[Federal Register Volume 59, Number 72 (Thursday, April 14, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-6910]


[[Page Unknown]]

[Federal Register: April 14, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-NM-162-AD; Amendment 39-8859; AD 94-07-01]

 

Airworthiness Directives; McDonnell Douglas Model MD-11 and MD-
11F Series 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 MD-11 and MD-11F series 
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 16, 1994. -
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of May 16, 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 MD-11 and MD-11F series 
airplanes was published in the Federal Register on November 4, 1993 (58 
FR 58808). That action proposed to require modification of the cavity 
vent drain tube assembly located in 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 lightning 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 MD-11 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. 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 73 McDonnell Douglas Model MD-11 and MD-11F 
series airplanes of the affected design in the worldwide fleet. The FAA 
estimates that 29 airplanes of U.S. registry will be affected by this 
AD, that it will take approximately 3 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 $8,265, or $285 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:


94-07-01 McDonnell Douglas: Amendment 39-8859. Docket 93-NM-162-AD.

     -Applicability: Model MD-11 and MD-11F series airplanes; as 
listed in McDonnell Douglas MD-11 Service Bulletin 28-42, dated 
August 12, 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 MD-
11 Service Bulletin 28-42, dated August 12, 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 MD-11 Service Bulletin 28-42, dated August 12, 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, 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, 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.
    -(e) This amendment becomes effective on May 16, 1994.

    Issued in Renton, Washington, on March 18, 1994.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-6910 Filed 4-13-94; 8:45 am]
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