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

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-08-AD; Amendment 39-8807; AD 94-03-01]

Airworthiness Directives; McDonnell Douglas Model DC-9 Series

Airplanes and C-9 (Military) 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 series airplanes and

C-9 (military) airplanes, that currently requires the implementation of

a program of structural inspections to detect and correct fatigue

cracking in order to ensure the continued airworthiness of these

airplanes as they approach the manufacturer's original fatigue design

life goal. This amendment requires, among other things, revision of the

existing program to require visual inspections of additional structure.

This amendment is prompted by new data submitted by the manufacturer

indicating that certain revisions to the program are necessary in order

to increase the confidence level of the statistical program to ensure

timely detection of cracks in various airplane structures. The actions

specified by this AD are intended to prevent fatigue cracking that

could compromise the structural integrity of these airplanes.

DATES: Effective on March 14, 1994.

The incorporation by reference of certain publications listed in

the regulations was approved previously by the Director of the Federal

Register as of November 21, 1988 (53 FR 46866).

The incorporation by reference of certain other publications listed

in the regulations was approved by the Director of the Federal Register

as of March 14, 1994.

ADDRESSES: The service information referenced in this AD may be

obtained from McDonnell Douglas Corporation, P.O. Box 1771, Long Beach,

California 90846-1771, Attention: Business Unit Manager, Technical

Publications--Technical Administrative Support, C1-L5B. This

information may be examined at the Federal Aviation Administration

(FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue,

SW., Renton, Washington; or at the FAA, Transport Airplane Directorate,

Los Angeles Aircraft Certification Office, 3229 East Spring Street,

Long Beach, California; or at the Office of the Federal Register, 800

North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: David Hsu, Aerospace Engineer,

Airframe Branch, ANM-122L, FAA, Transport Airplane Directorate, Los

Angeles Aircraft Certification Office, 3229 East Spring Street, Long

Beach, California 90806-2425; telephone (310) 988-5323; fax (310) 988-

5210.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations by superseding AD 87-14-07 R1, Amendment 39-6019

(53 FR 46866, November 21, 1988), which is applicable to McDonnell

Douglas Model DC-9 series airplanes and C-9 (military) airplanes, was

published in the Federal Register on March 29, 1993 (58 FR 16505). The

action proposed to require, among other things, revision of the

existing Structural Inspection Document (SID) sampling program to

require additional visual inspections of all Principal Structural

Elements (PSE) on certain airplanes.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

One commenter supports the proposal.

Several commenters objected to the proposed repair requirements

which would require that any cracked structure detected during the

required inspections be repaired ``in accordance with a method approved

by the Manager of the Los Angeles Aircraft Certification Office

(LAACO).'' These commenters prefer the language of AD 87-14-07 R1,

which permitted cracked structure to be repaired ``in accordance with

an FAA-approved method,'' and request that the rule be revised to

include this language. This requested language would allow repairs to

be approved routinely by the manufacturer, Designated Engineering

Representatives (DER), or SFAR 36-authorized organizations, without

prior approval by the Manager of LAACO. The commenters' justification

for this request involves three points:

1. The commenters contend that it is not logical that the manner of

repair approval should differ between repairs of PSE's found cracked

during a SID inspection and repairs of PSE's found cracked during

inspections other than those directly called for by the SID program.

2. The commenters also contend that it should not be necessary to

involve the Manager of the LAACO in the repair approval process, since

the process takes too much time. The commenters consider that adequate

repair procedures already are available in the DC-9 Structural Repair

Manual (SRM) and the service bulletins referenced in the SID; repair

procedures can also be designed and approved by DER's without further

review and approval of the LAACO.

3. Several of the commenters also request that the airplane

manufacturer, operator DER's, and SFAR 36-authorized operators be

allowed to approve repairs that are outside the scope of the SRM, at

least temporarily, in order to allow the airplane to be returned to

revenue service pending the outcome of a subsequent damage tolerance

assessment (DTA) of the repair, which is required by the SID program of

all repairs. These commenters state that restricting approval of such

repairs to the LAACO Manager would hamper repair efforts and ``would

have an appreciable effect on the airplane's return-to-service times.''

The FAA does not concur with the commenters' requests. While it is

true that DER's and SFAR 36-authorized organizations are authorized to

approve certain repairs of cracking that is found during routine

maintenance or opportunity inspections, the FAA considers that any

cracking detected in PSE structure during an inspection required by

this AD (and the SID program) is indication of an airworthiness concern

of a complex nature. Such cracking does not warrant ``routine''

handling, but requires expeditious action and a special approach to

address it. It is crucial that the FAA be aware of all repairs made to

PSE's or to their configuration. Where repair data do not exist, it is

essential that the FAA have feedback as to the type of repairs being

made. Given that possible new relevant issues might be revealed during

this process, it is imperative that the FAA have such feedback. Only by

reviewing repair approvals can the FAA be assured of this feedback and

of the adequacy of the repair methods. The FAA has determined that

standardization and continuity of repair approvals can best be

maintained by having one single point of approval for all repairs of

cracks in PSE's identified during SID inspections required by this AD.

Since the Manager of the LAACO is accountable for the primary oversight

for the actions regarding this AD, it is appropriate that he be this

single point of approval. His involvement, therefore, is warranted in

the development and approval of repairs.

Standardization and continuity of repair approval is especially

important in light of the complexity of the DC-9 SID program. This

program is unique in that it is based on the principle of statistical

sampling, which requires cooperation between aircraft operators, the

manufacturer, and the FAA in selecting airplane samples, accomplishing

inspections, reporting discrepancies as they are found, and evaluating

the safety impact of the discrepancies so that timely program

adjustments can be made and the appropriate corrective actions taken to

protect both the discrepant airplane and the fleet. For example, when

one bona fide fatigue crack is determined, the inspection and repair

requirements must be developed in a timely manner to protect the entire

Model DC-9 fleet. This requires coordination with the Manager of the

LAACO for the review of all SID findings and a timely determination of

bona fide fatigue cracking.

Further, cracked PSE structure detected during an inspection that

is not directly required by the SID must first be reported to the FAA

by the operator via a Service Difficulty Report (SDR), as is required

by the relevant operating rules of the Federal Aviation Regulations.

These SDR reports are compiled in an SDR data base that is used by the

FAA for trend analysis and data studies used in planning, directing,

controlling, and evaluating various airworthiness programs. Cracked PSE

structure found during an inspection called out by the SID program (and

this AD) are compiled into a SID data base that is used by the FAA for

many of the same purposes as SDR data base, including identification of

necessary revisions to the SID program itself. The Manager of the LAACO

has access to both the SDR and the SID data bases and, therefore, he is

in a unique position that affords him a broad overview both to

understand and assess the overall cracking and repair environment, and

to implement timely initiatives to address and manage it.

As part of the SID program, every repair of PSE structure is

required to have a DTA in order to establish its effect on the fatigue

life of the affected PSE structure. The DTA process involves the review

and use of type design data that are proprietary and may not be

available to those persons (such as a DER) who are generally authorized

to approve routine repairs. For this reason, it is appropriate that the

Manager of the LAACO be the focal point in the DTA approval process.

In some cases, repairs are made to PSE structure as a result of

cracking that was found during an opportunity inspection, and the

approval of the repair is made without the coordination of the

manufacturer and the LAACO. When the time arrives for that PSE to be

inspected in compliance with the AD, the PSE becomes a ``discrepant

PSE.'' If a DTA were not accomplished on the ``discrepant PSE'' at the

time of the repair, compliance with the AD could require that the

repair be removed or modified at a later time. In either case, the

Manager of the LAACO is asked to ensure that all repairs to cracked

PSE's comply with the AD.

The FAA considers that any repair to cracked PSE's without the

required DTA can only be temporary, and will eventually require

coordination with the Manager of the LAACO. Most methods of repair

specified in the DC-9 Structural Repair Manual, the relevant service

bulletins, or 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 LAACO are working

very closely with the manufacturer to expedite interim repair approval

requests. Such requests may be made under the provisions of paragraph

(d) of the final rule.

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 as proposed.

There are approximately 920 Model DC-9 series airplanes and C-9

(military) airplanes of the affected design in the worldwide fleet. The

FAA estimates that 586 airplanes of U.S. registry and 19 U.S. operators

would be affected by this proposed AD.

Incorporation of the SID program into an operator's maintenance

program, as was required by AD 87-14-07 R1, necessitates approximately

1,000 work hours (per operator), at an average labor cost of $55 per

work hour. Based on these figures, the cost to the 19 affected U.S.

operators to incorporate the SID program, which was required previously

in accordance with AD 87-14-07 R1, is estimated to be $1,045,000.

The incorporation of the additional procedures that are required by

this new AD action will require approximately 62 additional work hours

per operator to accomplish, at an average labor cost of $55 per work

hour. Based on these figures, the cost to the 19 affected U.S.

operators to incorporate these additional procedures into the SID

program into an operator's maintenance program is estimated to be

$64,790.

The recurring inspection costs, as was required by AD 87-14-07 R1

and continues to be required by this new AD action, is approximately

341 work hours per airplane per year, at an average labor cost of $55

per work hour. Based on these figures, these recurring inspection costs

are estimated to be $18,755 per airplane, or $10,990,430 for the

affected U.S. fleet.

The recurring inspection procedures that are added to the program

by this new AD action will require approximately 21 additional work

hours per airplane per year to accomplish, at an average labor charge

of $55 per work hour. Based on these figures, the additional recurring

inspection cost impact added by this AD on U.S. operators is estimated

to be $1,155 per airplane, or $676,830 for the affected U.S. fleet.

Based on the figures discussed above, the total cost impact of this

AD is estimated to be $11,732,050 for the first year, and $11,667,260

for each year thereafter. These ``total cost impact'' figures assume

that no operator has yet accomplished any of the requirements of this

AD. However, it can be reasonably assumed that a majority of affected

operators have already initiated the original SID program (as required

by AD 87-14-07 R1) and many may have already initiated the additional

inspections required by this new AD action.

Additionally, the number of required work hours for each inspection

requirement of this AD (and the SID program), as indicated above, is

presented as if the accomplishment of those actions were to be

conducted as ``stand alone'' actions. However, in actual practice,

these actions for the most part will be accomplished coincidentally or

in combination with normally scheduled airplane inspections and other

maintenance program tasks. Therefore, the actual number of necessary

additional work hours will be minimal in many instances. Further, any

costs associated with special airplane scheduling can be expected to be

minimal.

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 14 CFR part

39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing amendment 39-6019 (53 FR

46866, November 21, 1988), and by adding a new airworthiness directive

(AD), amendment 39-8807, to read as follows:

94-03-01 McDonnell Douglas: Amendment 39-8807. Docket 93-NM-08-AD.

Supersedes AD 87-14-07 R1, Amendment 39-6019.

Applicability: Model DC-9-10, -20, -30, -40, -50 series

airplanes, and C-9 (Military) airplanes; certificated in any

category.

Compliance: Required as indicated, unless accomplished

previously.

To ensure the continuing structural integrity of these

airplanes, accomplish the following:

(a) Within one year after December 23, 1988 (the effective date

of AD 87-14-07 R1, Amendment 39-6019), incorporate a revision into

the FAA-approved maintenance inspection program which provides for

inspection(s) of the Principal Structural Elements (PSE) defined in

McDonnell Douglas Report No. L26-008, ``DC-9 Supplemental Inspection

Document (SID),'' Section 2 of Volume I (All Series) of Revision 1,

dated November 1987, in accordance with Section 2 of Volume III-87,

dated November 1987, of the SID. The non-destructive inspection

(NDI) techniques set forth in Section 2 of Volume II, dated November

1987, of the SID provide acceptable methods for accomplishing the

inspections required by this paragraph. All inspection results

(negative or positive) must be reported to McDonnell Douglas, in

accordance with the instructions contained in Section 2 of Volume

III-87, dated November 1987, of the SID. Information collection

requirements contained in this regulation have been approved by the

Office of Management and Budget (OMB) under the provisions of the

Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have

been assigned OMB Control Number 2120-0056.

Note 1: Volume II, dated November 1987, of the SID is comprised

of the following:

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

Revision

Volume designation- level shown

on volume

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

Volume II-10/20-......................................... Original.-

Volume II-20/30-......................................... 1.

Volume II-40-............................................ Original.-

Volume II-50-............................................ Original.

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-(b) Within 6 months after the effective date of this AD,

replace the revision of the FAA-approved maintenance inspection

program required by paragraph (a) of this AD, with a revision that

provides for inspection(s) of the PSE's defined in McDonnell Douglas

Report No. L26-008, ``DC-9 Supplemental Inspection Document (SID),''

Section 2 of Volume I of Revision 3, dated April 1991, in accordance

with Section 2 of Volume III-92, dated July 1992, of the SID.

(1) Visual inspections of all PSE's on airplanes listed in

Volume III-92, dated July 1992, of the SID planning data, are

required by the fleet leader-operator sampling (FLOS) program at

least once during the interval between the start date (SDATE) and

the end date (EDATE) established for each PSE. These visual

inspections are defined in Section 3 of Volume II, dated April 1991,

of the SID, and are required only for those airplanes that have not

been inspected previously in accordance with Section 2 of Volume II,

dated April 1991, of the SID.

(2) The NDI techniques set forth in Section 2 of Volume II,

dated April 1991, of the SID provide acceptable methods for

accomplishing the inspections required by this paragraph.

(3) All inspection results (negative or positive) must be

reported to McDonnell Douglas, in accordance with the instructions

contained in section 2 of Volume III-92, dated July 1992, of the

SID. Information collection requirements contained in this

regulation have been approved by the OMB under the provisions of the

Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have

been assigned OMB Control Number 2120-0056.

Note 2: Volume II, dated April 1991, of the SID is comprised of

the following:

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

Revision

Volume Designation- level shown

on volume

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

Volume II-10/20............................................ 3

Volume II-20/30............................................ 4

Volume II-40............................................... 3

Volume II-50............................................... 3

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

Note 3: NDI inspections accomplished in accordance with the

following Volume II of the SID provide acceptable methods for

accomplishing the inspections required by this paragraph:

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

Revision Date of

Volume Designation-- level-- revision

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

Volume II-10/20-- -....................... 3---......... April 1991.

Volume II-10/20-- -....................... 2---......... April 1990.

Volume II-10/20---........................ 1---......... June 1989.

Volume II-10/20--......................... Original- -.. November

1987.

Volume II-20/30---........................ 4---......... April 1991.

Volume II-20/30---........................ 3---......... April 1990.

Volume II-20/30---........................ 2---......... June 1989.

Volume II-20/30---........................ 1---......... November

1987.

Volume II-40---........................... 3---......... April 1991.

Volume II-40---........................... 2---......... April 1990.

Volume II-40--............................ 1---......... June 1989.

Volume II-40---........................... Original-.... November

1987.

Volume II-50---........................... 3---......... April 1991.

Volume II-50---........................... 2---......... April 1990.

Volume II-50---........................... 1---......... June 1989.

Volume II-50---........................... Original--... November

1987.

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(c) Any cracked structure detected during the inspections

required by paragraph (a) or (b) of this AD must be repaired before

further flight, in accordance with a method approved by the Manager,

Los Angeles Aircraft Certification Office (ACO), FAA, Transport

Airplane Directorate.

-Note 4: Requests for approval of any PSE repair that would

affect the FAA-approved maintenance inspection program that is

required by this AD should include a damage tolerance assessment for

that PSE.

-(d) 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 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 5: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Los Angeles ACO.

-(e) Special flight permits may be issued in accordance with

FAR 21.197 and 21.199 to operate the airplane to a location where

the requirements of this AD can be accomplished.

(f) Certain of the inspections to be added to the FAA-approved

maintenance program shall be done in accordance with McDonnell

Douglas Report No. L26-008, ``DC-9 Supplemental Inspection Document

(SID),'' dated November 1987. The incorporation by reference of this

document 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 December 23, 1988 (53 FR 46866, November 21, 1988). Certain other

of the inspections to be added to the FAA-approved maintenance

program shall be done in accordance with the following volumes of

McDonnell Douglas Report No. L26-008, ``DC-9 Supplemental Inspection

Document (SID),'' that contain the lists of effective pages

indicated below:---------

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Revision

Document Page number level Date

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Volume I--All Series............. List of Effective Pages A, B, C.................................................... 3............ April 1991.

Volume II-10/20.................. List of Effective Pages A, B, C, D, E, F, G, H, I, J, K............................ 3............ April 1991.

L.................................................................................. 2............ April 1990.

Volume II-20/30.................. List of Effective Pages A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, U. 4............ April 1991.

T.................................................................................. Original..... April 1990.

Volume II-40..................... List of Effective Pages A, B, C, D, E, F, G, H, I, J, K, L, M, N, O................ 3............ April 1991.

Volume II-50..................... List of Effective Pages A, B, C, D, E, F, G, H, I, J, K, L, M, N, O................ 3............ April 1991.

Volume III-92 All Series......... Entire Document.................................................................... Original..... July 1992.

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This incorporation by reference was 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,

P.O. Box 1771, Long Beach, California 90846-1771, Attention:

Business Unit Manager, Technical Publications--Technical

Administrative Support, C1-L5B. 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, 3229 East Spring Street, Long

Beach, California; or at the Office of the Federal Register, 800

North Capitol Street, NW., suite 700, Washington, DC.

(g) This amendment becomes effective on March 14, 1994.

Issued in Renton, Washington, on January 20, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-1584 Filed 2-10-94; 8:45 am]

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