[Federal Register Volume 60, Number 12 (Thursday, January 19, 1995)]
[Rules and Regulations]
[Pages 3739-3741]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-1362]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-217-AD; Amendment 39-9108; AD 94-26-13]


Airworthiness Directives; Boeing Model 737-300, -400, and -500 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 737-300, -400, and -500 series 
airplanes. This action requires modification of the leading edge slat 
access panel and internal structure at Front Spar Station (FSS) 
250.663. This amendment is prompted by reports that fuel leaking from 
the fuel line at FSS 250.663 flowed through a drain hole in a slat 
access panel and leaked into the turbine exhaust area. The actions 
specified in this AD are intended to prevent drainage from such a fuel 
leak into the turbine exhaust area, which could cause an external fire 
under the wing.

DATES: Effective on February 3, 1995.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of February 3, 1995.
    Comments for inclusion in the Rules Docket must be received on or 
before March 20, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 94-NM-217-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    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 FAA, Transport 
Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington; or at 
the Office of 

[[Page 3740]]
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Stephen S. Bray, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (206) 227-2681; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: On March 10, 1994, the FAA issued AD 94-06-
11, amendment 39-8858 (59 FR 13444, March 22, 1994), applicable to 
certain Boeing Model 737-300, -400, and -500 series airplanes. That AD 
requires modification of the leading edge slat access panel and 
internal structure at Front Spar Station (FSS) 250.663. That action was 
prompted by reports that fuel leaking from the fuel line at FSS 250.663 
flowed through a drain hole in a slat access panel and leaked into the 
turbine exhaust area. (The strut drain system installed on these 
airplanes is designed to divert fuel leakage to a point five feet from 
the turbine exhaust area.) One of the incidents caused an external fire 
under the wing. Typically, such a fire could occur on the ground after 
the engines have been shut down. The resultant fire could spread from 
the turbine exhaust area to the strut and, subsequently, could ignite 
fuel within the strut. This condition, if not detected and corrected, 
could cause an external fire under the wing.
    Since issuance of AD 94-06-11, the FAA has determined that the same 
unsafe condition addressed in that AD may exist on certain additional 
Model 737-300, -400, and -500 series airplanes; therefore, these 
additional airplanes also are subject to fuel leakage into the turbine 
exhaust area, which could cause an external fire under the wing. AD 94-
06-11 is applicable only to airplanes having line positions 1001 
through 1976 inclusive, 1978 through 2183 inclusive, 2185 through 2186 
inclusive, and 2188 through 2193 inclusive. The additional airplanes 
identified are those having line positions 2184, 2187, 2194 through 
2197 inclusive, and 2199. These additional airplanes are operated 
currently by non-U.S. operators under foreign registry.
    The FAA has reviewed and approved Boeing Service Bulletin 737-57-
1221, Revision 2, dated November 17, 1994, that describes procedures 
for modifying the leading edge slat access panel and internal structure 
at FSS 250.663. Incorporation of this modification entails sealing the 
drain hole in Slat Access Panels 6307L and 6407R, changing the internal 
structure of the leading edge panel by creating a drain path to the 
strut drain system, and sealing the slat access panel and the internal 
structure of the leading edge panel to keep fuel leakage within the new 
drain path.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design, this AD is 
being issued to prevent drainage from a fuel leak into the turbine 
exhaust area, which could cause an external fire under the wing. This 
AD requires modification of the leading edge slat access panel and 
internal structure at FSS 250.663. The actions are required to be 
accomplished in accordance with the service bulletin described 
previously. This AD applies only to Model 737-300, -400, and -500 
series airplanes having line positions 2184, 2187, 2194 through 2197 
inclusive, and 2199.

    Note: The FAA's normal policy is that when an AD requires a 
substantive change, such as a change (expansion) in its 
applicability, the ``old'' AD is superseded by removing it from the 
system and a new AD is added. In the case of this AD action, the FAA 
normally would have proposed superseding AD 94-06-11 to expand its 
applicability to include the additional affected airplanes. However, 
in reconsideration of the entire fleet size that would be affected 
by a supersedure action, and the consequent workload associated with 
revising maintenance record entries, the FAA has determined that a 
less burdensome approach is to issue a separate AD applicable only 
to these additional airplanes. This AD does not supersede AD 94-06-
11; airplanes listed in the applicability of AD 94-06-11 are 
required to continue to comply with the requirements of that AD. 
This AD is a separate AD action, and is applicable on to Model 737-
300, -400, and -500 series airplanes, line positions 2184, 2187, 
2194 through 2197 inclusive, and 2199.]

    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 included in this rule to clarify this requirement.
    None of the Model 737-300, -400, or -500 series airplanes affected 
by this action is on the U.S. Register. All airplanes included in the 
applicability of this rule currently are operated by non-U.S. operators 
under foreign registry; therefore, they are not directly affected by 
this AD action. However, the FAA considers that this rule is necessary 
to ensure that the unsafe condition is addressed in the event that any 
of these subject airplanes are imported and placed on the U.S. Register 
in the future.
    Should an affected airplane be imported and placed on the U.S. 
Register in the future, it would require approximately 10 work hours to 
accomplish the required actions, at an average labor charge of $60 per 
work hour. The cost of required parts is expected to be negligible. 
Based on these figures, the total cost impact of this AD would be $600 
per airplane.
    Since this AD action does not affect any airplane that is currently 
on the U.S. register, it has no adverse economic impact and imposes no 
additional burden on any person. Therefore, notice and public 
procedures hereon are unnecessary and the amendment may be made 
effective in less than 30 days after publication in the Federal 
Register.

Comments Invited

    Although this action is in the form of a final rule and was not 
preceded by notice and opportunity for public comment, comments are 
invited on this rule. Interested persons are invited to comment on this 
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 under the caption 
ADDRESSES. All communications received on or before the closing date 
for comments will be considered, and this rule may be amended in light 
of the comments received. Factual information that supports the 
commenter's ideas and suggestions is extremely helpful in evaluating 
the effectiveness of the AD action and determining whether additional 
rulemaking action would be needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 


[[Page 3741]]
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 94-NM-217-AD.'' The postcard will be date stamped and 
returned to the commenter.
    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:

94-26-13 Boeing: Amendment 39-9108. Docket 94-NM-217-AD.

    Applicability: Model 737-300, -400, and -500 series airplanes; 
line positions 2184, 2187, 2194 through 2197 inclusive, and 2199; 
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 prevent drainage from a fuel leak into the turbine exhaust 
area, which could cause an external fire under the wing, accomplish 
the following:
    (a) Within 24 months after the effective date of this AD, modify 
the leading edge slat access panel and internal structure at Front 
Spar Station (FSS) 250.663 in accordance with Boeing Service 
Bulletin 737-57-1221, Revision 2, dated November 17, 1994.
    (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 modification shall be done in accordance with Boeing 
Service Bulletin 737-57-1221, Revision 2, dated November 17, 1994. 
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 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 February 3, 1995.

    Issued in Renton, Washington, on December 21, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-1362 Filed 1-18-95; 8:45 am]
BILLING CODE 4910-13-U