This section of the FEDERAL REGISTER

contains regulatory documents having general

applicability and legal effect, most of which

are keyed to and codified in the Code of

Federal Regulations, which is published under

50 titles pursuant to 44 U.S.C. 1510.

The Code of Federal Regulations is sold by

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REGISTER issue of each week.

Rules and Regulations Federal Register

9679

Vol. 62, No. 42

Tuesday, March 4, 1997

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.

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
9680 Federal Register / Vol. 62, No. 42 / Tuesday, March 4, 1997 / Rules and Regulations

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.

§ 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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