Airworthiness Directives; McDonnell Douglas Model DC-10-30 and - 40 Series Airplanes and KC-10A (Military) Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-154-AD; Amendment 39-8860; AD 94-07-02]

Airworthiness Directives; McDonnell Douglas Model DC-10-30 and -

40 Series Airplanes and KC-10A (Military) Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to certain McDonnell Douglas Model DC-10 series airplanes

and KC-10A (military) airplanes, that requires modification of the

cavity vent drain tube assembly at the center wing lower auxiliary fuel

tank cavity. This amendment is prompted by a report that the cavity

vent tube, if not properly grounded, could act as an electrical path in

the event of a lightning strike. The actions specified by this AD are

intended to prevent arcing in the tank cavity and possible resulting

fire.

DATES: Effective May 23, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of May 23, 1994.

ADDRESSES: The service information referenced in this AD may be

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

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

Administrative Support, Dept. L51, M.C. 2-98. 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, Los Angeles Aircraft Certification Office

(ACO), 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: Raymond Vakili, Aerospace Engineer,

Propulsion Branch, ANM-140L, FAA, Transport Airplane Directorate, Los

Angeles Aircraft Certification Office, 3229 East Spring Street, Long

Beach, California 90806-2425; telephone (310) 988-5262; fax (310) 988-

5210.

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

Aviation Regulations to include an airworthiness directive (AD) that is

applicable to certain McDonnell Douglas Model DC-10 series airplanes

and KC-10A (military) airplanes was published in the Federal Register

on November 4, 1993 (58 FR 58807). That action proposed to require

modification of the cavity vent drain tube assembly at the center wing

lower auxiliary fuel tank.

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 proposed rule.

The Air Transport Association (ATA) of America, on behalf of one of

its member operators, requests that the proposal be withdrawn. The

commenter maintains that the proposed modification will allow some fuel

leakage within specified limits into the lower auxiliary tank cavity.

This commenter asserts that, if this modification is not mandated by

the FAA, then fuel will not be permitted to leak into the cavity and,

unless fuel/vapor is present, there is no risk of fire in this cavity

in the event of a lighting strike. The commenter also points out that a

daily check to detect fuel leakage in the cavity drain valve is

currently specified in the On Aircraft Maintenance Planning (OAMP)

document for Model DC-10 series airplanes. The commenter concludes

that, since these inspections are performed on a daily basis, and since

fuel will not be permitted to leak into the cavity if the modification

is not mandated, then a lightning strike will not pose a threat to an

area containing fuel or fuel vapor.

The FAA does not concur that withdrawal of the proposal is

appropriate. First, the FAA points out that the OAMP document is not a

mandated, FAA-approved document; therefore, regardless of the number or

types of inspections that are contained in it, there is no assurance

that operators will strictly comply with those inspections or the

indicated inspection intervals. Additionally, there is always the

potential that a fuel leak could develop during flight between

inspection intervals. Second, the FAA has determined that, since the

required modification of the cavity vent drain tube assembly will

prevent the possibility of a lightning strike traveling up the cavity

vent tube, the possibility of arcing in the fuel tank cavity is thereby

eliminated (regardless of whether or not fuel/vapor is present).

Further, the FAA has determined that long term continued operational

safety will be better assured by actual modification of the cavity vent

drain tube assembly to remove the source of the problem, rather than by

continuous inspections. Long term inspections may not be providing the

degree of safety assurance necessary for the transport airplane fleet.

This, coupled with a better understanding of the human factors

associated with numerous continual inspections, has led the FAA to

consider placing less emphasis on inspections and more emphasis on

design improvements. The modification required by this AD is in

consonance with these considerations.

The ATA also requests that the proposed compliance time of 12

months for the modification be extended to 18 months. Such an extension

would permit accomplishment of the proposed modification during

regularly scheduled maintenance visits for most affected operators and

would preclude special scheduling at considerable expense. The FAA

concurs. Upon consideration of the information provided by the

commenter, and the fact that there have been no in-service incidents of

arcing or fire in the tank cavity (related to grounding problems in the

cavity vent drain tube assembly), the FAA has determined that extending

the compliance time by 6 additional months will not adversely affect

safety. Such extension will align with operators normal ``C'' checks,

and will allow the modification to be performed at a base during

regularly scheduled maintenance where special equipment and trained

maintenance personnel will be available if necessary. Paragraph (a) of

the final rule has been revised accordingly.

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 change previously

described. The FAA has determined that this change will neither

increase the economic burden on any operator nor increase the scope of

the AD.

There are approximately 294 McDonnell Douglas Model DC-10-30 and -

40 series airplanes and KC-10A (military) airplanes of the affected

design in the worldwide fleet. The FAA estimates that 127 airplanes of

U.S. registry will be affected by this AD, that it will take

approximately 3.5 work hours per airplane to accomplish the required

actions, and that the average labor rate is $55 per work hour. Required

parts will cost approximately $120 per airplane. Based on these

figures, the total cost impact of the AD on U.S. operators is estimated

to be $39,687.50, or $312.50 per airplane.

The total cost impact figure discussed above is based on

assumptions that no operator has yet accomplished any of the

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

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

The 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 adding the following new

airworthiness directive:

94-07-02 McDonnell Douglas: Amendment 39-8860. Docket 93-NM-154-AD.

Applicability: McDonnell Douglas Model DC-10-30 and -40 series

airplanes, and KC-10A (military) airplanes; as listed in McDonnell

Douglas DC-10 Service Bulletin 28-204, dated August 5, 1993;

certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent arcing in the tank cavity and possible resulting

fire, accomplish the following:

(a) Within 18 months after the effective date of this AD, modify

the cavity vent drain tube assembly at the center wing lower

auxiliary fuel tank cavity in accordance with McDonnell Douglas DC-

10 Service Bulletin 28-204, dated August 5, 1993.

(b) 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: Information concerning the existence of approved

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

obtained from the Los Angeles ACO.

(c) Special flight permits may be issued in accordance with

Federal Aviation Regulations (FAR) 21.197 and 21.199 to operate the

airplane to a location where the requirements of this AD can be

accomplished.

(d) The modification shall be done in accordance with McDonnell

Douglas DC-10 Service Bulletin 28-204, dated August 5, 1993. 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, CA 90801-1771, Attention: Business Unit

Manager, Technical Administrative Support, Dept. L51, M.C. 2-98.

Copies may be inspected at the FAA, Transport Airplane Directorate,

1601 Lind Avenue SW., Renton, Washington; or at the FAA, Los Angeles

ACO, 3229 E. Spring Street, Long Beach, California; or at the Office

of the Federal Register, 800 North Capitol Street NW., suite 700,

Washington, DC.

(e) This amendment becomes effective on May 23, 1994.

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

John J. Hickey,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-6911 Filed 4-20-94; 8:45 am]

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