[Federal Register Volume 63, Number 33 (Thursday, February 19, 1998)]
[Proposed Rules]
[Pages 8369-8371]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-4112]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-133-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).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Boeing Model 737-
100, -200, -300, -400, and -500 series airplanes, that currently 
requires an inspection of reworked aileron/elevator power control units 
(PCU's) and rudder PCU's 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. That AD was prompted 
by a review of the design of the flight control systems on Model 737 
series airplanes. The actions specified by that 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. This action would expand the 
applicability of the existing AD to include airplanes equipped with 
certain rudder PCU's.

DATES: Comments must be received by April 6, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-133-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, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2798; 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 97-NM-133-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. 97-NM-133-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On April 24, 1997, the FAA issued AD 97-09-14, amendment 39-10010 
(62 FR 24008, May 2, 1997), applicable to certain Boeing Model 737-100, 
-200, -300, -400, and -500 series airplanes, to require an inspection 
of reworked aileron/elevator power control units (PCU's) and rudder 
PCU's 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. That action was prompted by a review 
of the design of the flight control systems on Model 737 series 
airplanes. The requirements of that 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.

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, the manufacturer has requested that 
the applicability of the existing AD be revised to include airplanes 
equipped with a rudder power control unit (PCU) having part number 
65C37052-( ). The manufacturer points out that AD 94-01-07, amendment 
39-8789 (59 FR 4570, February 1, 1994), currently requires certain 
modifications to the rudder PCU having part number 65-44861. This 
modification involves replacing the existing dual servo valve in the 
rudder PCU with an improved servo valve, which revises the existing 
part number of the rudder PCU to part number 65C37052-( ). However, AD 
94-01-07 does not require an inspection of rudder PCU's to determine if 
reworked PCU manifold cylinder bores containing chrome plating are 
installed. Upon examination of the request, the FAA finds that Model 
737-100, -200, -300, -400, and -500 series airplanes equipped with a 
rudder PCU having part number 65C37052-( ) are also subject to the 
addressed unsafe condition of AD 97-09-14 and has included this part 
number in the applicability of this proposed AD.
    In addition, the manufacturer pointed out that it erroneously 
indicated in comments submitted to the notice of proposed rulemaking 
(NPRM) for AD 97-09-14 that only aileron/elevator actuators having a 
part number that includes ``ss'' could be eliminated from the 
applicability of that rule. (Based on these comments, the FAA revised 
the final rule of that AD accordingly.) However, the ``ss'' is in the 
serial number, not the part number. The manufacturer also pointed out 
that it indicated that the ``ss'' only applied to the aileron and 
elevator PCU's, when it also applies to the rudder PCU's. The FAA has 
specified this information in the applicability and paragraph (a) of 
the proposed AD.

[[Page 8370]]

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 supersede AD 97-09-14 to continue to require an 
inspection of reworked aileron/elevator power control units (PCU's) and 
rudder PCU's 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. The proposed AD would 
expand the applicability of the existing AD to include airplanes 
equipped with rudder PCU's having part number 65C37052-( ). The 
proposed AD also revises the existing AD to exclude rudder PCU's (in 
addition to aileron/elevator actuators) having serial numbers that 
contain ``ss'' from the requirements of this proposed AD.

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.
    The actions that are currently required by AD 97-09-14, and 
retained in this proposed AD, take approximately 5 work hours per 
airplane to accomplish, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the currently required 
actions on U.S. operators is estimated to be $327,300, or $300 per 
airplane.
    The new actions that are proposed in this AD action would take 
approximately 5 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the proposed requirements of this AD on U.S. operators is 
estimated to be $300 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or 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 removing amendment 39-10010 (62 FR 
24008, May 2, 1997), and by adding a new airworthiness directive (AD), 
to read as follows:

Boeing: Docket 97-NM-133-AD. Supersedes AD 97-09-14, Amendment 39-
10010.

    Applicability: Model 737-100, -200, -300, -400, and -500 series 
airplanes equipped with a rudder power control unit (PCU), having 
part number (P/N) 65-44861-( ) or P/N 65/C37052-( ) (except those 
having serial numbers that contain ``ss''), and a serial number less 
than 1252A; or an aileron or elevator PCU having P/N 65-44761-( ) 
(except those having serial numbers that contain an ``ss'') and a 
serial number less than 5360A; 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 (g) 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:

Restatement of Requirements of AD 97-09-14, Amendment 39-10010

    (a) Perform an inspection of reworked or overhauled aileron and 
elevator PCU's having P/N 65-44761-( ) (except those having serial 
numbers that contain an ``ss''), and a serial number less than 
5360A; and rudder PCU's having P/N 65-44861-( ) and a serial number 
less than 1252A (except those having serial numbers that contain 
``ss''); 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. Accomplish the 
inspection at the earlier of the times specified in paragraphs 
(a)(1) and (a)(2) of this AD.
    (1) Within 5 years or 15,000 flight hours after June 6, 1997 
(the effective date of AD 97-09-14, amendment 39-10010), whichever 
occurs first.
    (2) At the next time the PCU is sent to a repair facility.
    (b) If any reworked PCU mainfold cylinder bores containing 
chrome plating are found to be installed during the inspection 
required by paragraph (a) of this AD: 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 June 6, 1997, 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 
65-44861-( ), 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.

New Requirement of This AD

    (d) Perform an inspection of reworked or overhauled rudder PCU's 
having P/N 65C37052-( ) and a serial number less than 1252A (except 
those having serial numbers that contain ``ss''); 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. Accomplish the inspection at the earlier of the 
times specified in paragraphs (d)(1) and (d)(2) of this AD.
    (1) Within 5 years or 15,000 flight hours after the effective 
date of this AD, whichever occurs first.

[[Page 8371]]

    (2) At the next time the PCU is sent to a repair facility.
    (e) If any reworked PCU mainfold cylinder bores containing 
chrome plating are found to be installed during the inspection 
required by paragraph (d) of this AD: 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.
    (f) As of the effective date of this AD, no person shall install 
a reworked PCU manifold cylinder bore containing chrome plating on a 
rudder PCU having P/N 65C37052-( ), on 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.
    (g) 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.

    (h) 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 11, 1998.
Gilbert L. Thompson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-4112 Filed 2-18-98; 8:45 am]
BILLING CODE 4910-13-U