Airworthiness directives: Boeing,
[Federal Register: January 11, 1999 (Volume 64, Number 6)]
[Proposed Rules]
[Page 1549-1552]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr11ja99-18]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-11-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 737 series airplanes. This proposal would require inspections of certain bonded skin panel assemblies to detect delamination of the skin doublers (tear straps) from the skin panels; and follow-on corrective actions, if necessary. This proposal is prompted by reports indicating that certain skin doublers were delaminated from their skin panels due to improper processing of certain skin panels. The actions specified by the proposed AD are intended to detect and correct such delamination, which could result in fatigue cracks in the skin doublers and skin panels, and consequent rapid decompression of the airplane.
DATES: Comments must be received by February 25, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 98-NM-11-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays.
The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: Rick Kawaguchi, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-1153; fax (425) 227-1181.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received.
Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filedin the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 98-NM-11-AD.'' The postcard will be date stamped and returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 98-NM-11-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.
Discussion
The FAA has received reports indicating that skin doublers (tear straps) were found delaminated from their skin panels on certain Boeing Model 737 series airplanes. These airplanes had accumulated as few as 10,200 total flight cycles. The subject skin doublers and skin panels are installed above stringer S-26 from body station (BS) 259 to BS 1016 on both sides of the airplane. The cause of such delamination in all incidents has been attributed to improper processing during the phosphoric anodize application of the skin panels. This condition, if not detected and corrected, could result in fatigue cracks in the skin doublers and skin panels, and consequent rapid decompression of the airplane.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Service Bulletin 737-53- 1179, dated June 22, 1995, as revised by Notice of Status Change (NSC) 737-53-1179 NSC 1, dated August 17, 1995, which describes procedures for performing a one-time internal inspection (terminating inspection) of the bonded skin panel assemblies to detect delamination of the skin doublers from the skin panels; and follow-on corrective actions, if necessary.
The above inspection includes an internal close visual inspection (Figure 3 of the service bulletin), an internal close visual inspection while trying to separate the skin doublers from the skin panels (Figure 3 of the service bulletin), and an ultrasonic inspection (Figure 4 of the service bulletin). The service bulletin recommends that operators perform these inspections on bonded skin panel assemblies, which are composed of skin doublers (tear straps) that are bonded to skin panels located above stringer S-26 from BS 259 to BS 1016 on both sides of the airplane. In lieu of accomplishing the internal close visual inspections of bonded skin panel assemblies (Figure 3 of the service bulletin), the service bulletin describes procedures for performing an internal or external ultrasonic inspection to detect delamination.
The follow-on corrective actions include internal close visual, low frequency eddy current, and high frequency eddy current inspections; and repair, if necessary. The service bulletin recommends that operators perform such inspections to detect corrosion and cracks that may have resulted from any skin doubler delaminating from its skin panel.
The service bulletin also describes procedures for performing repetitive external visual inspections (interim inspection) to detect cracks in skin panels; and repair, if necessary. This service bulletin recommends that operators perform the external visual inspections until accomplishment of the one-time internal inspection described previously.
Boeing has also issued NSC 737-53-1179 NSC 1, dated August 17, 1995. This NSC contains no new technical information but corrects two typographical errors and adds a general note.
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Accomplishment of the actions specified in the service bulletin and the NSC are intended to adequately address the identified unsafe condition.
Explanation of Requirements of Proposed Rule
Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require accomplishment of the actions specified in the service bulletin and the NSC described previously, except as discussed below.
Differences Between Proposed Rule and Service Bulletin
Operators should note that, although the service bulletin recommends accomplishing a one-time internal inspection (terminating inspection), as described previously, prior to the accumulation of 40,000 total flight cycles or within 20,000 flight cycles after the release of the service bulletin, whichever occurs later, the FAA has determined that such a compliance time would not address the identified unsafe condition in a timely manner. As described previously, operators have found doublers delaminated from skin panels on certain Boeing Model 737 series airplanes that had accumulated as few as 10,200 total flight cycles. The FAA has determined that to have a high probability of detecting cracking before it reaches a critical length, the inspections described previously must be accomplished prior to the accumulation of 20,000 total flight cycles. In developing an appropriate compliance time for this proposed AD, the FAA considered not only the manufacturer's recommendation, but the degree of urgency associated with addressing the subject unsafe condition, the average utilization of the affected fleet, and the time necessary to perform the one-time inspection (136 work hours). In light of all of these factors, the FAA finds that a proposed compliance time of 20,000 total flight cycles, or 4,500 flight cycles or 18 months after the effective date of this AD, whichever occurs later, for initiating the proposed actions to be warranted. The FAA has determined that the proposed compliance time represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety.
For those operators that elect to perform repetitive external visual inspections (i.e., the interim inspection), the service bulletin recommends accomplishing the one-time inspections within 20,000 flight cycles (after the release of the service bulletin). For the same reasons stated above, the FAA has determined that such a compliance time would not address the identified unsafe condition in a timely manner. Therefore, the FAA finds that a proposed compliance time of 15,000 flight cycles or 60 months after the effective date of this proposed AD, whichever occurs first, for initiating the proposed actions [i.e., the one-time (terminating) inspection] to be warranted. The FAA has determined that the proposed compliance time represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety.
Operators also should note that the service bulletin does not specify that the one-time inspection be accomplished after airplanes accumulate 4,500 flight cycles on certain bonded skin panel assemblies. Service history indicates that the bonded skin panel assemblies on the affected airplanes need to be subjected to a minimal amount of loading and environment before disbonding becomes detectable. For this reason, the FAA finds a 4,500 flight cycle interval to be an appropriate interval of time for ensuring that the operators are able to detect delamination of the skin doublers from the skin panels. Therefore, the proposed AD requires that the one-time inspection be performed after the affected airplanes accumulate 4,500 total flight cycles or after the affected airplanes accumulate 4,500 flight cycles after the date of installation of any new or serviceable bonded skin panel assembly.
Although the effectivity listing of the service bulletin includes airplanes having line numbers 611 through 2725 inclusive, the applicability of this proposed AD includes airplanes having line numbers 1 through 3072 inclusive. The service bulletin does not specify that operators perform an inspection of any new or serviceable bonded skin panel assembly that was installed prior to October 1, 1997, on any airplane having line numbers 1 through 3072 inclusive. The FAA has determined that the identified unsafe condition could exist or develop on those airplanes having such replacement bonded skin panel assemblies. In light of this, the FAA finds that it is necessary that the applicability of this proposed AD include Boeing Model 737 series airplanes on which the bonded skin panel assemblies were replaced with any new or serviceable bonded skin panel assemblies prior to October 1, 1997. Therefore, the applicability of this proposed AD includes line numbers 1 through 3072 inclusive.
Operators should note that, although the service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, this proposal would require the repair of those conditions to be accomplished in accordance with a method approved by the FAA; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle Aircraft Certification Office, to make such findings.
Additionally, the service bulletin specifies that certain actions may be accomplished in accordance with ``an equivalent'' procedure. However, this proposed AD requires that those actions be accomplished in accordance with the procedures specified in Part 6, Subject 51-00- 00, Figure 4, of the 737 Nondestructive Test Manual. An ``equivalent'' procedure may be used only if approved as an alternative method of compliance in accordance with the provisions of paragraph (j) of the proposed AD.
Cost Impact
There are approximately 2,083 airplanes of the affected design in the worldwide fleet. The FAA estimates that 863 airplanes of U.S. registry would be affected by this proposed AD.
It would take approximately 136 work hours per airplane to accomplish the proposed terminating inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the terminating inspection proposed by this AD on U.S. operators is estimated to be $7,042,080, or $8,160 per airplane.
It would take approximately 32 work hours per airplane to accomplish the proposed interim inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the interim inspection proposed by this AD on U.S. operators is estimated to be $1,656,960, or $1,920 per airplane, per inspection cycle.
The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.
Regulatory Impact
The regulations proposed herein would not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the
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various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed regulation (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ``ADDRESSES.''
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39--AIRWORTHINESS DIRECTIVES
-
The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
-
Section 39.13 is amended by adding the following new airworthiness directive:
Boeing: Docket 98-NM-11-AD.
Applicability: Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, line numbers 1 through 3072 inclusive, certified 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 in accordance with paragraph (j) 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.
Note 2: Where there are differences between this AD and the referenced service bulletin, the AD prevails.
Compliance: Required as indicated, unless accomplished previously.
To detect and correct delamination of the skin doublers (tear straps) from the skin panels, which could result in fatigue cracks in the skin doublers and the skin panels, and consequent rapid decompression of the airplane, accomplish the following:
(a) For airplanes having line numbers 611 through 2725 inclusive, on which any bonded skin panel assembly has not been replaced with any new or serviceable bonded skin panel assembly: Accomplish the actions required either by paragraph (a)(1) of this AD, or by both paragraphs (a)(2) and (a)(3) of this AD, in accordance with Boeing Service Bulletin 737-53-1179, dated June 22, 1995, as revised by Notice of Status Change 737-53-1179 NSC 1, dated August 17, 1995.
Note 3: For the purposes of this AD, bonded skin panel assemblies consist of skin doublers (tear straps) that are bonded to skin panels located above stringer S-26 from body station (BS) 259 to BS 1016 on both sides of the airplane.
Note 4: If the skin panel is solid with no doublers (tear straps) bonded to it, the inspections required by this AD are not necessary for that skin panel.
(1) Prior to the accumulation of 20,000 total flight cycles, but after the accumulation of 4,500 total flight cycles; or within 18 months or 4,500 flight cycles after the effective date of this AD; whichever occurs latest; perform a one-time internal inspection (terminating inspection) of the bonded skin panel assemblies to detect delamination of the skin doublers from the skin panels, in accordance with Figures 3 and 4 of the service bulletin. In lieu of accomplishing the inspections specified in Figure 3 of the service bulletin, operators can perform an internal or external ultrasonic inspection in accordance with Note 1. of paragraph A. of the ``Terminating Inspection'' Section of the Accomplishment Instructions of the service bulletin.
Note 5: For the purposes of this AD, the one-time internal inspection includes an internal close visual inspection (Figure 3), an internal close visual inspection while trying to separate the skin doublers from the skin panels (Figure 3), and an ultrasonic inspection (Figure 4).
(2) Within 4,500 flight cycles or 18 months after the effective date of this AD, whichever occurs later, perform an external visual inspection of the bonded skin panel assemblies to detect cracks in the skin panels, in accordance with paragraph A. of the ``Interim Inspection'' Section of the Accomplishment Instructions of the service bulletin. Repeat the external visual inspection thereafter at intervals not to exceed 4,500 flight cycles, until accomplishment of the requirements specified in paragraph (a)(3) of this AD.
(3) Within 15,000 flight cycles or 60 months after the effective date of this AD, whichever occurs first, accomplish the one-time internal inspection required by paragraph (a)(1) of this AD. Accomplishment of this action constitutes terminating action for the repetitive inspections required by paragraph (a)(2) of this AD.
(b) For airplanes having line numbers 611 through 2725 inclusive, on which any bonded skin panel assembly was replaced with any new or serviceable bonded skin panel assembly prior to October 1, 1997: Accomplish the actions required by both paragraphs (b)(1) and (b)(2) of this AD, or by both paragraphs (b)(3) and (b)(4) of this AD, in accordance with Boeing Service Bulletin 737-53-1179, dated June 22, 1995, as revised by Notice of Status Change 737-53- 1179 NSC 1, dated August 17, 1995.
(1) Prior to the accumulation of 20,000 total flight cycles, but after the accumulation of 4,500 total flight cycles; or within 4,500 flight cycles or 18 months after the effective date of this AD; whichever occurs latest; perform a one-time internal inspection (terminating inspection) of the bonded skin panel assemblies that have not been replaced to detect delamination of the skin doublers from the skin panels, in accordance with Figures 3 and 4 of the service bulletin. In lieu of accomplishing the inspections specified in Figure 3 of the service bulletin, operators can perform an internal or external ultrasonic inspection in accordance with Note 1. of paragraph A. of the ``Terminating Inspection'' Section of the Accomplishment Instructions of the service bulletin.
(2) Prior to the accumulation of 20,000 flight cycles after the date of replacement of the skin panel assembly, but not prior to the accumulation of 4,500 flight cycles after the date of such replacement; or within 4,500 flight cycles or 18 months after the effective date of this AD; whichever occurs latest; perform a one- time internal inspection (terminating inspection) of the bonded skin panel assemblies that have been replaced to detect delamination of the skin doublers from the skin panels, in accordance with Figures 3 and 4 of the service bulletin. In lieu of accomplishing the inspections identified in Figure 3 of the service bulletin, operators can perform an internal or external ultrasonic inspection in accordance with Note 1. of paragraph A. of the ``Terminating Inspection'' Section of the Accomplishment Instructions of the service bulletin.
(3) Within 4,500 flight cycles or 18 months after the effective date of this AD, whichever occurs later, perform an external visual inspection of the skin panel assemblies that have and have not been replaced to detect cracks in the skin panels, in accordance with paragraph A. of the ``Interim Inspection'' Section of the Accomplishment Instructions of the service bulletin. Repeat the external visual inspection thereafter at intervals not to exceed 4,500 flight cycles, until accomplishment of the requirements specified in paragraph (b)(4) of this AD.
(4) Within 15,000 flight cycles or 60 months after the effective date of this AD, whichever occurs first, accomplish the one-time internal inspection required by both paragraphs (b)(1) and (b)(2) of this AD. Accomplishment of this action constitutes terminating action for the repetitive inspections required by paragraph (b)(3) of this AD.
(c) For airplanes having line numbers 611 through 2725 inclusive, on which any
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bonded skin panel assembly was replaced with any new or serviceable bonded skin panel assembly after September 30, 1997: Accomplish the actions required either by paragraph (c)(1) or by both paragraphs (c)(2) and (c)(3) of this AD, in accordance with Boeing Service Bulletin 737-53-1179, dated June 22, 1995, as revised by Notice of Status Change 737-53-1179 NSC 1, dated August 17, 1995.
(1) Prior to the accumulation of 20,000 total flight cycles, but not prior to the accumulation of 4,500 total flight cycles; or within 4,500 flight cycles or 18 months after the effective date of this AD; whichever occurs latest; perform a one-time internal inspection (terminating inspection) of the bonded skin panel assemblies that have not been replaced to detect delamination of the skin doublers from the skin panels, in accordance with Figures 3 and 4 of the service bulletin. In lieu of accomplishing the inspections identified in Figure 3 of the service bulletin, operators can perform an internal or external ultrasonic inspection in accordance with NOTE 1. of paragraph A. of the ``Terminating Inspection'' Section of the Accomplishment Instructions of the service bulletin.
(2) Within 4,500 flight cycles or 18 months after the effective date of this AD, whichever occurs later, perform an external visual inspection of the bonded skin panel assemblies that have not been replaced to detect cracks in the skin panels, in accordance with paragraph A. of the ``Interim Inspection'' Section of the Accomplishment Instructions of the service bulletin. Repeat the external visual inspection thereafter at intervals not to exceed 4,500 flight cycles, until accomplishment of the requirements specified in paragraph (c)(3) of this AD.
(3) Within 15,000 flight cycles or 60 months after the effective date of this AD, whichever occurs first, accomplish the one-time internal inspection required by paragraph (c)(1) of this AD. Accomplishment of this action constitutes terminating action for the repetitive inspections required by paragraph (c)(2) of this AD.
(d) For airplanes having line numbers 1 through 610 inclusive, and 2726 through 3072 inclusive, on which any bonded skin panel assembly was replaced with any new or serviceable bonded skin panel assembly prior to October 1, 1997: Accomplish the actions required either by paragraph (d)(1) or by both paragraphs (d)(2) and (d)(3) of this AD, in accordance with Boeing Service Bulletin 737-53-1179, dated June 22, 1995, as revised by Notice of Status Change 737-53- 1179 NSC 1, dated August 17, 1995.
(1) Prior to the accumulation of 20,000 flight cycles after the date of replacement of the skin panel assembly, but not prior to the accumulation of 4,500 flight cycles after the date of such replacement; or within 4,500 flight cycles or 18 months after the effective date of this AD; whichever occurs latest; perform a one- time internal inspection (terminating inspection) of the bonded skin panel assemblies that have been replaced to detect delamination of the skin doublers from the skin panels, in accordance with Figures 3 and 4 of the service bulletin. In lieu of accomplishing the inspections specified in Figure 3 of the service bulletin, operators can perform an internal or external ultrasonic inspection in accordance with NOTE 1. of paragraph A. of the ``Terminating Inspection'' Section of the Accomplishment Instructions of the service bulletin.
(2) Within 4,500 flight cycles or 18 months after the effective date of this AD, whichever occurs later, perform an external visual inspection of the bonded skin panel assemblies that have been replaced to detect cracks in the skin panels, in accordance with paragraph A. of the Interim Inspection of the Accomplishment Instructions of the service bulletin. Repeat the external visual inspection thereafter at intervals not to exceed 4,500 flight cycles, until accomplishment of the requirements specified in paragraph (d)(3) of this AD.
(3) Within 15,000 flight cycles or 60 months after the effective date of this AD, whichever occurs first, accomplish the one-time internal inspection required by paragraph (d)(1) of this AD. Accomplishment of this action constitutes terminating action for the repetitive inspections required by paragraph (d)(2) of this AD.
(e) If any crack is detected during any inspection required by paragraph (a)(2), (b)(3), (c)(2), or (d)(2) of this AD, prior to further flight, accomplish the actions required by paragraph (b)(1) and (b)(2) of this AD, as applicable.
(1) If any crack is detected in any skin panel that is above stringer S-10 or between stringers S-14 and S-26, repair in accordance with Boeing Service Bulletin 737-53-1179, dated June 22, 1995, as revised by Notice of Status Change 737-53-1179 NSC 1, dated August 17, 1995.
(2) If any crack is detected in any skin panel that is between stringers S-10 and S-14 (window belt), repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings.
(f) If no delamination is detected during any inspection required by paragraph (a)(1), (a)(3), (b)(1), (b)(2), (b)(4), (c)(1), (c)(3), (d)(1), or (d)(3) of this AD, no further action is required by this AD.
(g) If any delamination is detected during any inspection required by paragraph (a)(1), (a)(3), (b)(1), (b)(2), (b)(4), (c)(1), (c)(3), (d)(1), or (d)(3) of this AD, prior to further flight, accomplish the actions required by either paragraph (g)(1) or (g)(2) of this AD, as applicable.
(1) If the delaminated area is less than 3 square inches and is not at the edge of a skin doubler or under a fastener head, no further action is required by this AD for that delaminated area.
(2) If the delaminated area is equal to or greater than 3 square inches or is located at the edge of a skin doubler or under a fastener head, prior to further flight, accomplish the follow-on corrective actions in accordance with the ``Terminating Inspection'' Section of the Accomplishment Instructions of Boeing Service Bulletin 737-53-1179, dated June 22, 1995, as revised by Notice of Status Change 737-53-1179 NSC 1, dated August 17, 1995, except as provided by paragraphs (h) and (i) of this AD.
(h) Where Boeing Service Bulletin 737-53-1179, dated June 22, 1995, as revised by Notice of Status Change 737-53-1179 NSC 1, dated August 17, 1995, specifies that the actions required by this AD may be accomplished in accordance with an ``equivalent'' procedure, the actions must be accomplished in accordance with the chapter of the Boeing 737 Nondestructive Test Manual specified in the service bulletin.
(i) Where Boeing Service Bulletin 737-53-1179, dated June 22, 1995, as revised by Notice of Status Change 737-53-1179 NSC 1, dated August 17, 1995, specifies that the repair of a delaminated lap splice is to be accomplished in accordance with instructions received from Boeing, this AD requires that the repair be accomplished in accordance with a method approved by the Manager, Seattle ACO; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings.
(j) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle ACO. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.
Note 6: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.
(k) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.
Issued in Renton, Washington, on December 31, 1998. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 99-481Filed1-8-99; 8:45 am]
BILLING CODE 4910-13-U
