Airworthiness Directives; Boeing Model 747 Airplanes

[Federal Register Volume 71, Number 208 (Friday, October 27, 2006)]
[Rules and Regulations]
[Pages 62904-62906]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-17941]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-24119; Directorate Identifier 2005-NM-100-AD; 
Amendment 39-14806; AD 2006-22-09]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain Boeing Model 747 airplanes. This AD requires repetitive mid- 
and low-frequency eddy current inspections for cracks in the overlapped 
skin panels in the fuselage skin lap joints in sections 41, 42, 44, and 
46, and corrective actions if necessary. This AD results from a report 
indicating that an operator found multiple small cracks in the 
overlapped skin panels in the fuselage skin lap joints. We are issuing 
this AD to detect and correct cracks in the overlapped skin panels, 
which could join together and result in reduced structural capability 
in the skin and consequent rapid decompression of the airplane.

DATES: This AD becomes effective December 1, 2006.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of December 1, 
2006.

ADDRESSES: You may examine the AD docket on the Internet at http://dms.dot.gov or in person at the Docket Management Facility, U.S. 
Department of Transportation, 400 Seventh Street, SW., Nassif Building, 
Room PL-401, Washington, DC.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for service information identified in this AD.

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:

Examining the Docket

    You may examine the airworthiness directive (AD) docket on the 
Internet at http://dms.dot.gov or in person at the Docket Management 
Facility office between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. The Docket Management Facility office 
(telephone (800) 647-5227) is located on the plaza level of the Nassif 
Building at the street address stated in the ADDRESSES section.

Discussion

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 to include an AD that would apply to certain Boeing Model 
747 airplanes. That NPRM was published in the Federal Register on March 
14, 2006 (71 FR 13055). That NPRM proposed to require repetitive mid- 
and low-frequency eddy current inspections for cracks in the overlapped 
skin panels in the fuselage skin lap joints in sections 41, 42, 44, and 
46, and corrective actions if necessary.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments received.

Support for the NPRM

    Boeing supports the NPRM as proposed.

Request To Delay Final Rule Pending New Service Information

    Japan Airlines (JAL) states that Boeing Alert Service Bulletin 747-
53A2501, dated March 24, 2005, which was referenced as the appropriate 
source of service information for accomplishing the actions proposed in 
the NPRM, contains various errors and omissions. For example, the alert 
service bulletin does not have inspection procedures for certain 
internal structural details that cover the lap, and there is no 
inspection procedure specific to the Boeing Model 747-400 converted 
freighter. JAL would like us to delay issuing the final rule until 
Boeing has revised the alert service bulletin.
    We partially agree with JAL. We agree that there are details and 
configurations that could be changed in future revisions of the alert 
service bulletin. The issues JAL mentions would require an alternative 
method of compliance (AMOC) to the inspection instructions as given in 
the original issue of the alert service bulletin. Operators may request 
an AMOC in accordance with the procedures in paragraph (j) of the final 
rule. We disagree that we should delay the final rule until Boeing 
revises the alert service bulletin. We have identified an unsafe 
condition, and delaying issuance of the final rule until Boeing revises 
its service information would result in an unwarranted delay of the 
inspections that are intended to address that unsafe condition. We have 
not changed the final rule in this regard.

Request To Revise Inspection Threshold

    Air Transport Association (ATA), on behalf of its member Northwest 
Airlines (NWA), requests that we allow the initial inspection to occur 
within 3,000 flight cycles after the most recent Supplemental 
Structural Inspection Document (SSID) inspection for items F-25K, F-
25L, and F-25M in Boeing SSID D6-35022.
    We disagree with the commenters. The SSID program is an exploratory 
inspection program. The inspection intervals in the SSID were derived 
from required damage tolerance ratings (DTRs) that were based on 
``fleet crack'' criteria. This means that at the time the DTRs were 
developed, there was no known cracking in the area; therefore, the 
required DTRs could remain at a lower level until cracking was 
discovered. However, operators subsequently found cracking in certain 
lap joint lower skins, and Boeing issued Alert Service Bulletin 747-
53A2501 to detect and correct this cracking. The required DTRs that 
drive the thresholds and intervals were developed using ``first crack'' 
criteria, which is higher than ``fleet crack'' criteria. ``First 
crack'' criteria must detect cracking that is known to have occurred on 
other airplanes and, therefore, cannot rely on a worldwide fleet of 
airplanes as a statistical sample group.

[[Page 62905]]

    The inspection specified in Boeing Alert Service Bulletin 747-
53A2501 is an internal medium frequency eddy current (MFEC) inspection, 
which is able to detect a crack size smaller than that detectable by 
the external low frequency eddy current (LFEC) inspection required by 
the SSID program. Both inspection techniques are used to detect cracks 
on the outer surface of the lower skin panel at the lower row of 
fasteners of the lap splice. However, the LFEC inspection looks through 
the upper skin panel; the MFEC technique uses a probe that is in direct 
contact with the lower skin panel on the inner surface. Therefore, a 
3,000-flight-cycle repetitive interval using an LFEC method does not 
provide the same level of certainty as a 3,000-flight-cycle repetitive 
inspection using the MFEC method.
    We have not changed the final rule in this regard.

Request To Change Costs of Compliance

    ATA, on behalf of NWA, also requests that we change the costs of 
compliance. NWA states that it has determined that approximately 120 
work hours would be required to accomplish the non-destructive test 
procedures specified in Boeing Alert Service Bulletin 747-53A2501. The 
NPRM gives a cost estimate of 68 hours to do this task. NWA states that 
it is worth noting that if the inspection has to be performed 
independent of other major fuselage internal inspections, then over 
1,000 additional hours of access and restoration labor will be 
required. NWA states that this scenario is likely if the initial 
inspection is required independent of the SSID or fuselage fatigue 
inspection programs. The 1,000-flight-cycle initial inspection 
threshold could prompt such a scenario.
    We disagree with the request to change the costs of compliance. The 
68 work-hour estimate represents the time necessary to perform only the 
action actually required by the AD. The action in the NPRM reflects 
only the direct costs of the specific required action (inspection) 
based on the best available data from the manufacturer. The cost 
analysis in AD rulemaking actions typically does not include incidental 
costs such as the time required to gain access and close up, time 
necessary for planning, or time necessary for other administrative 
tasks. Those incidental costs, which may vary significantly among 
operators, are almost impossible to calculate. We have not changed the 
final rule in this regard.

Request To Revise Compliance Time

    ATA also recommends that we align the compliance period for the 
non-destructive test procedures specified in Boeing Alert Service 
Bulletin 747-53A2501, with scheduled maintenance intervals in order to 
avoid the order-of-magnitude increase in the effect of the proposed 
actions if they must be accomplished on an unscheduled basis.
    We disagree with the request to revise the compliance time. We 
acknowledge that for certain airplanes the inspections may have to be 
performed independent of the SSID or fuselage fatigue inspection 
programs. In developing an appropriate compliance time for this action, 
including the 1,000-flight-cycle initial inspection threshold, we 
considered the urgency associated with the subject unsafe condition, 
the manufacturer's recommendations, and the practical aspect of 
accomplishing the required inspections within a period of time that 
corresponds to the normal scheduled maintenance for most affected 
operators. We have not changed the final rule in this regard. However, 
according to the provisions of paragraph (j) of the final rule, we may 
approve requests to adjust the compliance time if the request includes 
data that prove that the new compliance time would provide an 
acceptable level of safety.

Conclusion

    We have carefully reviewed the available data, including the 
comments received, and determined that air safety and the public 
interest require adopting the AD as proposed.

Costs of Compliance

    There are about 1,081 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this AD.

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                 Number of U.S.-
            Action               Work hours     Average labor      Cost per        registered       Fleet cost
                                                rate per hour      airplane         airplanes
----------------------------------------------------------------------------------------------------------------
Inspection for Model 747SP                 48             $80  $3,840, per                   10  $38,400, per
 series airplanes.                                              inspection                        inspection
                                                                cycle.                            cycle.
Inspection for all other                   68              80  $5,440, per                  196  $1,066,240, per
 Model 747 series airplanes.                                    inspection                        inspection
                                                                cycle.                            cycle.
----------------------------------------------------------------------------------------------------------------

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 AD will not have federalism 
implications under Executive Order 13132. This AD will 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 this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866;
    (2) Is not a ``significant rule'' under 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 AD and placed it in the AD docket. See the ADDRESSES 
section for a location to examine the regulatory evaluation.

[[Page 62906]]

List of Subjects in 14 CFR Part 39

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

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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 
adding the following new airworthiness directive (AD):

2006-22-09 Boeing: Amendment 39-14806. Docket No. FAA-2006-24119; 
Directorate Identifier 2005-NM-100-AD.

Effective Date

    (a) This AD becomes effective December 1, 2006.

Affected ADs

    (b) 2004-13-02.

Applicability

    (c) This AD applies to Boeing Model 747-100, 747-100B, 747-100B 
SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-
400F, 747SR, and 747SP series airplanes, certificated in any 
category; as identified in Boeing Alert Service Bulletin 747-
53A2501, dated March 24, 2005.

Unsafe Condition

    (d) This AD results from a report indicating that an operator 
found multiple small cracks in the overlapped skin panels in the 
fuselage skin lap joints. We are issuing this AD to detect and 
correct cracks in the overlapped skin panels, which could join 
together and result in reduced structural capability in the skin and 
consequent rapid decompression of the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Inspections and Corrective Actions: For Airplanes With Line Numbers 1 
Through 200 Inclusive

    (f) For airplanes with line numbers 1 through 200 inclusive, at 
the applicable time in paragraph (f)(1) or (f)(2) of this AD: Do the 
applicable eddy current inspection or inspections for cracks in the 
overlapped skin panels in the fuselage skin lap joints in sections 
41, 42, 44, and 46; and do all applicable corrective actions before 
further flight. Except as provided by paragraph (f)(1)(ii) of this 
AD, repeat the applicable inspection or inspections thereafter at 
intervals not to exceed 3,000 flight cycles. Except as provided by 
paragraph (h) of this AD, do all actions in accordance with the 
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
53A2501, dated March 24, 2005.
    (1) Except as provided by paragraph (f)(2) of this AD, do the 
applicable action in paragraph (f)(1)(i) or (f)(1)(ii) of this AD.
    (i) For airplanes that have accumulated fewer than 29,000 total 
flight cycles as of the effective date of this AD: Before the 
accumulation of 25,000 total flight cycles, or within 1,000 flight 
cycles after the effective date of this AD, whichever occurs later, 
do a mid-frequency eddy current inspection for cracks of the 
internal surface at the overlapped skin around the bottom row of 
fasteners in the lap joint.
    (ii) For airplanes that have accumulated 29,000 or more total 
flight cycles, do the inspections in accordance with the 
requirements of AD 2004-13-02, amendment 39-13682, at the applicable 
threshold and intervals in that AD. Doing the repeat inspections in 
accordance with AD 2004-13-02, terminates the repetitive inspection 
requirements of this AD only for airplanes with line numbers 1 
through 200 inclusive.
    (2) For airplanes that have had overlapped skin panels replaced: 
Do the eddy current inspections of the replaced overlapped panel 
prior to the accumulation of 25,000 total flight cycles since panel 
replacement, or within 1,000 flight cycles after the effective date 
of this AD, whichever occurs later. Skin panel replacement, along 
with ongoing inspections in accordance with paragraph (f) of this 
AD, terminates the requirements of paragraphs (a) and (d) of AD 
2004-13-02, only for the skin lap sections where the overlapped 
panel has been replaced.

Inspections and Corrective Actions: For Airplanes With Line Numbers 201 
and Subsequent

    (g) For airplanes with line numbers 201 and subsequent: Before 
the accumulation of 25,000 total flight cycles, within 1,000 flight 
cycles after the effective date of this AD, or within 25,000 flight 
cycles after the time when the overlapped skin was replaced, 
whichever occurs later, do the applicable inspection in paragraphs 
(g)(1) and (g)(2) of this AD for cracks in the overlapped skin 
panels in the fuselage skin lap joints in sections 41, 42, 44, and 
46; and do all applicable corrective actions before further flight. 
Repeat the applicable inspection thereafter at intervals not to 
exceed 3,000 flight cycles. Except as provided by paragraph (h) of 
this AD, do all actions in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-53A2501, dated 
March 24, 2005.
    (1) Do a mid-frequency eddy current inspection for cracks of the 
internal surface at the overlapped skin around the bottom row of 
fasteners in the lap joint.
    (2) Do a low-frequency eddy current inspection for cracks of the 
overlapped skin around the bottom row of fasteners at the section 41 
lap joints with four rows of fasteners.

Repair Instructions

    (h) If any crack is found during any inspection required by this 
AD, and Boeing Alert Service Bulletin 747-53A2501, dated March 24, 
2005, specifies to contact Boeing for appropriate action: Before 
further flight, repair the crack using a method approved in 
accordance with the procedures specified in paragraph (j) of this 
AD.

No Reporting Required

    (i) Although Boeing Alert Service Bulletin 747-53A2501, dated 
March 24, 2005, specifies to submit certain information to the 
manufacturer, this AD does not include that requirement.

Alternative Methods of Compliance (AMOCs)

    (j)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) An AMOC that provides an acceptable level of safety may be 
used for any repair required by this AD, if it is approved by an 
Authorized Representative for the Boeing Commercial Airplanes 
Delegation Option Authorization Organization who has been authorized 
by the Manager, Seattle ACO, to make those findings. For a repair 
method to be approved, the repair must meet the certification basis 
of the airplane, and the approval must specifically refer to this 
AD.
    (3) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.

Material Incorporated by Reference

    (k) You must use Boeing Alert Service Bulletin 747-53A2501, 
dated March 24, 2005, to perform the actions that are required by 
this AD, unless the AD specifies otherwise. The Director of the 
Federal Register approved the incorporation by reference of this 
document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 
Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for a copy of this service information. You 
may review copies at the Docket Management Facility, U.S. Department 
of Transportation, 400 Seventh Street SW., Room PL-401, Nassif 
Building, Washington, DC; on the Internet at http://dms.dot.gov; or 
at the National Archives and Records Administration (NARA). For 
information on the availability of this material at the NARA, call 
(202) 741-6030, or go to http://www.archives.gov/federal_register/code_of --federal --regulations/ibr--locations.html.

    Issued in Renton, Washington, on October 18, 2006.
Jeffrey E. Duven,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E6-17941 Filed 10-26-06; 8:45 am]
BILLING CODE 4910-13-P

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