Document ID: FAA-2007-0043-0005
Agency: faa
Document Type: Rule
Title: 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
Posted Date: 2008-05-07T04:00Z

[Federal Register: May 7, 2008 (Volume 73, Number 89)]
[Proposed Rules]               
[Page 25601-25606]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr07my08-27]                         

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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: Supplemental notice of proposed rulemaking (NPRM); reopening of 
comment period.

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SUMMARY: The FAA is revising an earlier NPRM for an airworthiness 
directive (AD) that applies to certain Boeing Model 747 series 
airplanes. The original NPRM would have superseded an existing AD that 
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. The original NPRM proposed to 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. The original 
NPRM also included an inspection at an additional lap joint. The 
original NPRM resulted 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. This new action revises the original NPRM 
by including inspections at additional lap joint locations and by 
removing inspections at certain other lap joint locations. We are 
proposing this supplemental NPRM to prevent reduced structural 
integrity of the fuselage.

DATES: We must receive comments on this supplemental NPRM by June 2, 
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

[[Page 25602]]

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

    We proposed to amend part 39 of the Federal Aviation Regulations 
(14 CFR part 39) with a notice of proposed rulemaking (NPRM) for an AD 
(the ``original NPRM'') to supersede AD 94-15-06, amendment 39-8977 (59 
FR 37659, July 25, 1994). The original NPRM applied to certain Boeing 
Model 747 series airplanes. The original NPRM was published in the 
Federal Register on October 17, 2007 (72 FR 58777). The original NPRM 
proposed to retain certain requirements of AD 94-15-06. The original 
NPRM also proposed to 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. The original NPRM also proposed to require an 
inspection at an additional lap joint.

Actions Since Original NPRM Was Issued

    Since we issued the original NPRM, we have determined that the 
requirements of AD 94-15-06 included additional errors in lap joint 
locations that would require a general visual inspection for 
countersunk fasteners for certain Boeing Model 747SP airplanes. The 
errors are as follows:
     The requirements of AD 94-15-06 included body station (BS) 
520 to 1000 at stringer (S)-34L, S-34R, S-39L, S-39R, S-44L, and S-44R, 
but should have included only BS 560 to 800 at those stringer 
locations. (See paragraph (j)(2) of this supplemental NPRM.)
     The requirements of AD 94-15-06 included BS 1480 to 1741 
at S-34L, S-34R, S-40L, and S-40R, but should have included only BS 
1640 to 1741 at those stringer locations. (See paragraph (j)(2) of this 
supplemental NPRM.)
     The requirements of AD 94-15-06 did not include BS 1741 to 
1901 at S-34L, S-34R, S-40L, and S-40R. (See paragraph (q)(1) of this 
supplemental NPRM.)
     The requirements 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 airplanes. We included BS 520 to 1000 at 
that stringer location in the original NPRM, but should instead have 
included BS 1640 to 1901. (See paragraph (q)(1) of this supplemental 
NPRM.)
    Therefore, we have revised paragraphs (j)(2) and (q)(1) of this 
supplemental NPRM to correct the body station and stringer locations.

Comments

    We have considered the following comments on the original NPRM.

Request To Revise Alternative Methods of Compliance (AMOCs) Paragraph

    Boeing requests that we revise paragraph (v)(4) of the original 
NPRM to read: ``AMOCs approved previously in accordance with AD 94-15-
06 for airplane line numbers 630 through 814 inclusive, are approved as 
AMOCs for the corresponding provisions of this AD if the AMOC does not 
involve using the existing sliding probe HFEC or alternate skin 
inspection method specified in Boeing Service Bulletin 747-53A2312, 
Revision 2, dated October 8, 1992, or an earlier version. AMOCs 
approved previously in accordance with AD 94-15-06 for airplane line 
numbers 201 through 629 inclusive are approved as AMOCs for the 
corresponding provisions of this AD regardless if the AMOC involves 
using the existing sliding probe HFEC or alternate skin inspection 
method specified in Boeing Service Bulletin 747-53A2312, Revision 2, 
dated October 8, 1992, or an earlier version.'' Boeing explains that 
for airplane line numbers 630 through 814, the sliding probe HFEC 
inspection method can produce incorrect results due to the possibility 
that Alodine rivets are installed. However, airplanes with line numbers 
in the range 201 through 629 did not have Alodine rivets installed in 
production, and therefore the sliding probe HFEC inspection method is a 
valid inspection.
    We agree with the commenter for the reasons stated. We have 
included the requested information in a revised paragraph (v)(4) and a 
new paragraph (v)(5) in this supplemental NPRM.

Request To Specify Use of Only Revision 3 of Service Bulletin

    Boeing requests that we specify in paragraph (q) of the original 
NPRM that Boeing Alert Service Bulletin 747-53A2312, Revision 3, dated 
February 8, 2007 (the appropriate source of service information for 
certain actions proposed in the NPRM), must be used after the effective 
date of the AD. Boeing explains that this change would ensure that the 
most recent revision of the service bulletin is followed.
    We agree with Boeing's request. The procedures in Revision 2 of the 
service bulletin specify to inspect a smaller area than that specified 
in Revision 3. Therefore, we have changed paragraph (q) of this 
supplemental NPRM to include only Revision 3 of the service bulletin as 
the appropriate source of service information for doing the proposed 
actions.

Request To Revise ``Actions Since Existing AD Was Issued'' Section of 
NPRM

    Boeing asks that we revise the ``Actions Since Existing AD Was 
Issued'' paragraph of the original NPRM to add the words ``for certain 
airplanes'' to the end of the following sentence: ``The sliding probe 
HFEC (high frequency eddy current) inspection specified in the previous 
revisions of the service bulletin would no longer be allowed in this 
proposed AD.'' Boeing explains that Boeing Alert Service Bulletin 747-
53A2312, Revision 3, allows using the sliding probe procedure as an 
alternative HFEC inspection procedure for Group 1 airplanes only, as 
specified in Note 2 of Figure 5 of the service bulletin. Those 
airplanes were not delivered with Alodine rivets.
    We partially agree. We agree that the sliding probe HFEC inspection

[[Page 25603]]

procedure is an acceptable inspection procedure for Group 1 airplanes, 
as the commenter explained. However the ``Actions Since Existing AD Was 
Issued'' section of the preamble of the original NPRM is not repeated 
in this supplemental NPRM. Therefore, we have not changed this 
supplemental NPRM in this regard.

Request To Revise ``Relevant Service Information'' Section of NPRM

    Boeing asks that we delete the words ``and repair if necessary'' 
from the end of the following sentence in the ``Relevant Service 
Information'' section of the original NPRM: ``However, Revision 3 * * * 
gives instructions for a special (one-time) inspection for cracking of 
airplanes * * * and on which the sliding probe HFEC inspection method 
was used during the last skin inspection, and repair if necessary.'' 
Boeing states that this change would eliminate potential confusion 
because the sliding probe inspection does not apply to modifications or 
repairs.
    We disagree with the requested change. The phrase ``repair if 
necessary'' is intended to state that the repair is necessary if a 
crack is found during the special (one-time) inspection. Furthermore, 
the ``Relevant Service Information'' section is not repeated in this 
supplemental NPRM. Therefore, we have not changed this supplemental 
NPRM in this regard.

Request To Capitalize ``Alodine''

    Boeing points out that the term ``Alodine'' in the original NPRM 
should be capitalized because ``Alodine'' is a trademarked name.
    We agree. We have revised several sections of this supplemental 
NPRM to reflect this change.

Explanation of Clarification

    We have clarified paragraph (p), ``Post-modification Inspections 
for all Airplanes,'' of this supplemental NPRM to specify that the 
post-modification inspection is done at all fastener locations where a 
countersunk fastener was found during the inspection required by 
paragraph (j) or (q)(1) of the proposed AD.

FAA's Determination and Proposed Requirements of the Supplemental NPRM

    The changes to the body station and stringer locations and the 
change to the service information specified in paragraph (q) discussed 
above expand the scope of the original NPRM; therefore, we have 
determined that it is necessary to reopen the comment period to provide 
additional opportunity for public comment on this supplemental NPRM.

Costs of Compliance

    There are about 348 airplanes in the worldwide fleet. We estimate 
that this proposed AD would affect 90 airplanes of U.S. registry. The 
issue associated with Alodine-coated aluminum rivets occurs on 162 
airplanes in the worldwide fleet and affects 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 94-              14         $0              90  $1,120, per        $100,800, per
 15-06 and retained in this AD).                                             inspection cycle.  inspection
                                                                                                cycle.
Inspections (required by AD 94-              82          0              90  $6,560, per        $590,400, per
 15-06 and retained in this AD).                                             inspection cycle.  inspection
                                                                                                cycle.
Modification (required by AD 94-            124      (\1\)              90  $9,920...........  $892,800.
 15-06 and retained in this
 proposed AD).
One-time inspection (new                      4          0              24  $320.............  $7,680.
 proposed action).
----------------------------------------------------------------------------------------------------------------
\1\ Minimal.

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 supplemental NPRM 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:

[[Page 25604]]

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 by 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 June 2, 
2008.

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 With Revised Body Station and Stringer 
Locations

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 560 to 800 at S-
34L, S-34R, S-39L, S-39R, S-44L, and S-44R, and from BS 1640 to 1741 
at S-34L, S-34R, S-40L, and S-40R.

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 during the inspection 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.

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 during the inspection required by 
paragraph (j) or (q)(1) of this AD, 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

[[Page 25605]]

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 
fasteners 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, operators 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 during the inspection 
required by paragraph (j) or (q)(1) of this AD, 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 during the inspection required by paragraph (j) or (q)(1) of 
this AD, 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 Stringers S-34L, S-34R, S-40L, S-40R, and 
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 1640 to 1901 at stringer 
S-46L, and from BS 1741 to 1901 at S-34L, S-34R, S-40L, and S-40R, 
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 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 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, 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 after 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 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 paragraph (f), (l), or 
(m) of this AD.

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

[[Page 25606]]

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 for 
airplane line numbers 630 through 814 inclusive 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.
    (5) AMOCs approved previously in accordance with AD 94-15-06 for 
airplane line numbers 201 through 629 inclusive are approved as 
AMOCs for the corresponding provisions of this AD. In addition, the 
provisions of paragraph (r) of this AD must be applied to AMOCs 
approved previously in accordance with AD 94-15-06, where 
applicable.

    Issued in Renton, Washington, on April 30, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E8-10060 Filed 5-6-08; 8:45 am]

BILLING CODE 4910-13-P