FR Doc 03-30192

[Federal Register: December 4, 2003 (Volume 68, Number 233)]
[Proposed Rules]
[Page 67812-67814]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr04de03-15]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NM-327-AD]
RIN 2120-AA64

Airworthiness Directives; Boeing Model 737-600, 737-700, 737-
700C, 737-800, and 737-900 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 Model 737-600, 737-700,
737-700C, 737-800, and 737-900 series airplanes. This proposal would
require measuring the electrical resistance of the support bracket for
the fire extinguisher bottle located in the left main landing gear
wheel well to ensure that it does not exceed the maximum allowed
resistance; and corrective actions, if necessary. This action is
necessary to prevent high electrical resistance in the squib firing
circuit, which could result in insufficient electrical current to fire
the fire extinguisher bottle squib and discharge the fire extinguishing
agent, which could lead to an uncontrolled engine fire. This action is
intended to address the identified unsafe condition.

DATES: Comments must be received by January 20, 2004.

ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 2002-NM-327-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. 2002-NM-327-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 or 2000 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: Doug Pegors, Aerospace Engineer;
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification
Office, 1601 Lind Avenue, SW., Renton, Washington; telephone (425) 917-
6504; fax (425) 917-6590.

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:
[sbull] 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.
[sbull] For each issue, state what specific change to the proposed
AD is being requested.
[sbull] 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 action must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 2002-NM-327-AD.'' The postcard will be date stamped
and returned to the commenter.

[[Page 67813]]

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 No. 2002-NM-327-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.

Discussion

The FAA has received a report indicating that, during a routine
inspection in production at Boeing, the electrical resistance of the
ground studs installed on the support bracket for the fire extinguisher
bottles in the left main wheel well of certain Boeing Model 737 series
airplanes was found to exceed the maximum allowed level. During
manufacture, the anodize coating was not removed properly from the
holes in the support bracket into which the ground studs are inserted,
thereby increasing the electrical resistance between the studs and the
bracket. Therefore, the electrical resistance between the bracket and
the grounding studs may exceed the maximum allowed resistance. This
condition, if not corrected, could result in insufficient electrical
current to fire the fire extinguisher bottle squib and discharge the
fire extinguishing agent, which could lead to an uncontrolled engine
fire.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Alert Service Bulletin
737-26A1118, dated October 17, 2002, which describes procedures for:
[sbull] Measuring the electrical resistance of the dual ground
studs to ensure that the electrical resistance is no greater than 0.5
milliohms;
[sbull] Measuring the bond resistance from the top terminal lug of
each ground stud to the adjacent structure; and
[sbull] Corrective actions, if necessary.
The corrective actions include replacing the affected ground stud
with a new ground stud; reworking the ground stud; and relocating the
support bracket hole; as applicable. Accomplishment of the actions
specified in the service bulletin 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 bulletin described previously, except as discussed below.

Difference Between Proposed Rule and Service Bulletin

Because the service bulletin does not specify a corrective action
to take if the bond resistance measurement found in Figure 4 of the
service bulletin is greater than 1.0 milliohms, this proposed AD would
require operators to rework per a method approved by the Manager,
Seattle Aircraft Certification Office (ACO), FAA.

Cost Impact

There are approximately 133 airplanes of the affected design in the
worldwide fleet. The FAA estimates that 28 airplanes of U.S. registry
would be affected by this proposed AD, that it would take approximately
2 work hours per airplane to accomplish the proposed actions, and that
the average labor rate is $65 per work hour. Based on these figures,
the cost impact of the proposed AD on U.S. operators is estimated to be
$3,640, or $130 per airplane.
The cost impact figure discussed above is 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 2002-NM-327-AD.

Applicability: Model 737-600, 737-700, 737-700C, 737-800, and
737-900 series airplanes, as listed in Boeing Alert Service Bulletin
737-26A1118, dated October 17, 2002; certificated in any category.
Compliance: Required as indicated, unless accomplished
previously.
To prevent high electrical resistance in the squib firing
circuit, which could result in insufficient electrical current to
fire the fire extinguisher bottle squib and discharge the fire
extinguishing agent, which could lead to an uncontrolled engine
fire, accomplish the following:

Inspection, Rework, Replacement, Relocation and Installation

(a) Except as provided by paragraph (b) of this AD: Within 90
days after the effective date of this AD, measure the electrical
resistance of the dual ground studs of the support brackets for the
fire extinguisher bottle located in the left main landing gear wheel
well (including the applicable corrective actions) by accomplishing
all actions specified in the Accomplishment Instructions of Boeing
Alert Service Bulletin 737-26A1118, dated October 17, 2002. Do the
actions per the service bulletin. Any applicable corrective action
must be accomplished prior to further flight.

Additional Rework

(b) If, when accomplishing the bond resistance measurement
described in Figure 4 of the Boeing Alert Service Bulletin 737-
26A1118, dated October 17, 2002, the resistance is found to be
greater than 1.0 milliohms (0.001 ohms): Before further flight,
rework per a method approved by the Manager, Seattle Aircraft
Certification Office (ACO), FAA.

Alternative Methods of Compliance

[[Page 67814]]

FAA, is authorized to approve alternative methods of compliance
(AMOCs) for this AD.

Issued in Renton, Washington, on November 28, 2003.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 03-30192 Filed 12-3-03; 8:45 am]

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