[Federal Register Volume 61, Number 168 (Wednesday, August 28, 1996)]
[Proposed Rules]
[Pages 44245-44247]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-21884]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 96-NM-152-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-100 and -200 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 and -200
series airplanes. This proposal would require replacement of certain
outboard and inboard wheel halves with improved wheel halves. This
proposal also would require cleaning and inspecting certain outboard
and inboard wheel halves for corrosion, missing paint in large areas,
and cracks; and repair or replacement of the wheel halves with
serviceable wheel halves, if necessary. This proposal is prompted by a
review of the design of the flight control systems on Model 737 series
airplanes. The actions specified by the proposed AD are intended to
prevent failure of the wheel flanges, which could result in failure of
the hydraulics systems, jammed flight controls, loss of electrical
power, or other combinations of failures; and consequent reduced
controllability of the airplane.
DATES: Comments must be received by October 24, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 96-NM-152-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 Allied Signal Aerospace Company, Bendix Wheels and Brakes
Division, South Bend, Indiana 46624; and Bendix, Aircraft Brake and
Strut Division, 3520 West Mestmoor Street, South Bend, Indiana 46624.
This information may be examined at the FAA, Transport Airplane
Directorate, 1601 Lind Avenue, SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: David Herron, Aerospace Engineer,
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft
Certification Office, 1601 Lind Avenue, SW., Renton, Washington;
telephone (206) 227-2672; fax (206) 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.
[[Page 44246]]
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 96-NM-152-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. 96-NM-152-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
In October 1994, the FAA organized a team to conduct a Critical
Design Review (CDR) of the flight control systems installed on Boeing
Model 737 series airplanes in an effort to confirm the continued
operational safety of these airplanes. The formation of the CDR team
was prompted by questions that arose following an accident involving a
Model 737-200 series airplane that occurred near Colorado Springs,
Colorado, and one involving a Model 737-300 series airplane that
occurred near Pittsburgh, Pennsylvania. The CDR team's analysis of the
flight control systems was performed independent of the investigations
of these accidents, which are conducted by the National Transportation
Safety Board (NTSB). The cause of the accidents has not yet been
determined.
The CDR team was composed of representatives from the FAA, the
NTSB, other U.S. government organizations, and foreign airworthiness
authorities. The team reviewed the service history and the design of
the flight control systems of Model 737 series airplanes. The team
completed its review in May 1995. The recommendations of the team
include various changes to the design of the flight control systems of
these airplanes, as well as correction of certain design deficiencies.
This proposed AD is one of nine rulemaking actions being issued by the
FAA to address the recommendations of the CDR team.
Reports Received by FAA
The FAA received a report indicating that failure of the wheel
flanges can result in metallic debris impacting the hydraulics systems
and other critical elements associated with control of the airplane
that are within the proximity of the wheel. Such impact can result in
failure of the hydraulics systems, jammed flight controls, loss of
electrical power, or other combinations of failures. These conditions,
if not corrected, could result in reduced controllability of the
airplane.
Explanation of Relevant Service Information
The FAA has reviewed and approved Bendix Service Information Letter
(SIL) 392, Revision 1, dated November 15, 1979, which describes
procedures for replacement of any outboard wheel half having serial
number (S/N) H-999 and lower with an outboard wheel half having part
number (P/N) 2607047; and replacement of any inboard wheel half having
S/N H-1799 and lower with a wheel half having P/N 2607046. These
replacements must be accomplished on airplanes equipped with a Bendix
main wheel assembly having part number (P/N) 2601571-1, S/N B-5999 and
lower. The improved wheel halves incorporate additional material that
will ensure greater tolerance for corrosion and handling damage of the
wheel.
The FAA also has reviewed and approved Allied Signal Service
Bulletin No. 737-32-026, dated April 26, 1988, including Attachments 1
and 2. The service bulletin describes procedures for cleaning any
outboard wheel half having P/N 2601454, S/N H0001 through H1049
inclusive, and any inboard wheel half having P/N 2601567, S/N H0001
through H1799 inclusive; inspecting the wheel halves for corrosion or
missing paint in large areas, stripping or removing any paint, and
removing any corrosion; and performing an eddy current inspection for
cracks. These actions must be accomplished on airplanes equipped with a
Bendix main wheel assembly having P/N 2601571, S/N B0001 through B5999
inclusive.
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 replacement of certain outboard and inboard
wheel halves with improved wheel halves. The proposed AD also would
require cleaning and inspecting certain outboard and inboard wheel
halves for corrosion, missing paint in large areas, and cracks; and
repair or replacement of the wheel halves with serviceable wheel
halves, if necessary. Replacement of inboard and outboard wheel halves
would be required to be accomplished in accordance with the SIL
described previously. The cleaning and inspection would be required to
be accomplished in accordance with the service bulletin described
previously.
Explanation of Proposed Compliance Time
In developing an appropriate compliance time for the proposed
actions, the FAA's intent is that it be performed during a regularly
scheduled maintenance visit for the majority of the affected fleet,
when the airplanes would be located at a base where special equipment
and trained personnel would be readily available, if necessary. In
addition, the FAA considered the availability of necessary parts. The
FAA finds that 180 days corresponds closely to the interval
representative of most of the affected operators' normal maintenance
schedules. The FAA considers that this interval will provide an
acceptable level of safety.
Cost Impact
There are approximately 634 Model 737-100 and -200 series airplanes
of the affected design in the worldwide fleet. The FAA estimates that
241 airplanes of U.S. registry would be affected by this proposed AD.
The FAA estimates that it would take approximately 4 work hours per
airplane to accomplish the proposed replacement of wheel halves, and
that the average labor rate is $60 per work hour. Required parts would
cost approximately $20,212 per airplane. Based on these figures, the
cost impact of the proposed replacement on U.S. operators is estimated
to be $4,928,932, or $20,452 per airplane.
The FAA also estimates that it would take approximately 2 work
hours per airplane to accomplish the proposed cleaning and inspection,
and that the average labor rate is $60 per work hour. Based on these
figures, the cost impact of the proposed cleaning and inspection on
U.S. operators is estimated to be $28,920, or $120 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.
The FAA recognizes that the obligation to maintain aircraft in an
airworthy condition is vital, but sometimes expensive. Because AD's
require specific actions to address
[[Page 44247]]
specific unsafe conditions, they appear to impose costs that would not
otherwise be borne by operators. However, because of the general
obligation of operators to maintain aircraft in an airworthy condition,
this appearance is deceptive. Attributing those costs solely to the
issuance of this AD is unrealistic because, in the interest of
maintaining safe aircraft, prudent operators would accomplish the
required actions even if they were not required to do so by the AD.
A full cost-benefit analysis has not been accomplished for this
proposed AD. As a matter of law, in order to be airworthy, an aircraft
must conform to its type design and be in a condition for safe
operation. The type design is approved only after the FAA makes a
determination that it complies with all applicable airworthiness
requirements. In adopting and maintaining those requirements, the FAA
has already made the determination that they establish a level of
safety that is cost-beneficial. When the FAA, as in this proposed AD,
makes a finding of an unsafe condition, this means that the original
cost-beneficial level of safety is no longer being achieved and that
the proposed actions are necessary to restore that level of safety.
Because this level of safety has already been determined to be cost-
beneficial, a full cost-benefit analysis for this proposed AD would be
redundant and unnecessary.
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 96-NM-152-AD.
Applicability: All Model 737-100 and -200 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 (d) 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 wheel flanges, which could result in
failure of the hydraulics systems, jammed flight controls, loss of
electrical power, or other combinations of failures; and consequent
reduced controllability of the airplane, accomplish the following:
(a) For airplanes equipped with a Bendix main wheel assembly
having part number (P/N) 2601571-1, serial number (S/N) B-5999 or
lower: Within 180 days after the effective date of this AD,
accomplish the actions specified in paragraphs (a)(1) and (a)(2) of
this AD, in accordance with Bendix Service Information Letter (SIL)
392, Revision 1, dated November 15, 1979.
(1) Remove any outboard wheel half having S/N H-999 or lower,
and replace it with an outboard wheel half having P/N 2607047; and
(2) Remove any inboard wheel half having S/N H-1799 or lower,
and replace it with a wheel half having P/N 2607046.
(b) For airplanes equipped with a Bendix main wheel assembly
having P/N 2601571, S/N B0001 through B5999 inclusive, accomplish
the following:
(1) Within 180 days after the effective date of this AD, and
thereafter at each tire change, accomplish the actions specified in
paragraphs (b)(1)(i), (b)(1)(ii), and (b)(1)(iii) of this AD, in
accordance with the Accomplishment Instructions of Allied Signal
Service Bulletin No. 737-32-026, dated April 26, 1988, including
Attachments 1 and 2.
(i) Clean any outboard wheel half having P/N 2601454, S/N H0001
through H1049 inclusive, and any inboard wheel half having P/N
2601567, S/N H0001 through H1799 inclusive; and
(ii) Inspect the wheel halves for corrosion or missing paint in
large areas, strip or remove any paint, and remove any corrosion;
and
(iii) Perform an eddy current inspection to detect cracks.
(2) If any cracking is found during the inspections required by
this paragraph, prior to further flight, repair or replace the wheel
halves with serviceable wheel halves in accordance with procedures
specified in the Component Maintenance Manual.
(c) As of the effective date of this AD, no person shall install
an outboard wheel half having S/N H-999 or lower, or an inboard
wheel half having S/N H-1799 or lower, on a main wheel assembly
having P/N 2601571, S/N B0001 through B5999 inclusive, on any
airplane.
(d) 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.
(e) 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 August 21, 1996.
Ronald T. Wojnar,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-21884 Filed 8-23-96; 9:03 am]
BILLING CODE 4910-13-U
