[Federal Register Volume 60, Number 30 (Tuesday, February 14, 1995)]
[Rules and Regulations]
[Pages 8292-8294]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-1846]



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



DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-52-AD; Amendment 39-9126; AD 95-02-07]


Airworthiness Directives; Boeing Model 747 Series Airplanes 
Equipped With General Electric CF6-45 or CF6-50 Engines or Pratt & 
Whitney JT9D Series Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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

SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 747 series airplanes, that requires 
installation of a seal on the wing front spar at each engine strut. 
This amendment is prompted by a report of a fire that occurred due to 
fuel leakage from the fuel line coupling in the engine strut area along 
the wing front spar while the airplane was on the ground after engine 
shutdown. The actions specified by this AD are intended to ensure that 
fuel is contained within the strut drainage area and channeled away 
from ignition sources.

DATES: Effective March 16, 1995. -
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 16, 1995.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. 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 Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: G. Michael Collins, Aerospace 
Engineer, Propulsion Branch, ANM-140S, FAA, Transport Airplane 
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, 
SW., Renton, Washington 98055-4056; telephone (206) 227-2689; fax (206) 
227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain Boeing Model 747 series 
airplanes was published in the Federal Register on June 9, 1994 (59 FR 
29744). That action proposed to require installation of a seal on the 
wing front spar at each engine strut. -
    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.
    Several commenters state that the one reported incident was an 
``isolated incident'' and is not characteristic of industry findings. 
One commenter also states that the incident was not a safety-of-flight 
issue since the reported fire occurred while the airplane was on the 
ground. Because of this, these commenters request that the FAA withdraw 
the proposed rule. The FAA does not concur. As explained in detail in 
the preamble to the proposed rule, airflow when the airplane is in 
flight or airflow from the engine running when the airplane is on the 
ground does prevent fuel from leaking onto hot engine surface. However, 
a potential unsafe condition still exists because fire can occur after 
engine shutdown as a result of the fuel dripping onto the hot engine 
surface. The reported fire demonstrates that the design of the 
flammable fluid drainage system does not adequately separate the fuel 
leak from the hot surface of the engine following engine shutdown. The 
FAA has determined that the actions required by this AD are warranted 
in order to address that unsafe condition.
    Several commenters contend that the proposed installation of a seal 
on the wing front spar at each engine will not prevent a fuel leak from 
occurring. One commenter states that individual modifications, such as 
the proposed modification, should only be required as part of a more 
comprehensive program of modifications that will address all known fuel 
system leakage problems. (The commenter did not, however, provide any 
specific details of a program.) Another commenter states that periodic 
replacement of the O-rings in the fitting would prevent the leakage of 
fuel; therefore, the proposed installation is not necessary. Because of 
these items, these commenters request that the rule not be issued. The 
FAA does not concur. Each incident report and each modification 
presented to correct causes of fuel leakage incidents is evaluated by 
the FAA. Both the effectiveness of the modification and the economic 
impact to accomplish corrective action required by an AD are 
considered. The FAA has determined that the installation required by 
this AD will improve the drainage system and prevent future fires that 
could be caused by fuel leakage from the fuel line (Wiggins) coupling 
in the engine strut area. Scheduled replacement of the O-rings may 
reduce the potential for fuel leaks caused by worn or aged O-rings, but 
it will not eliminate all causes of fuel leakage in the area of the 
modification.
    One commenter states that the seal described in the proposed rule 
will be replaced during an anticipated ``Boeing Model 747 strut 
modification program,'' and that installing the seal before modifying 
the strut area would provide a short-lived increase in safety. This 
commenter, therefore, considers the proposed installation to be 
unwarranted. The FAA does not concur. The planned strut modification 
program does not include a requirement for incorporation of the 
installation required by this AD, nor has a compliance time for the 
strut modifications been established; it is likely that the compliance 
time may be a period of three to five years. Although the planned strut 
modifications may require the removal and reinstallation of the seal 
installation required by this AD, the risk of a fire occurring before 
the planned strut modification program is implemented outweighs the 
convenience of waiting to install the seal until the strut modification 
is accomplished. The installation required by this AD can be 
incorporated during normal scheduled maintenance periods, thereby 
reducing the costs associated with this installation since access to 
this area will be necessitated in order to accomplish other scheduled 
maintenance actions.
    Several commenters request that the FAA extend the proposed 
compliance time for the installation. Some of the commenters request 
the compliance time be extended from the proposed 12 months to as much 
as 48 months. This would permit ample time to accomplish the 
installation during scheduled maintenance periods. One of these 
commenters requests that the compliance time be extended to coincide 
with the planned strut modification program to reduce the additional 
cost to the operators. The FAA concurs that the compliance time may be 
extended somewhat. In [[Page 8293]] developing an appropriate 
compliance time for this AD action, the FAA considered not only the 
degree of urgency associated with addressing the subject unsafe 
condition, but the practical aspect of incorporating the required 
installation into affected operators' scheduled maintenance visits, 
when the airplanes would be located at a base where facilities and 
trained personnel would be readily available, if necessary. The FAA has 
reviewed data submitted by the manufacturer as to recommended 
installation time, and concurs with the commenters' requests for an 
extension. The FAA has determined that extending the compliance time 
from 12 months to 18 months will not compromise safety. Paragraph (a) 
of the final rule has been revised accordingly.
    As a result of recent communications with the Air Transport 
Association (ATA) of America, the FAA has learned that, in general, 
some operators may misunderstand the legal effect of AD's on airplanes 
that are identified in the applicability provision of the AD, but that 
have been altered or repaired in the area addressed by the AD. The FAA 
points out that all airplanes identified in the applicability provision 
of an AD are legally subject to the AD. If an airplane has been altered 
or repaired in the affected area in such a way as to affect compliance 
with the AD, the owner or operator is required to obtain FAA approval 
for an alternative method of compliance with the AD, in accordance with 
the paragraph of each AD that provides for such approvals. A note has 
been added to this final rule to clarify this requirement.
    Additionally, the FAA has recently reviewed the figures it has used 
over the past several years in calculating the economic impact of AD 
activity. In order to account for various inflationary costs in the 
airline industry, the FAA has determined that it is necessary 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.
    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.
    There are approximately 610 Boeing Model 747 series airplanes of 
the affected design in the worldwide fleet. The FAA estimates that 183 
airplanes of U.S. registry will be affected by this AD, that it will 
take approximately 14 work hours per airplane to accomplish the 
required actions, and that the average labor rate is $60 per work hour. 
Required parts will cost approximately $57 per airplane. Based on these 
figures, the total cost impact of the AD on U.S. operators is estimated 
to be $164,151, or $897 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 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 adding the following new 
airworthiness directive:

95-02-07  Boeing: Amendment 39-9126. Docket 94-NM-52-AD.

    Applicability: Model 747 series airplanes, equipped with General 
Electric CF6-45 or CF6-50 engines, or Pratt & Whitney JT9D series 
engines; as listed in Boeing Service Bulletin 747-28-2160, Revision 
1, dated December 16, 1993; 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 use the authority 
provided in paragraph (b) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition; or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any airplane from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To ensure that fuel is contained within the strut drainage area 
and channeled away from ignition sources, accomplish the following:
    (a) Within 18 months after the effective date of this AD, 
install a seal on the wing front spar at each engine strut in 
accordance with Boeing Service Bulletin 747-28-2160 dated July 23, 
1992, or Revision 1, dated December 16, 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, Seattle 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, Seattle ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (c) 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.
    (d) The installation shall be done in accordance with Boeing 
Service Bulletin 747-28-2160, dated July 23, 1992, or Boeing Service 
Bulletin 747-28-2160, Revision 1, dated December 16, 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 Boeing Commercial 
[[Page 8294]] Airplane Group, P.O. Box 3707, Seattle, Washington 
98124-2207. Copies may be inspected at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.
    (e) This amendment becomes effective on March 16, 1995.

    Issued in Renton, Washington, on January 19, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-1846 Filed 2-13-95; 8:45 am]
BILLING CODE 4910-13-U