[Federal Register Volume 62, Number 219 (Thursday, November 13, 1997)]
[Proposed Rules]
[Pages 60808-60810]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-29820]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-157-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 to revise an existing airworthiness 
directive (AD), applicable to all Boeing Model 737-100, -200, -300, -
400, and -500 series airplanes, that currently requires a one-time 
inspection to determine the part number of the engage solenoid valve of 
the yaw damper on the rudder power control unit, and replacement of the 
valve with a valve having a different part number, 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 sudden uncommanded yawing of the airplane due to 
potential failures within the yaw damper system, and consequent injury 
to passengers and crewmembers. This action would make certain editorial 
changes to clarify the requirements of the existing AD.

DATES: Comments must be received by December 29, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 97-NM-157-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

[[Page 60809]]

Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Tin Truong, Aerospace Engineer, ANM-
130S, FAA, Transport Airplane Directorate, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-
4056; telephone (425) 227-2764; 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-157-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. 97-NM-157-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On April 24, 1997, the FAA issued AD 97-09-15, amendment 39-10011 
(62 FR 24325, May 5, 1997), applicable to all Boeing Model 737-100, -
200, -300, -400, and -500 series airplanes, to require a one-time 
inspection to determine the part number of the engage solenoid valve of 
the yaw damper, and replacement of the valve with a valve having a 
different part number, 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 sudden 
uncommanded yawing of the airplane due to potential failures within the 
yaw damper system, and consequent injury to passengers and crewmembers.

Actions Since Issuance of Previous Rule

    Since the issuance of AD 97-09-15, the FAA has re-reviewed the 
requirements of paragraph (a) and the information specified in ``Note 
3'' of that AD.
    The FAA finds that, as paragraph (a) of AD 97-09-15 is currently 
worded, operators could misinterpret exactly which engage solenoid 
value of the yaw damper must be inspected. Therefore, the FAA has 
revised the phrase ``engage solenoid valve of the yaw damper'' to read 
``engage solenoid valve of the yaw damper on the rudder power control 
unit (PCU).''
    The FAA also finds that paragraph (a) of AD 97-09-15 specifies only 
the Boeing part number (P/N) for some affected parts. For clarification 
purposes, the FAA has revised paragraph (a) of the existing AD to 
include both the Boeing P/N and the vendor P/N's for all affected 
parts.
    The FAA also has revised paragraph (a) of the existing AD to 
reference Chapter 22-11-61 (for Model 737-100 and -200 series 
airplanes) and Chapter 22-12-21 (for Model 737-300, -400, and -500 
series airplanes) of the Boeing Maintenance Manual as the appropriate 
sources of service information for accomplishment of the actions 
required by that paragraph.
    Furthermore, the FAA finds that some engage solenoid valves may be 
labeled with only the name ``Bertea,'' rather than ``Parker'' or 
``Parker-Bertea.'' Therefore, the FAA has revised ``Note 3'' of AD 97-
09-15 to include such information regarding the labeling of the engage 
solenoid valves.

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 revise AD 97-09-15 to continue to require a one-time 
inspection to determine the part number of the engage solenoid valve of 
the yaw damper on the rudder PCU, and replacement of the valve with a 
valve having a different part number, if necessary. The proposed AD 
would make certain editorial changes to clarify the requirements of the 
existing AD.

Cost Impact

    There are approximately 2,675 Boeing 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 FAA estimates that it would take approximately 1 work hour per 
airplane to accomplish the proposed one-time inspection, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the inspection proposed by this AD on U.S. operators is 
estimated to be $65,460, or $60 per airplane. The requirements of this 
AD will add no new costs to affected operators.
    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.

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

[[Page 60810]]

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 39-10011 (62 FR 
24325, May 5, 1997), and by adding a new airworthiness directive (AD), 
to read as follows:

Boeing: Docket 97-NM-157-AD. Revises AD 97-09-15, Amendment 39-
10011.
    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 (b) 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 sudden uncommanded yawing of the airplane due to 
potential failures within the yaw damper system, and consequent 
injury to passengers and crewmembers, accomplish the following:
    (a) Perform a one-time inspection of the engage solenoid valve 
of the yaw damper on the rudder power control unit (PCU) to 
determine the part number (P/N) of the valve. If any valve having 
Parker P/N 59600-5011 (Boeing P/N 10-60811-9), Parker P/N 59600-5007 
(Boeing P/N 10-60811-3), or Parker P/N 59600-5003 (Boeing P/N 10-
60811-1) is installed, prior to further flight, replace it with a 
valve having Parker P/N 881600-1001 (Boeing P/N 10-60811-13), Sterer 
P/N 45080-1 (Boeing P/N 10-60811-8), or Sterer P/N 45080 (Boeing P/N 
10-60811-3). Accomplish the actions in accordance with procedures 
specified in Chapter 22-11-61 (for Model 737-100 and -200 series 
airplanes) or Chapter 22-12-21 (for Model 737-300, -400, and -500 
series airplanes) of the Boeing Maintenance Manual, as applicable. 
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 9, 1997 
(the effective date of AD 97-09-15, amendment 39-10011), whichever 
occurs first.
    (2) At the next time the PCU is sent to a repair facility.

    Note 2: Boeing In-Service Activities Report 95-03-2725-10, dated 
February 16, 1995 (for Model 737-100 and -200 series airplanes), or 
95-04-2725-10, dated February 24, 1995 (for Model 737-300, -400, and 
-500 series airplanes), provides additional information concerning 
interchangeability of solenoid valve part numbers.
    Note 3: Operators should note that, as specified in paragraph 
(a) of this AD, both the Parker and Sterer P/N's have the same 
Boeing P/N (10-60811-3). If, upon inspection, Boeing P/N 10-60811-3 
is found to be installed, operators must ascertain the vendor P/N. 
Parts having Boeing P/N 10-60811-3 and Parker P/N 59600-5007 must be 
replaced and are not considered to be acceptable replacement parts. 
In addition, some engage solenoid valves may be labeled with only 
the name ``Bertea,'' rather than ``Parker'' or ``Parker-Bertea.''

    (b) 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 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (c) 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 November 6, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-29820 Filed 11-12-97; 8:45 am]
BILLING CODE 4910-13-U