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Proposed Rule

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

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Information about this document as published in the Federal Register.

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AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

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: 9-anm-nprmcomment@faa.gov. 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.

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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.

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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 theStart Printed Page 11951pressure 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.

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List of Subjects in 14 CFR Part 39

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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:

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PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

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Authority: 49 U.S.C. 106(g), 40113, 44701.

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[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 thatStart Printed Page 11952provides 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.

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Issued in Renton, Washington, on March 11, 2002.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

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[FR Doc. 02-6332 Filed 3-15-02; 8:45 am]

BILLING CODE 4910-13-U