[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