[Federal Register: April 7, 2004 (Volume 69, Number 67)]
[Rules and Regulations]               
[Page 18250-18255]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr07ap04-3]                         

-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2003-NM-47-AD; Amendment 39-13566; AD 2004-07-22]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This amendment supersedes two existing airworthiness 
directives (ADs), applicable to all Boeing Model 747 series airplanes, 
that currently require that the FAA-approved maintenance inspection 
program be revised to include inspections that will give no less than 
the required damage tolerance rating for each structural significant 
item, and repair of cracked structure. Those ADs were prompted by a 
structural re-evaluation that identified additional structural elements 
where, if damage were to occur, supplemental inspections may be 
required for timely detection of fatigue cracking. This amendment 
requires additional and expanded inspections, and repair of cracked 
structure. This action also expands the applicability of the existing 
ADs to include additional airplanes. The actions specified by this AD 
are intended to ensure the continued structural integrity of the entire 
fleet of Model 747 series airplanes. This action is intended to address 
the identified unsafe condition.

DATES: Effective May 12, 2004.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of May 12, 2004.
    The incorporation by reference of certain other publications, as 
listed in the regulations, was approved previously by the Director of 
the Federal Register as of September 12, 1994 (59 FR 41233, August 11, 
1994) and August 10, 1994 (59 FR 37933, July 26, 1994).

ADDRESSES: 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, 
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: Tamara L. Anderson, Aerospace 
Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane 
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, 
SW., Renton, Washington 98055-4056; telephone (425) 917-6421; fax (425) 
917-6590.

SUPPLEMENTARY INFORMATION: A notice of proposed rulemaking (NPRM) to 
amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by 
superseding AD 94-15-12, amendment 39-8983 (59 FR 37933, July 26, 
1994), and AD 94-15-18, amendment 39-8989 (59 FR 41233, August 11, 
1994), which are applicable to certain Boeing Model 747 series 
airplanes, was published in the Federal Register on March 12, 2003 (68 
FR 11764). The NPRM proposed to continue to require that the FAA-
approved maintenance inspection program be revised to include 
inspections that will give no less than the required damage tolerance 
rating (DTR) for each structural significant item, and repair of 
cracked structure. The NPRM also proposed to require additional and 
expanded inspections, and repair of cracked structure. Additionally, 
the NPRM also proposed to expand the applicability of the existing ADs 
to include additional airplanes.

Definitions

    For the purposes of the discussions following in the ``Comments'' 
section of this AD, references to Boeing Document No. D6-35022, 
``Supplemental Structural Inspection Document,'' (SSID) for Model 747 
Airplanes, Revision G, dated December 2000, are referred to as 
``Revision G.''

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Requests To Allow Training Flights Equivalent

    Two commenters request that two training flights be considered 
equivalent to one revenue flight for all Structural Significant Items 
(SSIs), except SSIs F-46, F-49, F-50, F-51, W-3, S-1, S-2, and E-1 
through E-10. One of the commenters, the manufacturer, states that 
analyses show that for all SSIs, except for the above excluded SSIs, 
fatigue damage accumulated during a touch-and-go training flight 
conducted at less than 2.0 pounds per square inch (psi) internal cabin 
pressure is significantly less than half of the fatigue damage 
accumulated on a typical revenue flight.
    The FAA does not concur with the commenters' request. In this case, 
we do not consider it appropriate to include various provisions in an 
AD applicable to a unique use of an affected airplane. We have 
determined that for clarity of the final rule, such a request is best 
evaluated through submitting a request for alternative methods of 
compliance as provided for in paragraph (h)(1) of this AD.

Request To Extend the Repetitive Intervals

    One commenter, an operator, notes that paragraph (c) of the NPRM 
does not allow the provisions to increase task repetitive intervals by 
10%, as specified in paragraph 5.1.8 of Revision G. The commenter 
requests that such provisions be allowed to accommodate unanticipated 
scheduling requirements similar to the provisions allowed in the 
Corrosion Prevention and Control Program (CPCP) required by AD 90-25-
05, amendment 39-6790, (55 FR 49268, November 27, 1990).
    We do not agree that the repetitive inspection interval may be 
increased up to 10% without further evaluation. Any unsubstantiated 
increases in the task repetitive intervals may not maintain the level 
of safety this AD requires. The task repetitive intervals in Revision G 
are based on the assumption that the entire Boeing Model 747 fleet is 
inspected at a minimum with the required DTR prescribed in the 
document. Therefore, any unsubstantiated increases in the task 
repetitive intervals will lower the

[[Page 18251]]

corresponding DTR to below the minimum required, which may invalidate 
the methodology employed in the inspection program. However, we do 
agree that, on a case-by-case basis, the repetitive inspection 
interval, which may include interim instructions, may be extended to 
accommodate unanticipated scheduling requirements. We will consider 
requests for adjustment of the compliance time that maintains an 
acceptable level of safety per paragraph (h)(1) of this AD.

Requests To Revise the Cost Impact

    One commenter requests that a more extensive cost breakdown be 
provided. The commenter states that the cost of complete repetition of 
the whole SSID program for every D-Check is not included in the cost 
estimates of the NPRM. The commenter concludes, therefore, that it will 
require more than three times the number of work hours specified in the 
NPRM to perform the SSID program completely. A second commenter states 
that, based on its experience, it takes approximately 3,500 work hours 
per airplane to accomplish the initial inspection of all SSIs during a 
D-Check and 6,600 work hours per airplane during a C-Check. The second 
commenter also points out that it would require additional ground time 
to accomplish the inspections to ensure the availability of non-
destructive testing (NDT) inspectors and because of the maintenance 
limitations during the x-ray inspections. The second commenter also 
notes that further costs would be incurred because the additional 
ground time would reduce airplane utilization.
    We acknowledge that the cost estimate of work hours specified in 
the NPRM may be too low. Based on the commenters' information and 
experience and the fact that approximately 25% of the airplanes will be 
able to accomplish the initial inspection during a D-Check, we agree to 
increase the estimated work hours to accomplish the inspections from 
1,275 to 5,825 work hours. We point out, however, that the compliance 
time specified in this AD should allow ample time for the inspections 
to be accomplished at the same time as scheduled inspections and 
maintenance for the majority of affected operators, which will minimize 
the costs associated with special airplane scheduling. We provide the 
cost estimate of a single inspection cycle because there is no way to 
accurately project how many repetitive inspections would be necessary 
for all affected airplanes. Clearly, based on the ``life'' of each 
affected airplane, the number of required repetitive inspections would 
vary.
    We recognize that this AD will take many work hours to accomplish, 
and we acknowledge that maintaining airplanes in an airworthy condition 
is vital, but sometimes expensive. ADs require specific actions to 
address specific unsafe conditions and consequently may appear to 
impose costs that would not otherwise be borne by operators. However, 
because operators have a general obligation to maintain their airplanes 
in an airworthy condition, this appearance is deceptive. Attributing 
those costs solely to this AD is unrealistic because, in the interest 
of maintaining safe airplanes, prudent operators would accomplish these 
actions even if they were not required by the AD. We cannot provide a 
further break-down of costs, since the commenter did not provide such 
information, and we have not received any additional cost information 
from any other source.

Request To Revise Paragraph (e) of the NPRM

    One commenter, the manufacturer, requests that we revise paragraph 
(e) of the NPRM to provide authorization for Boeing Designated 
Engineering Representatives (DERs) to approve repair methods. The 
commenter suggests the following rewrite:
    ``(e) Damage found during any inspection required by this AD shall 
be repaired prior to further flight per a method approved by the 
Manager, Seattle Aircraft Certification Office (ACO), FAA; or per data 
meeting the type certification basis of the airplane approved by a 
Boeing Company DER who has been authorized by the Manager, Seattle ACO, 
to make such findings. For a repair method to be approved, the approval 
must specifically reference this AD.''
    We acknowledge that authorization to approve repairs may be 
delegated to certain Boeing DERs. However, we do not agree to replace 
the wording in paragraph (e ) of this AD that specifies repairing the 
structure per an FAA-approved method. Repairs approved by Boeing DERs 
with an FAA Form 8110-3 are, by definition, ``FAA-approved.'' This AD 
also allows use of other FAA-approved repairs, including repairs 
described in the Boeing Structural Repair Manual and repairs approved 
by other qualified DERs. Therefore, no change is necessary to the AD to 
allow approval by an authorized Boeing Company Designated Engineering 
Representative.

Request To Clarify Requirements of Section 6.0 of Revision G

    One commenter requests that the NPRM be clarified to state that 
Section 6.0, ``SSI Discrepancy Reporting'' is also a requirement. The 
commenter also requests that we include the section number in paragraph 
(c) of the NPRM that is being referred to, because paragraph 5.3 of 
Revision G does not refer to ``Damage Tolerant Rating (DTR) System 
Application.'' Additionally, the commenter requests that the sections 
be stated in sequential order as they appear in Revision G. The 
commenter believes that Section 6.0 should be clearly stated in the 
requirements, since many of the affected airplanes are not of U.S. 
registry and would not be required to provide mechanical reliability 
reports under CFR part 121.703.
    We agree that clarification is necessary and have revised paragraph 
(c) of the AD to specify that revision of the maintenance or inspection 
program shall include and shall be implemented per the procedures in 
Section 5.0, ``Damage Tolerance Rating (DTR) System Application,'' and 
Section 6.0, ``SSI Discrepancy Reporting'' of Revision G, excluding 
paragraphs 5.1.2; 5.1.6, item 5; 5.1.8; 5.2; 5.2.1; 5.2.2; 5.2.3; and 
5.2.4.
    However, since the ``DTR System Application'' is the subject of all 
of Section 5.0, we do not consider it to be an issue with labeling and 
sequencing of the paragraphs of Section 5.0 of Revision G. No change to 
the AD is necessary in this regard.

Request To Clarify Paragraph (c) of the NPRM

    One commenter requests clarification on whether phased inspections 
are permitted under the requirements of paragraph (c) of the NPRM. The 
commenter acknowledges that the NPRM does exclude paragraph 5.2 of 
Revision G; however, paragraph 5.1.11 is included in the NPRM and that 
paragraph refers back to paragraph 5.2 of Revision G. The commenter 
notes that paragraph 5.1.11 states, in part, ``* * * inspections shall 
be accomplished at frequency F but not necessarily on 100 percent of 
the operator's affected fleet.'' The commenter states that it believes 
that the goal is to move away from a sample-based approach to a 
threshold-based approach to be consistent with other Boeing airplane 
models.
    We agree that it is necessary to clarify that phased inspections 
are not permitted. We have added a new Note 4 to the AD clarifying 
that, even though paragraph 5.2 of Revision G is referenced in 
paragraph 5.1.11,

[[Page 18252]]

paragraph 5.2 is still excluded as a method of compliance with the 
requirements of this AD.

Requests To Revise the Initial Inspection Compliance Time

    Several commenters suggest using alternative compliance time 
schedules. Two commenters state that the compliance time specified in 
the NPRM does not reflect the existing candidate fleet program for 
damage tolerance based inspections that has been in place for 19 years. 
One commenter believes that the proposed actions specified in the NPRM 
are an exploratory effort to detect unknown cracking. Further, the 
commenter states that the thresholds and intervals specified in the 
Supplemental Structural Inspection Program (SSIP) are purely analytical 
and do not reflect the fact that the candidate fleet inspection program 
has been providing real data feedback. Another commenter expressed 
agreement with these comments. Several commenters believe that the 
compliance time for the transition from the current candidate fleet 
program to the threshold based program specified in the NPRM can be 
phased in over a longer period of time. One of the commenters considers 
the compliance times in the NPRM to be too stringent. Another commenter 
suggests that since it has accomplished the SSID inspections on 22 
airplanes and has found only known defects, the compliance time can be 
extended longer than 1,000 flight cycles. Yet another commenter states 
that the grace period would impose significant costs and scheduling 
difficulties on operators because many of the specified inspections are 
scheduled similar to D-Check inspections.
    We do not agree with the commenters' requests to extend the 
compliance times. The SSIP is based on a certain probability that 
cracking will be found on the inspected fleet before the cracking 
initiates in other airplanes that have not been inspected. High-cycle 
airplanes in the fleet are more likely to experience initial fatigue 
damage. The current candidate fleet approach has resulted in a 
statistically invalid number of airplanes being inspected; therefore, 
we do not concur that an extended phase-in period for initial 
inspection of high-cycle airplanes provides an acceptable level of 
safety. As mentioned in the preamble of the NPRM, the threshold 
required by the existing AD for the candidate fleet is much lower, 
12,000 total flight cycles for Model 747SR and 10,000 total flight 
cycles for Model 747-100 and -200 series airplanes, than that specified 
in this AD. Additionally, the commenters do not provide any statistical 
information on how the participation level of the current SSID 
candidate program provides an acceptable level of safety. Therefore, no 
change to the final rule is necessary regarding the specified 
compliance times.

Requests To Inspect a Sample of the Fleet

    Several commenters request that a percentage of the fleet, as 
specified in the DTR form, be inspected at a maximum interval specified 
by the D-Check maintenance schedule. The commenters state that 
paragraph 5.1.11 of Revision G establishes a D-Check maximum frequency 
be applied to a percentage of an operator's fleet, depending upon the 
DTR. Removing the percent sampling while maintaining the D-Check 
maximum frequency, results in unnecessarily forcing repeat inspections 
at shorter intervals than that indicated by the DTR form.
    We do not agree. For reasons discussed in the NPRM and earlier in 
this preamble, we have considered the candidate fleet approach and have 
moved to a threshold approach. In doing so, we require inspections of 
all SSIs when the threshold has been reached. Only inspecting a sample 
of SSIs where the damage tolerance rating (DTR) provides an interval 
greater than a D-Check would not provide an acceptable level of safety. 
If operators wish to request an adjustment to the compliance time, they 
may do so according to the provisions specified in paragraph (h)(1) of 
this AD. Such requests should include a new proposed inspection 
interval and must include data to substantiate that such an adjustment 
would provide an acceptable level of safety. No change is necessary to 
the final rule in this regard.

Requests To Remove the D-Check Cap

    Several commenters request that we remove the proposed requirement 
to perform all applicable SSID tasks on every airplane at the maximum 
interval of a D-Check or equivalent time, as specified in paragraph 
5.1.11 of Revision G. One commenter states that such a requirement 
creates an undue burden for the operator because more inspections would 
have to be performed than if performed under the technical requirements 
of the SSID program where sampling is permitted. Another commenter 
asserts that such a requirement does not conform to other analytical 
methods to define a necessary inspection interval. The commenter 
asserts that the D-Check capping requirement would lead to a 
significant burden for operators that have a shorter interval at the 
fourth, fifth, and subsequent D-Checks. One commenter poses the 
following condition as an example: The 5th D-Check is equivalent to 
approximately 2,500 flight cycles. The SSID estimates that a D-Check is 
approximately 6,000 flight cycles. Therefore, it is the commenter's 
understanding that the inspection interval could be increased for some 
SSID items to higher intervals than the intervals of the D-Check, 
without decreasing the level of safety below the required DTR. The 
commenter also states that, by increasing the inspection interval and 
removing the sampling concept at the same time, the entire SSID program 
will be easier to incorporate, understand, and track. Further, the 
commenter asserts that cost reduction can be achieved by omitting 
certain inspections that are not necessary at each D-Check. Another 
operator states that the proposed requirement will require operators to 
repeat some inspections unnecessarily.
    We do not agree with removing the D-Check cap from the AD. The D-
Check cap will provide confidence in the existing analytical methods by 
providing more than one inspection on SSIs with long repetitive 
intervals. One-time inspections at a threshold do not give the 
confidence that cracking will not develop on aging airplanes that have 
accumulated flight cycles beyond the design service objective (DSO). 
However, for operators that have shorter intervals for their later D-
Checks, we will consider requests for alternative methods of compliance 
(AMOCs) in accordance with paragraph (h)(1) of this AD.

Request To Redefine SSI

    One commenter, the manufacturer, requests that the definition of 
SSI as specified in the NPRM be redefined from ``principal structural 
element,'' to a ``principal structural element as listed in Revision G 
of the SSID D6-35022.''
    We do not agree. Revision G defines an SSI as a principal 
structural element (PSE). Further, Revision G of the SSID does not say 
that an SSI is a ``principal structural element as listed in Revision 
G.'' No change to the final rule is necessary in this regard.

Request To Redefine PSE

    One commenter, an operator, requests that the definition of a PSE 
in Note 3 of the NPRM be revised to read: ``Any detail, element, or 
assembly, which contributes significantly to the carrying of flight, 
ground, pressurization or control loads and whose failure could affect 
the structural integrity necessary for the safety of the aircraft.'' 
The

[[Page 18253]]

commenter points out that there are many published definitions of PSE, 
and that confusion may occur as a result. The commenter requests that 
we provide one consistent definition and considers that the definition 
used in the Maintenance Steering Group 3 (MSG 3), Revision 2b, to be 
the industry standard definition. The commenter also notes that Boeing 
Model 747 series airplanes have recently been subject to a MSG 3, 
Revision 2b program review.
    We do not agree with the commenter's request. We consider that the 
definition provided in Advisory Circular 25.571-1C, dated April 29, 
1998, to be the standard, and that is the definition provided in this 
AD.

Request To Revise Compliance Times of Parts Replaced With New 
Structures

    One commenter, an operator, requests that we add paragraph 5.1.17 
of Revision G to the paragraphs that are excluded from the requirements 
of paragraph (c) of the NPRM, or that Boeing change paragraph 5.1.17 of 
Revision G to specify 20,000 flight cycles or 10,000 flight cycles from 
part replacement, whichever is later. The commenter notes that 
paragraph 5.1.17 of Revision G refers to the inspection requirements 
for the portion of an SSI that has been replaced with new structure, 
and that the inspection may be deferred until a new threshold of 10,000 
flight cycles are accumulated. The commenter states that, in some 
cases, the replaced structure would have to be inspected prior to the 
threshold specified in the NPRM. The commenter points out that the 
10,000 flight cycle threshold is consistent with the requirements of AD 
94-15-12, since the inspections are required to begin upon the 
accumulation of 10,000 total flight cycles for airplanes in the 
candidate fleet.
    We acknowledge the commenter's position and recognize that 
clarification is necessary. It is not our intent to have operators 
inspect replaced structure prior to the threshold of the AD. To clarify 
that intent, we have revised paragraph (d) of the AD by adding 
paragraph (d)(3) to the AD to specify that, for the portion of an SSI 
that has been replaced with new structure, the inspections can be 
deferred until the later of the times specified in paragraph (d)(3)(i) 
or (d)(3)(ii) of the AD, as applicable. We have added this 
clarification to paragraph (d) of the AD, since it also includes 
compliance times for wing structure and all other structures. 
Additionally, clarifying paragraph (d) of the AD will prevent time lost 
in issuance of the AD due to a delay in having Boeing revise and 
republish Revision G.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Changes to 14 CFR Part 39/Effect on the AD

    On July 10, 2002, the FAA issued a new version of 14 CFR part 39 
(67 FR 47997, July 22, 2002), which governs the FAA's airworthiness 
directives system. The regulation now includes material that relates to 
altered products, special flight permits, and alternative methods of 
compliance (AMOCs). Because we have now included this material in part 
39, only the office authorized to approve AMOCs is identified in each 
individual AD. However, for clarity and consistency in this final rule, 
we have retained the language of the NPRM regarding that material.

Change to Labor Rate Estimate

    We have reviewed the figures we have used over the past several 
years to calculate AD costs to operators. To account for various 
inflationary costs in the airline industry, we find it necessary to 
increase the labor rate used in these calculations from $60 per work 
hour to $65 per work hour. The cost impact information, below, reflects 
this increase in the specified hourly labor rate.

Cost Impact

    There are approximately 1,000 airplanes of the affected design in 
the worldwide fleet.
    The FAA estimates that 87 airplanes of U.S. registry are currently 
affected by the actions that are currently required by AD 94-15-12 and 
AD 94-15-18. We estimate that it takes approximately 1,000 work hours 
per airplane to accomplish, at an average labor rate of $65 per work 
hour to accomplish those actions. Based on these figures, the cost 
impact of the currently required actions on U.S. operators is estimated 
to be $5,655,000, or $65,000 per airplane, per inspection cycle.
    We estimate that 181 airplanes of U.S. registry are affected by 
this AD. The new actions that are required by this new AD will take 
approximately 5,825 work hours per airplane to accomplish, at an 
average labor rate of $65 per work hour. Based on these figures, the 
cost impact of the new requirements of this AD on U.S. operators is 
estimated to be $68,531,125, or $378,625 per airplane, per inspection 
cycle.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the requirements of this 
AD action, and that no operator would accomplish those actions in the 
future if this AD were not adopted.
    The number of work hours, as indicated above, is presented as if 
the accomplishment of the actions in this AD are to be conducted as 
``stand alone'' actions. However, in actual practice, these actions for 
the most part will be accomplished coincidentally or in combination 
with normally scheduled airplane inspections and other maintenance 
program tasks. Therefore, the actual number of necessary additional 
work hours will be minimal in many instances. Additionally, any costs 
associated with special airplane scheduling will be minimal.

Regulatory Impact

    The regulations adopted herein 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. Therefore, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    For the reasons discussed above, I certify that this action (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. A final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it 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.

Adoption of the Amendment

0
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:

[[Page 18254]]

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]

0
2. Section 39.13 is amended by removing amendments 39-8983 (59 FR 
37933, July 26, 1994) and 39-8989 (59 FR 41233, August 11, 1994), and 
by adding a new airworthiness directive (AD), amendment 39-13566, to 
read as follows:

2004-07-22 Boeing: Amendment 39-13566. Docket 2003-NM-47-AD. 
Supersedes AD 94-15-12, amendment 39-8983, and AD 94-15-18, 
amendment 39-8989.

    Applicability: All Model 747 series airplanes, certificated in 
any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
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 per paragraph (h)(1) 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 ensure the continued structural integrity of the entire fleet 
of Model 747 series airplanes, accomplish the following:

    Note 2: Where there are differences between this AD and the 
Supplemental Structural Inspection Document (SSID) specified in this 
AD, the AD prevails.

Inspection Program Required by AD 94-15-12

    (a) For Model 747-100SR series airplanes having line numbers 
346, 351, 420, 426, 427, and 601: Within 1 year after August 10, 
1994 (the effective date of AD 94-15-12, amendment 39-8983), 
incorporate a revision into the FAA-approved maintenance inspection 
program that provides no less than the required damage tolerance 
rating (DTR) for each structural significant item (SSI) listed in 
Boeing Document No. D6-35655, ``Supplemental Structural Inspection 
Document (SSID) for 747-100SR,'' dated April 2, 1986. The revision 
to the maintenance program must include and be implemented per the 
procedures specified in Sections 5.0 and 6.0 of the SSID D6-35655. 
Revision to the maintenance program shall be per the SSID D6-35655, 
dated April 2, 1986, until Revision G of the SSID D6-35022 is 
incorporated into the FAA-approved maintenance or inspection program 
per the requirements of paragraph (c) of this AD.

    Note 3: For the purposes of this AD, an SSI is defined as a 
principal structural element (PSE). A PSE is a structural element 
that contributes significantly to the carrying of flight, ground, or 
pressurization loads, and whose integrity is essential in 
maintaining the overall structural integrity of the airplane.

Inspection Program Required by AD 94-15-18

    (b) For airplanes listed in Boeing Document No. D6-35022, 
Volumes 1 and 2, ``Supplemental Structural Inspection Document 
(SSID) for Model 747 Airplanes,'' Revision E, dated June 17, 1993; 
and manufacturer's line numbers 42, 174, 221, 231, 234, 239, 242, 
and 254: Within 12 months after September 12, 1994 (the effective 
date of AD 94-15-18, amendment 39-8989), incorporate a revision into 
the FAA-approved maintenance inspection program that provides no 
less than the required DTR for each SSI listed in Boeing Document 
No. D6-35022, Volumes 1 and 2, ``Supplemental Structural Inspection 
Document (SSID) for Model 747 Airplanes,'' Revision E, dated June 
17, 1993. Revision F, dated May 1996, is acceptable for compliance 
with this paragraph. (The required DTR value for each SSI is listed 
in the document.) The revision to the maintenance program shall 
include Sections 5.0 and 6.0 of the SSID D6-35022 and shall be 
implemented per the procedures contained in those sections. Revision 
to the maintenance program shall be per Revision E or F of SSID D6-
35022, until Revision G of the SSID D6-35022 is incorporated into 
the FAA-approved maintenance or inspection program per the 
requirements of paragraph (c) of this AD.

New Inspection Program Requirements

    (c) For all Model 747 series airplanes: Prior to reaching either 
of the thresholds specified in paragraph (d)(1)(i) or (d)(2)(i) of 
this AD, or within 12 months after the effective date of this AD, 
whichever occurs later, incorporate a revision into the FAA-approved 
maintenance or inspection program that provides no less than the 
required DTR for each SSI listed in Boeing Document No. D6-35022, 
``Supplemental Structural Inspection Document,'' Revision G, dated 
December 2000 (hereinafter referred to as ``Revision G''). (The 
required DTR value for each SSI is listed in Revision G.) The 
revision to the maintenance or inspection program shall include and 
shall be implemented per the procedures in Section 5.0, ``DTR System 
Application'' and Section 6.0, ``SSI Discrepancy Reporting'' of 
Revision G, excluding paragraphs 5.1.2; 5.1.6, item 5; 5.1.8; 5.2; 
5.2.1; 5.2.2; 5.2.3; and 5.2.4 of Revision G. Under the provisions 
of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.), the 
Office of Management and Budget (OMB) has approved the information 
collection requirements (Section 6.0, ``SSI Discrepancy Reporting'') 
contained in this AD and has assigned OMB Control Number 2120-0056. 
Upon incorporation of Revision G required by this paragraph, the 
revision required by either paragraph (a) or (b) of this AD, as 
applicable, may be removed.

    Note 4: Operators should note that, although paragraph 5.2 is 
referenced in paragraph 5.1.11 of Revision G, paragraph 5.2 is 
excluded as a method of compliance with the requirements of this AD.

Initial Inspection

    (a) For all Model 747 series airplanes: Perform an inspection to 
detect cracks of all structure identified in Revision G of SSID D6-
35022 at the time specified in paragraph (d)(1), (d)(2), or (d)(3) 
of this AD, as applicable.
    (1) For wing structure: At the times specified in paragraph 
(d)(1)(i) or (d)(1)(ii) of this AD, whichever occurs later.
    (i) Prior to the accumulation of 20,000 total flight cycles or 
100,000 total flight hours, whichever comes first. Or,
    (ii) Within 1,000 flight cycles measured from 12 months after 
the effective date of this AD.
    (2) For all other structure: At the times specified in paragraph 
(d)(2)(i) or (d)(2)(ii) of this AD, whichever occurs later.
    (i) Prior to the accumulation of 20,000 total flight cycles, or
    (ii) Within 1,000 flight cycles measured from 12 months after 
the effective date of this AD.
    (3) For any portion of an SSI that has been replaced with new 
structure: At the later of the times specified in paragraph 
(d)(3)(i) or (d)(3)(ii) of this AD.
    (i) At the times specified in either paragraph (d)(1) or (d)(2) 
of this AD, as applicable, or
    (ii) Within 10,000 flight cycles after the replacement of the 
part with a new part.

    Note 5: Notwithstanding the provisions of paragraphs 5.1.2, 
5.1.6, item 5, 5.2, 5.2.1, 5.2.2, 5.2.3, and 5.2.4 of the General 
Instructions of Revision G, which would permit operators to perform 
fleet and rotational sampling inspections to perform inspections on 
less than whole airplane fleet sizes and to perform inspections on 
substitute airplanes, this AD requires that all airplanes that 
exceed the threshold be inspected per Revision G. Although paragraph 
5.1.8 of Revision G allows provisions for touch-and-go training 
flights, fleet averaging, and 10% escalations of flight cycles to 
achieve the required DTR, this AD does not allow for those 
provisions.


    Note 6: Once the initial inspection has been performed, 
operators are required to perform repetitive inspections at the 
intervals specified in Revision G in order to remain in compliance 
with their maintenance or inspection programs, as revised per 
paragraph (c) of this AD.

Repair

    (e) Cracked structure found during any inspection required by 
this AD shall be repaired, prior to further flight, in accordance 
with an FAA-approved method.

Inspection Program for Transferred Airplanes

    (f) Before any airplane that is subject to this AD and that has 
exceeded the applicable compliance times specified in paragraph (d) 
of this AD can be added to an air carrier's operations 
specifications, a program for the accomplishment of the inspections 
required by this AD must be established per paragraph (f)(1) or 
(f)(2) of this AD, as applicable.
    (1) For airplanes that have been inspected per this AD, the 
inspection of each SSI must

[[Page 18255]]

be accomplished by the new operator per the previous operator's 
schedule and inspection method, or the new operator's schedule and 
inspection method, at whichever time would result in the earlier 
accomplishment for that SSI inspection. The compliance time for 
accomplishment of this inspection must be measured from the last 
inspection accomplished by the previous operator. After each 
inspection has been performed once, each subsequent inspection must 
be performed per the new operator's schedule and inspection method.
    (2) For airplanes that have not been inspected per this AD, the 
inspection of each SSI required by this AD must be accomplished 
either prior to adding the airplane to the air carrier's operations 
specification, or per a schedule and an inspection method approved 
by the Manager, Seattle ACO. After each inspection has been 
performed once, each subsequent inspection must be performed per the 
new operator's schedule.

Alternative Methods of Compliance

    (g)(1) 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.
    (2) Alternative methods of compliance, approved previously per 
AD 94-15-12, amendment 39-8983, are approved as alternative methods 
of compliance with paragraphs (a) and (e) of this AD.
    (3) Alternative methods of compliance, approved previously per 
AD 94-15-18, amendment 39-8989, are approved as alternative methods 
of compliance with paragraphs (b) and (e) of this AD.
    (4) Alternative methods of compliance, approved previously per 
AD 94-15-18 and AD 94-15-12 that provide alternative inspections are 
approved as alternative methods of compliance for the inspections of 
that area only in this AD.

    Note 7: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (h) Special flight permits may be issued per 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.

Incorporation by Reference

    (i) Unless otherwise specified in this AD, the actions shall be 
done in accordance with Boeing Document No. D6-35655, ``Supplemental 
Structural Inspection Document for 747-100SR,'' dated April 2, 1986; 
Boeing Document No. D6-35022, Volumes 1 and 2, ``Supplemental 
Structural Inspection Document (SSID) for Model 747 Airplanes,'' 
Revision E, dated June 17, 1993; and Boeing Document No. D6-35022, 
``Supplemental Structural Inspection Document (SSID) for Model 747 
Airplanes,'' Revision G, dated December 2000; as applicable.
    (1) The incorporation by reference of Boeing Document D6-35022, 
``Supplemental Structural Inspection Document (SSID) for Model 747 
Airplanes,'' Revision G, dated December 2000, is approved by the 
Director of the Federal Register in accordance with 5 U.S.C. 552(a) 
and 1 CFR part 51. This document contains the following effective 
pages:


------------------------------------------------------------------------
        Revision level page number                  Shown on page
------------------------------------------------------------------------
List of Effective Pages...................  G
Pages A.1 thru A.10.......................  ............................
------------------------------------------------------------------------

(The issue date of Revision G is indicated only on the title page; 
no other page of the document is dated.)
    (2) The incorporation by reference of Boeing Document No. D6-
35022, Volumes 1 and 2, ``Supplemental Structural Inspection 
Document (SSID) for Model 747 Airplanes,'' Revision E, dated June 
17, 1993, was approved previously by the Director of the Federal 
Register as of September 12, 1994 (59 FR 41233, August 11, 1994).
    (3) The incorporation by reference of Boeing Document No. D6-
35655, ``Supplemental Structural Inspection Document for 747-
100SR,'' dated April 2, 1986, was approved previously by the 
Director of the Federal Register as of August 10, 1994 (59 FR 37933, 
July 26, 1994).
    (4) Copies may be obtained from Boeing Commercial Airplanes, 
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.

Effective Date

    (j) This amendment becomes effective on May 12, 2004.

    Issued in Renton, Washington, on March 24, 2004.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-7449 Filed 4-6-04; 8:45 am]

BILLING CODE 4910-13-P