[Federal Register Volume 61, Number 168 (Wednesday, August 28, 1996)]
[Proposed Rules]
[Pages 44241-44242]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-21882]
[[Page 44241]]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 96-NM-150-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 all Boeing Model 737-100, -200, -
300, -400, and -500 series airplanes. This proposal would require an
inspection of the aileron/elevator power control units (PCU's) and the
rudder PCU to determine if reworked PCU manifold cylinder bores
containing chrome plating are installed, and replacement of the
cylinder bores with bores that have been reworked using the oversize
method or the steel sleeve method, 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 a reduced rate of movement of the elevator,
aileron, or rudder due to contamination of hydraulic fluid from chrome
plating chips; such reduced rate of movement, if not corrected, could
result in 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-150-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: Don Kurle, Senior Engineer, Systems
and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification
Office, 1601 Lind Avenue, SW., Renton, Washington; telephone (206) 227-
2798; 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.
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-150-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-150-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 has received reports indicating that the chrome plating
separated from reworked cylinder bores of the aileron/elevator power
control units (PCU's). Investigation revealed that a number of aileron/
elevator and rudder PCU's were repaired using chrome plating on the
aluminum cylinder bores. Separation of the chrome plating has occurred
on several of these repaired units, which can result in contamination
of hydraulic fluid from chrome plating chips. Such contamination could
result in blocked or jammed valves in the rudder PCU, which could
result in reduced movement capability of the rudder or partial or total
deflection of the rudder. In addition, such contamination could result
in scored piston seals or cylinder bores and consequent reduced
performance of the aileron/elevator PCU's. A reduced rate of movement
of the elevator, aileron, or rudder, if not corrected, could result in
reduced controllability of the airplane.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Service Letter 737-SL-27-
30, dated April 1, 1985, which describes procedures for an inspection
of the aileron/elevator PCU's and the rudder PCU to determine if
reworked PCU manifold cylinder bores containing chrome plating are
installed, and replacement of the cylinder bores with bores that have
been reworked using the oversize method or the steel sleeve method, if
necessary.
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 an inspection of the aileron/elevator PCU's
and the rudder PCU to determine if reworked PCU manifold
[[Page 44242]]
cylinder bores containing chrome plating are installed, and replacement
of the cylinder bores with bores that have been reworked using the
oversize method or the steel sleeve method, if necessary. The actions
would be required to be accomplished in accordance with the service
letter described previously.
Explanation of Proposed Compliance Time
In developing an appropriate compliance time for the proposed
actions, the FAA's intent is that they 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. In
light of these considerations, the FAA has specified a compliance time
of 18 months for accomplishment of the proposed inspection. The FAA
finds that 18 months corresponds closely to the interval representative
of most of the affected operators' normal maintenance schedules. The
FAA considers that the proposed compliance time will provide an
acceptable level of safety.
Cost Impact
There are approximately 2,675 Model 737 series 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 5 work hours per airplane to accomplish the
proposed inspection, and that the average labor rate is $60 per work
hour. Based on these figures, the cost impact of the proposed AD on
U.S. operators is estimated to be $327,300, or $300 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.
Should an operator be required to accomplish the necessary
replacement, it would take approximately 18 work hours per airplane to
accomplish, at an average labor rate of $60 per work hour. Required
parts will cost approximately $15,800 per airplane. Based on these
figures, the cost impact of any necessary replacement action is
estimated to be $16,880 per airplane.
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-150-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 (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 a reduced rate of movement of the elevator, aileron,
or rudder, which, if not corrected, could result in reduced
controllability of the airplane, accomplish the following:
(a) Within 18 months after the effective date of this AD:
Perform an inspection of the aileron and elevator PCU's, part number
(P/N) 65-44761-( ), and the rudder PCU, P/N 65-44681-( ), to
determine if reworked PCU manifold cylinder bores containing chrome
plating are installed, in accordance with Boeing Service Letter 737-
SL-27-30, dated April 1, 1985.
(b) If any reworked PCU manifold cylinder bores containing
chrome plating are installed: Prior to further flight, replace the
cylinder bores with bores that have been reworked using the oversize
method or the steel sleeve method specified in Boeing Service Letter
737-SL-27-30, dated April 1, 1985. Accomplish the replacement in
accordance with the service letter.
(c) As of the effective date of this AD, no person shall install
a reworked PCU manifold cylinder bore containing chrome plating on
an aileron or elevator PCU having P/N 65-44761-( ), or on a rudder
PCU having P/N 65-44681-( ), of any airplane unless the cylinder
bore has been reworked using the oversize method or the steel sleeve
method specified in Boeing Service Letter 737-SL-27-30, dated April
1, 1985.
(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. 96-21882 Filed 8-23-96; 9:02 am]
BILLING CODE 4910-13-U