[Federal Register Volume 67, Number 52 (Monday, March 18, 2002)]
[Proposed Rules]
[Pages 11950-11952]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-6332]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-422-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -200C, -
300, -400, and -500 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 737-100, -
200, -200C, -300, -400, and -500 series airplanes. This proposal would 
require replacing the existing pressure relief valve on the potable 
water tank with a new, improved pressure relief valve, which is made of 
stainless steel and is non-adjustable. For certain airplanes, this 
proposal would also require modification of certain piping to re-locate 
the pressure relief valve. This action is necessary to prevent rupture 
of the potable water tank during flight of the airplane, which could 
result in structural damage to the airplane and inability to sustain 
flight loads. This action is intended to address the identified unsafe 
condition.

DATES: Comments must be received by May 2, 2002.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket Number 2000-NM-422-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 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. 2000-NM-422-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.
    The service information referenced in the proposed rule 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.

FOR FURTHER INFORMATION CONTACT: Don Eiford, Aerospace Engineer, ANM-
130S, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056; telephone (425) 227-2788; fax (425) 227-
1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed 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 above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this action may be changed in 
light of the comments received.
    Submit comments using the following format:
     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.
     For each issue, state what specific change to the proposed 
AD is being requested.
     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 proposed 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 summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NM-422-AD.'' The postcard will be date stamped 
and returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket Number 2000-NM-422-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that there have been 
several occurrences of potable water tanks rupturing while the airplane 
was in flight. In one case the potable water tank relief valve was 
incorrectly located, so that the relief valve could not protect the 
tank from overpressurization. In other cases, the pressure relief valve 
on the water tank was correctly located, but malfunctioned, leading to 
rupture of the water tank with consequent structural damage to the 
airplane. Such malfunctioning has been found to be caused by corrosion 
or by inadvertent adjustment of the pressure relief valve. Malfunction 
of the pressure relief valve for the potable water tank or the 
incorrect location of that valve, if not corrected, could cause a 
rupture of the potable water tank during flight of the airplane, which 
could result in structural damage to the airplane and inability to 
sustain flight loads.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletins 737-
38A1038, Revision 2, dated September 25, 1997, and 737-38A1047, 
Revision 1, dated September 27, 2001, which describe procedures for 
replacing the existing pressure relief valve in the potable water tank 
with a new stainless steel, non-adjustable pressure relief valve. In 
addition, the FAA has reviewed and approved Boeing Service Bulletin 
737-38-1029, Revision 1, dated August 19, 1993, which describes 
procedures for modification of piping to re-locate the pressure relief 
valve so that the relief valve can protect the potable water tank 
against over-pressurization. Accomplishment of the actions specified in 
those service bulletins is intended to adequately address the 
identified unsafe condition.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require accomplishment of the actions specified in 
the service bulletins described previously, except as discussed below.

Differences Between Service Bulletins and Proposed AD

    One difference concerns the compliance times recommended in the 
service bulletins and those in the proposed AD. Boeing Service 
Bulletins 737-38A1038 and 737-38A1047 recommend that the replacement of 
the

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pressure relief valve on the potable water tank be done as soon as 
manpower and materials are available. Boeing Service Bulletin 737-38-
1029 describes procedures for modification of the system to relocate 
the check valve and pressure relief valve but does not recommend a 
compliance time for that action. The proposed AD specifies a compliance 
time of 18 months after the effective date of the AD for replacement of 
the existing pressure relief valve with a new valve, so that the 
required actions can be done during an operator's regularly-scheduled 
``C'' check.
    Another change concerns re-installation of the existing pressure 
relief valve after the modification of the system which is required for 
certain airplanes listed in Boeing Service Bulletin 737-38-1029. The 
proposed AD specifies replacement of the existing pressure relief valve 
with a new, improved valve for these certain airplanes as well as for 
all other affected airplanes.

Cost Impact

    There are approximately 2,221 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 1,208 airplanes of U.S. 
registry would be affected by this proposed AD.
    The FAA estimates that of the 1,208 airplanes of U.S. registry, 2 
would be affected by the proposed modification of piping to re-locate 
the pressure relief valve, that it would take approximately 6 work 
hours per airplane to accomplish the proposed modification, and that 
the average labor rate is $60 per work hour. Based on these figures, 
the cost impact of the proposed modification of piping on U.S. 
operators is estimated to be $1,320, or $660 per airplane.
    The FAA estimates that all of the 1,208 airplanes of U.S. registry 
would be affected by the proposed replacement of the pressure relief 
valve, that it would take approximately 2 work hours per airplane to 
accomplish the proposed replacement, and that the average labor rate is 
$60 per work hour. Required parts would cost approximately $300 per 
airplane. Based on these figures, the cost impact of the proposed 
replacement of the pressure relief valve on U.S. operators is estimated 
to be $507,360, or $420 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the proposed requirements 
of this AD action, and that no operator would accomplish those actions 
in the future if this proposed AD were not adopted. The cost impact 
figures discussed in AD rulemaking actions represent only the time 
necessary to perform the specific actions actually required by the AD. 
These figures typically do not include incidental costs, such as the 
time required to gain access and close up, planning time, or time 
necessitated by other administrative actions.

Regulatory Impact

    The regulations proposed herein would 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 proposal would not have federalism implications 
under Executive Order 13132.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting 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.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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:

Boeing: Docket 2000-NM-422-AD.

    Applicability: Model 737-100, -200, -200C, -300, -400, and -500 
series airplanes, line numbers 1 through 2696, 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 request approval for an 
alternative method of compliance in accordance with paragraph (c) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent rupture of the potable water tank during flight of 
the airplane, which could result in structural damage to the 
airplane and inability to sustain flight loads, accomplish the 
following:

Modification and Replacement

    (a) Within 18 months after the effective date of this AD, 
perform the requirements of paragraph (a)(1) or (a)(2) of this AD, 
as applicable.
    (1) For those airplanes listed in the effectivity section of 
Boeing Service Bulletin 737-38-1029, Revision 1, dated August 19, 
1993: Modify the potable water pressurization system in accordance 
with the service bulletin, but do not reinstall the existing 
pressure relief valve having part number (P/N) 520A-6DB-50. Prior to 
further flight, perform the requirements of paragraph (a)(2) of this 
AD.

    Note 2: Modification of the potable water pressurization system, 
done in accordance with Boeing Service Bulletin 737-38-1029, dated 
June 6, 1991, is acceptable for compliance with paragraph (a)(1) of 
this AD.

    (2) For those airplanes having line numbers 1 through 2523: 
Remove the existing pressure relief valve from the potable water 
tank, and replace the valve with a new pressure relief valve having 
part number P/N RV05-362, in accordance with Boeing Service Bulletin 
737-38A1047, Revision 1, dated September 27, 2001.

    Note 3: For those airplanes having line numbers 1 through 2523, 
installation of a new pressure relief valve having P/N RV05-362, 
done in accordance with Boeing Service Bulletin 737-38A1047, dated 
November 9, 2000, is acceptable for compliance with paragraph (a)(2) 
of this AD.

    (b) For those airplanes having line numbers 2524 through 2696: 
Within 18 months after the effective date of this AD, remove the 
existing pressure relief valve from the potable water tank, and 
replace the valve with a new pressure relief valve having P/N RV05-
362, in accordance with Boeing Service Bulletin 737-38A1038, 
Revision 2, dated September 25, 1997.

    Note 4: For those airplanes having line numbers 2524 through 
2696, installation of a new pressure relief valve having P/N RV05-
362, done in accordance with Boeing Service Bulletin 737-38A1038, 
dated December 1, 1994, or Revision 1, dated February 2, 1995, is 
acceptable for compliance with paragraph (b) of this AD.

Alternative Methods of Compliance

    (c) An alternative method of compliance or adjustment of the 
compliance time that

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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 Maintenance Inspector, who may add comments and then send 
it to the Manager, Seattle ACO.

    Note 5: 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

    (d) 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.

    Issued in Renton, Washington, on March 11, 2002.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-6332 Filed 3-15-02; 8:45 am]
BILLING CODE 4910-13-U