[Federal Register Volume 62, Number 42 (Tuesday, March 4, 1997)]
[Rules and Regulations]
[Pages 9679-9680]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-5159]



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 Rules and Regulations
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  Federal Register / Vol. 62, No. 42 / Tuesday, March 4, 1997 / Rules 
and Regulations  

[[Page 9679]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-26-AD; Amendment 39-9954; AD 97-05-10]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to all Boeing Model 737 series airplanes. This action 
requires removal of the main rudder power control unit (PCU) and 
replacement with a serviceable unit. This amendment is prompted by a 
report of the installation of an incorrect bolt on the main rudder PCU. 
The actions specified in this AD are intended to prevent cracking of 
the bearing of the main rudder PCU due to installation of an incorrect 
bolt; such cracking could result in seizure of the bearing and 
resultant uncommanded rudder movement.

DATES: Effective March 19, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 19, 1997.
    Comments for inclusion in the Rules Docket must be received on or 
before May 5, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 97-NM-26-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056.
    The service information referenced in this AD 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; telephone (206) 227-2673; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: The FAA has received a report of cracking of 
the internal summing lever assembly bearing of the main rudder power 
control unit (PCU) on a Model 737 series airplane. Investigation 
revealed that a Hi-Lock bolt had been installed in the lever assembly 
bearing instead of the correct bolt, Boeing Part Number (P/N) 66-22749-
1. Apparently, installation of the incorrect bolt was approved by the 
repair station performing the installation. The Hi-Lock bolt has a 
larger radius in the shoulder-to-shank transition than the correct 
bolt. The larger bolt radius created an interference fit that caused 
the inner race of the bearing to crack. Such cracking, if not detected 
and corrected, could cause the bearing to seize and, consequently, lead 
to an uncommanded rudder movement.

Explanation of Relevant Service Information

    The FAA has reviewed Boeing Service Letter, 737-SL-27-112-B, dated 
February 6, 1997, which lists serial numbers of certain PCU's of the 
main rudder that have been identified as those having incorrect bolts. 
The service letter describes procedures for removal of those PCU's from 
the airplanes, and a one-time visual inspection to detect cracking of 
the lever assembly bearing with a 10-power magnification and strong 
light, a one-time eddy current inspection, and repair, if necessary, 
before the PCU can be reinstalled on the airplane.

Explanation of the Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other Boeing Model 737 series airplanes of the same 
type design, this AD is being issued to prevent cracking of the bearing 
of the main rudder power control unit (PCU) due to the installation of 
an incorrect bolt; such cracking could result in seizure of the bearing 
and a consequent uncommanded rudder movement. This AD requires removal 
of the PCU and replacement with a serviceable unit. This AD also 
prohibits installation of a subject PCU on any airplane in the future 
unless the PCU has been inspected (visually and by eddy current) to 
detect cracking, repaired (if necessary), and tested. The actions are 
required to be accomplished in accordance with the service letter 
described previously.
    This AD also requires that operators submit a report to the FAA of 
the inspection results whenever a PCU is inspected for cracking.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

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

[[Page 9680]]

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 97-NM-26-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    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 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. 106(g), 40113, 44701.

Sec. 39.13  [Amended]

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

97-05-10 Boeing: Amendment 39-9954. Docket 97-NM-26-AD.

    Applicability: Model 737 series airplanes, having a main rudder 
power control unit (PCU) that is identified in Boeing Service Letter 
737-SL-27-112-B, dated February 6, 1997; 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 cracking and seizing of the internal summing lever 
assembly bearing of the main rudder power control unit (PCU), which 
could result in uncommanded rudder movement, accomplish the 
following:
    (a) Within 90 days after the effective date of this AD, remove 
the main rudder PCU and replace it with a serviceable unit in 
accordance with Boeing Service Letter 737-SL-27-112-B, dated 
February 6, 1997.
    (b) As of 90 days after the effective date of this AD, no person 
shall install on any airplane a main rudder PCU having a serial 
number specified in Boeing Service Letter 737-SL-27-112-B, dated 
February 6, 1997, unless the following actions have been 
accomplished in accordance with Boeing Service Letter 737-SL-27-112-
B, dated February 6, 1997.
    (1) Remove the internal summing lever assembly of the main 
rudder PCU in accordance with the service letter.
    (2) Perform a one-time visual inspection using 10-power 
magnification and strong light to detect cracking of the bearing, in 
accordance with the service letter.
    (i) If no cracking is detected during the visual inspection, 
perform an eddy current inspection to detect cracking of the bearing 
in accordance with the service letter.
    (A) If no cracking is detected during the eddy current 
inspection, the unit may be reinstalled on the airplane after it is 
reassembled and tested in accordance with the service letter.
    (B) If any cracking is detected during the eddy current 
inspection, before reinstallation of the PCU on any airplane, repair 
the lever assembly, reassemble, and test; in accordance with the 
service letter.
    (ii) If any cracking is detected during the visual inspection, 
before reinstallation of the PCU on any airplane, repair the lever 
assembly, reassemble, and test, in accordance with the service 
letter.
    (c) Within 14 days after accomplishing the requirements of 
paragraph (b) of this AD, submit a report of any cracked PCU bearing 
to the Manager, Seattle Aircraft Certification Office (ACO), FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, WA 
98055-4056; fax (206) 227-1181. The report shall include the 
information specified in paragraphs (c)(1) and (c)(2) of this AD. 
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.
    (1) The PCU part number and serial number.
    (2) The date of the inspection and the inspection findings.
    (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 
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.
    (f) The actions shall be done in accordance with Boeing Service 
Letter 737-SL-27-112-B, dated February 6, 1997. This incorporation 
by reference was approved by the Director of the Federal Register in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 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 March 19, 1997.

    Issued in Renton, Washington, on February 25, 1997.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-5159 Filed 2-28-97; 12:40 pm]
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