[Federal Register Volume 61, Number 219 (Tuesday, November 12, 1996)]
[Rules and Regulations]
[Pages 57994-57998]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-28169]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-251-AD; Amendment 39-9807; AD 96-23-02]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain Boeing Model 747 series airplanes. This action 
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 amendment is 
prompted by a report of skin cracking due to disbonding of the internal 
doubler of the cracked skin panels. The actions specified in this AD 
are intended to prevent rapid decompression of the airplane due to 
disbonding and subsequent cracking of the skin panels.

DATES: Effective November 27, 1996.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of November 27, 1996.
    Comments for inclusion in the Rules Docket must be received on or 
before January 13, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-251-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    The service information referenced in this AD may be obtained from 
Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 
98124-2207. This information may be examined at the FAA, Transport 
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at 
the Office of the Federal Register, 800 North Capitol Street, NW., 
suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Bob Breneman, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington; telephone (206) 227-2776; 
fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: Recently, the FAA received a report 
indicating that skin cracking was found on a Boeing Model 747-200 
series airplane that had accumulated 14,486 total flight cycles. 
Multiple one-inch skin cracks were found through four adjacent fastener 
holes along the number 2 doorstop intercostal between body station (BS) 
488 and BS 500. The FAA received another report indicating that skin 
cracking was found in the same location on a Model 747-200 series 
airplane that had accumulated 13,517 total flight cycles. This cracking 
measured approximately 17 inches in length.
    Results of subsequent inspections of both airplanes revealed 
extensive disbonding of the internal doubler of the cracked skin 
panels, as well as disbonding at several stringer locations from BS 340 
to BS 520 between stringer (S) 6 and S-14. The cause of this disbonding 
has been attributed to improper processing during the phosphoric acid 
anodize (PAA) phase of manufacture of the skin panels.
    Disbonding of the internal skin doublers could result in increased 
operational stress on the fuselage skin, and could lead to multiple-
site skin cracking. This condition, if not corrected, could result in 
rapid decompression of the airplane.

[[Page 57995]]

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-53A2409, dated September 26, 1996, which describes procedures for 
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 
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:
     Method 1: One-time external ultrasonic inspections (for 
Area 1 only) of the skin for disbonded doublers; and an external 
inspection of the skin for cracks, and repair, if necessary;
     Method 2: One-time internal visual 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 close visual 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.

Explanation of the Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other Boeing Model 747 series airplanes of the same 
type design, this AD is being issued to prevent rapid decompression of 
the airplane due to disbonding and subsequent cracking of the skin 
panels. This 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. Certain 
repairs are required to be accomplished in accordance with a method 
approved by the FAA. Other actions are required to be accomplished in 
accordance with the alert service bulletin described previously.
    This AD also requires that operators submit a report to the FAA of 
any findings of disbonding detected during the inspections required by 
this AD.

Differences Between Alert Service Bulletin and This AD

    While the alert service bulletin describes procedures for 
inspections of four particular areas of the airplane, this AD requires 
inspections of only two of those areas. The FAA is considering further 
rulemaking to require inspections of the other two areas that are not 
addressed in this AD; however, the proposed compliance time for 
accomplishment of those inspections is sufficiently long so that prior 
notice and time for public comment will be practicable.
    Additionally, the alert service bulletin specifies that, based on 
continued mixed operation at lower cabin differential pressures, the 
thresholds and intervals specified in the alert service bulletin can be 
multiplied by a 1.2 adjustment factor for Model 747SR and 747-400 
series airplanes (domestic only). The FAA finds that insufficient data 
exist to support such an adjustment to flight cycles. In fact, data are 
available which indicate that the use of a 1.2 adjustment factor 
provides inaccurate data and unjustified relief for inspection 
intervals. Consequently, this AD does not allow for such an adjustment 
factor.
    Further, the alert service bulletin indicates that if any cracking 
is found that is outside specified limits, operators should contact the 
manufacturer for repair data. However, this AD requires that such 
cracking be repaired in accordance with a method approved by the FAA.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this rule by 
submitting such written data, views, or arguments as they may desire. 
Communications shall identify the Rules Docket number and be submitted 
in triplicate to the address specified under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before and after the closing date for comments, in the 
Rules Docket for examination by interested persons. A report that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 96-NM-251-AD''. The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    The regulations adopted herein will not have substantial direct 
effects 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. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from the Rules Docket at the 
location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

[[Page 57996]]

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (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. Section 39.13 is amended by adding the following new 
airworthiness directive:

96-23-02  Boeing: Amendment 39-9807. Docket 96-NM-251-AD.

    Applicability: Model 747 series airplanes; line numbers 1 
through 200 inclusive on which the skin panel replacement specified 
in Boeing Service Bulletin 747-53A2321 has been accomplished; line 
numbers 201 through 430 inclusive that have been modified by Boeing 
to a Stretched Upper Deck (SUD) configuration; and line numbers 431 
through 1075 inclusive; certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (u) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent rapid decompression of the airplane due to disbonding 
and subsequent cracking of the skin panels, accomplish the 
following:

Disallowance of Adjustment Factor

    (a) For Model 747SR and 747-400 series airplanes operating at a 
cabin differential pressure lower than 8.9 pounds per square inch 
(psi): An adjustment factor of 1.2 shall not be used as a multiplier 
for thresholds and intervals specified in Boeing Alert Service 
Bulletin 747-53A2409, dated September 26, 1996.

Initial Inspection of Area 1: Group 1 Airplanes

    (b) For airplanes identified as Group 1 in Boeing Alert Service 
Bulletin 747-53A2409, dated September 26, 1996, on which the skin 
panel replacement specified in Boeing Alert Service Bulletin 747-
53A2321 has been accomplished: Perform an inspection to detect 
disbonding, corrosion, and/or cracking of the skin at the location 
specified as Area 1 in Table 1 of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 747-53A2409, dated September 26, 1996, 
using an inspection technique identified as Method 1, 2, 3, or 4 in 
paragraph A., Part I, of the Accomplishment Instructions of the 
alert service bulletin. Accomplish the inspection at the time 
specified in paragraph (b)(1) or (b)(2) of this AD, as applicable. 
In any case, any inspection using Method 1 or 2 shall not be 
accomplished prior to the accumulation of 2,000 total flight cycles 
with cabin differential pressure above 2.0 psi since skin panel 
replacement in accordance with Boeing Alert Service Bulletin 747-
53A2321. If inspection Method 1 or 2 is used and no disbonded 
doubler is found, no further action is required by this AD.
    (1) For airplanes on which zones 1 and 2 of the fuselage have 
not been modified in accordance with Boeing Service Bulletin 747-53-
2272: Inspect at the later of the times specified in paragraphs 
(b)(1)(i) and (b)(1)(ii) of this AD.
    (i) Prior to the accumulation of 8,000 total flight cycles, or 
within 150 flight cycles after the effective date of this AD, 
whichever occurs later.
    (ii) Within 60 days after the effective date of this AD.
    (2) For airplanes on which zones 1 and 2 of the fuselage have 
been modified in accordance with Boeing Service Bulletin 747-53-
2272: Inspect at the later of the times specified in paragraphs 
(b)(2)(i) and (b)(2)(ii) of this AD.
    (i) Prior to the accumulation of 10,000 total flight cycles, or 
within 150 flight cycles after the effective date of this AD, 
whichever occurs later.
    (ii) Within 60 days after the effective date of this AD.

On-Condition Repairs and Repetitive Inspections: Group 1 Airplanes

    (c) If inspection Method 1 or 2 was used to accomplish the 
inspection required by paragraph (b) of this AD, and any disbonded 
doubler was found during that inspection: Prior to further flight, 
perform external detailed visual inspections (Method 3) or external 
HFEC inspections (Method 4) to detect cracking of the fuselage skin 
in the areas where the disbonded doubler was found, in accordance 
with Boeing Alert Service Bulletin 747-53A2409, dated September 26, 
1996.
    (1) If inspection Method 3 was used to accomplish the inspection 
required by paragraph (c) of this AD, and no cracking was found 
during the inspection: Repeat the inspection thereafter at intervals 
not to exceed 150 flight cycles for up to 1,000 flight cycles; 
thereafter, perform external HFEC inspections (Method 4) at 
intervals not to exceed 2,000 flight cycles in accordance with the 
alert service bulletin.
    (2) If inspection Method 4 was used to accomplish the inspection 
required by paragraph (c) of this AD, and no cracking was found 
during the inspection: Repeat the inspection thereafter at intervals 
not to exceed 2,000 flight cycles in accordance with the alert 
service bulletin.
    (d) If inspection Method 3 was used to accomplish the inspection 
required by paragraph (b) of this AD, and no cracking was found 
during the inspection: Repeat the inspection thereafter at intervals 
not to exceed 150 flight cycles for up to 1,000 flight cycles; 
thereafter, accomplish either paragraph (d)(1) or (d)(2) of this AD 
in accordance with Boeing Alert Service Bulletin 747-53A2409, dated 
September 26, 1996.
    (1) Perform a one-time inspection using Method 1 or 2; or
    (2) Perform repetitive inspections using inspection Method 4 at 
intervals not to exceed 2,000 flight cycles.
    (e) If inspection Method 4 was used to accomplish the inspection 
required by paragraph (b) of this AD, and no cracking was found 
during the inspection: Repeat the inspection thereafter at intervals 
not to exceed 2,000 flight cycles in accordance with Boeing Alert 
Service Bulletin 747-53A2409, dated September 26, 1996.
    (f) If any cracking is found during any inspection required by 
paragraphs (b), (c), (d), or (e) of this AD, and the cracking is 
within the limits specified in Boeing Alert Service Bulletin 747-
53A2409, dated September 26, 1996, prior to further flight, repair 
in accordance with the alert service bulletin. Following repair, 
perform repetitive inspections using inspection Method 4 thereafter 
at intervals not to exceed 2,000 flight cycles in accordance with 
the alert service bulletin.
    (g) If any cracking is found during any inspection required by 
paragraphs (b), (c), (d), or (e) of this AD, and the cracking is 
outside the limits specified in Boeing Alert Service Bulletin 747-
53A2409, dated September 26, 1996, prior to further flight, repair 
in accordance with a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA, Transport Airplane 
Directorate.

Initial Inspection of Areas 1 and 4: Groups 2, 3, 6, and 8 Airplanes

    (h) For airplanes identified as Group 2, 3, 6, or 8 in Boeing 
Alert Service Bulletin 747-53A2409, dated September 26, 1996: 
Perform inspections to detect disbonding, corrosion, and/or cracking 
of the skin at the locations specified as Areas 1 and 4 in Table 1 
of the Accomplishment Instructions of Boeing Alert Service Bulletin 
747-53A2409, dated September 26, 1996, using an inspection technique 
identified as Method 1, 2, 3, or 4 (for Area 1), or Method 2, 3, or 
4 (for Area 4) in paragraph A., Part I, of the Accomplishment 
Instructions of the alert service bulletin. Accomplish the 
inspection at the time specified in paragraph (h)(1) or (h)(2) of 
this AD, as applicable. In any case, any inspection using Method 1 
or 2 shall not be accomplished prior to the accumulation of 2,000 
total flight cycles with cabin differential pressure above 2.0 psi 
since delivery, or since modification to the SUD configuration. If 
inspection Method 1 or 2 is used and no disbonded doubler is found, 
no further action is required by this AD.
    (1) For airplanes on which zones 1, 2, and 3 of the fuselage 
have not been modified in accordance with Boeing Service Bulletin

[[Page 57997]]

747-53-2272: Inspect at the later of the times specified in 
paragraphs (h)(1)(i) and (h)(1)(ii) of this AD.
    (i) Prior to the accumulation of 8,000 total flight cycles, or 
within 150 flight cycles after the effective date of this AD, 
whichever occurs later.
    (ii) Within 60 days after the effective date of this AD.
    (2) For airplanes on which zones 1, 2, and 3 of the fuselage 
have been modified in accordance with Boeing Service Bulletin 747-
53-2272: Inspect at the later of the times specified in paragraphs 
(h)(2)(i) and (h)(2)(ii) of this AD.
    (i) Prior to the accumulation of 10,000 total flight cycles, or 
within 150 flight cycles after the effective date of this AD, 
whichever occurs later.
    (ii) Within 60 days after the effective date of this AD.

On-Condition Repairs and Repetitive Inspections: Groups 2, 3, 6, and 8 
Airplanes

    (i) If inspection Method 1 or 2 was used to accomplish the 
inspection required by paragraph (h) of this AD, and any disbonded 
doubler was found during that inspection: Prior to further flight, 
perform external detailed visual inspections (Method 3) or external 
HFEC inspections (Method 4) to detect cracking of the fuselage skin 
in the areas where the disbonded doubler was found, in accordance 
with Boeing Alert Service Bulletin 747-53A2409, dated September 26, 
1996.
    (1) If inspection Method 3 was used to accomplish the inspection 
required by paragraph (i) of this AD, and no cracking was found 
during the inspection: Repeat the inspection thereafter at intervals 
not to exceed 150 flight cycles (for Area 1) or 250 flight cycles 
(for Area 4), as applicable, for up to 1,000 flight cycles; 
thereafter, perform external HFEC inspections (Method 4) at 
intervals not to exceed 2,000 flight cycles (for Area 1) or 3,000 
flight cycles (for Area 4), as applicable, in accordance with the 
alert service bulletin.
    (2) If inspection Method 4 was used to accomplish the inspection 
required by paragraph (i) of this AD, and no cracking was found 
during the inspection: Repeat the inspection thereafter at intervals 
not to exceed 2,000 flight cycles (for Area 1) or 3,000 flight 
cycles (for Area 4), as applicable, in accordance with the alert 
service bulletin.
    (j) If inspection Method 3 was used to accomplish the inspection 
required by paragraph (h) of this AD, and no cracking was found 
during the inspection: Repeat the inspection thereafter at intervals 
not to exceed 150 flight cycles (for Area 1) or 250 flight cycles 
(for Area 4), as applicable, for up to 1,000 flight cycles; 
thereafter, accomplish either paragraph (j)(1) or (j)(2) of this AD 
in accordance with Boeing Alert Service Bulletin 747-53A2409, dated 
September 26, 1996.
    (1) Perform a one-time inspection using Method 1 or 2 (for Area 
1), or Method 2 (for Area 4 only); or
    (2) Perform repetitive inspections using inspection Method 4 at 
intervals not to exceed 2,000 flight cycles (for Area 1) or 3,000 
flight cycles (for Area 4), as applicable.
    (k) If inspection Method 4 was used to accomplish the inspection 
required by paragraph (h) of this AD, and no cracking was found 
during the inspection: Repeat the inspection thereafter at intervals 
not to exceed 2,000 flight cycles (for Area 1) or 3,000 flight 
cycles (for Area 4), as applicable, in accordance with Boeing Alert 
Service Bulletin 747-53A2409, dated September 26, 1996.
    (l) If any cracking is found during any inspection required by 
paragraphs (h), (i), (j), or (k) of this AD, and the cracking is 
within the limits specified in Boeing Alert Service Bulletin 747-
53A2409, dated September 26, 1996, prior to further flight, repair 
in accordance with the alert service bulletin. Following repair, 
perform repetitive inspections using inspection Method 4 thereafter 
at intervals not to exceed 2,000 flight cycles (for Area 1) or 3,000 
flight cycles (for Area 4), as applicable, in accordance with the 
alert service bulletin.
    (m) If any cracking is found during any inspection required by 
paragraphs (h), (i), (j), or (k) of this AD, and the cracking is 
outside the limits specified in Boeing Alert Service Bulletin 747-
53A2409, dated September 26, 1996, prior to further flight, repair 
in accordance with a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA, Transport Airplane 
Directorate.

Initial Inspection of Areas 1 and 4: Groups 4, 5, 7, 9, and 10 
Airplanes

    (n) For airplanes identified as Group 4, 5, 7, 9, or 10 in 
Boeing Alert Service Bulletin 747-53A2409, dated September 26, 1996: 
Perform inspections to detect disbonding, corrosion, and/or cracking 
of the skin at the locations specified as Areas 1 and 4 in Table 1 
of the Accomplishment Instructions of Boeing Alert Service Bulletin 
747-53A2409, dated September 26, 1996, using an inspection technique 
identified as Method 1, 2, 3, or 4 (for Area 1) or Method 2, 3, or 4 
(for Area 4) in paragraph A., Part I, of the Accomplishment 
Instructions of the alert service bulletin. Accomplish the 
inspection at the later of the times specified in paragraphs (n)(1) 
and (n)(2) of this AD. In any case, any inspection using Method 1 or 
2 shall not be accomplished prior to the accumulation of 2,000 total 
flight cycles with cabin differential pressure above 2.0 psi since 
delivery. If inspection Method 1 or 2 is used and no disbonded 
doubler is found, no further action is required by this AD.
    (1) Prior to the accumulation of 10,000 total flight cycles, or 
within 150 flight cycles after the effective date of this AD, 
whichever occurs later.
    (2) Within 60 days after the effective date of this AD.

On-Condition Repairs and Repetitive Inspections: Groups 4, 5, 7, 9, and 
10 Airplanes

    (o) If inspection Method 1 or 2 was used to accomplish the 
inspection required by paragraph (n) of this AD, and any disbonded 
doubler was found during that inspection: Prior to further flight, 
perform external detailed visual inspections (Method 3) or external 
HFEC inspections (Method 4) to detect cracking of the fuselage skin 
in the areas where the disbonded doubler was found, in accordance 
with Boeing Alert Service Bulletin 747-53A2409, dated September 26, 
1996.
    (1) If inspection Method 3 was used to accomplish the inspection 
required by paragraph (o) of this AD, and no cracking was found 
during the inspection: Repeat the inspection thereafter at intervals 
not to exceed 150 flight cycles (for Area 1) or 250 flight cycles 
(for Area 4), as applicable, for up to 1,000 flight cycles; 
thereafter, perform external HFEC inspections (Method 4) at 
intervals not to exceed 2,000 flight cycles (for Area 1) or 3,000 
flight cycles (for Area 4), as applicable, in accordance with the 
alert service bulletin.
    (2) If inspection Method 4 was used to accomplish the inspection 
required by paragraph (o) of this AD, and no cracking was found 
during the inspection: Repeat the inspection thereafter at intervals 
not to exceed 2,000 flight cycles (for Area 1) or 3,000 flight 
cycles (for Area 4), as applicable, in accordance with the alert 
service bulletin.
    (p) If inspection Method 3 was used to accomplish the inspection 
required by paragraph (n) of this AD, and no cracking was found 
during the inspection: Repeat the inspection thereafter at intervals 
not to exceed 150 flight cycles (for Area 1) or 250 flight cycles 
(for Area 4), as applicable, for up to 1,000 flight cycles; 
thereafter, accomplish either paragraph (p)(1) or (p)(2) of this AD 
in accordance with Boeing Alert Service Bulletin 747-53A2409, dated 
September 26, 1996.
    (1) Perform a one-time inspection using Method 1 or 2 (for Area 
1), or Method 2 (for Area 4 only); or
    (2) Perform repetitive inspections using inspection Method 4 at 
intervals not to exceed 2,000 flight cycles (for Area 1) or 3,000 
flight cycles (for Area 4), as applicable.
    (q) If inspection Method 4 was used to accomplish the inspection 
required by paragraph (n) of this AD, and no cracking was found 
during the inspection: Repeat the inspection thereafter at intervals 
not to exceed 2,000 flight cycles (for Area 1) or 3,000 flight 
cycles (for Area 4), as applicable, in accordance with Boeing Alert 
Service Bulletin 747-53A2409, dated September 26, 1996.
    (r) If any cracking is found during any inspection required by 
paragraphs (n), (o), (p), or (q) of this AD, and the cracking is 
within the limits specified in Boeing Alert Service Bulletin 747-
53A2409, dated September 26, 1996, prior to further flight, repair 
in accordance with the alert service bulletin. Following repair, 
perform repetitive inspections using inspection Method 4 thereafter 
at intervals not to exceed 2,000 flight cycles (for Area 1) or 3,000 
flight cycles (for Area 4), as applicable.
    (s) If any cracking is found during any inspection required by 
paragraphs (n), (o), (p), or (q) of this AD, and the cracking is 
outside the limits specified in Boeing Alert Service Bulletin 747-
53A2409, dated September 26, 1996, prior to further flight, repair 
in accordance with a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA, Transport Airplane 
Directorate.

[[Page 57998]]

    (t) Within 10 days after accomplishing any inspection to detect 
disbonding required by paragraphs (b), (d)(1), (h), (j)(1), (n), and 
(p)(1) this AD, report any findings of disbonding to the Manager, 
Seattle Manufacturing Inspection District Office, FAA, Transport 
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056; fax (206) 227-1159. The report shall include the 
information specified in paragraphs (t)(1), (t)(2), and (t)(3) of 
this AD. Information collection requirements contained in this 
regulation have been approved by the Office of Management and Budget 
(OMB) under the provisions of the Paperwork Reduction Act of 1980 
(44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 
2120-0056.
    (1) The line number of the airplane on which disbonding was 
found.
    (2) The number of disbonded skin panels that were found.
    (3) The part number of any disbonded skin panel that is found.
    (u) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Seattle ACO. Operators shall submit 
their requests through an appropriate FAA Principal Maintenance 
Inspector, who may add comments and then send it to the Manager, 
Seattle ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (v) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.
    (w) The actions shall be done in accordance with Boeing Alert 
Service Bulletin 747-53A2409, dated September 26, 1996. This 
incorporation by reference was approved by the Director of the 
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 
51. Copies may be obtained from Boeing Commercial Airplane Group, 
P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be 
inspected at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
    (x) This amendment becomes effective on November 27, 1996.

    Issued in Renton, Washington, on October 28, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-28169 Filed 11-8-96; 8:45 am]
BILLING CODE 4910-13-U