Airworthiness Directives; McDonnell Douglas Model DC-10 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-NM-51-AD]

Airworthiness Directives; McDonnell Douglas Model DC-10 Series

Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing

airworthiness directive (AD), applicable to certain McDonnell Douglas

Model DC-10 series airplanes, that currently requires inspection of the

wing rear spar lower cap aft tang fastener and the wing trailing edge

access door sill to detect fatigue cracking, and repair, if necessary.

This action would require installation of a crack preventative

modification of the wing rear spar lower cap, and follow-on

inspections. This proposal is prompted by reports of additional

cracking found in the current inspection area. The actions specified by

the proposed AD are intended to prevent propagation of cracks in the

subject area, which could compromise the structural integrity of the

airplane.

DATES: Comments must be received by October 11, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 94-NM-51-AD, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056. Comments may be inspected at this location

between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal

holidays.

The service information referenced in the proposed rule may be

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

California 90801-1771, Attention: Business Unit Manager, Technical

Administrative support, Dept. L51, M.C. 2-98 . This information may be

examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue,

SW., Renton, Washington; or at the FAA, Los Angeles Aircraft

Certification Office, Transport Airplane Directorate, 3229 East Spring

Street, Long Beach, California.

FOR FURTHER INFORMATION CONTACT: Maureen Moreland, Aerospace Engineer,

Airframe Branch, ANM-120L, Los Angeles Aircraft Certification Office,

FAA, Transport Airplane Directorate, 3229 East Spring Street, Long

Beach, California 90806-2425; telephone (310) 988-5238; fax (310) 988-

5210.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the

proposed rule by submitting such written data, views, or arguments as

they may desire. Communications shall identify the Rules Docket number

and be submitted in triplicate to the address specified above. All

communications received on or before the closing date for comments,

specified above, will be considered before taking action on the

proposed rule. The proposals contained in this notice may be changed in

light of the comments received.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the proposed rule. All

comments submitted will be available, both before and after the closing

date for comments, in the Rules Docket for examination by interested

persons. A report summarizing each FAA-public contact concerned with

the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments

submitted in response to this notice must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket Number 94-NM-51-AD.'' The postcard will be date stamped and

returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request

to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules

Docket No. 94-NM-51-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

On September 25, 1991, the FAA issued AD 91-21-05, amendment 39-

8052 (56 FR 50650, October 8, 1991), which is applicable to certain

McDonnell Douglas Model DC-10 series airplanes. That AD requires

repetitive inspections to detect fatigue cracking of the wing rear spar

lower cap aft tang and the wing trailing edge access door sill, and

repair of any cracking found. That action was prompted by reports of

fatigue cracks found in the wing rear spar lower cap aft tang on four

Model DC-10 series airplanes. This cracking was found during an

inspection conducted in accordance with the Supplemental Inspection

Document (SID) program; that program was required to be implemented by

AD 89-22-10, amendment 39-6330 (54 FR 42291, October 16, 1989). The

requirements of AD 91-21-05 are intended to prevent fatigue cracking in

the subject area. Such cracking, if not detected and corrected in a

timely manner, could compromise the structural integrity of the

airplane.

Since the issuance of that AD, there have been 10 additional

reports of fatigue cracks found in the wing rear spar lower cap aft

tang. Such cracking presents the same unsafe condition as addressed by

the existing AD 91-21-05.

Additionally, since the issuance of that AD, the manufacturer has

developed a crack preventative modification of the wing rear spar lower

cap aft tang and wing trailing edge access door sill that is intended

to minimize the possibility of cracking in these areas.

The FAA has reviewed and approved McDonnell Douglas Alert Service

Bulletin A57-123, Revision 1, dated June 8, 1993, which contains

procedures for conducting various inspections to detect fatigue

cracking of the wing rear spar lower cap aft tang fastener and the wing

trailing edge access door sill, and procedures for repairing any

cracking found. This revised service bulletin is essentially identical

to the original version, which was referenced in AD 91-21-05 as the

appropriate source of service information. The only relevant changes

are a revised listing of current operators of affected airplanes, and

the inclusion of additional repair options.

The FAA has also reviewed and approved McDonnell Douglas Service

Bulletin 57-123, dated June 8, 1993, that describes procedures for

installing a crack preventative modification of the wing rear spar

lower cap aft tang and wing trailing edge access door sill. This

modification entails replacing Taper-Lok fasteners with straight

titanium fasteners, and cold working the holes in the wing rear spar

lower cap forward and aft tangs between stations Xors=430.000 and

Xors=410.000. Accomplishment of this modification will minimize

the possibility of fatigue cracking in the subject areas.

Since an unsafe condition has been identified that is likely to

exist or develop on other products of this same type design, the

proposed AD would supersede AD 91-21-05 to continue to require

repetitive inspections of the wing rear spar lower cap aft tang

fastener and the wing trailing edge access door sill to detect fatigue

cracking, and repair of any cracking found. These actions would be

required to be accomplished in accordance with either the original or

revised version of McDonnell Douglas Alert Service Bulletin A57-123.

This proposed AD would also require the eventual installation of

the crack preventative modification. Once this modification is

accomplished, repetitive post-modification inspections would be

required after the accumulation of a certain number of landings. These

actions would be required to be accomplished in accordance with

McDonnell Douglas Service Bulletin 57-123.

There are approximately 282 Model DC-10 series airplanes of the

affected design in the worldwide fleet. The FAA estimates that 175

airplanes of U.S. registry would be affected by this proposed AD.

The currently required inspections take approximately 8 work hours

per airplane to accomplish, at an average labor rate of $55 per work

hour. Based on these figures, the total cost impact of the current

inspection requirements of this AD on U.S. operators is estimated to be

$77,000, or $440 per airplane, per inspection.

The proposed modification would take approximately 12 work hours to

accomplish, at an average labor rate of $55 per work hour. Required

parts would cost between $3,730 and $6,730 per airplane, depending upon

the airplane model. Based on these figures, the total cost impact of

the proposed modification requirement of this AD on U.S. operators is

estimated to be between $4,390 and $7,390 per airplane.

The proposed post-modification inspections would take approximately

12 work hours per airplane to accomplish, at an average labor rate of

$55 per work hour. Based on these figures, the total cost impact of the

proposed post-modification inspection requirement of this AD on U.S.

operators is estimated to be $115,500, or $660 per airplane, per

inspection.

The total cost impact figure discussed above is based on

assumptions that no operator has yet accomplished any of the current or

proposed requirements of this AD action, and that no operator would

accomplish those actions in the future if this AD were not adopted.

The regulations proposed herein would not have substantial direct

effects on the States, on the relationship between the national

government and the States, or on the distribution of power and

responsibilities among the various levels of government. Therefore, in

accordance with Executive Order 12612, it is determined that this

proposal would not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this proposed

regulation (1) is not a ``significant regulatory action'' under

Executive Order 12866; (2) is not a ``significant rule'' under the DOT

Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);

and (3) if promulgated, will not have a significant economic impact,

positive or negative, on a substantial number of small entities under

the criteria of the Regulatory Flexibility Act. A copy of the draft

regulatory evaluation prepared for this action is contained in the

Rules Docket. A copy of it may be obtained by contacting the Rules

Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration proposes to amend

part 39 of the Federal Aviation Regulations (14 CFR part 39) as

follows:

PART 39--AIRWORTHINESS DIRECTIVES

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 39-8052 (56 FR

50650, October 8, 1991), and by adding a new airworthiness directive

(AD), to read as follows:

McDonnell Douglas: Docket 94-NM-51-AD. Supersedes AD 91-21-05,

Amendment 39-8052.

Applicability: Model DC-10-10, -10F, and -15 series airplanes,

fuselage numbers through 379, inclusive; and Model DC-10-30, -30F,

and -40 series airplanes, fuselage numbers through 275, inclusive;

certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To ensure the structural integrity of these airplanes,

accomplish the following:

(a) Except as provided in paragraphs (b) through (e) of this AD,

prior to the accumulation of 7,000 landings or within 30 days after

October 23, 1991 (the effective date of AD 91-21-05, amendment 39-

8051), which ever occurs later, conduct the initial inspections

specified in either paragraph (a)(1), (a)(2), or (a)(3) of this AD.

(1) Conduct an eddy current inspection of the wing rear spar

lower cap aft tang, and a dye penetrant inspection of the wing

trailing edge access door sill located between Xors=417.000 and

Xors=424.000, in accordance with Option III of McDonnell

Douglas Alert Service Bulletin A57-123, dated July 25, 1991, or

Revision 1, dated June 8, 1993. In addition, within 1,500 landings

after performing the eddy current and dye penetrant inspections,

conduct the inspections specified in either paragraph (a)(2) or

(a)(3) of this AD, and repeat them thereafter as indicated. Or

(2) Conduct an ultrasonic inspection of the area around the six

wing rear spar lower cap aft tang fastener holes, and a dye

penetrant inspection of the wing trailing edge access door sill

located between stations Xors=417.000 and Xors=424.000, in

accordance with Option II of McDonnell Douglas Alert Service

Bulletin A57-123, dated July 25, 1991, or Revision 1, dated June 8,

1993. Repeat these inspections thereafter at intervals not to exceed

1,900 landings until the modification required by paragraph (g) of

this AD is accomplished. Or

(3) Conduct an eddy current inspection of the six wing rear spar

lower cap aft tang fastener holes, and a dye penetrant inspection of

the wing trailing edge access door sill located between stations

Xors=417.000 and Xors=424.000, in accordance with Option I

of McDonnell Douglas Alert Service Bulletin A57-123, dated July 25,

1991, or Revision 1, dated June 8, 1993. Repeat these inspections

thereafter at intervals not to exceed 3,300 landings until the

modification required by paragraph (g) of this AD is accomplished.

(b) The requirements of paragraph (c) of this AD apply to

airplanes on which both of the following actions have been

accomplished:

(1) A dye penetrant inspection of the wing trailing edge access

door sill located between stations Xors=417.000 and

Xors=422.000 has been accomplished prior to October 23, 1991,

in accordance with McDonnell Douglas Service Bulletin 57-61,

Revision 2, dated August 15, 1990; and

(2) An eddy current inspection of the wing rear spar lower cap

aft tang has been accomplished prior to October 23, 1991, per DC-10

Supplemental Inspection Document, Principal Structural Element (PSE)

57.10.007 and 57.10.008, in accordance with McDonnell Douglas

Service Bulletin 57-61, Revision 2, dated August 15, 1990.

(c) For airplanes specified in paragraph (b) of this AD: Conduct

the initial inspections specified in either paragraph (c)(1) or

(c)(2) of this AD within 1,500 landings after accomplishing the

inspections (dye penetrant and eddy current) specified in paragraph

(b) of this AD, or within 30 days after October 23, 1991, whichever

occurs later.

(1) Conduct an ultrasonic inspection of the area around the six

wing rear spar lower cap aft tang fastener holes, and a dye

penetrant inspection of the wing trailing edge access door sill

located between stations Xors=417.000 and Xors=424.000, in

accordance with Option II of McDonnell Douglas Alert Service

Bulletin A57-123, dated July 25, 1991, or Revision 1, dated June 8,

1993. Repeat these inspections thereafter at intervals not to exceed

1,900 landings until the modification required by paragraph (g) of

this AD is accomplished. Or

(2) Conduct an eddy current inspection of the six wing rear spar

lower cap aft tang fastener holes, and a dye penetrant inspection of

the wing trailing edge access door sill located between stations

Xors=417.000 and Xors=424.000, in accordance with Option I

of McDonnell Douglas Alert Service Bulletin A57-123, dated July 25,

1991, or Revision 1, dated June 8, 1993. Repeat these inspections

thereafter at intervals not to exceed 3,300 landings until the

modification required by paragraph (g) of this AD is accomplished.

(d) The requirements of paragraph (e) of this AD apply to

airplanes on which both of the following actions have been

accomplished:

(1) A dye penetrant inspection of the wing trailing edge access

door sill located between stations Xors=417.000 and

Xors=422.000 has been accomplished prior to October 23, 1991,

in accordance with McDonnell Douglas Service Bulletin 57-61,

Revision 2, dated August 15, 1990; and

(2) An eddy current inspection of the wing rear spar lower cap

aft tang fastener holes located between stations Xors=417.000

and Xors=422.000 has been accomplished prior to October 23,

1991, per DPS 4.735-9, in accordance with McDonnell Douglas Service

Bulletin 57-61, Revision 2, dated August 15, 1990.

(e) For airplanes specified in paragraph (d) of this AD: Conduct

the initial inspections specified in either paragraph (e)(1) or

(e)(2) of this AD within 3,300 landings after the accomplishment of

the inspection specified in paragraph (d)(1) of this AD, or within

30 days after October 23, 1991, whichever occurs later.

(1) Conduct an ultrasonic inspection of the area around the six

wing rear spar lower cap aft tang fastener holes, and a dye

penetrant inspection of the wing trailing edge access door sill

located between stations Xors=417.000 and Xors=424.000, in

accordance with Option II of McDonnell Douglas Alert Service

Bulletin A57-123, dated July 25, 1991, or Revision 1, dated June 8,

1993. Repeat these inspections thereafter at intervals not to exceed

1,900 landings until the modification required by paragraph (g) of

this AD is accomplished. Or

(2) Conduct an eddy current inspection of the six wing rear spar

lower cap aft tang fastener holes, and a dye penetrant inspection of

the wing trailing edge access door sill located between stations

Xors=417.000 and Xors=424.000, in accordance with Option I

of McDonnell Douglas Alert Service Bulletin A57-123, dated July 25,

1991, or Revision 1, dated June 8, 1993. Repeat these inspections

thereafter at intervals not to exceed 3,300 landings until the

modification required by paragraph (g) of this AD is accomplished.

(f) If any crack(s) is found during any inspection conducted in

accordance with paragraphs (a) through (e) of this AD, prior to

further flight, repair in a manner approved by the Manager, Los

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

Directorate.

(g) Prior to the accumulation of 10,000 total landings, or

within 5 years after the effective date of this AD, whichever occurs

later, accomplish the crack preventative modification in accordance

with McDonnell Douglas Service Bulletin 57-123, dated June 8, 1993.

Accomplishment of this modification constitutes terminating action

for the inspection requirements of paragraphs (a) through (e) of

this AD.

(h) Prior to the accumulation of 10,000 landings after the

accomplishment of the crack preventative modification required by

paragraph (g) of this AD, conduct an inspection of the wing rear

spar lower cap in accordance with McDonnell Douglas Service Bulletin

57-123, dated June 8, 1993. Repeat this inspection thereafter in

accordance with the following schedule. Any crack(s) found during

any inspection required by this paragraph must be repaired, prior to

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

Los Angeles ACO, FAA, Transport Airplane Directorate.

(1) For Model DC-10-10, -10F, and -15 series airplanes: Repeat

the inspection at intervals not to exceed 4,550 landings.

(2) For Model DC-10-30 and -30F series airplanes: Repeat the

inspection at intervals not to exceed 2,810 landings.

(3) For Model DC-10-40 series airplanes: Repeat the inspection

at intervals not to exceed 3,400 landings.

(i) 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: Information concerning the existence of approved

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

obtained from the Los Angeles ACO.

(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.

Issued in Renton, Washington, on July 18, 1994.

S.R. Miller,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-17860 Filed 7-21-94; 8:45 am]

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