This section of the FEDERAL REGISTER

contains notices to the public of the proposed

issuance of rules and regulations. The

purpose of these notices is to give interested

persons an opportunity to participate in the

rule making prior to the adoption of the final

rules.

Proposed Rules Federal Register

38116

Vol. 63, No. 135

Wednesday, July 15, 1998

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98–NM–148–AD]

RIN 2120–AA64

Airworthiness Directives; Boeing

Model 737 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 series

airplanes. This proposal would require

repetitive ultrasonic inspections to

detect broken bolts that attach the

terminal support fittings to the upper

part of the Body Station 1088 bulkhead,

and corrective actions, if necessary. This

proposal also would require eventual

replacement of the existing bolts with

new, improved bolts, which, when

accomplished, would terminate the

requirements of the AD. This proposal

is prompted by reports that bolts that

attach the terminal support fittings to

the upper part of the bulkhead were

found broken. The actions specified by

the proposed AD are intended to

prevent such broken bolts, which could

result in reduced structural integrity of

the vertical fin installation and possible

loss of the vertical fin.

DATES: Comments must be received by

August 31, 1998.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–114,

Attention: Rules Docket No. 98–NM–

148–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

Airplane Directorate, 1601 Lind

Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Rick

Kawaguchi, Aerospace Engineer,

Airframe Branch, ANM–120S, FAA,

Transport Airplane Directorate, Seattle

Aircraft Certification Office, 1601 Lind

Avenue, SW., Renton, Washington

98055–4056; telephone (425) 227–1153;

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 98–NM–148–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–114, Attention: Rules Docket No.

98–NM–148–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

The FAA has received reports

indicating that broken bolts were found

in the terminal support fittings that

attach the aft spar of the vertical fin to

the upper part of the bulkhead at Body

Station 1088 on Boeing Model 737

series airplanes. The broken bolts were

made of H–11 steel alloy. Bolts made of

such material are susceptible to stress

corrosion cracking. Such broken bolts, if

not corrected, could result in reduced

structural integrity of the vertical fin

installation, and multiple broken bolts

could result in loss of the vertical fin.

Explanation of Relevant Service

Information

The FAA has reviewed and approved

Boeing Service Bulletin 737–53–1107,

Revision 3, dated August 26, 1993; as

revised by Notices of Status Change

737–53–1107 NSC 3, dated June 9, 1994,

and 737–53–1107 NSC 4, dated

September 22, 1994; and Boeing Service

Bulletin 737–53–1107, Revision 4, dated

February 8, 1996. These service

bulletins describe procedures for

repetitive ultrasonic inspections to

detect broken bolts that attach the

terminal support fittings to the upper

part of the Body Station 1088 bulkhead,

and replacement of the existing bolts

with new, improved bolts. The

replacement includes removing the

bolts, performing an eddy current

inspection to detect cracking or

corrosion of the bolt holes, oversizing

the bolt holes, and installing new

Inconel bolts. Installation of the new

Inconel bolts would eliminate the need

for the repetitive inspections described

previously. Accomplishment of the

actions specified in the service bulletins

is intended to adequately address the

identified unsafe condition.

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 accomplishment of the actions

specified in the service bulletins and

notices of status change described

previously, except as discussed below.

Differences Between Proposed Rule and

Service Bulletin

Operators should note that, although

the service bulletins specify that the
Federal Register / Vol. 63, No. 135 /Wednesday, July 15, 1998 / Proposed Rules 38117

manufacturer may be contacted for

disposition of certain repair conditions,

this proposal would require the repair of

those conditions to be accomplished in

accordance with a method approved by

the FAA.

Cost Impact

There are approximately 1,485

airplanes of the affected design in the

worldwide fleet. The FAA estimates that

630 airplanes of U.S. registry would be

affected by this proposed AD.

It would take approximately 3 work

hours per airplane to accomplish the

proposed 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 $113,400, or

$180 per airplane, per inspection cycle.

It would take approximately 9 work

hours per airplane to accomplish the

proposed replacement, at an average

labor rate of $60 per work hour.

Required parts would cost

approximately $471 per airplane. Based

on these figures, the cost impact of the

replacement proposed by this AD on

U.S. operators is estimated to be

$636,930, or $1,011 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

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 98–NM–148–AD.

Applicability: Model 737 series airplanes,

line numbers 1 through 1485 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

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 broken bolts that attach the

terminal support fittings to the upper part of

the Body Station (BS) 1088 bulkhead, which

could result in reduced structural integrity of

the vertical fin installation and possible loss

of the vertical fin, accomplish the following:

(a) Within 18 months after the effective

date of this AD, perform an ultrasonic

inspection to detect broken bolts that attach

the terminal support fittings to the upper part

of the BS 1088 bulkhead, in accordance with

Boeing Service Bulletin 737–53–1107,

Revision 3, dated August 26, 1993; as revised

by Notice of Status Change 737–53–1107

NSC 3, dated June 9, 1994, and Notice of

Status Change 737–53–1107 NSC 4, dated

September 22, 1994; or Boeing Service

Bulletin 737–53–1107, Revision 4, dated

February 8, 1996.

(1) If no broken bolt is found, repeat the

ultrasonic inspection thereafter at intervals

not to exceed 18 months.

(2) If any broken bolt is found, prior to

further flight, perform the actions specified

in paragraph (b) of this AD.

(b) Prior to the accumulation of 20 years

since date of manufacture of the airplane, or

within 18 months after the effective date of

this AD, whichever occurs later, remove all

16 H–11 steel alloy bolts that attach the

terminal support fittings to the upper part of

the bulkhead, and perform an eddy current

inspection to detect cracking or corrosion of

the bolt holes, in accordance with Figure 2

of Boeing Service Bulletin 737–53–1107,

Revision 3, dated August 26, 1993; as revised

by Notice of Status Change 737–53–1107

NSC 3, dated June 9, 1994, and Notice of

Status Change 737–53–1107 NSC 4, dated

September 22, 1994; or Boeing Service

Bulletin 737–53–1107, Revision 4, dated

February 8, 1996.

(1) If no cracking or corrosion is found,

prior to further flight, oversize all 16 bolt

holes and install new Inconel bolts, in

accordance with Figure 2 of the service

bulletin. Accomplishment of this installation

constitutes terminating action for the

repetitive inspection requirements of this

AD.

(2) If any corrosion is found, prior to

further flight, oversize the bolt hole within

the limits specified in Figure 2, Step 4, of the

service bulletin, and install a new Inconel

bolt, in accordance with Figure 2 of the

service bulletin. Accomplishment of the

installation for all 16 bolt holes constitutes

terminating action for the repetitive

inspection requirements of this AD. If

corrosion does not clean up within the limits

specified in Figure 2, Step 4, of the service

bulletin, prior to further flight, repair in

accordance with a method approved by the

Manager, Seattle Aircraft Certification Office

(ACO), FAA, Transport Airplane Directorate.

(3) If any cracking is found, prior to further

flight, oversize the bolt hole within the limits

specified in Figure 2, Step 5, of the service

bulletin, and perform another eddy current

inspection to ensure cracks have been

removed, in accordance with Figure 2 of the

service bulletin.

(i) If, after oversizing, no cracking is found,

prior to further flight, oversize the bolt hole

again, and install a new Inconel bolt, in

accordance with Figure 2 of the service

bulletin. Accomplishment of the installation

for all 16 bolt holes constitutes terminating

action for the repetitive inspection

requirements of this AD.

(ii) If, after oversizing, any cracking is

found, prior to further flight, repair in

accordance with a method approved by the

Manager, Seattle ACO.

Note 2: Replacement of all H–11 steel alloy

bolts accomplished prior to the effective date

of this AD, in accordance with Boeing

Service Bulletin 737–53–1107, dated October

15, 1987; Revision 1, dated June 22, 1989; or

Revision 2, dated September 10, 1992; is

considered acceptable for compliance with

the applicable actions specified in paragraph

(b) of this AD.

(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

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.
38118 Federal Register / Vol. 63, No. 135 /Wednesday, July 15, 1998 / Proposed Rules

Note 3: 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 July 8,

1998.

S.R. Miller,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 98–18779 Filed 7–14–98; 8:45 am]

BILLING CODE 4910–13–U

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97–NM–296–AD]

RIN 2120–AA64

Airworthiness Directives; Boeing

Model 747 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 747 series

airplanes. This proposal would require

repetitive inspections to detect cracks in

the edge frame web and doubler of the

number 1 main entry door cutout; and

repair, if necessary. This proposed AD

also provides for optional terminating

action for the repetitive inspections.

This proposal is prompted by reports

indicating that fatigue cracks were

found in the edge frame web and

doubler at the door stop number 1 of the

number 1 main entry door cutout. The

actions specified by the proposed AD

are intended to detect and correct such

fatigue cracking, which could result in

rapid decompression of the airplane.

DATES: Comments must be received by

August 31, 1998.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–114,

Attention: Rules Docket No.97–NM–

296–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

Airplane Directorate, 1601 Lind

Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Bob

Breneman, Aerospace Engineer,

Airframe Branch, ANM–120S, FAA,

Transport Airplane Directorate, Seattle

Aircraft Certification Office, 1601 Lind

Avenue, SW., Renton, Washington

98055–4056; telephone (425) 227–2776;

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–296–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–114, Attention: Rules Docket No.

97–NM–296–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

The FAA has received reports

indicating that, while replacing the

inner chord of the frame on Boeing

Model 747 series airplanes, cracks were

found in the edge frame web and

doubler of the number 1 main entry

door cutout at station 488, between

stringers 25 and 26 (door stop number

1). The edge frame web in each incident

was almost completely severed. These

airplanes had accumulated as few as

18,502 total flight cycles. In addition,

the FAA has received a report indicating

that, during fatigue testing on a Boeing

Model 747SR test article, cracking

occurred in the edge frame web at

27,500 total pressure cycles and in the

inner chord at 30,750 total pressure

cycles. The cause of such cracking in all

incidents has been attributed to fatigue.

This condition, if not detected and

corrected, could result in rapid

decompression of the airplane.

Explanation of Relevant Service

Information

The FAA has reviewed and approved

Boeing Alert Service Bulletin 747–

53A2414, dated August 7, 1997. This

alert service bulletin describes

procedures for repetitive high frequency

eddy current (HFEC) inspections to

detect cracks in both the aft side of the

edge frame web along the lower edge of

the backup structure attachment at the

stop fitting number 1, and the forward

side of the doubler at the lower edge of

door stop number 1 of the number 1

main entry door cutout; and repair, if

necessary.

The alert service bulletin specifies

that operators of Group 1 airplanes are

to perform those inspections of the

subject areas on both the left and right

sides of the airplane; whereas, operators

of Group 2 airplanes are to perform

those inspections of the subject areas on

the left side only of the airplane. Group

1 airplanes are those Model 747 series

airplanes that have a number 1 main

entry door on both the left and right

sides of the airplane. Group 2 airplanes

are those Model 747 series airplanes

that only have a number 1 main entry

door on the left side of the airplane.

This alert service bulletin also

describes procedures for a preventative

modification of the edge frame web and

doubler, which involves trimming the

lower portion of the subject web;

removing the trimmed web and the

doubler; and installing a new web,

doubler, and splice plate. For airplanes

on which the inner chord of the edge

frame is not being replaced concurrently

with the repair specified in the alert

service bulletin, the procedures also

include an open hole HFEC inspection

of the inner chord of the edge frame.

Accomplishment of the preventative

modification would eliminate the need

for the repetitive inspections.

Accomplishment of the actions

specified in the alert service bulletin is