[Federal Register Volume 64, Number 43 (Friday, March 5, 1999)]
[Proposed Rules]
[Pages 10578-10579]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-5431]
========================================================================
Proposed Rules
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
========================================================================
Federal Register / Vol. 64, No. 43 / Friday, March 5, 1999 / Proposed
Rules
[[Page 10578]]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-353-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).
-----------------------------------------------------------------------
SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain Boeing Model 737-100, -
200, -300, -400, and -500 series airplanes. This proposal would require
modification of certain filter module assemblies of the generator
control units (GCU). This proposal is prompted by reports of smoke and
occassional fire in the flight compartment as a direct result of a GCU
failure. The actions specified by the proposed AD are intended to
prevent failure of the filter module assemblies of the GCU's due to
overcurrent conditions, which could result in an increased risk of
smoke, and/or fire in the flight compartment.
DATES: Comments must be received by April 19, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 98-NM-353-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.
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: Forrest Keller, Senior 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) 227-2790;
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 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 98-NM-353-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 No. 98-NM-353-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
Over the past several years, the FAA has received numerous reports
of smoke and occasional fire in the flight compartment of certain
Boeing Model 737 series airplanes. Many of these incidents are
attributed to an overcurrent condition in the generator control units
(GCU), during in-flight operation of the airplane, which resulted from
transformer and/or diode failure in the GCU's power supply and exiter
field power supply circuits. Failure of these components causes a
localized overheat condition in a GCU. Such overcurrent and overheat
conditions, if not detected and corrected could result in an increased
risk of smoke and/or fire in the flight compartment.
Related Rulemaking
On March 10, 1989, the FAA issued AD 89-07-13, amendment 39-6165
(54 FR 11366, April 28, 1989), applicable to all Boeing Model 737
series airplanes, that requires replacement or modification of certain
GCU filter modules. However, this proposed AD would not affect the
requirements of that AD.
Explanation of Relevant Service Information
The FAA has reviewed and approved Sundstrand Corporation Service
Bulletin SB92-101, Revision 1, dated December 10, 1996, which describes
procedures for modification of the filter module assemblies of the
GCU's. The modification involves installation of a terminal board with
additional fuses and a protection cap. This modification will allow
certain fuses to open when an overcurrent condition occurs.
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.
Differences Between Proposed Rule and Service Bulletin
Operators should note that, although the service bulletin specifies
modification of the GCU's as interim action, pending determination of
the
[[Page 10579]]
root cause of a GCU failure. The FAA has determined that, for this
proposed AD, the modification adequately addresses the identified
unsafe condition. Therefore, this proposal is not considered to be
interim action.
Cost Impact
There are approximately 2,675 airplanes of the affected design in
the worldwide fleet. The FAA estimates that 1,091 airplanes of U.S.
registry would be affected by this proposed AD, that it would take
approximately 3 work hours per airplane to accomplish the proposed
modification, at an average labor rate of $60 per work hour. Required
parts would cost approximately $450 per airplane. Based on these
figures, the cost impact of the modification proposed by this AD on
U.S. operators is estimated to be $687,330, or $630 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 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 98-NM-353-AD.
Applicability: Model 737-100, -200, -300, -400, and -500 series
airplanes equipped with generator control units (GCU) having part
numbers as listed in Sundstrand Corporation Service Bulletin SB92-
101, Revision 1, dated December 10, 1996; 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 failure of the filter module assemblies of the
generator control units (GCU) due to overcurrent conditions, which
could result in an increased risk of smoke, and/or fire in the
flight compartment, accomplish the following:
(a) Within 2 years after the effective date of this AD, modify
the filter module assemblies of the GCU's identified in Sundstrand
Corporation Service Bulletin SB92-101, Revision 1, in accordance
with paragraph 2.A or 2.B of the Accomplishment Instructions of the
service bulletin, as applicable.
(b) Within 2 years after the effective date of this AD, no
person shall install on any airplane a GCU type AVZ122 having part
number (P/N) 948F458-1 (Boeing P/N 10-61224-11), and type AVZ22C/D
having P/N 915F212-4/-5 (Boeing P/N 10-61224-3), unless modified in
accordance with this AD.
(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 Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate. 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 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. Issued in Renton,
Washington, on February 26, 1999.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-5431 Filed 3-4-99; 8:45 am]
BILLING CODE 4910-13-P
