[Federal Register Volume 61, Number 96 (Thursday, May 16, 1996)]
[Rules and Regulations]
[Pages 24675-24684]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-12020]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-92-AD; Amendment 39-9618; AD 96-10-11]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-9 and DC-9-
80 Series Airplanes, Model MD-88 Airplanes, and C-9 (Military) Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to McDonnell Douglas Model DC-9 and DC-9-80 series 
airplanes, Model MD-88 airplanes, and C-9 (military) series airplanes, 
that currently requires certain inspections and structural 
modifications. This

[[Page 24676]]

amendment requires additional inspections and structural modifications. 
This amendment is prompted by an evaluation conducted by the 
Airworthiness Assurance Working Group, which identified additional 
inspections and structural modifications for mandatory action. The 
actions specified by this AD are intended to prevent degradation in the 
structural capabilities of the affected airplanes.

DATES: Effective June 20, 1996.
    The incorporation by reference of ``DC-9/MD-80 aging Aircraft 
Service Action Requirements Document,'' McDonnell Douglas Report No. 
MDC K1572, Revision B, dated January 15, 1993, as listed in the 
regulations, is approved by the Director of the Federal Register as of 
June 20, 1996.
    The incorporation by reference of ``DC-9/MD-80 Aging Aircraft 
Service Action Requirements Document,'' McDonnell Douglas Report No. 
MDC K1572, Revision A, dated June 1, 1990, as listed in the 
regulations, was approved previously by the Director of the Federal 
Register as of September 24, 1990 (55 FR 34704, August 24, 1990).

ADDRESSES: The service information referenced in this AD may be 
obtained from McDonnell Douglas Corporation, 3855 Lakewood Boulevard, 
Long Beach, California 90846, Attention: Technical Publications 
Business Administration, Department C1-L51 (2-60). This information may 
be examined at the Federal Aviation Administration (FAA), Transport 
Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, 
Washington; or at FAA, Transport Airplane Directorate, Los Angeles 
Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, 
California; or at the Office of the Federal Register, 800 North Capitol 
Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: David Y. J. Hsu, Aerospace Engineer, 
Airframe Branch, ANM-120L, FAA, Transport Airplane Directorate, Los 
Angeles Aircraft Certification Office, 3960 Paramount Boulevard, 
Lakewood, California 90712-4137; telephone (310) 627-5323; fax (310) 
627-5210.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) was published in the Federal 
Register on November 10, 1994 (59 FR 56011). The action proposed to 
supersede AD 90-18-03, amendment 39-6701 (55 FR 34704, August 24, 
1990), which is applicable to McDonnell Douglas Model DC-9 and DC-9-80 
series airplanes, and Model MD-88 airplanes, and C-9 (military) series 
airplanes. That action proposed to require certain additional 
structural modifications and inspections.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Support for the Proposal

    Several commenters support the proposed rule.

Request for FAA to Review Future Revisions of the Service Action 
Requirements Document (SARD)

    One commenter requests that the FAA review all subsequent revisions 
of service bulletins that are referenced in McDonnell Douglas Report 
No. MDC K1572, ``DC-9/MD-80 Aging Aircraft Service Action Requirements 
Document,'' Revision B, dated January 15, 1993 (hereafter referred to 
as ``SARD, Revision B''), to determine acceptability for compliance 
with the requirements of the proposal. The FAA concurs. Whenever the 
FAA reviews and approves a service document, that document will 
indicate that it has been approved by the FAA, and that if is 
considered an acceptable alternative method of compliance for any 
existing AD's. For example, two sources of service information 
referenced in the final rule bear such a statement. (See page ii, 
``Alternative Means of Compliance,'' of SARD, Revision B; and page 22, 
paragraph 1.E. ``Approval,'' of McDonnell Douglas DC-9 Service Bulletin 
53-230, Revision 1, dated January 12, 1993.)

Request to Permit Operators to Join in FAA's Review of Future Revisions 
to the SARD

    The same commenter also requests that the FAA, as part of the 
review process, obtain input from affected operators prior to approving 
any McDonnell Douglas service bulletin. The commenter states that this 
would reduce the number of errors in service bulletins, which would 
eliminate the need for revisions of service bulletins to correct any 
errors in them.
    The FAA does not concur. While the FAA recognizes the value of 
operators' review of service bulletins, it considers their 
participation to be more timely and appropriate during the development 
of the service bulletin by the manufacturer, rather than after it has 
been submitted to the FAA for approval. After the FAA has identified an 
unsafe condition, the FAA relies upon the manufacturer to provide the 
method to correct that unsafe condition. When that method of correction 
of the unsafe condition results in the issuance of a service bulletin, 
the FAA must review and approve that service bulletin based upon 
whether that service bulletin positively addresses the identified 
unsafe condition and whether that method of correction meets the 
airworthiness requirements for the type design of the affected 
aircraft. Further, operators may not be able to provide in- depth 
engineering analysis, such as that performed by the FAA, since type 
design data are proprietary and may not be available to all operators.
    However, the Air Transport Association (ATA) of America has in 
place a system whereby member operators are afforded the opportunity to 
provide input to airworthiness concerns. The FAA encourages operators 
to take advantage of this ATA system to effect changes to 
manufacturer's service bulletins. Additionally, operators have the 
option of contacting the manufacturer directly to resolve such 
difficulties.

Request that Manufacturer Provide Alternative Rework Drawings to 
Operators

    The same commenter requests that, when an earlier version of a 
rework drawing is referenced in any rulemaking action, the FAA ensure 
that the manufacturer provide operators with the most recent revision 
of that rework drawing if it has been approved by the FAA as an 
alternative method of compliance for the requirements of that 
rulemaking action.
    The FAA does not concur. Section 21.99(b), of the Federal Aviation 
Regulations [14 CFR 21.99(b)], ``Required design changes,'' requires 
that the manufacturer make information on design changes that 
contribute to the safety of the product available to all operators of 
the affected product. However, the revised rework drawings may not 
necessarily contribute to the safety of the product. The FAA encourages 
operators to contact the manufacturer directly to obtain revisions of 
rework drawings. However, in the event any operator finds it impossible 
to accomplish the requirements of this AD due to the inability to 
obtain necessary rework drawings, those operators are reminded of the 
provisions of paragraph (h) of the final rule, which permit any 
operator to apply for approval of an alternative method of compliance 
with the requirements of the final rule.

[[Page 24677]]

Request for Removal of Certain Service Bulletins from Requirements 
of the Rule

    The same commenter requests that the proposed rule be revised by 
removing McDonnell Douglas DC-9 Service Bulletins 53-174 and 53-147 
from the requirements. These service bulletins are referenced in SARD, 
Revision B, which is referenced in the proposal as the appropriate 
source of service information. The commenter contends that these two 
service bulletins do not fit within the parameters of the proposal 
since they specify continual repetitive inspections after 
accomplishment of the proposed modification. The commenter asserts that 
this contradicts the stated purpose of the proposal, which is to 
``reflect the FAA's decision that long term continued operational 
safety should be assured by actual modification of the airframe.''
    The FAA does not concur. The FAA finds that the commenter has 
restated only a portion of the purpose of this rulemaking action; the 
commenter omitted two key words from the Summary section of this 
rulemaking action. The FAA's intent is to require ``modification of the 
airframe, where feasible.'' Service Bulletin 53-174 specifies 
replacement of a limited number of rivets with bolts and hi-lok 
fasteners and installation of doublers in the non-ventral bulkhead web 
and tee. Service Bulletin 53-147 specifies installation of an external 
doubler and internal finger doublers between longerons (LN) 14L and 14R 
in the aft pressure bulkhead skin splice doubler. Since fatigue testing 
and service history have demonstrated that the location of the 
modifications addressed in these two service bulletins is susceptible 
to fatigue cracking, the FAA has determined that modification alone 
cannot ensure safety of the fleet; therefore, repetitive inspections 
must continue to be performed to prevent degradation in the structural 
capabilities of the affected airplanes.
    Along this same line, the same commenter states that it cannot 
accomplish the inspections that are required to be performed following 
accomplishment of the modification specified in McDonnell Douglas DC-9 
Service Bulletin 53-174. The commenter notes that although the service 
bulletin provides a method for accomplishing the modification, it does 
not provide a method for accomplishing the inspections of the modified 
structure. From this comment, the FAA infers that the commenter is 
requesting a delay in issuance of the final rule until such time that 
the manufacturer has developed an acceptable inspection method of the 
modified structure. The FAA does not concur. The FAA does not consider 
that delaying this action until that time is warranted since sufficient 
technology currently exists to accomplish the follow-on inspections 
within the compliance time. However, the FAA points out that for 
airplanes on which modifications affect performing the required 
inspections, operators must use the provisions of paragraph (h) of the 
final rule to request, from the FAA, approval for an alternative method 
of compliance.

Request to Reference Latest Revision of Service Bulletins

    The same commenter requests a revision to the proposal to reference 
two service bulletins that have been revised since issuance of the 
notice. The commenter states that McDonnell Douglas DC-9 Service 
Bulletin 57-129, Revision 3, dated November 6, 1987, has been re-issued 
as two separate service bulletins: McDonnell Douglas DC-9 Service 
Bulletin 57-129, Revision 5, dated November 10, 1994; and McDonnell 
Douglas DC-9 Service Bulletin 57-200, dated November 10, 1994. The FAA 
concurs. Three new notes have been added to the final rule: NOTE 4, 
NOTE 11, and NOTE 12. These notes state that accomplishment of both of 
these service bulletins is acceptable for compliance with the 
requirement to accomplish Service Bulletin 57-129, Revision 3.

Request to Convert Compliance Time from Flight Hours to Flight 
Cycles

    The same commenter requests a revision to the proposal that would 
provide further guidance for converting flight hours to an equivalent 
number of flight cycles. The commenter notes that most operators track 
rotatable components in terms of flight hours, rather than flight 
cycles, as expressed in the service bulletins referenced in SARD, 
Revision B. Further, the commenter contends that repairable components 
are tracked neither by serial number nor by flight cycles/hours. The 
commenter states that ten of the service bulletins listed in SARD, 
Revision B, express thresholds in terms of flight cycles accumulated on 
the affected component.
    The FAA does not concur. In re-evaluating expressions of thresholds 
in terms of flight cycles, the FAA has verified with several affected 
operators (including the commenter) and has found that repairable and 
rotatable components have been tracked by flight cycles, as well as 
flight hours. Since this commenter did not submit utilization data for 
each of its airplanes, the FAA could not provide an appropriate method 
to convert flight hours to an equivalent number of flight cycles. 
However, the FAA would address these unique circumstances, including 
conversion of flight hours to flight cycles, under the alternative 
method of compliance provisions of paragraph (h) of the final rule.

Request to Revise Compliance Threshold for One Service Bulletin

    This same commenter requests a revision of the threshold specified 
in McDonnell Douglas DC-9 Service Bulletin 53-60, Revision 1 
(referenced in Table 2.3 of SARD, Revision B). The commenter states 
that a more appropriate threshold would be ``prior to the accumulation 
of 89,000 total landings,'' which would coincide with the threshold 
specified in McDonnell Douglas DC-9 Service Bulletin 53-166 (referenced 
in Table 2.1 of SARD, Revision B). The commenter notes that Service 
Bulletin 53-166 recommends accomplishment of the modification described 
in that service bulletin prior to the accumulation of 89,000 total 
landings, while Service Bulletin 53-60 recommends accomplishment of the 
modification described in that service bulletin prior to January 15, 
1997. The commenter further states that Service Bulletin 53-60 must be 
accomplished prior to the accomplishment of Service Bulletin 53-166.
    The FAA does not concur. Service Bulletin 53-166 states that it 
``assumes that Service Bulletins * * * 53-60 have been accomplished;'' 
it does not state that Service Bulletin 53-60 must be accomplished 
prior to Service Bulletin 53-166. In fact, Service Bulletin 53-166 goes 
on to state that ``if these service bulletins have not been 
accomplished on applicable aircraft, contact the Douglas Aircraft 
Company for special instructions.'' Further, the FAA points out that 
the final rule does not require accomplishment of Service Bulletin 53-
60 prior to the accomplishment of Service Bulletin 53-166, but it would 
permit such accomplishment. Therefore, no change to the final rule is 
necessary.

Request to Revise Repair Approval Process

    This same commenter questions why structural repairs accomplished 
in accordance with the DC-9 Structural Repair Manual (SRM), which is an 
FAA-approved document; and Douglas Service Rework Drawings, which, for 
the most part, are FAA-approved documents, must be again approved by 
the FAA for the purpose of this AD. The commenter notes that paragraph 
(c) of

[[Page 24678]]

the proposal requires FAA-approval of structural repairs, including 
those that are accomplished in accordance with either of these 
documents, despite the fact that they are FAA-approved documents.
    The FAA infers that the commenter is requesting that proposed 
paragraph (c) be revised to allow repairs in accordance with the SRM 
and Service Rework Drawings, without further approval by the ACO. The 
FAA does not concur. The repairs required by paragraph (c) were not 
intended to terminate the requirements for inspection contained in 
paragraphs (a) and (b) of the AD. However, the inspection procedures 
referenced in those paragraphs may not be appropriate for structure 
repaired as required by paragraph (c). Therefore, it is necessary to 
obtain ACO approval of such repairs in order to ensure that the 
approval is conditioned upon identification of appropriate inspection 
methods that will continue to meet the intent of paragraphs (a) and 
(b). For example, if a crack identified as a result of an inspection 
under paragraph (a) is within the limits specified for an appropriate 
repair in the SRM, an operator would be required to obtain the ACO's 
approval for that repair. The approval would be conditioned either on 
the ACO's determination that the inspection required by paragraph (a) 
continues to be appropriate, or on the operator's identification of an 
acceptable alternative inspection method.

Request to Clarify Effect of Requirements on Supplemental Inspection 
Document (SID) Program

    The same commenter asks what effect the proposed requirement to 
modify Principal Structural Elements (PSE) will have on AD 94-03-01, 
amendment 39-8807 (59 FR 6538, February 11, 1994), which requires 
implementation of a SID sampling program of structural inspections to 
detect fatigue cracking. The commenter notes that, in many cases, 
accomplishment of the terminating modifications required by the 
proposal will affect the fleet-leader operator sampling (FLOS) program 
of AD 94-03-01.
    The FAA acknowledges that certain repair and modification 
requirements of the final rule may affect the FLOS program of AD 94-03-
01. For this reason, standardization and continuity of repairs are 
especially important in light of the complexity of the DC-9 SID 
program. The FAA has determined that standardization and continuity of 
repairs can best be maintained by having one single point of approval 
[i.e., the Manager of the Los Angeles Aircraft Certification Office 
(ACO)] for all repairs of cracks in Principal Structural Element (PSE), 
including those required by this final rule.
    Further, every repair of PSE structure requires a Damage Tolerance 
Assessment (DTA) to be performed (of each repair) to establish its 
effect on the original inspection requirements of the repaired 
structure. The FAA considers that any repair of any cracked PSE without 
the required DTA can only be considered temporary, and will eventually 
need to be coordinated with the Manager of the Los Angeles ACO. A PSE 
structure on which repairs are made without the required DTA and not 
coordinated with the manufacturer and the Los Angeles ACO, becomes a 
``discrepant PSE'' when the time arrives for that PSE to be re-
inspected. In these cases, the repair may need to be removed or 
reworked at a later time. In either case, the Manager of the Los 
Angeles ACO must ensure that all repairs of cracked PSE's comply with 
the requirements of AD 94-03-01, as well as with the requirements of 
this final rule.
    Most methods of repair specified in the DC-9 SRM or in relevant 
service bulletins, or Designated Engineering Representative (DER)-
designed repairs, do not include a continuing inspection program to 
ensure that the repair is inspected at the same level of safety as the 
original PSE structure. A DTA can be done most easily at the time of 
repair, rather than at a later date when the details of the repair may 
be hard to obtain and, undoubtedly, would be more costly. Currently, 
the Manager and staff of the Los Angeles ACO are working very closely 
with the manufacturer to expedite interim repair approval requests. 
Such requests may be made under the provisions of paragraph (h) of the 
final rule.

Request to Include Corrosion Inspections

    Another commenter requests a revision to proposed paragraphs (a) 
and (b) to include inspections to detect corrosion. The commenter 
states that proposed paragraphs (a) and (b), as well as AD 90-18-03 
only require inspections to detect cracking.
    The FAA does not concur that revision is necessary. NOTE 4 of the 
final rule (which was designated NOTE 2 in the proposal) and the Note 
following paragraph A.1. of AD 90-18-03 state that corrective action is 
required for discrepancies other than cracking. Additionally, on May 
24, 1993, the FAA issued AD 92-22-08 R1, amendment 39-8591 (58 FR 
32281, June 9, 1993), which requires the implementation of a corrosion 
prevention and control program. Therefore, the FAA finds that it is 
unnecessary to include in this final rule any additional inspections to 
detect corrosion.

Request for Clarification of Requirements of Service Bulletin 55-31

    The same commenter requests a revision to the proposal to clarify 
the requirements specified in McDonnell Douglas DC-9 Service Bulletin 
55-31, which is referenced in SARD, Revision B. The commenter notes 
that confusion may arise because Service Bulletin 55-31 is listed in 
various sections of SARD, Revision B.
    The FAA concurs. Service Bulletin 55-31 is listed in Table 2.3 and 
Table 2.4 of SARD, Revision B. Paragraph (b) of the final rule requires 
inspections of aircraft structure specified in Table 2.3 or 2.4 of 
SARD, Revision B, while paragraph (e) of the final rule requires 
modifications of aircraft structure specified in Table 2.3 or 2.4 of 
SARD, Revision B. A new NOTE 7 has been added to the final rule to 
clarify that the revisions of the service bulletins that are listed 
under ``Recommended Modification'' are acceptable for inspections 
performed prior to the effective date of the final rule. Additionally, 
NOTE 8 of the final rule (which was designated NOTE 5 in the proposal) 
provides additional clarification by stating that only those revision 
levels of the service bulletins listed in Tables 2.3 and 2.4 are 
acceptable for compliance with the modification requirements of the 
final rule. Therefore, the inspections described in Service Bulletin 
55-31 are required to be performed in accordance with Revision 4, and 
the modifications are required to be accomplished in accordance with 
Revision 3 or Revision 4 of Service Bulletin 55-31.

Request to Delete FAA-Approval of Repair Methods

    One commenter requests a revision to paragraph (c) of the proposal, 
which requires repair of cracks prior to further flight in accordance 
with a method approved by the Manager of the Los Angeles ACO. The 
commenter states that this proposed requirement would impose a severe 
hardship on operators since most operators work 365 days a year, 
whereas, the Los Angeles ACO operates on a standard 5-day work week. 
The commenter notes that this difference in hours of operation creates 
a problem for operators to obtain FAA approvals for repair methods. As 
an alternative to staffing the Los Angeles

[[Page 24679]]

ACO offices 24 hours a day, 7 days a week, the commenter suggests that 
the FAA provide its engineers and managers in the Los Angeles ACO with 
pagers.
    The FAA does not concur. Since repairs are only required when 
cracks are found during the inspections required by this final rule, 
the FAA anticipates that operators will accomplish those inspections 
and repairs at a maintenance base during regularly scheduled ``heavy'' 
maintenance visits. Therefore, the FAA anticipates that operators will 
have ample time to obtain approvals from the Los Angeles ACO without 
adversely affecting their operations.
    Further, the FAA recognizes that the required modifications will 
necessitate a large number of work hours to accomplish. However, the 
thresholds specified in the service bulletins referenced in SARD, 
Revision B, were developed only after extensive and detailed 
consultations between a large number of operators of Model DC-9 series 
airplanes and the manufacturer. Among other things, these consultations 
were conducted in order to establish timeframes (for accomplishing 
necessary actions) that would minimize the economic impacts on 
operators to the maximum extent possible, while still maintaining 
safety objectives. Consequently, where safety considerations allow, the 
FAA attempts to impose thresholds that generally coincide with 
operators' maintenance schedules.

Request for Clarification of When To Repair vs. When To Modify

    The same commenter also requests clarification of the relationship 
between proposed paragraph (c) and proposed paragraph (f). The 
commenter points out that:
    1. Paragraph (c) would require that, if any crack is found during 
an inspection, it must either be repaired or the applicable terminating 
modification must be installed; and
    2. Paragraph (f) would require that the terminating modifications 
be installed by the time the airplane accumulates a certain number of 
landings.
    The FAA concurs that clarification is warranted. Paragraph (c) of 
the final rule is applicable to all airplanes, while paragraph (f) of 
the final rule is applicable only to Model DC-9-10, -20, -30, -40, and 
-50 series airplanes and C-9 (military) series airplanes.
    Further, the repair or modification specified in paragraph (c) is 
an ``on condition'' requirement; as such, the terminating modifications 
required by paragraph (c) of the final rule are required to be 
accomplished, prior to further flight, on the condition that cracking 
is found. Paragraph (f) of the final rule, on the other hand, requires 
the eventual modification of all applicable airplanes (prior to the 
accumulation of 100,000 total landings), regardless of whether or not 
cracking has been found.

Request for Clarification of the Rule's Relationship to Modification 
Requirements of Other Related AD's

    The same commenter points to an inconsistency that may exist 
between several existing AD's that reference various service bulletins 
(that are referenced in SARD, Revision B) and NOTE 6 of the proposal. 
The commenter states that a majority of the service bulletins 
referenced in SARD, Revision B, that describe procedures for 
inspections, are required currently by various other existing AD's. 
However, those AD's do not provide for termination of those inspections 
by accomplishing the modifications described in those service 
bulletins. Therefore, the commenter questions the intent of NOTE 6 of 
the proposal, which states that the modifications required by 
paragraphs (d) and (e) of the proposal do not terminate the inspection 
requirement of other related AD's unless those other related AD's 
specifically state so.
    The FAA does not find any inconsistencies between proposed NOTE 6, 
which is now designated as NOTE 14 in the final rule, and the 
requirements of other related AD's. The NOTE clearly specifies that a 
modification required by this final rule does not automatically 
terminate inspections required by another AD, unless that other AD 
specifically states that the modification does constitute terminating 
action for that AD's inspection requirements (or unless this final rule 
specifically states that the modification constitutes terminating 
action for another AD).

Request for Alternatives to Modifications

    Further, the same commenter supports the proposed modifications 
specified in paragraph (e) of the proposal, but only in cases where:
    1. A superior inspection technique is not subsequently developed;
    2. There is no record, worldwide, of subsequent cracking of 
aircraft structure that has had terminating action modification 
incorporated;
    3. Test data and service experience support that the terminating 
action modification is, without a doubt, effective; and
    4. The accomplishment of the modification would not pose the threat 
of rework included damage/error, as evidenced by historical 
catastrophic failures.
    When these conditions do not exist, the commenter requests that the 
FAA consider alternatives to the proposed modifications.
    Since the commenter did not provide the specifics for any kind of 
alternative, the FAA infers that the commenter is requesting that the 
proposed inspections of paragraph (b) be continued repetitively, 
without terminating modifications. In that case, the FAA does not 
concur. The FAA has determined that the degree of assurance necessary 
as to the adequacy of inspections needed to maintain the safety of the 
aging transport airplane fleet, coupled with a better understanding of 
the human factors associated with numerous repetitive inspections, has 
caused the FAA to place less emphasis on repetitive inspections and 
more emphasis on design improvements and material replacement. Thus, in 
lieu of its previous position of allowing continual inspection, and 
repair or modification on condition if cracking is found, the FAA has 
decided to require, whenever practicable, airplane modifications that 
remove the source of the particular aging phenomena.
Request to Supersede AD 88-24-08 R2
    One commenter requests that the proposal be revised by deleting the 
requirements of proposed paragraph (f), and including those 
requirements in AD 88-24-08 R2, amendment 39-6469 (55 FR 1002, January 
11, 1990). The commenter notes that proposed paragraph (f) refers to 
McDonnell Douglas DC-9 Service Bulletin 53-230, Revision 1, dated 
January 12, 1993; while AD 88-24-08 R2 refers to McDonnell Douglas DC-9 
Alert Service Bulletin A53-230, Revision 3, dated September 28, 1989. 
The commenter states that superseding AD 88-24-08 R2 would ease the 
administrative burden on operators, in lieu of superseding the proposal 
whenever the manufacturer issues new revisions of any of the service 
bulletins that are referenced in the SARD.
    The FAA does not concur. The modifications (specified in Service 
Bulletin 53-230 and) required by paragraph (f) of the final rule 
terminate the inspections (specified in Alert Service Bulletin A53-230 
and) required by AD 88-24-08 R2. Alert Service Bulletin A53-230 does 
not specify procedures for termination of the inspections described in 
that service bulletin. Whereas, Service Bulletin 53-

[[Page 24680]]

230 describes procedures for modifications of the fuselage frames 
between LN's 10L and 10R at various overwing stations between Y=484.000 
and Y=851.000. As explained in paragraph (f) of the final rule, 
accomplishment of the modifications specified in Service Bulletin 53-
230 terminates the inspection requirements of AD 88-24-08 R2. Further, 
as stated in the Discussion section of the preamble to the notice, 
although Service Bulletin 53-230 was not included in SARD, Revision B, 
the FAA concurs with the recommendations of the Airworthiness Assurance 
Working Group (AAWG), which recommended that modifications described in 
it be made mandatory in order to prevent structural degradation of the 
fleet. Therefore, the FAA finds it appropriate to include Service 
Bulletin 53-230 in the modification requirements of the final rule.
    However, the FAA will consider issuing separate rulemaking actions, 
including supersedure of existing AD's, whenever the manufacturer 
issues new revisions to the service bulletins referenced in those AD's.

Request To Delete Redundant Language Concerning Terminating 
Modifications

    One commenter asserts that proposed paragraph (g) is redundant to 
proposed paragraphs (a) and (b), which state that the modifications in 
the service bulletins terminate the inspection requirements. From this 
comment, the FAA infers that the commenter is requesting the deletion 
of proposed paragraph (g), which states that accomplishment of certain 
modifications terminates certain inspection requirements. The FAA 
concurs. Proposed paragraph (g) has been deleted from the final rule.

Request for Explanation for the Exclusion of Certain Service 
Bulletins

    This same commenter requests that proposed rule be revised to 
include an explanation as to why MD-80 Service Bulletins 53-186 (which 
is referenced in Tables 2.1 and 2.2 of SARD, Revision B) and 53-216 
(which is referenced in Table 2.2 of SARD, Revision B) are excluded 
from the proposed requirements. The FAA concurs and acknowledges that 
the reason for excluding these service bulletins from the requirements 
of the final rule was omitted unintentionally. AD 94-08-04, amendment 
39-8875 (59 FR 18952, April 21, 1994) requires inspections to detect 
cracking in the skin and doublers around the upper anticollision light 
cutout, and repair, if necessary; and stress coining the plate nut 
clearance holes; which are specified in those service bulletins. 
Therefore, paragraph (g) of the final rule [which was designated 
paragraph (h) in the proposal] has been revised to state that AD 94-08-
04 addresses the actions specified in Service Bulletins 53-186 and 53-
216; it is for this reason that the actions specified in those service 
bulletins are excluded from the requirements of the final rule.
    Along this same line, the FAA finds that the actions specified in 
DC-9 Service Bulletin 54-30 are excluded from the requirements of the 
final rule since AD 77-14-19, amendment 39-2971 (42 FR 36811, July 18, 
1977), already addresses the actions specified in that service 
bulletin. AD 77-14-19 requires repetitive inspections to detect fatigue 
cracking of the engine pylon front spar attachments and upper cap; and 
modification of cracked structure. Procedures for these actions are 
described in DC-9 Service Bulletin 54-30. Paragraph (g) of the final 
rule has been revised to reflect this change.
    The FAA also finds that the actions specified in DC-9 Service 
Bulletins 27-196 and 27-250 are excluded from the requirements of the 
final rule since AD 92-11-10, amendment 39-8260 (57 FR 27149, June 18, 
1992), already addresses the actions specified in these service 
bulletins. AD 92-11-10 requires repetitive inspections to detect 
cracking of the forward slat drive drums' bellcrank shafts, and 
replacement, as applicable. Procedures for these actions are described 
in DC-9 Service Bulletins 27-196 and 27-50. Paragraph (g) of the final 
rule has been revised accordingly.
    The FAA also finds that the actions specified in DC-9 Service 
Bulletins 57-125 and 57-148 are excluded from the requirements of the 
final rule since AD 96-01-05, amendment 39-9481 (61 FR 2403, January 
26, 1996), already addresses the actions specified in those service 
bulletins. DC-9 Service Bulletin 57-125 describes procedures for 
replacement of the attach fittings of the main landing gear (MLG); and 
DC-9 Service Bulletin 57-148 describes procedures for inspection and 
modification of the attach fittings of the MLG. Since these actions 
currently are required by AD 96-01-05, paragraph (g) of the final rule 
has been revised to exclude these actions.
    Additionally, paragraphs (a), (b), (d), (e) of the final rule have 
been revised to note the exclusion provision of paragraph (g) of the 
final rule.

Clarification of Provisions for Obtaining Alternative Methods of 
Compliance (AMOC)

    One commenter requests further guidance to determine exactly when 
FAA-approval of an AMOC is necessary. The FAA acknowledges that 
additional guidance may be warranted, and has added a new NOTE 1 to 
provide this. The new note specifies that, when performance of the 
requirements of the AD is ``affected,'' an operator should apply for 
approval of an AMOC in order to show compliance with the AD. The 
meaning of the term ``affected'' can be understood by applying it to 
typical scenarios:
    One scenario is when performance of the requirements of the AD is 
``affected'' in such a way that the operator is unable to perform those 
requirements in the manner described in the AD. An example of this is 
when an AD requires a visual inspection in accordance with a certain 
service bulletin, but the operator cannot perform that inspection 
because of the placement of a repair doubler over the structure to be 
inspected; in this case, ``performance of the AD is affected.''
    Another scenario is when it is physically possible to perform the 
requirements of an AD, but the results achieved are different from 
those specified in the AD. An example of this is when an AD requires a 
non-destructive test (NDT) inspection in accordance with a certain 
service bulletin, and the operator is able to move the NDT probe over 
the specified area in the specified manner, but the results are either 
meaningless or inaccurate because of a repair doubler placed over that 
area; in this case, ``performance of the AD is affected.''
    While it is not possible to address every possible situation, 
``affected'' is normally an easy standard to apply: either it is 
possible to perform the requirements as specified in the AD and achieve 
the specified results, or it is not possible. Therefore, if the 
requirements of this AD cannot be performed, then operators must submit 
a request for an approval of an AMOC from the FAA, in accordance with 
the provision of paragraph (h) of the final rule.
    Any requirement of an AD, such as a modification or repair doesn't 
``affect performance of the AD;'' it is performance of the AD. 
Accordingly, every AD includes a provision that states, ``Compliance 
required as indicated, unless previously accomplished.'' If an operator 
performs such a requirement before the AD is issued, the FAA is 
confident that the operator will recognize that it has

[[Page 24681]]

already complied with the AD and no further action (including obtaining 
approval of an AMOC) is required.

Request That FAA Publish Its Policies on Granting AMOC's for Aging 
Aircraft AD's

    One commenter requests a revision of the proposed rule to include 
all FAA policies pertinent to granting approvals of alternative methods 
of compliance for aging aircraft AD's. The commenter made specific 
reference to an FAA memo, dated June 9, 1994, which outlined the 
criteria that the Aircraft Certification Offices (ACO) would be using 
to grant approvals for alternative methods of compliance with the aging 
aircraft AD's. (The subject of the memo was ``Denial of Requests for 
Extended Compliance Times with the Aging Aircraft Modification 
Airworthiness Directives.'') The commenter notes that the FAA has been 
inconsistent in granting approvals of alternative methods of compliance 
for aging aircraft AD's.
    The FAA does not concur. Part 39 of the Federal Aviation 
Regulations (14 CFR part 39), ``Airworthiness Directives,'' is for the 
purpose of correcting unsafe conditions that may exist or develop in 
aircraft, not for the purpose of publishing FAA policy decisions. The 
FAA points out that it will continue to use the criteria outlined in 
the memo referenced by the commenter to review data substantiating 
requests for alternative methods of compliance to the aging aircraft 
AD's on a case-by-case basis. Since the commenter did not provide any 
specific examples of inconsistencies in the approval of alternative 
methods of compliance that have been granted by the FAA, the FAA cannot 
address those inconsistencies. However, the FAA attempts, to the 
maximum extent possible, to accommodate each operators' specific 
operating conditions, aircraft configurations, maintenance practices, 
and other variables, provided they do not adversely impact safety.

Requests to Clarify Validity of Previously Approved AMOC's

    This same commenter requests a revision to the proposal to indicate 
that alternative methods of compliance that were previously approved by 
the FAA for the modification requirements of other related AD's 
continue to be considered acceptable for compliance with the 
requirements of the proposal. The commenter states that the proposal is 
too limiting in that only those AMOC's that were previously approved 
for the requirements of AD 90-18-03 are to be considered acceptable for 
compliance with the requirements of the proposal. The commenter 
contends that revising proposed rule to accept previously approved 
AMOC's would preclude operators from needlessly resubmitting additional 
requests for AMOC's for the inspections and modifications that are 
required by proposed paragraphs (a), (b), (d), and (f).
    The FAA does not concur. The intent of paragraph (i) of the final 
rule [which was designated paragraph (j) in the proposal] is to have 
approvals for alternative methods of compliance to AD 90-18-03 remain 
in effect for this AD. The inspection requirements of paragraph (a) of 
the final rule (contained in Table 2.1 and Table 2.2 of SARD, Revision 
A and) is a restatement of paragraph A. of AD 90-18-03, and the 
modification requirements of paragraph (d) of the final rule is a 
restatement of paragraph B. of AD 90-18-03. However, other 
modifications (contained in Table 2.3, Table 2.4, and Table 3.1 of 
SARD, Revision B) that are required by this final rule provide for a 
higher level of safety than that provided by other modifications 
required by other related AD's. Therefore, alternative methods of 
compliance that were previously approved by the FAA for those other 
related AD's may not provide for an adequate level of safety as that 
provided by the modifications required by the final rule; therefore, 
they must be reviewed individually to determine their acceptability, as 
provided in paragraph (i) of the final rule.

Request that Necessary Parts Be Available

    This commenter further requests FAA's intervention to ensure that 
the manufacturer take no longer than 15 days to provide required parts 
to operators. This commenter states that it has taken up to 18 months 
to obtain necessary parts for modifications required by AD's. The FAA 
cannot concur with this commenter's request, since the FAA has no 
regulatory requirement to ensure that manufacturers of aircraft produce 
spare parts in a timely manner. Part 39 of the Federal Aviation 
Regulations (14 CFR part 39), ``Airworthiness Directives,'' limits the 
FAA's authority to correct findings of unsafe conditions that may exist 
or develop in aircraft.
    Regardless, the FAA has verified with the manufacturer that parts 
necessary for the modifications required by the final rule will be 
available to operators upon submission of a purchase order to the 
manufacturer. Additionally, under the provisions of paragraph (h) of 
the final rule, operators may apply for the approval of an alternative 
method of compliance or adjustment of the compliance time if sufficient 
parts are unavailable to operators to accomplish the requirements of 
the final rule.

Request for Revision of Cost Estimate Figures

    One commenter requests that the cost impact information of the 
proposal be revised to reflect the ``true cost'' over the entire 
``modification period.'' The commenter notes that, in the proposal, the 
costs estimated ``over the initial 4-year time period,'' depicts an 
inaccurately low figure, since only 33 percent of the service bulletins 
referenced in SARD, Revision B, recommend a threshold of 4 years.
    The FAA does not concur that revision is necessary. The economic 
impact information, below, was developed with data provided by the 
manufacturer. In this case, the cost estimate in the final rule was 
developed by the McDonnell Douglas Corporation only after extensive and 
detailed consultations with large numbers of operators of Model DC-9 
and DC-9-80 series airplanes. The FAA acknowledges that only 33 percent 
of the service bulletins referenced in the SARD recommend a threshold 
of 4 years; the remaining 67 percent of the service bulletins recommend 
a threshold based on the number of flight cycles the airplane has 
accumulated or on the age of the airplane. Given the significant 
differences in operators' usage of these airplanes, an accurate 
assessment of when each airplane would reach that flight cycle 
threshold would be nearly impossible to calculate accurately. 
Additionally, there is no way of knowing how many airplanes will be 
``phased'' out of service as they approach or exceed the original 
economic life goal of these airplanes. Therefore, the FAA considers the 
4-year time period as an appropriate baseline to calculate the 
estimated costs for all of the actions required by the final rule.
    Additionally, subsequent to the issuance of the notice, the FAA 
reviewed the figures it used in calculating the cost of labor relevant 
to accomplishing AD activity. In order to account for various 
inflationary costs in the airline industry, the FAA finds it 
appropriate to increase the labor rate used in these calculations from 
$55 per work hour to $60 per work hour. The economic impact 
information, below, has been revised to reflect this increase in the 
specified hourly labor rate.

Editorial Changes to the Final Rule

    For purposes of readability, the FAA has revised paragraphs (a), 
(b), (d), and (e); NOTE 10 [which was designated

[[Page 24682]]

NOTE 4 in the proposal] and NOTE 13 [which was designated NOTE 5 in the 
proposal] of the final rule to remove the parenthetical phrase that 
describes the airplanes applicable to each Table in the SARD . A new 
NOTE 2 has been added to the final rule to explain that Tables 2.1, 
2.3, and 3.1 of the SARD are applicable to Model DC-9-10, -20, -30, -
40, and -50 series airplanes, and C-9 (military) series airplanes; and 
Tables 2.2 and 2.4 of the SARD are applicable to Model DC-9-81, -82, -
83, and -87 (MD-81, -82, -83, and -87) series airplanes, and Model MD-
88 airplanes.

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.

Cost Impact

    There are approximately 892 Model DC-9 and C-9 (military) series 
airplanes of the affected design in the worldwide fleet.
    The FAA estimates that 568 Model DC-9 and C-9 (military) series 
airplanes of U.S. registry were originally affected by AD 90-18-03. The 
requirements of that AD were estimated to take approximately 946 work 
hours to accomplish, at a current average labor rate of $60 per work 
hour. The cost for required modification kits was estimated to be 
$15,140 per airplane. Based on these figures, the FAA estimated that 
the cost impact of AD 90-18-03 on U.S. operators of Model DC-9 and C-9 
(military) series airplanes will be $40,839,200, or $71,900 per 
airplane, over the initial 4-year time period. (These figures do not 
include the cost of downtime, planning, set-up, familiarization, or 
tool acquisition.)
    The FAA estimates that 511 Model DC-9 and C-9 (military) series 
airplanes of U.S. registry will be affected by the new requirements 
specified in this AD. The new additional requirements of this AD action 
will take approximately 638 additional work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Required 
parts will cost approximately $37,027 per airplane. Based on these 
figures, the cost impact of the AD on U.S. operators is estimated to be 
$38,481,877, or $75,307 per airplane, over a 4-year time period. (These 
figures do not include the cost of downtime, planning, set-up, 
familiarization, and tool acquisition.)
    There are approximately 1,090 Model DC-9-80 series airplanes and 
Model MD-88 airplanes of the affected design in the worldwide fleet.
    The FAA estimates that 173 Model DC-9-80 series airplanes and Model 
MD-88 airplanes of U.S. registry were originally affected by AD 90-18-
03. The requirements of that AD were estimated to take approximately 47 
work hours to accomplish, at a current average labor rate of $60 per 
work hour. The cost for required modification kits was estimated to be 
$752 per airplane. Based on these figures, the FAA estimated that the 
cost impact of AD 90-18-03 on U.S. operators of Model DC-9-80 series 
airplanes and Model MD-88 airplanes will be $617,956, or $3,572 per 
airplane, over the initial 4-year time period. (These figures do not 
include the cost of downtime, planning, set-up, familiarization, or 
tool acquisition.)
    The FAA estimates that a total of 615 Model DC-9-80 series 
airplanes and Model MD-88 airplanes of U.S. registry will be affected 
by the new requirements specified in this AD. This increase in the 
number of affected airplanes is due to various reasons, including 
transfer of ownership and the fact that additional airplanes have 
accumulated time-in-service since the issuance of AD 90-18-03 and have 
reached the threshold for modification/inspection. The new additional 
requirements of this AD action will take approximately 13 additional 
work hours per airplane to accomplish, at an average labor rate of $60 
per work hour. Required parts will cost an additional $943 per 
airplane. Based on these figures, the additional cost impact of this AD 
on U.S. operators is estimated to be $1,059,645, or $1,723 per 
airplane, over a 4-year time period. (These figures do not include the 
cost of downtime, planning, set-up, familiarization, or tool 
acquisition.)
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished the currently required or the newly 
required actions of this AD; however, it can reasonably be assumed that 
a majority of affected operators have already initiated the inspections 
and structural modifications required by AD 90-18-03 [retained in 
paragraphs (a) and (d) of this AD] and many may have already initiated 
the additional inspections and structural modifications in this new AD 
action.
    The number of required work hours, as indicated above, is presented 
as if the accomplishment of the actions proposed in this AD were to be 
conducted as ``stand alone'' actions. However, in actual practice, 
these actions for the most part would 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 would be minimal in many instances. Additionally, 
any costs associated with special airplane scheduling would be minimal.

Regulatory Impact

    The regulations adopted herein will not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    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 USC 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-6701 (55 FR 
34704, August 24, 1990), and by adding

[[Page 24683]]

a new airworthiness directive (AD), amendment 39-9618, to read as 
follows:

96-10-11  McDonnell Douglas: Amendment 39-9618. Docket 94-NM-92-AD. 
Supersedes AD 90-18-03, Amendment 39-6701.

    Applicability: Model DC-9-10, -20, -30, -40, and -50 series 
airplanes; Model DC-9-81 (MD-81), -82 (MD-82), -83 (MD-83), and -87 
(MD-87) series airplanes; Model MD-88 airplanes; and C-9 (military) 
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 in accordance with paragraph (h) 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: For purposes of this AD, references to Tables 2.1, 2.3, 
and 3.1 of the Service Action Requirements Document (SARD) are 
applicable to Model DC-9-10, -20, -30, -40, and -50 series 
airplanes, and C-9 (military) series airplanes; and Tables 2.2 and 
2.4 of the SARD are applicable to Model DC-9-81, -82, -83, and -87 
(MD-81, -82, -83, and -87) series airplanes, and Model MD-88 
airplanes.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent structural failure, accomplish the following:

    Note 3: Paragraph (a) of this AD restates the requirements for 
an initial inspection and the repetitive inspections contained in 
paragraph A. of AD 90-18-03. Therefore, for operators who have 
previously accomplished at least the initial inspection in 
accordance with AD 90-18-03, paragraph (a) of this AD requires that 
the next scheduled inspection be performed within the specified 
repetitive inspection interval after the last inspection performed 
in accordance with paragraph A. of AD 90-18-03.

    (a) Except as provided by paragraph (g) of this AD, within the 
threshold for inspections specified in the service bulletins listed 
in either Table 2.1 or Table 2.2 , as applicable, of ``DC-9/MD-80 
Aging Aircraft Service Action Requirements Document,'' McDonnell 
Douglas Report No. MDC K1572, Revision A, dated June 1, 1990 
(hereinafter referred to as ``SARD, Revision A''), or within one 
repetitive inspection period specified in those service bulletins 
after September 24, 1990 (the effective date of AD 90-18-03, 
Amendment 39-6701); whichever occurs later: Inspect to detect cracks 
in accordance with those service bulletins. Repeat these inspections 
thereafter at the intervals specified in the service bulletins 
listed in either Table 2.1, or Table 2.2, as applicable, of SARD, 
Revision A, until the applicable terminating modification required 
by paragraph (d) of this AD is accomplished.

    Note 4: Table 2.1 of SARD, Revision A, includes the inspections 
specified in DC-9 Service Bulletin 57-129, Revision 3, dated 
November 6, 1987. Since issuance of the SARD, Revision A, that 
service bulletin has been re-issued as two separate service 
bulletins: DC-9 Service Bulletin 57-129, Revision 5, and DC-9 
Service Bulletin 57-200; both dated November 10, 1994. Therefore, 
accomplishment of both DC-9 Service Bulletins 57-129, Revision 5, 
and 57-200 is considered acceptable for compliance with the 
inspections specified in DC-9 Service Bulletin 57-129, Revision 3.

    Note 5: The service bulletin revision levels list under 
``Recommended Modification'' in either Table 2.1 or Table 2.2, as 
applicable, of SARD, Revision A, are acceptable revisions for 
inspections performed prior to September 24, 1994.

    (b) Except as provided by paragraph (g) of this AD, within the 
threshold for inspections specified in the service bulletins listed 
in Tables 2.3 and 3.1, or Table 2.4, as applicable, of ``DC-9/MD-80 
Aging Aircraft Service Action Requirements Document,'' McDonnell 
Douglas Report No. MDC K1572, Revision B, dated January 15, 1993 
(hereinafter referred to as ``SARD, Revision B''), or within one 
repetitive inspection period specified in those service bulletins 
after the effective date of this AD, whichever occurs later: Inspect 
to detect cracks in accordance with those service bulletins. Repeat 
these inspections thereafter at the intervals specified in the 
service bulletins listed in either paragraph (b)(1) or (b)(2) of 
this AD, as applicable, until the applicable terminating 
modification required by paragraph (e) of this AD is accomplished.

    Note 6: Accomplishment of the inspections in accordance with 
McDonnell Douglas DC-9 Service Bulletin 57-129, Revision 5, dated 
November 10, 1994; and McDonnell Douglas DC-9 Service Bulletin 57-
200, dated November 10, 1994; is acceptable for compliance with the 
inspections described in McDonnell Douglas DC-9 Service Bulletin 57-
129, Revision 3, which is referenced in SARD, Revision B.

    (1) For Model DC-9-10, -20, -30, -40, -50, and C-9 (military) 
series airplanes: The service bulletins listed in Tables 2.3 and 3.1 
of SARD, Revision B. Or
    (2) For Model DC-9-81, -82, -83, -87 (MD-81, -82, -83, -87), and 
Model MD-88 airplanes: The service bulletins listed in Table 2.4 of 
SARD, Revision B.

    Note 7: The service bulletin revision levels list under 
``Recommended Modification'' or ``Recommended Inspection'' in Tables 
2.3 and 3.1, or Table 2.4, as applicable, of SARD, Revision B, are 
acceptable revisions for inspections performed prior to the 
effective date of this AD.

    (c) If any crack is found during any inspection required by this 
AD, prior to further flight, either accomplish the applicable 
terminating modification in accordance with paragraph (d) or (e) of 
this AD, or repair in accordance with a method approved by the 
Manager, Los Angeles Aircraft Certification Office (ACO), FAA, 
Transport Airplane Directorate.

    Note 8: Detection of any discrepancy, other than cracking, 
necessitates appropriate corrective action in accordance with the 
provisions of part 43 of the Federal Aviation Regulations (14 CFR 
part 43).

    (d) Except as provided by paragraph (g) of this AD, prior to 
reaching the incorporation thresholds listed in either Table 2.1, or 
Table 2.2, as applicable, of SARD, Revision A or Revision B; or 
within 4 years after September 24, 1990 (the effective date of AD 
90-18-03); whichever occurs later: Accomplish the structural 
modifications specified in the service bulletins listed in either 
Table 2.1, or Table 2.2, as applicable, of SARD, Revision A or 
Revision B. Accomplishment of these modifications constitutes 
terminating action for the applicable inspections required by 
paragraph (a) of this AD.

    Note 9: Paragraph (d) of this AD restates the modification 
requirements of paragraph B. of AD 90-18-03. As allowed by the 
phrase, ``unless accomplished previously,'' if the requirements of 
paragraph B. of AD 90-18-03 have been accomplished previously, 
paragraph (d) of this AD does not require that they be repeated.

    Note 10: The service bulletin revision levels listed under 
``Recommended Modification'' in either Table 2.1, or Table 2.2, as 
applicable, of SARD, Revision A, are acceptable revisions for 
modifications accomplished prior to September 24, 1994.

    Note 11: Accomplishment of the modification in accordance with 
McDonnell Douglas DC-9 Service Bulletin 57-129, Revision 5, dated 
November 10, 1994; and McDonnell Douglas DC-9 Service Bulletin 57-
200, dated November 10, 1994; is acceptable for compliance with the 
modifications described in McDonnell Douglas DC-9 Service Bulletin 
57-129, Revision 3, which is referenced in SARD, Revision A.

    (e) Except as provided by paragraph (g) of this AD, prior to 
reaching the incorporation thresholds listed in either Table 2.3, or 
Table 2.4, as applicable, of SARD, Revision B, or within 4 years 
after the effective date of this AD, whichever occurs later: 
Accomplish the structural modifications specified in the service 
bulletins listed in either Table 2.3, or Table 2.4, as applicable, 
of SARD, Revision B. Accomplishment of this modification constitutes 
terminating action for the applicable inspections required by 
paragraph (b) of this AD.

    Note 12: Accomplishment of the modifications in accordance with 
McDonnell Douglas DC-9 Service Bulletin 57-129, Revision 5, dated 
November 10, 1994, and McDonnell Douglas DC-9 Service Bulletin 57-
200, dated November 10, 1994; is acceptable for compliance with the 
modifications described in McDonnell Douglas DC-9 Service Bulletin 
57-129, Revision 3, which is referenced in SARD, Revision B.

    Note 13: The service bulletin revision levels listed under 
``Recommended Modification'' in either Table 2.3, or Table 2.4 of 
SARD, Revision B, are acceptable revisions for modifications 
accomplished prior to the effective date of this AD.


[[Page 24684]]


    Note 14: The modifications required by paragraphs (d) and (e) of 
this AD do not terminate the inspection requirements of any other AD 
unless that AD specifies that any such modification constitutes 
terminating action for those specified inspection requirements.

    (f) For Model DC-9-10, -20, -30, -40, -50, and C-9 (military) 
series airplanes: Prior to the accumulation of 100,000 total 
landings, accomplish the modifications specified in McDonnell 
Douglas DC-9 Service Bulletin 53-230, Revision 1, dated January 12, 
1993. Accomplishment of these modifications constitute terminating 
action for the inspections required by AD 88-24-08 R2, amendment 39-
6469.
    (g) The McDonnell Douglas service bulletins that are listed 
below, are addressed in the following separate rulemaking actions. 
Therefore, the actions specified in these service bulletins that are 
referenced in the following tables of SARD, Revision A or Revision 
B, are excluded from the requirements of this AD.

------------------------------------------------------------------------
                     McDonnell Douglas Service                Amendment 
      Table(s)                Bulletin             AD No.        No.    
------------------------------------------------------------------------
3.1................  DC-9 Service Bulletin 54-     77-14-19      39-2971
                      30.                                               
2.1................  DC-9 Service Bulletin 27-     92-11-10      39-8260
                      196.                                              
2.1................  DC-9 Service Bulletin 27-     92-11-10      39-8260
                      250.                                              
2.1 and 2.2........  MD-80 Service Bulletin 53-    94-08-04      39-8875
                      186.                                              
2.2................  MD-80 Service Bulletin 53-    94-08-04      39-8875
                      216.                                              
2.1................  DC-9 Service Bulletin 57-     96-01-05      39-9481
                      125.                                              
2.3................  DC-9 Service Bulletin 57-     96-01-05      39-9481
                      148.                                              
------------------------------------------------------------------------

    (h) 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, Los Angeles Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. Operators shall 
submit their requests through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Los Angeles ACO.

    Note 15: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

    (i) Alternative methods of compliance previously granted for AD 
90-18-03, amendment 39-6701, continue to be considered as acceptable 
alternative methods of compliance for the relevant provisions of 
this amendment.
    (j) 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.
    (k) The inspections and modifications shall be done in 
accordance with ``DC-9/MD-80 Aging Aircraft Service Action 
Requirements Document,'' McDonnell Douglas Report No. MDC K1572, 
Revision A, dated June 1, 1990; and in accordance with ``DC-9/MD-80 
Aging Aircraft Service Action Requirements Document,'' McDonnell 
Douglas Report No. MDC K1572, Revision B, dated January 15, 1993, 
which contains the following list of effective pages:

------------------------------------------------------------------------
                                       Revision                         
                                        letter                          
              Page No.                 shown on     Date shown on page  
                                         page                           
------------------------------------------------------------------------
List of Effective Pages.............          B   January 15, 1993.     
Pages xi and xii....................                                    
------------------------------------------------------------------------

    The incorporation by reference of ``DC-9/MD-80 Aging Aircraft 
Service Action Requirements Document,'' McDonnell Douglas Report No. 
MDC K1572, Revision A, dated June 1, 1990, was approved previously 
by the Director of the Federal Register in accordance with 5 U.S.C. 
552(a) and 1 CFR part 51 as of September 24, 1990 (55 FR 34704, 
August 24, 1990). The incorporation by reference of ``DC-9/MD-80 
Aging Aircraft Service Action Requirements Document,'' McDonnell 
Douglas Report No. MDC K1572, Revision B, dated January 15, 1993, is 
approved by the Director of the Federal Register in accordance with 
5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from 
McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, 
California 90846, Attention: Technical Publications Business 
Administration, Department C1-L51 (2-60). Copies may be inspected at 
the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., 
Renton, Washington; or at the FAA, Transport Airplane Directorate, 
Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, 
Lakewood, California 90712; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
    (l) This amendment becomes effective on June 20, 1996.

    Issued in Renton, Washington, on May 8, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-12020 Filed 5-15-96; 8:45 am]
BILLING CODE 4910-13-U