Federal Register / Vol. 62, No. 4 / Tuesday, January 7, 1997 / Proposed Rules 947

of the requirements of this AD is affected, the

owner/operator must use the authority

provided in paragraph (f) of this AD to

request approval from the FAA. This

approval may address either no action, if the

current configuration eliminates the unsafe

condition; or different actions necessary to

address the unsafe condition described in

this AD. Such a request should include an

assessment of the effect of the changed

configuration on the unsafe condition

addressed by this AD. In no case does the

presence of any modification, alteration, or

repair remove any airplane from the

applicability of this AD.

Compliance: Required as indicated, unless

accomplished previously.

To detect and correct fatigue cracking,

which could result in reduced structural

integrity of the outboard chords, and

subsequent rapid decompression of the

airplane, accomplish the following:

(a) For airplanes on which the body station

(BS) 727 frame upper outboard chord has

been replaced in accordance with Boeing

Service Bulletin 737–53–1088: Prior to the

accumulation of 50,000 flight cycles since

replacement of the upper outboard chord, or

within 4,500 flight cycles after the effective

date of this AD, whichever occurs later,

perform close visual, pulse echo shear wave

(PESW), and high frequency eddy current

(HFEC) inspections to detect cracks in the

outboard chord of the frame at BS 727 and

in the outboard chord of stringer 18A.

Perform the inspections in accordance with

Part I of the Accomplishment Instructions of

either Boeing Alert Service Bulletin 737–

53A1166, dated June 30, 1994; or Boeing

Service Bulletin 737–53A1166, Revision 1,

dated May 25, 1995. Thereafter, repeat these

inspections at intervals not to exceed 4,500

flight cycles.

(b) For airplanes on which the BS 727

frame outboard chord has not been replaced

or on which only the lower outboard chord

has been replaced in accordance with Boeing

Service Bulletin 737–53–1088: Prior to the

accumulation of 50,000 total flight cycles, or

within 4,500 flight cycles after the effective

date of this AD, whichever occurs later,

perform close visual, PESW, and HFEC

inspections to detect cracks in the outboard

chord of the frame at BS 727 and in the

outboard chord of stringer 18A. Perform the

inspections in accordance with Part I of the

Accomplishment Instructions of either

Boeing Alert Service Bulletin 737–53A1166,

dated June 30, 1994; or Boeing Service

Bulletin 737–53A1166, Revision 1, dated

May 25, 1995. Thereafter, repeat these

inspections at intervals not to exceed 4,500

flight cycles.

(c) If any crack is found in the outboard

chord of stringer 18A during any inspection

required by this AD, prior to further flight,

repair in accordance with either paragraph

(c)(1) or (c)(2) of this AD.

(1) Repair in accordance with Boeing

Service Bulletin 737–53A1166, Revision 1,

dated May 25, 1995; or

(2) Repair in accordance with a method

approved by the Manager, Seattle Aircraft

Certification Office, (ACO) FAA, Transport

Airplane Directorate.

(d) If any crack is found in the outboard

chord of the frame at BS 727 during any

inspection required by this AD: Accomplish

paragraph (d)(1) or (d)(2) of this AD, as

applicable, in accordance with either Boeing

Alert Service Bulletin 737–53A1166, dated

June 30, 1994; or Boeing Service Bulletin

737–53A1166, Revision 1, dated May 25,

1995. Thereafter, repeat the inspections

required by either paragraph (a) or (b) of this

AD, as applicable, at intervals not to exceed

4,500 flight cycles.

(1) If any crack extends from the forward

edge of the chord or from the forward

fastener hole, but does not extend past the

second fastener hole, accomplish either

paragraph (d)(1)(i) or (d)(1)(ii) of this AD.

(i) Prior to further flight, install the timelimited repair. Prior to the accumulation of

4,500 flight cycles or within 18 months after

accomplishment of the repair, whichever

occurs first, replace the outboard chord. Or

(ii) Prior to further flight, replace the

outboard chord.

Note 2: Boeing Alert Service Bulletin 737–

53A1166 references Boeing Service Bulletin

737–53–1088 as an additional source of

service information for procedures to replace

the chord.

(2) If any crack extends from the forward

edge of the chord, or from the forward

fastener hole, and extends past the second

fastener hole, prior to further flight, replace

the outboard chord in accordance with either

the original issue or Revision 1 of the service

bulletin.

(e) Accomplishment of the following

actions in accordance with either Boeing

Alert Service Bulletin 737–53A1166, dated

June 30, 1994, or Boeing Service Bulletin

737–53A1166, Revision 1, dated May 25,

1995, constitutes terminating action for the

requirements of this AD.

(1) For airplanes on which no crack is

found: Install the preventative modification

in accordance with either the original issue

or Revision 1 of the service bulletin.

(2) For airplanes on which any crack is

found: Prior to further flight, replace the

cracked chord and install the preventative

modification in accordance with either the

original issue or Revision 1 of the service

bulletin.

(f) 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 3: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Seattle ACO.

(g) 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

December 31, 1996.

S. R. Miller,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 97–254 Filed 1–6–97; 8:45 am]

BILLING CODE 4910–13–U

14 CFR Part 39

[Docket No. 95–NM–207–AD]

RIN 2120–AA64

Airworthiness Directives; Boeing

Model 737–300, –400, and –500 Series

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Notice of proposed rulemaking

(NPRM).

SUMMARY: This document proposes the

adoption of a new airworthiness

directive (AD) that is applicable to

certain Boeing Model 737–300, –400,

and –500 series airplanes. This proposal

would require interchanging the

location of the hydraulic fuse and the

flow limiter of the standby hydraulic

system of the leading edge. The

proposed AD also would require

replacing the existing hydraulic fuses in

the standby hydraulic system with new

fuses. This proposal is prompted by

reports of a performance test of the

hydraulic fuses, which revealed that the

positioning of the flow limiter in the

existing configuration, and excessive

fusing volumes of some of the fuses, can

adversely affect the operation of the

fuse. The actions specified by the

proposed AD are intended to prevent

such adversely affected operation of the

fuse, which could result in the loss of

all hydraulic system pressure and

consequent severely reduced

controllability of the airplane.

DATES: Comments must be received by

February 18, 1997.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 95–NM–

207–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
948 Federal Register / Vol. 62, No. 4 / Tuesday, January 7, 1997 / Proposed Rules

Airplane Directorate, 1601 Lind

Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Kenneth W. Frey, Aerospace Engineer,

Systems and Equipment Branch, ANM–

130S, FAA, Seattle Aircraft Certification

Office, 1601 Lind Avenue, SW., Renton,

Washington; telephone (206) 227–2673;

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 95–NM–207–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.

95–NM–207–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

The FAA received a report indicating

that a performance test of the fuses in

the hydraulic systems of certain Boeing

Model 737 series airplanes was

conducted. Results of that performance

test revealed that, in the existing

configuration, the flow limiter of the

standby hydraulic system of the leading

edge is positioned upstream of the

hydraulic fuse. Such positioning of the

flow limiter can adversely affect the

operation of the fuse.

The FAA also received a report

indicating that certain fuses installed in

the standby hydraulic system exceed

specified ‘‘fusing volumes’’ (the fluid

volume allowed to pass through the fuse

before it shuts off) at low hydraulic fluid

temperatures. This condition also can

adversely affect the operation of the

fuse. The fuses in hydraulic systems A

and B are not affected by this condition.

However, the fuses in the standby

hydraulic system are affected, since they

are exposed to low temperatures

because of the intermittent operation of

the standby system.

The standby hydraulic system

provides a backup system after the

pressure of either (or both) the A or B

hydraulic system drops below a

minimum pressure setting. The

hydraulic fuse is designed to prevent

total loss of the hydraulics systems after

a certain volume of fluid passes through

the fuse within a specified time

following the development of a leak

downstream of the fuse. The hydraulic

fuse also allows part of the hydraulic

system to remain pressurized if such a

leak develops. If the A and B hydraulic

systems fail, and the standby hydraulic

system develops a leak downstream of

a failed fuse, the airplane could lose all

hydraulic system pressure. This

condition, if not corrected, could result

in severely reduced controllability of

the airplane.

Explanation of Relevant Service

Information

The FAA has reviewed and approved

Boeing Service Bulletin 737–29–1070,

dated June 8, 1995, which describes

procedures for interchanging the

location of the hydraulic fuse and the

flow limiter of the standby hydraulic

system of the leading edge so that the

hydraulic fuse is positioned upstream of

the flow limiter. Accomplishment of

this action will ensure normal operation

of the hydraulic fuse.

The FAA also has reviewed and

approved Boeing Service Bulletin 737–

29–1071, dated May 16, 1996, which

describes procedures for replacing the

existing hydraulic fuses in the standby

hydraulic system with new fuses that

are not affected by low temperature

operation. Installation of these new

fuses will prevent the possible loss of

the standby hydraulic system as a result

of fluid depletion if a leak occurs

downstream of the fuses.

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

require interchanging the location of the

hydraulic fuse and the flow limiter of

the standby hydraulic system of the

leading edge so that the hydraulic fuse

is positioned upstream of the flow

limiter. The proposed AD also would

require replacing the existing hydraulic

fuses in the standby hydraulic system

with new fuses that are not affected by

low temperature operation. The actions

would be required to be accomplished

in accordance with the service bulletins

described previously.

Cost Impact

There are approximately 1,791 Boeing

Model 737–300, –400, and –500 series

airplanes of the affected design in the

worldwide fleet. The FAA estimates that

596 airplanes of U.S. registry would be

affected by this proposed AD.

The FAA estimates that it would take

approximately 2 work hours per

airplane to accomplish the proposed

interchange of the hydraulic fuse and

the flow limiter, and that the average

labor rate is $60 per work hour. The cost

for required parts would be minimal.

Based on these figures, the cost impact

of the proposed interchange on U.S.

operators is estimated to be $71,520, or

$120 per airplane.

The FAA also estimates that it would

take approximately 4 work hours per

airplane to accomplish the proposed

replacement, at an average labor rate of

$60 per work hour. Required parts

would be provided by the manufacturer

at no cost to operators. Based on these

figures, the cost impact of the proposed

replacement on U.S. operators is

estimated to be $143,040, or $240 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’’

under Executive Order 12866; (2) is not

a ‘‘significant rule’’ under the DOT
Federal Register / Vol. 62, No. 4 / Tuesday, January 7, 1997 / Proposed Rules 949

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 95–NM–207–AD.

Applicability: Model 737–300, –400, and

–500 series airplanes having line numbers

1001 through 2791, inclusive; 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 adversely affected operation of

the fuse, which could result in the loss of all

hydraulic system pressure and consequent

severely reduced controllability of the

airplane, accomplish the following:

(a) For airplanes listed in Boeing Service

Bulletin 737–29–1070, dated June 8, 1995:

Within 4,000 flight hours after the effective

date of this AD, interchange the location of

the hydraulic fuse and the flow limiter of the

standby hydraulic system of the leading edge

so that the hydraulic fuse is positioned

upstream of the flow limiter, in accordance

with Boeing Service Bulletin 737–29–1070,

dated June 8, 1995.

(b) For airplanes listed in Boeing Service

Bulletin 737–29–1071, dated May 16, 1996:

Within 4,000 flight hours after the effective

date of this AD, replace the existing

hydraulic fuses in the standby hydraulic

system with new fuses that are not affected

by low temperature operation, in accordance

with Boeing Service Bulletin 737–29–1071,

dated May 16, 1996.

(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

December 31, 1996.

S.R. Miller,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 97–253 Filed 1–6–97; 8:45 am]

BILLING CODE 4910–13–U

14 CFR Part 39

[Docket No. 95–NM–143–AD]

RIN 2120–AA64

Airworthiness Directives; Airbus

Industrie Model A320 and A321 Series

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Notice of proposed rulemaking

(NPRM).

SUMMARY: This document proposes the

adoption of a new airworthiness

directive (AD) that is applicable to

certain Airbus Industrie Model A320

and A321 series airplanes. This

proposal would require replacement of

two elevator aileron computers (ELAC)

with ELAC’s that contain new software.

This proposal is prompted by reports

indicating that some of these airplanes

have experienced uncommanded

movements of the ailerons. The actions

specified by the proposed AD are

intended to prevent situations, such as

uncommanded rolls during turbulent

conditions, which could lead to reduced

controllability of the airplane.

DATES: Comments must be received by

February 18, 1997.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 95–NM–

143–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

Airbus Industrie, 1 Rond Point Maurice

Bellonte, 31707 Blagnac Cedex, France.

This information may be examined at

the FAA, Transport Airplane

Directorate, 1601 Lind Avenue, SW.,

Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Charles Huber, Aerospace Engineer,

Standardization Branch, ANM–113,

FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton,

Washington 98055–4056; telephone

(206) 227–2589; fax (206) 227–1149.

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, stamp

postcard on which the following

statement is made: ‘‘Comments to

Docket Number 95–NM–143–AD.’’ The

postcard will be date stamped and

returned to the commenter.