04-7449. 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 [phone]; fax [phone].

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 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, 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 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

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.

§ 39.13

[Amended]

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 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.