[Federal Register Volume 60, Number 72 (Friday, April 14, 1995)]
[Rules and Regulations]
[Pages 18981-18983]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-8828]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-NM-37-AD; Amendment 39-9199; AD 95-06-53]


Airworthiness Directives; Boeing Model 737 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This document publishes in the Federal Register an amendment 
adopting Airworthiness Directive (AD) T95-06-53 that was sent 
previously to all known U.S. owners and operators of Boeing Model 737 
series airplanes by individual telegrams. This AD requires 
identification of the part and serial numbers of the main rudder power 
control unit (PCU), and replacement of certain PCU's with serviceable 
parts, if necessary. This amendment is prompted by reports indicating 
that certain modified rudder PCU's malfunctioned and failed functional 
retesting. The actions specified by this AD are intended to prevent the 
rudder actuator piston and the rudder from operating with reduced force 
capability or moving in a direction opposite the intended direction due 
to malfunctioning of the rudder PCU; these conditions could result in 
reduced controllability of the airplane.

DATES: Effective May 1, 1995, to all persons except those persons to 
whom it was made immediately effective by telegraphic AD T95-06-53, 
issued March 14, 1995, which contained the requirements of this 
amendment.
    The incorporation by reference of Boeing Service Bulletin 737-27-
1185, [[Page 18982]] dated April 15, 1993, as listed in the 
regulations, was approved previously by the Director of the Federal 
Register as of March 3, 1994 (59 FR 4570, February 1, 1994).
    Comments for inclusion in the Rules Docket must be received on or 
before June 13, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-37-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056.
    The applicable service information 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; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Kenneth W. Frey, 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 (206) 227-2673; fax (206) 
227-1181.

SUPPLEMENTARY INFORMATION: On January 3, 1994, the FAA issued AD 94-01-
07, amendment 39-8789 (59 FR 4570, February 1, 1994), which is 
applicable to certain Boeing Model 737 series airplanes. That AD 
requires repetitive tests of existing main rudder power control units 
(PCU's), and eventual replacement of the main rudder PCU with a 
modified PCU. The modified PCU also was required to be functionally 
tested following modification and prior to installation. Recently, the 
FAA received two reports of in-service malfunctioning of certain rudder 
PCU's that had been modified by Aero Controls, Inc. Subsequently, these 
PCU's were removed from the airplanes and failed functional retesting.
    In both of the reported cases, the secondary slide in the servo 
valve of these PCU's went past the intended maximum travel position. An 
examination of the PCU's tested revealed that the spring retainer 
backed off from the spring guide. If the secondary slide goes past the 
intended maximum travel position, the rudder actuator piston and the 
rudder could operate with reduced force capability or move in a 
direction opposite the intended direction. These conditions, if not 
corrected, could result in reduced controllability of the airplane.
    Results of a preliminary investigation indicate that Aero Controls, 
Inc., may not have been using the proper tool to torque the spring 
retaining nut. The FAA has identified 36 PCU's that may have been 
modified and/or tested incorrectly by that repair station. This AD 
affects only those PCU's modified and/or tested by Aero Controls, Inc. 
The FAA is currently in the process of verifying that other repair 
stations and operators have properly modified and tested PCU's.
    The FAA has confirmed that the PCU installed on the USAir Model 737 
series airplane that was involved in an accident near Pittsburgh in 
September 1994 had not been modified. The PCU from that airplane has 
been subjected to thorough functional testing, and no evidence of 
failures or deficiencies has been found. The investigation of that 
accident is continuing. No determination has been made that the PCU was 
the cause of that accident. This AD is being issued to correct the 
conditions described above and is not related to the results of the 
Pittsburgh accident investigation.
    Since the unsafe condition described is likely to exist or develop 
on other airplanes of the same type design, the FAA issued Telegraphic 
AD T95-06-53. The AD requires identification of the part number and 
serial number of the main rudder PCU, and replacement of certain PCU's 
with serviceable parts, if necessary.
    As a result of recent communications with the Air Transport 
Association (ATA) of America, the FAA has learned that, in general, 
some operators may misunderstand the legal effect of AD's on airplanes 
that are identified in the applicability provision of the AD, but that 
have been altered or repaired in the area addressed by the AD. The FAA 
points out that all airplanes identified in the applicability provision 
of an AD are legally subject to the AD. If an airplane has been altered 
or repaired in the affected area in such a way as to affect compliance 
with the AD, the owner or operator is required to obtain FAA approval 
for an alternative method of compliance with the AD, in accordance with 
the paragraph of each AD that provides for such approvals. A note has 
been included in this rule to clarify this long-standing requirement.
    Since it was found that immediate corrective action was required, 
notice and opportunity for prior public comment thereon were 
impracticable and contrary to the public interest, and good cause 
existed to make the AD effective immediately by individual telegrams 
issued on March 14, 1995, to all known U.S. owners and operators of 
Boeing Model 737 series airplanes. These conditions still exist, and 
the AD is hereby published in the Federal Register as an amendment to 
Sec. 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make 
it effective to all persons.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 95-NM-37-AD.'' The postcard will be date stamped and 
returned to the commenter.
    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to [[Page 18983]] correct an 
unsafe condition in aircraft, and that it is not a ``significant 
regulatory action'' under Executive Order 12866. It has been determined 
further that this action involves an emergency regulation under DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If 
it is determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from the Rules Docket at the 
location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

95-06-53  Boeing: Amendment 39-9199. Docket 95-NM-37-AD.

    Applicability: All Model 737 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 
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 use the authority 
provided in paragraph (d) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition; or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any airplane from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent the rudder actuator piston and the rudder from 
operating with reduced force capability or moving in a direction 
opposite the intended direction, and resultant reduced 
controllability of the airplane, accomplish the following:
    (a) Within 5 flights after the effective date of this AD, 
identify the part number and serial number of the main rudder power 
control unit (PCU).
    (b) If the PCU is identified with a part number and serial 
number specified in the list below, prior to further flight, remove 
the PCU from the airplane, and replace it with a serviceable part.

------------------------------------------------------------------------
     Part No.                           Serial No.(s)                   
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65C37052-3........  17SS, 49, 90A, 101, 138, 149A, 191A, 308A, 374,     
                     EGG0282.                                           
65C37052-5........  1211A.                                              
65C37052-7........  399A, 710A, 926A, 935A, 1175A, 1237A, 1493A, 1504A, 
                     1546, 1561A, 67700.                                
65C37052-8........  1090A, 1223, 1920, 2023A.                           
65C37052-9........  0184, 247, 394A, 641A, 1739A, 1746A, 1796A, 1849A,  
                     1997A, 2181A.                                      
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    (c) As of the effective date of this AD, no person shall install 
on any airplane a rudder PCU having a part number and serial number 
that is specified in the list contained in paragraph (b) of this AD 
unless paragraphs (c)(1), (c)(2), (c)(3), and (c)(4) of this AD are 
accomplished.
    (1) Perform a functional test of the PCU in accordance with Part 
II of the Accomplishment Instructions of Boeing Service Bulletin 
737-27-1185, dated April 15, 1993. And
    (2) Check the torque value on the spring retainer, Part Number 
68021-5, to determine that it measures a minimum of 25 inch-pounds. 
If the torque value is less than 25 inch-pounds, repair in 
accordance with a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA, Transport Airplane Directorate. And
    (3) Repeat the functional test required by paragraph (c)(1) of 
this AD. The PCU must pass this functional test in order to be 
returned to service. And
    (4) The measurement required by paragraph (c)(2) of this AD must 
be reported to the FAA, Transport Airplane Directorate, Seattle ACO, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; fax (206) 227-
1181. Information collection requirements contained in this 
regulation have been approved by the Office of Management and Budget 
(OMB) under the provisions of the Paperwork Reduction Act of 1980 
(44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 
2120-0056.
    (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 ACO. 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 
Secs. 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.
    (f) The functional test shall be done in accordance with Boeing 
Service Bulletin 737-27-1185, dated April 15, 1993. The 
incorporation by reference of this document was approved previously 
by the Director of the Federal Register in accordance with 5 U.S.C. 
552(a) and 1 CFR part 51 as of March 3, 1994 (59 FR 4570, February 
1, 1994). Copies may be obtained from Boeing Commercial Airplane 
Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be 
inspected at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
    (g) This amendment becomes effective on May 1, 1995, to all 
persons except those persons to whom it was made immediately 
effective by telegraphic AD T95-06-53, issued on March 14, 1995, 
which contained the requirements of this amendment.

    Issued in Renton, Washington, on April 5, 1995.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-8828 Filed 4-13-95; 8:45 am]
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