Airworthiness Directives; Boeing Model 737 Series Airplanes

[Federal Register Volume 66, Number 80 (Wednesday, April 25, 2001)]
[Rules and Regulations]
[Pages 20733-20734]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-10177]



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Federal Register / Vol. 66, No. 80 / Wednesday, April 25, 2001 / 
Rules and Regulations

[[Page 20733]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-94-AD; Amendment 39-12201; AD 2001-08-24]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737 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) that 
is applicable to all Boeing Model 737 series airplanes. This action 
requires revising the Airplane Flight Manual to prohibit extended dry 
operation of the center tank fuel pumps (with no fuel passing through 
the pumps). This action is necessary to prevent ignition of fuel vapors 
due to the generation of sparks and a potential ignition source inside 
the center tank caused by metal-to-metal contact during dry fuel pump 
operation, which could result in a fire or explosion of the fuel tank. 
This action is intended to address the identified unsafe condition.

DATES: Effective May 10, 2001.
    Comments for inclusion in the Rules Docket must be received on or 
before June 25, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2001-NM-94-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. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2001-NM-94-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    Information related to this AD may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Sherry Vevea, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 227-1360; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: On March 3, 2001, a Boeing Model 737-400 
series airplane caught fire and burned while parked at a bay at the Don 
Muang International Airport, Bangkok, Thailand. Although the accident 
investigation is ongoing and the probable cause of the accident has not 
been identified, the Government of Thailand, in conjunction with the 
National Transportation Safety Board, has determined that the center 
tank exploded shortly after the main fuel tanks of the airplane were 
refueled. It appears that the center tank fuel pumps were operating dry 
(no fuel was passing through the pumps) at the time of the explosion.
    This accident is similar to the 1990 center tank explosion that 
occurred on a Boeing Model 737-300 series airplane. The ignition source 
of that explosion was never identified. The center tank fuel pumps were 
operating dry at the time of that explosion.
    Extended dry operation of the center tank fuel pumps, which had 
occurred prior to both incidents, is contrary to the manufacturer's 
procedures for safe operation of the fuel pumps. Extended dry pump 
operation can result in overheating and excessive wear of the pump 
bearings and consequent contact between rotating and nonrotating parts 
of the pumps. Both overheating of the bearings and contact between 
rotating and nonrotating parts have the potential to create an ignition 
source in the form of hot surfaces or sparks. In addition, during dry 
operation of the pumps, ignition of vapor in a fuel pump can create a 
flame front that can reach the fuel tank and cause a fuel tank 
explosion.
    In light of this information, the FAA finds that certain procedures 
should be included in the FAA-approved Airplane Flight Manual (AFM) for 
Model 737 series airplanes to prohibit dry operation of center tank 
fuel pumps. The FAA has determined that such procedures currently are 
not defined adequately in the AFM for these airplanes.

Explanation of the Requirements of the Rule

    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 ignition of fuel vapors due to the generation 
of sparks and a potential ignition source inside the center tank caused 
by metal-to-metal contact during dry fuel pump operation, which could 
result in a fire or explosion of the fuel tank. This AD requires 
revising the AFM to prohibit extended dry operation of the center tank 
fuel pumps.

Interim Action

    This is considered to be interim action until final action is 
identified, at which time the FAA may consider further rulemaking.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an 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

[[Page 20734]]

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.
    Submit comments using the following format:
    <bullet> Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
    <bullet> For each issue, state what specific change to the AD is 
being requested.
    <bullet> Include justification (e.g., reasons or data) for each 
request.
    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 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket No. 2001-NM-94-AD.'' The postcard will be date-stamped and 
returned to the commenter.

Regulatory Impact

    The regulations adopted herein will not have a substantial direct 
effect 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, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, 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, 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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

2001-08-24  Boeing: Amendment 39-12201. Docket 2001-NM-94-AD.

    Applicability: All Model 737 series airplanes, certificated in 
any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent ignition of fuel vapors due to the generation of 
sparks and a potential ignition source inside the center tank caused 
by metal-to-metal contact during dry fuel pump operation, which 
could result in a fire or explosion of the fuel tank, accomplish the 
following:

Revision of Airplane Flight Manual (AFM)

    (a) Within 7 days after the effective date of this AD, revise 
the Limitations Section of the FAA-approved AFM to include the 
following information. This may be accomplished by inserting a copy 
of this AD into the AFM.

``For ground operation, center tank fuel pump switches must not be 
positioned to ``ON'' unless the center tank fuel quantity exceeds 
1,000 pounds (453 kilograms), except when defueling or transferring 
fuel.
Center tank fuel pump switches must be positioned to ``OFF'' when 
both center tank fuel pump low pressure lights illuminate.
Center tank fuel pumps must not be ``ON'' unless personnel are 
available in the flight deck to monitor low pressure lights.''

Alternative Methods of Compliance

    (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. Operators shall submit their requests through an 
appropriate FAA Principal Operations Inspector, who may add comments 
and then send it to the Manager, Seattle ACO.

    Note 1: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (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.

Effective Date

    (d) This amendment becomes effective on May 10, 2001.

    Issued in Renton, Washington, on April 18, 2001.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-10177 Filed 4-24-01; 8:45 am]
BILLING CODE 4910-13-U

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