[Federal Register Volume 62, Number 219 (Thursday, November 13, 1997)]
[Proposed Rules]
[Pages 60810-60812]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-29819]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-238-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -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 all Boeing Model 737-100, -200, -
300, -400, and -500 series airplanes. This proposal would require 
installation of a placard that warns the cabin crew not to put the 
selector valve for the forward lavatory water supply in the ``DRAIN'' 
position during flight. This proposal also would require installation 
of an isolation valve in the drain line downstream of the selector 
valve. This proposal is prompted by reports of damage to the horizontal 
stabilizer and engine flameout caused by ice formed from water drained 
inadvertently through a mispositioned selector valve. The actions 
specified by the proposed AD are intended to prevent damage to the 
engines, airframe, or horizontal stabilizer, and/or prevent a hazard to 
persons or property on the ground, as a result of ice that could 
dislodge from the airplane.

DATES: Comments must be received by December 29, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 97-NM-238-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.

FOR FURTHER INFORMATION CONTACT: Don Eiford, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane 
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, 
SW., Renton, Washington 98055-4056; telephone (425) 227-2788; fax (425) 
227-1181.

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 notice may be changed in 
light of the comments received.
    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

[[Page 60811]]

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 97-NM-238-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-103, Attention: Rules 
Docket No. 97-NM-238-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received several reports that ice has formed on the 
skin of Boeing Model 737 series airplanes due to drainage of potable 
water through an incorrectly positioned selector valve for the forward 
lavatory water supply. Two of these incidents resulted in engine 
flameout and two other incidents resulted in damage to the horizontal 
stabilizer.
    The selector valve is a three-position (``DRAIN,'' ``SUPPLY,'' and 
``SHUTOFF'') selector valve for the forward lavatory water supply. It 
is possible to place the selector valve in the ``DRAIN'' position 
instead of the ``SHUTOFF'' position during flight, which results in the 
contents of the potable water supply tank draining onto the skin of the 
airplane. This condition, if not corrected, could result in the 
formation of ice that could dislodge from the airplane and, 
consequently, cause damage to the engines, airframe, or horizontal 
stabilizer and/or pose a hazard to persons or property on the ground.

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 installation of a placard to warn the cabin 
crew not to put the selector valve for the forward lavatory water 
supply in the ``DRAIN'' position during flight. In addition, the 
proposed AD would require installation of an isolation valve in the 
drain line downstream of the selector valve. These actions would be 
required to be accomplished in accordance with a method approved by the 
FAA.

Cost Impact

    There are approximately 2,830 Boeing Model 737-100, -200, -300, -
400, and -500 series airplanes of the affected design in the worldwide 
fleet. The FAA estimates that 1,037 airplanes of U.S. registry would be 
affected by this proposed AD.
    It would take approximately 1 work hour per airplane to accomplish 
the proposed placard installation, at an average labor rate of $60 per 
work hour. Based on these figures, the cost impact of this installation 
proposed by this AD on U.S. operators is estimated to be $62,220, or 
$60 per airplane.
    It would take approximately 6 work hours per airplane to accomplish 
the proposed installation of an isolation valve, 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 this installation proposed by this AD on U.S. operators is 
estimated to be $684,420, or $660 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 AD were not adopted.

Regulatory Impact

    The regulations proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    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 97-NM-238-AD.

    Applicability: All Model 737-100, -200, -300, -400, and -500 
series airplanes, certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 damage to the engines, airframe, or horizontal 
stabilizer, and/or a hazard to persons or property on the ground, 
accomplish the following:
    (a) Within 6 months after the effective date of this AD, install 
a placard (as shown in Figure 1 of this AD) on the door beneath the 
forward lavatory sink that warns the cabin crew not to put the 
selector valve for the forward lavatory water supply in the 
``DRAIN'' position during flight. The installation shall be 
accomplished in accordance with a method approved by the Manager, 
Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane 
Directorate.
    (b) Within 36 months after the effective date of this AD, 
install an isolation valve in the drain line downstream of the 
selector valve for the forward lavatory water supply, in accordance 
with a method approved by the Manager, Seattle ACO.
    (c) 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 ACO. 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

[[Page 60812]]

compliance with this AD, if any, may be obtained from the Seattle 
ACO.

    (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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[GRAPHIC] [TIFF OMITTED] TP13NO97.024


    Issued in Renton, Washington, on November 6, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-29819 Filed 11-12-97; 8:45 am]
BILLING CODE 4910-13-C