Federal Register / Vol. 62, No. 50 / Friday, March 14, 1997 / Proposed Rules 12123

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.

§ 39.13 [Amended]

2. Section 39.13 is amended by

adding the following new airworthiness

directive:

Boeing: Docket 97–NM–28–AD.

Applicability: All Model 737–100, –200,

–300, –400, and –500 series airplanes,

certificated in any category.

Note 2: 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 excessive rudder authority and

consequent reduced controllability of the

airplane; and malfunctions of the yaw

damper system, which could result in

sudden uncommanded yawing of the

airplane and consequent injury to passengers

and crewmembers; accomplish the following:

(a) Within 3 years after the effective date

of this AD, accomplish paragraphs (a)(1) and

(a)(2) of this AD in accordance with a method

approved by the Manager, Seattle Aircraft

Certification Office (ACO), FAA, Transport

Airplane Directorate.

(1) Install a newly designed rudderlimiting device that reduces the rudder

authority at altitudes above 1,500 feet above

ground level (AGL).

(2) Install a newly designed yaw damper

system that improves the reliability and fault

monitoring capability.

(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

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.

(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 March 7,

1997.

Ronald T. Wojnar,

Manager, Transport Airplane Directorate,

Aircraft Certification Service.

[FR Doc. 97–6436 Filed 3–13–97; 8:45 am]

BILLING CODE 4910–13–P

14 CFR Part 39

[Docket No. 96–NM–152–AD]

RIN 2120–AA64

Airworthiness Directives; Boeing

Model 737–100 and –200 Series

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Supplemental notice of

proposed rulemaking; reopening of

comment period.

SUMMARY: This document revises an

earlier proposed airworthiness directive

(AD), applicable to all Boeing Model

737–100 and –200 series airplanes, that

would have required replacement of

certain outboard and inboard wheel

halves with improved wheel halves.

That action also would have required

cleaning and inspecting certain

outboard and inboard wheel halves for

corrosion, missing paint in large areas,

and cracks; and repair or replacement of

the wheel halves with serviceable wheel

halves, if necessary. That proposal was

prompted by a review of the design of

the flight control systems on Model 737

series airplanes. This action revises the

proposed rule by extending the

compliance time, revising the

applicability of the AD, and clarifying

part and serial numbers of affected

wheel assemblies and halves. The

actions specified by this proposed AD

are intended to prevent failure of the

wheel flanges, which could result in

damage to the hydraulics systems,

jammed flight controls, loss of electrical

power, or other combinations of

failures; and consequent reduced

controllability of the airplane.

DATES: Comments must be received by

April 3, 1997.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 96–NM–

152–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

Allied Signal Aerospace Company,

Bendix Wheels and Brakes Division,

South Bend, Indiana 46624; and Bendix,

Aircraft Brake and Strut Division, 3520

West Mestmoor Street, South Bend,

Indiana 46624. This information may be

examined at the FAA, Transport

Airplane Directorate, 1601 Lind

Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

David Herron, Aerospace Engineer,

Systems and Equipment Branch, ANM–

130S, FAA, Seattle Aircraft Certification

Office, 1601 Lind Avenue, SW., Renton,

Washington; telephone (206) 227–2672;

fax (206) 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 96–NM–152–AD.’’ The

postcard will be date stamped and

returned to the commenter.
12124 Federal Register / Vol. 62, No. 50 / Friday, March 14, 1997 / Proposed Rules

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.

96–NM–152–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

A proposal to amend part 39 of the

Federal Aviation Regulations (14 CFR

part 39) to add an airworthiness

directive (AD), applicable to all Boeing

Model 737–100 and –200 series

airplanes, was published as a notice of

proposed rulemaking (NPRM) in the

Federal Register on August 28, 1996 (61

FR 44245). That NPRM would have

required replacement of certain

outboard and inboard wheel halves with

improved wheel halves. That NPRM

also would have required cleaning and

inspecting certain outboard and inboard

wheel halves for corrosion, missing

paint in large areas, and cracks; and

repair or replacement of the wheel

halves with serviceable wheel halves, if

necessary. That NPRM was prompted by

a review of the design of the flight

control systems on Model 737 series

airplanes. The actions specified by that

NPRM are intended to prevent damage

to the wheel flanges, which could result

in failure of the hydraulics systems,

jammed flight controls, loss of electrical

power, or other combinations of

failures; and consequent reduced

controllability of the airplane.

Actions Since Issuance of Previous

Proposal

Due consideration has been given to

the comments received in response to

the NPRM.

Support for the Proposal

Two commenters support the

proposed rule.

Requests to Reopen Comment Period

Several commenters request that the

proposal be reissued and the public

comment period reopened. The

commenters ask that the intent of the

proposal be clarified. The commenters

state that the proposal appears to

require that an inspection and a

replacement be accomplished

concurrently within 180 days. Allied

Signal indicates that it is unclear why

operators should be required to replace

wheel halves and then inspect those

wheel halves that were just removed.

In its justification for the request to

reopen the comment period, another

commenter states that the issue

addressed in the proposed AD arises

from a failure that occurred on a

military aircraft. The commenter

indicates that, when maintained

properly and operated on civilian

airliners, certain wheel halves are not

subject to the questionable maintenance

practices and adverse operational

conditions often associated with

military hardware. The commenter adds

that, in particular, the inspections

required at tire replacement occur far

more frequently due to utilization

differences. The commenter believes

that strengthened inspection

requirements in accordance with the

latest manufacturer’s recommendations

can provide for safe operation of the

older wheels until replacements would

normally be available.

The FAA concurs with the

commenters’ requests to reopen the

comment period for this proposed rule

and to provide clarification of the intent

of the proposal. The intent of this

proposed AD is that the affected fleet be

equipped eventually with more resilient

wheel halves that provide greater

tolerance for corrosion and handling

damage. Some failures of wheel halves

have occurred because indications of

corrosion or handling damage were not

detected in a timely manner. Therefore,

the FAA included a requirement in the

original NPRM indicating that, until the

time that the existing wheel halves can

be replaced with the more resilient

wheel halves, repetitive cleaning and

inspections of the wheel halves must be

performed in accordance with the

cleaning/inspection method described

in Allied Signal Service Bulletin No.

737–32–026. Accomplishment of these

repetitive actions will ensure that an

acceptable level of safety is maintained

until the wheel halves are replaced.

The FAA has revised this

supplemental NPRM to clarify these

issues:

• The repetitive inspection

requirement, which appeared as

paragraph (b) of the original NPRM, is

contained in paragraph (a) of this

supplemental NPRM. Paragraph (a) of

this supplemental NPRM has been

revised to clarify that the inspections of

the wheel halves must be repeated until

the wheel halves are replaced.

• The replacement requirement,

which appeared in paragraph (a) of the

original NPRM, is contained in

paragraph (b) of this supplemental

NPRM. Paragraph (b) of this

supplemental NPRM has been revised to

clarify that accomplishment of the

replacement terminates the repetitive

inspections required by paragraph (a).

Request for Extended Compliance Time

Three commenters express concern

that replacement of certain outboard

and inboard wheel halves with

improved halves cannot be supported

within the proposed compliance time of

180 days. One of these commenters,

Allied Signal, suggests that the

compliance time be extended to 365

days, and that paragraph (c) of the

original NPRM be deleted. Allied Signal

indicates that the lead time necessary to

order and receive forgings, machine,

finish, and ship replacement wheels

involves approximately 120 days, which

is a significant portion of the proposed

180-day compliance time. Allied Signal

states that it does not have sufficient

information to determine how many

wheels need replacement, and may not

have this information until a final rule

is effective and orders for replacements

arrive.

In light of these requests, the FAA has

reconsidered the compliance times

proposed in the original NPRM. The

FAA considers that the compliance time

of 180 days (and thereafter at each tire

change) for inspections of the wheel

halves, as proposed in paragraph (b) of

the original NPRM, is appropriate. The

FAA considers that these repetitive

inspections must be accomplished at the

originally proposed intervals in order to

provide an acceptable level of safety

until the replacement can be

accomplished.

However, in consideration of parts

availability, the FAA has determined

that the compliance time for

replacement of the wheel halves can be

extended from 180 days to two years

without compromising safety, and that

paragraph (c) of the original NPRM can

be removed from this supplemental

NPRM. Given this revised compliance

time for accomplishment of the

replacement, the FAA estimates that

approximately four tire changes would

be accomplished in the two-year period

prior to the time the replacement would

be required. The compliance time

specified in paragraph (b) of this

supplemental NPRM has been revised

accordingly. In addition, paragraph (c)

of the original NPRM has been removed

from this supplemental NPRM.

Requests for Clarification of Part

Numbering System

Two commenters request clarification

of the part numbering system specified

in the proposal. Further, Allied Signal

recommends that serial number H–1049

be used in all places where serial

number H–999 appeared in the NPRM

to avoid numerical discrepancies and to

ensure adequate coverage of these wheel

halves. Allied Signal submits two sets of

suggested changes to the NPRM: one set

based on an intent to remove all affected

wheels from service, and the other set

based on an intent to inspect all affected
Federal Register / Vol. 62, No. 50 / Friday, March 14, 1997 / Proposed Rules 12125

wheels and remove from service only

those with cracks.

Allied Signal states that a

misunderstanding exists with regard to

the serial numbering system used by

Aircraft Landing Systems (formerly

Bendix). Allied Signal clarifies that

wheels having a ‘‘B’’ prefix serial

number are original equipment wheels

shipped from the factory. Individual

inboard and individual outboard wheel

halves are given the same ‘‘B’’ serial

number on the final production line and

mated together to form a complete

wheel assembly. Wheel halves having

serial numbers with an ‘‘H’’ prefix are

replacement service halves. Availability

of a service wheel half allows an

operator to replace a damaged wheel

half instead of the entire wheel

assembly. Individual inboard and

outboard service halves are not mated

together to form a complete assembly;

they are shipped independently of each

other.

Allied Signal also clarifies that

Bendix Service Information Letter (SIL)

392, Revision 1, dated November 15,

1979, and Allied Signal Service Bulletin

No. 737–32–026, dated April 26, 1988,

apply to both the ‘‘H’’ and ‘‘B’’ prefix

serial numbers, not just the ‘‘H’’ prefix

serial numbers used in the ‘‘B’’ prefix

wheel assemblies.

The FAA agrees that clarification of

the part and serial numbers specified in

the original NPRM is necessary. As

stated previously, the FAA intends that

all affected wheels be removed from

service; the FAA concurs with the

changes suggested by Allied Signal

based on that intent. Paragraphs (a) and

(b) of this supplemental NPRM reflect

the appropriate part and serial numbers

provided by Allied Signal. In addition,

serial number H–1049 has been

specified in this supplemental NPRM in

place of serial number H–999.

Request to Revise the Applicability of

the Proposed AD

The Air Transport Association (ATA)

of America, on behalf of one of its

members, requests that the applicability

of the proposed AD be limited only to

the Bendix main wheel assemblies that

prompted the airworthiness concern.

The ATA states that the proposed

applicability affects even operators with

BFGoodrich brakes. The commenter

concludes that, unless operators of

airplanes equipped with BFGoodrich

brakes submit a request for and receive

approval of an alternative method of

compliance (AMOC), those operators are

considered in noncompliance with the

AD.

The FAA concurs with the

commenter’s request to revise the

applicability of the original NPRM. This

FAA has revised the applicability of this

supplemental NPRM to specify that the

proposed rule applies only to Boeing

Model 737–100 and –200 series

airplanes equipped with Bendix main

wheel assemblies having part number

2601571–1. Paragraphs (a) and (b) of the

supplemental NPRM specify the serial

numbers of the inboard and outboard

wheel halves that are affected.

The FAA also clarifies that operators

of airplanes equipped with BFGoodrich

brakes would not be required to submit

a request for approval of an AMOC.

Although the applicability of the

original NPRM identified the affected

airplanes as ‘‘all Model 737–100 and

–200 series airplanes,’’ paragraphs (a)

and (b) specified clearly that only those

airplanes equipped with Bendix main

wheel assemblies having certain part

and serial numbers are affected by the

proposed rule. Therefore, operators of

airplanes equipped with other main

wheel assemblies are not subject to the

requirements of this AD, and would

have no reason to apply for approval of

an AMOC.

Request to Revise Statement of Findings

of Critical Design Review Team

One commenter requests the second

paragraph of the Discussion section that

appeared in the preamble to the

proposed rule be revised to accurately

reflect the findings of the Critical Design

Review (CDR) team. The commenter

asks that the FAA delete the one

sentence in that paragraph, which read:

‘‘The recommendations of the team

include various changes to the design of

the flight control systems of these

airplanes, as well as correction of

certain design deficiencies.’’ The

commenter suggests that the following

sentences should be added: ‘‘The team

did not find any design issues that

could lead to a definite cause of the

accidents that gave rise to this effort.

The recommendations of the team

include various changes to the design of

the flight control systems of these

airplanes, as well as incorporation of

certain design improvements in order to

enhance its already acceptable level of

safety.’’

The FAA acknowledges that the CDR

team did not find any design issue that

could lead to a definite cause of the

accidents that gave rise to this effort.

However, as a result of having

conducted the CDR of the flight control

systems on Boeing Model 737 series

airplanes, the team indicated that there

are a number of recommendations that

should be addressed by the FAA for

each of the various models of the Model

737. In reviewing these

recommendations, the FAA has

concluded that they address unsafe

conditions that must be corrected

through the issuance of AD’s. Therefore,

the FAA does not concur that these

design changes merely ‘‘enhance [the

Model 737’s] already acceptable level of

safety.’’

Conclusion

Since these changes provide

significant clarification of the intent and

requirements of the originally proposed

rule, the FAA has determined that it is

in the public interest to reopen the

comment period to provide additional

opportunity for public comment.

Cost Impact

There are approximately 634 Boeing

Model 737–100 and –200 series

airplanes of the affected design in the

worldwide fleet. The FAA estimates that

241 airplanes of U.S. registry would be

affected by this proposed AD.

The FAA estimates that it would take

approximately 4 work hours per

airplane to accomplish the proposed

replacement of wheel halves, and that

the average labor rate is $60 per work

hour. Required parts would cost

approximately $20,212 per airplane.

Based on these figures, the cost impact

of the proposed replacement on U.S.

operators is estimated to be $4,928,932,

or $20,452 per airplane.

The FAA also estimates that it would

take approximately 2 work hours per

airplane to accomplish the proposed

cleaning and inspection, and that the

average labor rate is $60 per work hour.

Based on these figures, the cost impact

of the proposed cleaning and inspection

on U.S. operators is estimated to be

$28,920, or $120 per airplane.

The cost impact figures discussed

above are 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’’
12126 Federal Register / Vol. 62, No. 50 / Friday, March 14, 1997 / Proposed Rules

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.

§ 39.13 [Amended]

2. Section 39.13 is amended by

adding the following new airworthiness

directive:

BOEING: Docket 96-NM–152-AD.

Applicability: Boeing Model 737–100 and

-200 series airplanes equipped with Bendix

main wheel assemblies having part number

2601571–1, 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 (c) 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 failure of the wheel flanges,

which could result in damage to the

hydraulics systems, jammed flight controls,

loss of electrical power, or other

combinations of failures; and consequent

reduced controllability of the airplane,

accomplish the following:

(a) For airplanes equipped with a Bendix

main wheel assembly having part number (P/

N) 2601571–1 with an inboard wheel half

with serial number (S/N) B–5999 or lower, or

S/N H–1799 or lower; or with an outboard

wheel half with S/N B–5999 or lower, or S/

N H–1049 or lower; accomplish the

following:

(1) Within 180 days after the effective date

of this AD, and thereafter at each tire change

until the replacement required by paragraph

(b) of this AD is accomplished:

Accomplish the actions specified in

paragraphs (a)(1)(i), (a)(1)(ii), and (a)(1)(iii) of

this AD, in accordance with the

Accomplishment Instructions of Allied

Signal Service Bulletin No. 737–32–026,

dated April 26, 1988, including Attachments

1 and 2.

(i) Clean any inboard and outboard wheel

half specified in paragraph (a) of this AD.

And

(ii) Inspect the wheel halves for corrosion

or missing paint. If any corrosion is found,

or if any paint is missing in large areas, prior

to further flight, strip or remove paint, and

remove any corrosion. And

(iii) Perform an eddy current inspection to

detect cracks of the bead seat area.

(2) If any cracking is found during the

inspections required by this paragraph, prior

to further flight, repair or replace the wheel

halves with serviceable wheel halves in

accordance with procedures specified in the

Component Maintenance Manual.

(b) For airplanes equipped with a Bendix

main wheel assembly having P/N 2601571–

1 with an inboard wheel half with S/N B–

5999 or lower, or S/N H–1799 or lower; or

with an outboard wheel half with S/N B–

5999 or lower, or S/N H–1049 or lower;

accomplish the following: Within 2 years

after the effective date of this AD, accomplish

the actions specified in paragraphs (b)(1) and

(b)(2) of this AD, in accordance with Bendix

Service Information Letter (SIL) 392,

Revision 1, dated November 15, 1979.

Accomplishment of the replacement

constitutes terminating action for the

repetitive inspections required by paragraph

(a) of this AD.

(1) Remove any inboard wheel half

specified in paragraph (b) of this AD, and

replace it with an inboard wheel half having

P/N 2607046, S/N B–6000 or greater, or S/N

H–1800 or greater. And

(2) Remove any outboard wheel half

specified in paragraph (b) of this AD, and

replace it with an outboard wheel half having

P/N 2607047, S/N B–6000 or greater, or S/N

H–1050 or greater.

(c) 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.

(d) 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 March 7, 1997.

Darrell M. Pederson,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 97–6438 Filed 3–13–97; 8:45 am]

BILLING CODE 4910–13–U

14 CFR Part 39

[Docket No. 97–NM–29–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).

SUMMARY: This document proposes the

supersedure of two existing

airworthiness directives (AD),

applicable to certain Boeing Model 737

series airplanes, that currently require

tests of the main rudder power control

unit (PCU) to detect excessive internal

leakage of hydraulic fluid, stalling, or

reversal, and to verify proper operation

of the PCU; and replacement of the PCU

with a unit having a different part

number, if necessary. This action would

add requirements for replacement of the

PCU and the vernier control rod bolt

with newly designed units. This action

also would add a requirement for leak

tests of the PCU, and replacement of the

PCU with a serviceable or newly

designed unit, if necessary. This

proposal is prompted by reports of

fracturing of the vernier control rod

bolts as a result of the shank of the bolt

running into the threads on the nutplate

during installation of the rod. The

actions specified by the proposed AD

are intended to prevent such fracturing,

which could result in uncommanded

movements of the rudder, and

consequent reduced controllability of

the airplane.

DATES: Comments must be received by

April 23, 1997.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 97–NM–

29–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.