEC inspection 
method was used during the last skin inspection. The sliding probe HFEC 
inspection specified in the previous revisions of the service bulletin 
would no longer be allowed in this proposed AD.
    In addition, paragraph (e)(2) of AD 94-15-06 did not include the 
lap joint at stringer location S-46L in the list of lap joints 
requiring inspection for Model 747SP series airplanes. This proposed AD 
would include that stringer location.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 747-53A2312, 
Revision 3, dated February 8, 2007. The procedures in Revision 3 of the 
alert service bulletin are similar to those in Revision 2, dated 
October 8, 1992. However, Revision 3 changes the instructions for the 
optional sliding probe HFEC inspection method and also gives 
instructions for a special (one-time) inspection for cracking of 
airplanes that were not previously modified according to the service 
bulletin and on which the sliding probe HFEC inspection method was used 
during the last skin inspection, and repair if necessary. 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 other airplanes of the 
same type design. For this reason, we are proposing this AD, which 
would supersede AD 94-15-06 and would retain certain requirements of 
the existing AD. This proposed AD would also require accomplishing the 
additional 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

    Although the alert service bulletin specifies to submit certain 
information to the manufacturer, this proposed AD does not include that 
requirement.
    The service bulletin specifies to contact the manufacturer for 
appropriate action, but this proposed AD would require inspection or 
repairing those conditions, as applicable, 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.

Changes to Existing AD

    This proposed AD would retain certain requirements of AD 94-15-06. 
Paragraphs (c) and (d) of that AD specify that it is not necessary to 
count flight cycles at 2.0 psi or less cabin differential pressure; and 
that for Boeing Model 747SR airplanes, the modification compliance 
times specified in paragraphs (a) and (b) of that AD may be multiplied 
by a 1.2 adjustment factor. We find that insufficient data exist to 
support these adjustments. Consequently, this proposed AD would no 
longer allow for these adjustment factors. This change has been 
coordinated with Boeing.
    In addition, since AD 94-15-06 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
------------------------------------------------------------------------
                                           Corresponding  requirement in
       Requirement in  AD 94-15-06               this proposed  AD
------------------------------------------------------------------------
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).
Paragraph (h)...........................  Paragraph (m).
Paragraph (i)...........................  Paragraph (n).
Paragraph (j)...........................  Paragraph (o).
Paragraph (k)...........................  Paragraph (p).
------------------------------------------------------------------------

Costs of Compliance

    This proposed AD would affect about 348 airplanes in the worldwide 
fleet; 90 of those airplanes are of U.S. registry. The issue associated 
with alodine-coated aluminum rivets affects 162 airplanes in the 
worldwide fleet and 24 airplanes of U.S. registry. 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
----------------------------------------------------------------------------------------------------------------
                                                            Number of
              Action               Work hours     Parts     affected     Cost per airplane        Fleet cost
                                                            airplanes
----------------------------------------------------------------------------------------------------------------
Inspections (required by AD 90-10-         14          $0          90  $1,120, per           $100,800, per
 07 and retained in AD 94-15-06                                         inspection cycle.     inspection cycle.
 and this AD).
Inspections (required by AD 94-15-         82          $0          90  $6,560, per           $590,400, per
 06 and retained in this proposed                                       inspection cycle.     inspection cycle.
 AD).
Modification (required by AD 94-          124     Minimal          90  $9,920..............  $892,800.
 15-06 and retained in this
 proposed AD).
One-time inspection (new proposed           4          $0          24  $320................  $7,680.
 action).
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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

[[Page 58779]]

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 39-8977 (59 FR 37659, July 25, 1994) and adding the 
following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-0043; Directorate Identifier 2007-NM-
058-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by December 
3, 2007.

Affected ADs

    (b) This AD supersedes AD 94-15-06.

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, 747SR, and 
747SP series airplanes, certificated in any category, as identified 
in Boeing Alert Service Bulletin 747-53A2312, Revision 3, dated 
February 8, 2007.

Unsafe Condition

    (d) This AD results from reports of fuselage skin cracks found 
at certain countersunk fastener locations in the upper row of lap 
joints near the wing-to-body fairings, and from a report that the 
presence of alodine-coated rivets could cause faulty results during 
the required inspections using the optional sliding probe HFEC 
inspection method specified in AD 94-15-06. We are issuing this AD 
to prevent reduced structural integrity of the fuselage.

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 94-15-06

Inspections for Airplanes Having Line Numbers 201 Through 765 
Inclusive

    (f) For airplanes having line numbers 201 through 765 inclusive: 
Conduct a high frequency eddy current (HFEC) inspection to detect 
cracking of the lower lobe lap joints in the vicinity of the wing-
to-body fairings, in accordance with Boeing Alert Service Bulletin 
747-53A2312, dated June 12, 1989; Revision 1, dated March 29, 1990; 
Revision 2, dated October 8, 1992; or Revision 3, dated February 8, 
2007; except as provided by paragraph (u) of this AD; at the time 
specified in paragraph (f)(1), (f)(2), (f)(3), or (f)(4) of this AD, 
as applicable. As of the effective date of this AD, only Revision 3 
shall be used. Repeat this inspection thereafter at intervals not to 
exceed 4,000 landings until the inspection required by paragraph (j) 
of this AD is accomplished.
    (1) For airplanes that have accumulated less than 11,200 total 
landings as of February 5, 1990 (the effective date of AD 90-01-07, 
amendment 39-6440, which was superseded by AD 94-15-06): Prior to 
the accumulation of 11,000 total landings, or within the next 1,000 
landings after February 5, 1990, whichever occurs later.
    (2) For airplanes that have accumulated 11,200 or more total 
landings but less than 15,201 total landings as of February 5, 1990: 
Within the next 1,000 landings after February 5, 1990, or prior to 
the accumulation of 15,500 total landings, whichever occurs earlier.
    (3) For airplanes that have accumulated 15,201 or more total 
landings but less than 18,200 total landings as of February 5, 1990: 
Within the next 300 landings after February 5, 1990, or prior to the 
accumulation of 18,250 total landings, whichever occurs earlier.
    (4) For airplanes that have accumulated 18,200 or more landings 
as of February 5, 1990: Within the next 50 landings after February 
5, 1990.

Repair and Modification for Airplanes Having Line Numbers 201 
Through 765 Inclusive

    (g) For airplanes having line numbers 201 through 765 inclusive: 
Accomplish the requirements of paragraphs (g)(1) and (g)(2) of this 
AD.
    (1) If any cracking is detected during the inspections required 
by paragraph (f) of this AD, prior to further flight, repair in 
accordance with Boeing Alert Service Bulletin 747-53A2312, dated 
June 12, 1989; Revision 1, dated March 29, 1990; Revision 2, dated 
October 8, 1992; or Revision 3, dated February 8, 2007; except as 
provided by paragraph (u) of this AD. As of the effective date of 
this AD, only Revision 3 shall be used.
    (2) Prior to the accumulation of 20,000 total landings or within 
the next 3,000 landings after February 5, 1990 (the effective date 
of AD 90-01-07), whichever occurs later, modify the airplane by 
replacing countersunk fasteners in the upper row of the lower lobe 
lap joints in the vicinity of the wing-to-body fairings with 
protruding head fasteners, in accordance with the procedures 
described in Boeing Alert Service Bulletin 747-53A2312, dated June 
12, 1989; Revision 1, dated March 29, 1990; Revision 2, dated 
October 8, 1992; or Revision 3, dated February 8, 2007; except as 
provided by paragraph (u) of this AD. As of the effective date of 
this AD, only Revision 3 shall be used.

Adjustments for Cabin Differential Pressure for Airplanes Having 
Line Numbers 201 Through 765 Inclusive

    (h) For airplanes having line numbers 201 through 765 inclusive: 
Before the effective date of this AD, for purposes of complying with 
paragraphs (f) and (g) of this AD, the number of landings may be 
determined to equal the number of pressurization cycles where the 
cabin pressure differential was greater than 2.0 psi.
    (i) For airplanes having line numbers 201 through 765 inclusive: 
Before the effective date of this AD, for Model 747SR series 
airplanes only, based on continued mixed operation of lower cabin 
differentials, the inspection and modification compliance times 
specified in paragraphs (f) and (g) of this AD may be multiplied by 
a 1.2 adjustment factor.

General Visual Inspection for Countersunk Fasteners for All 
Airplanes

    (j) For all airplanes: Prior to the accumulation of 11,000 total 
landings, or within 1,000 landings after August 24, 1994 (the 
effective date of AD 94-15-06), whichever occurs later, conduct a 
general visual inspection, unless previously accomplished within the 
last 3,000 landings prior to August 24, 1994, to determine if 
countersunk fasteners have been installed in the lap joints listed 
in paragraph (j)(1) or (j)(2) of this AD, as applicable, in 
accordance with the procedures described in Boeing Service Bulletin 
747-53A2312, Revision 2, dated October 8, 1992; or Revision 3, dated 
February 8, 2007; except as provided by paragraph (u) of this AD. As 
of the effective date of this AD, only Revision 3 shall be used. 
Accomplishment of this inspection terminates the inspection 
requirements of paragraph (f) of this AD.
    (1) For Model 747-100, -200, -300, -400, and 747SR series 
airplanes: From body stations (BS) 741 to 1000 at Stringers (S-)34L, 
S-34R, S-39L, S-39R, S-44L, and S-44R, and from BS 1480 to 1741 at 
S-34L, S-34R, S-40L, and S-40R.
    (2) For Model 747SP series airplanes: From BS 520 to 1000 at S-
34L, S-34R, S-39L, S-39R, S-44L, and S-44R, and from BS 1480 to 1741 
at S-34L, S-34R, S-40L, and S-40R.

[[Page 58780]]

Corrective Action for Countersunk Fasteners for All Airplanes

    (k) For all airplanes: If no countersunk fastener is found in 
the upper row of a lap joint during the inspection required by 
paragraph (j) of this AD, no further action is required by this AD 
for that lap joint.
    (l) For all airplanes: If any countersunk fastener is found in 
the upper row of a lap joint during the inspection required by 
paragraph (j) of this AD, prior to further flight, perform a high 
frequency eddy current (HFEC) inspection to detect cracking at all 
fastener locations in the lap joint where a countersunk fastener was 
found, in accordance with the procedures described in Boeing Service 
Bulletin 747-53A2312, Revision 2, dated October 8, 1992; or Revision 
3, dated February 8, 2007; except as provided by paragraph (u) of 
this AD. As of the effective date of this AD, only Revision 3 shall 
be used.

Repetitive Inspections

    (m) If no cracking is detected during any inspection required by 
paragraphs (l) and (q) of this AD, at any fastener location where a 
countersunk fastener was found, repeat the HFEC inspection 
thereafter at intervals not to exceed 4,000 landings, in accordance 
with the procedures described in Boeing Service Bulletin 747-
53A2312, Revision 2, dated October 8, 1992; or Revision 3, dated 
February 8, 2007; except as provided by paragraph (u) of this AD. As 
of the effective date of this AD, only Revision 3 shall be used. As 
an alternative to the HFEC inspection, operators may perform a 
detailed inspection to detect cracking at any fastener location 
where a countersunk fastener was found, in accordance with the 
procedures described in Boeing Service Bulletin 747-53A2312, 
Revision 3, dated February 8, 2007; except as provided by paragraph 
(u) of this AD. Perform the detailed inspection within the next 
4,000 landings after the HFEC inspection required by paragraph (l) 
of this AD, and repeat the inspection thereafter at intervals not to 
exceed 500 landings. At any of the subsequent inspection cycles, 
operator may use either inspection method provided that the 
corresponding inspection interval is used to determine the 
compliance time of the next inspection.
    (n) If cracking is detected during any inspection required by 
paragraph (l), (m), (p), or (q) of this AD, at any fastener location 
where a countersunk fastener was found, prior to further flight, 
repair and modify that lap joint in accordance with Boeing Service 
Bulletin 747-53A2312, Revision 2, dated October 8, 1992; or Revision 
3, dated February 8, 2007; except as provided by paragraph (u) of 
this AD. As of the effective date of this AD, only Revision 3 shall 
be used. Accomplishment of this repair and modification terminates 
the repetitive inspections required by paragraph (m) of this AD for 
that lap joint.

Modification of Countersunk Fasteners for All Airplanes

    (o) For all airplanes: Prior to the accumulation of 20,000 total 
landings or within 1,000 landings after August 24, 1994, whichever 
occurs later, modify all fastener locations where a countersunk 
fastener was found during the inspections required by paragraph (j) 
of this AD, in accordance with the procedures described in Boeing 
Service Bulletin 747-53A2312, Revision 2, dated October 8, 1992; or 
Revision 3, dated February 8, 2007; except as provided by paragraph 
(u) of this AD. As of the effective date of this AD, only Revision 3 
shall be used. For purposes of complying with the requirements of 
this paragraph, fastener locations that were previously modified in 
accordance with paragraph (g) or (n) of this AD do not need to be 
modified again. Accomplishment of this modification terminates the 
repetitive inspections required by paragraph (m) of this AD for the 
modified fastener locations.

Post-Modification Inspections for All Airplanes

    (p) For all airplanes: Prior to the accumulation of 10,000 total 
landings following the modification required by paragraph (g), (n), 
(o), (q) or (s) of this AD, perform an HFEC inspection to detect 
cracking at all fastener locations where a countersunk fastener was 
found, and repeat this inspection thereafter at intervals not to 
exceed 4,000 landings, in accordance with the procedures described 
in Boeing Service Bulletin 747-53A2312, Revision 2, dated October 8, 
1992; or Revision 3, dated February 8, 2007; except as provided by 
paragraph (u) of this AD. As of the effective date of this AD, only 
Revision 3 shall be used.

New Requirements of This AD

General Visual Inspection for Countersunk Fasteners and 
Modification for Model 747SP Airplanes at Stringer S-46L

    (q) For Model 747SP series airplanes having line numbers 201 
through 814 inclusive, do the actions in paragraphs (q)(1) and 
(q)(2) of this AD at the times specified in those paragraphs.
    (1) Prior to the accumulation of 11,000 total landings, or 
within 1,000 landings as of the effective date of this AD, whichever 
occurs later, unless previously accomplished within the last 3,000 
landings prior to the effective date of this AD, conduct a general 
visual inspection of the lap joint from BS 520 to 1000 at stringer 
S-46L to determine if countersunk fasteners have been installed in 
the specified area, in accordance with the procedures described in 
Boeing Service Bulletin 747-53A2312, Revision 2, dated October 8, 
1992; or Revision 3, dated February 8, 2007; except as provided by 
paragraph (u) of this AD.
    (i) If no countersunk fastener is found in the upper row of the 
lap joint during the inspection, no further action is required by 
this AD for the lap joint.
    (ii) If any countersunk fastener is found in the upper row of 
the lap joint, prior to further flight, perform an HFEC inspection 
to detect cracking at all fastener locations where a countersunk 
fastener was found, in accordance with the procedures described in 
Boeing Service Bulletin 747-53A2312, Revision 3, dated February 8, 
2007; except as provided by paragraph (u) of this AD.
    A. If no cracking is found, repeat the inspection thereafter in 
accordance with the requirements of paragraph (m) of this AD.
    B. If any cracking is found, prior to further flight, repair and 
modify the lap joint as required by paragraph (n) of this AD.
    (2) Prior to the accumulation of 20,000 total landings, or 
within 1,000 landings as of the effective date of this AD, whichever 
occurs later, modify all fastener locations where a countersunk 
fastener was found, during the inspection required by paragraph 
(q)(1) of this AD, in accordance with the Accomplishment 
Instructions of Boeing Service Bulletin 747-53A2312, Revision 2, 
dated October 8, 1992; or Revision 3, dated February 8, 2007; except 
as provided by paragraph (u) of this AD. For purposes of complying 
with the requirements of this AD, fastener locations that were 
previously modified in accordance with paragraph (n) of this AD do 
not need to be modified again. Accomplishment of this modification 
terminates the repetitive inspections required by paragraph (m) of 
this AD for the modified fastener locations.

Adjustments to Compliance Time: Cabin Differential Pressure

    (r) For the purposes of calculating the compliance threshold and 
repetitive intervals for actions required by paragraphs (f) and (g) 
of this AD, on or as of the effective date of this AD: All flight 
cycles, including the number of flight cycles in which cabin 
differential pressure is at 2.0 psi or less, must be counted when 
determining the number of flight cycles that have occurred on the 
airplane, and a 1.2 adjustment factor may not be used. However, for 
airplanes on which the repetitive intervals for the actions required 
by paragraph (f) of this AD have been calculated in accordance with 
paragraph (h) and/or (i) of this AD by excluding the number of 
flight cycles in which cabin differential pressure is at 2.0 pounds 
psi or less, and/or by using a 1.2 adjustment factor: Continue to 
adjust the repetitive intervals in accordance with paragraph (h) 
and/or (i) of this AD until the next inspection required by 
paragraph (f) of this AD is accomplished. Thereafter, no adjustment 
to compliance times based on paragraph (h) and/or (i) of this AD is 
allowed.

Special One-Time Inspection for Cracking of Certain Airplanes

    (s) For airplanes with line numbers 630 through 814 inclusive 
that meet the conditions specified in paragraphs (s)(1) and (s)(2) 
of this AD: Within 300 flight cycles as of the effective date of 
this AD, or within 500 flight cycles after the most recent sliding 
probe inspection done in accordance with Boeing Alert Service 
Bulletin 747-53A2312, Revision 1, dated March 29, 1990; or Revision 
2, dated October 8, 1992, whichever occurs later, do a special one-
time HFEC inspection or a special one-time detailed inspection for 
cracking, in accordance with the Accomplishment Instructions of 
Boeing Alert Service Bulletin 747-53A2312, Revision 3, dated 
February 8, 2007. If any cracking is found in a lap joint, before 
further flight, repair and modify that lap joint in accordance with 
Boeing Service Bulletin

[[Page 58781]]

747-53A2312, Revision 3, dated February 8, 2007; except as provided 
by paragraph (u) of this AD. Accomplishment of this repair and 
modification terminates the repetitive inspections required by 
paragraph (m) of this AD for that lap joint. This special one-time 
inspection is not required for lap joints that have been modified in 
accordance with paragraph (g), (n), (o), or (q) of this AD.
    (1) Airplanes that have not been modified in accordance with 
paragraph (g) or (o) of this AD.
    (2) Airplanes on which the sliding probe HFEC inspection method 
specified in Boeing Service Bulletin 747-53A2312, Revision 1, dated 
March 29, 1990; or Revision 2, dated October 8, 1992; was used 
during the last skin inspection required by AD 94-15-06.

Actions After the Special One-Time Inspection if No Cracking Is Found

    (t) For airplanes specified in paragraph (s) of this AD on which 
no cracking is found during the special one-time inspection, do the 
applicable repetitive inspections specified in paragraph (t)(1) or 
(t)(2) of this AD.
    (1) If the special one-time inspection was done using the HFEC 
inspection method in accordance with paragraph (s) of this AD, 
perform the next inspection required by paragraph (m) of this AD 
within the next 4,000 flight cycles after doing the inspection 
required by paragraph (s) of this AD, and repeat the inspection 
thereafter in accordance with paragraph (m) of this AD.
    (2) If the special one-time inspection was done using the 
detailed inspection method in accordance with paragraph (s) of this 
AD, perform the next inspection required by paragraph (m) of this AD 
within the next 500 flight cycles after doing the inspection 
required by paragraph (s) of this AD, and repeat the inspection 
thereafter in accordance with paragraph (m) of this AD.

Contacting the Manufacturer

    (u) Where Boeing Alert Service Bulletin 747-53A2312, Revision 3, 
dated February 8, 2007 specifies to contact Boeing for appropriate 
action for a repair or inspection, before further flight, do the 
applicable action in paragraph (u)(1) or (u)(2) of this AD.
    (1) Do the repair using a method approved in accordance with the 
procedures specified in paragraph (v) of this AD.
    (2) Do the inspection using a method approved by the Manager, 
Seattle Aircraft Certification Office (ACO), FAA. For a repair 
method to be approved by the Manager, Seattle ACO, as required by 
this paragraph, the Manager's approval letter must specifically 
refer to this AD.

Alternative Methods of Compliance (AMOCs)

    (v)(1) The Manager, Seattle 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 shall 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.
    (4) AMOCs approved previously in accordance with AD 94-15-06, 
are approved as AMOCs for the corresponding provisions of this AD if 
the AMOC does not involve using the existing sliding probe HFEC skin 
inspection method specified in Boeing Service Bulletin 747-53A2312, 
Revision 2, dated October 8, 1992, or an earlier version. In 
addition, the provisions of paragraph (r) of this AD must be applied 
to AMOCs approved previously in accordance with AD 94-15-06, 
amendment 39-8977, where applicable.

    Issued in Renton, Washington, on October 5, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-20468 Filed 10-16-07; 8:45 am]

BILLING CODE 4910-13-P
