Federal Register / Vol. 63, No. 149 /Tuesday, August 4, 1998 / Proposed Rules 41483

Issued in Renton, Washington, on July 27,

1998.

S.R. Miller,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 98–20677 Filed 8–3–98; 8:45 am]

BILLING CODE 4910–13–U

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97–NM–87–AD]

RIN 2120–AA64

Airworthiness Directives; Boeing

Model 747–100, –200, and –300 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 747–100, –200,

and –300 series airplanes. This proposal

would require repetitive inspections to

detect cracking of certain lower lobe

fuselage frames, and repair, if necessary.

This proposal is prompted by reports

indicating that fatigue cracks were

found in lower lobe frames on the left

side of the fuselage. The actions

specified by the proposed AD are

intended to detect and correct fatigue

cracking of certain lower lobe fuselage

frames, which could lead to fatigue

cracks in the fuselage skin, and

consequent rapid decompression of the

airplane.

DATES: Comments must be received by

September 18, 1998.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–114,

Attention: Rules Docket No. 97–NM–

87–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–87–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–87–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

The FAA has received reports

indicating that fatigue cracking was

found on a total of 19 lower lobe

fuselage frames on Boeing Model 747

series airplanes. Two of these airplanes

had completely severed frame inner

chords, webs, and fail-safe chords on

adjacent frames. A severed frame will

result in increased fuselage skin

stresses, which could lead to skin

cracking. In the area of the lower lobe

fuselage frames from Body Station (BS)

1820 to BS 2100, the fuselage skin does

not have tearstraps to arrest a skin crack.

Instead of tearstraps, this area has failsafe chords attached to the fuselage

frames which reduce the stress levels in

the fuselage skin such that a crack in the

skin would be stopped. With a

completely severed fuselage frame inner

chord, web, and fail-safe chord, there is

nothing to prevent a skin crack from

propagating beyond several fuselage

frame bays. 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–

53A2408, dated April 25, 1996, which

describes procedures for repetitive

detailed visual inspections to detect

cracking of the lower lobe fuselage

frames from BS 1820 to BS 2100, and

repair, if necessary.

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 alert service bulletin

described previously, except as

discussed below.

Differences Between the Proposed AD

and Relevant Service Bulletin

Operators should note that, unlike the

initial compliance time (specified as

prior to the accumulation of 16,000 total

flight cycles, or within 1,500 flight

cycles or 18 months, whichever occurs

first) for airplanes identified in the alert

service bulletin, the proposed AD would

require that those airplanes be inspected

prior to the accumulation of 15,000 total

flight cycles, or within 1,500 flight

cycles or 18 months, whichever occurs

first. Because the FAA received a report

of cracking on an airplane that had

accumulated only 15,227 total flight

cycles, the FAA finds a compliance

threshold of 15,000 total flight cycles for

initiating the proposed actions to be

warranted, in that it represents an

appropriate interval of time allowable

for affected airplanes to continue to

operate without compromising safety.

Operators also should note that,

although the alert service bulletin

allows discount from the compliance

threshold of all flight cycles at or below

a cabin pressure differential of 2.0

pounds per square inch (psi), the

proposed AD does not. The FAA

received a report of cracking on an

airplane that had accumulated 12,817

full pressure cycles, plus 8,761 cycles at

less than 2.0 psi differential pressure.

The reported cracking was more
41484 Federal Register / Vol. 63, No. 149 /Tuesday, August 4, 1998 / Proposed Rules

indicative of an airplane that had

accumulated 20,000 total flight cycles. If

this proposed AD were to allow

discount of flight cycles, as

recommended in the alert service

bulletin, the actions required by this

proposed AD would not be required to

be accomplished on the airplane

discussed previously. Therefore,

cracking on that airplane would have

gone undetected. These facts indicate

that discounting cycles at or below a

cabin pressure differential of 2.0 psi is

not warranted for the proposed AD.

The alert service bulletin also allows

operators of Model 747SR series

airplanes to use a 1.2 adjustment factor

for the reduction of the inspection

compliance threshold and interval. In

previous AD’s, the FAA has allowed the

use of the 1.2 adjustment factor for these

airplanes; however, data have since

become available to the FAA that

indicate the use of the 1.2 adjustment

factor is unconservative. The FAA has

determined that use of the 1.2

adjustment factor is not in the best

interest of aviation safety, and that its

use shall be discontinued. Therefore,

the proposed AD does not allow

reduction of the inspection compliance

threshold and interval for operators of

Model 747SR series airplanes that

operate at reduced cabin differential

pressure.

The alert service bulletin specifies

that, in the event that cracking is found

during the inspection of the lower lobe

frames, an inspection of the fuselage

skin should be conducted in accordance

with the 747 Structural Repair Manual

(SRM) or inspection data supplied by

the manufacturer. However, the

proposed AD requires a detailed visual

inspection of the adjacent structure

within 20 inches of the crack location

on the frame to detect fuselage skin

cracking.

In addition, although the alert service

bulletin specifies that certain repairs

required by this proposed AD may be

accomplished in accordance with the

747 SRM or repair data supplied by the

manufacturer, the proposed AD would

require that those repairs be

accomplished in accordance with the

747 SRM or in accordance with a

method approved by the FAA.

Interim Action

This is considered to be interim

action until the accomplishment of AD

93–08–12, amendment 39–8559 (58 FR

27927, May 12, 1993). That AD requires

a detailed visual internal inspection to

detect cracks in the Section 46 lower

lobe frames, and repair, if necessary, in

accordance with Boeing Service Bulletin

747–53–2349, dated June 27, 1991. The

initial inspection required by AD 93–

08–12 is required prior to the

accumulation of 22,000 total flight

cycles. The FAA now finds that earlier

inspection (i.e., prior to accumulation of

15,000 total flight cycles) of the lower

lobe frames is warranted, as required by

this proposed AD.

Cost Impact

There are approximately 452

airplanes of the affected design in the

worldwide fleet. The FAA estimates that

152 airplanes of U.S. registry would be

affected by this proposed AD, that it

would take approximately 2 work hours

per airplane to accomplish the proposed

inspection, and that the average labor

rate is $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 $18,240, or

$120 per airplane, per inspection cycle.

The cost impact figure discussed

above is 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 97–NM–87–AD.

Applicability: Model 747–100, –200, and

–300 series airplanes, as listed in Boeing

Alert Service Bulletin 747–53A2408, dated

April 25, 1996; 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 (e) 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 detect and correct fatigue cracking of

certain lower lobe fuselage frames, which

could lead to fatigue cracks in the fuselage

skin, and consequent rapid decompression of

the airplane, accomplish the following:

Note 2: Although Boeing Alert Service

Bulletin 747–53A2408, dated April 25, 1996,

allows discount from the compliance

threshold of all flight cycles at or below a

cabin pressure differential of 2.0 pounds per

square inch (psi), this AD requires that all

flight cycles be counted.

(a) For airplanes on which the initial

detailed visual internal inspection of the

Section 46 lower lobe frames required by

paragraph (a)(3) of AD 93–08–12, amendment

39–8559, has not been accomplished:

Perform a detailed visual inspection to detect

cracking of the lower lobe fuselage frames

from Body Station 1820 to Body Station

2100, in accordance with Boeing Alert

Service Bulletin 747–53A2408, dated April

25, 1996, at the later of the times specified

in paragraphs (a)(1) and (a)(2) of this AD:

(1) Prior to the accumulation of 15,000

total flight cycles; or

(2) Within 1,500 flight cycles or 18 months

after the effective date of this AD, whichever

occurs first.

Note 3: Paragraph (a)(3) of AD 93–08–12

requires a detailed visual internal inspection
Federal Register / Vol. 63, No. 149 /Tuesday, August 4, 1998 / Proposed Rules 41485

to detect cracks in the Section 46 lower lobe

frames, in accordance with Boeing Service

Bulletin 747–53–2349, dated June 27, 1991.

The initial inspection is required prior to the

accumulation of 22,000 total flight cycles, or

within 1,000 flight cycles after June 11, 1993

(the effective date of AD 93–08–12),

whichever occurs later.

(b) If no cracking is detected during the

inspection required by paragraph (a) of this

AD, repeat the inspection thereafter at

intervals not to exceed 3,000 flight cycles.

(c) If any cracking is detected during any

inspection required by paragraph (a) of this

AD, prior to further flight, accomplish

paragraphs (c)(1) and (c)(2) of this AD:

(1) Within 20 inches of the crack location

on the frame, perform a detailed visual

inspection of the adjacent structure to detect

cracking. If any cracking is detected, prior to

further flight, repair in accordance with a

method approved by the Manager, Seattle

Aircraft Certification Office (ACO), FAA,

Transport Airplane Directorate, or in

accordance with the Boeing 747 Structural

Repair Manual.

(2) Repeat the inspection required by

paragraph (a) of this AD thereafter at

intervals not to exceed 3,000 flight cycles.

(d) Accomplishment of the initial detailed

visual internal inspection of the Section 46

lower lobe frames required by paragraph

(a)(3) of AD 93–08–12 constitutes terminating

action for the requirements of this AD.

(e) 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 4: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Seattle ACO.

(f) 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 27,

1998.

S.R. Miller,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 98–20675 Filed 8–3–98; 8:45 am]

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 71

[Airspace Docket No. 97–ASO–19]

RIN 2120–AA66

Proposed Modification of Jet Route J–

41; Florida

AGENCY: Federal Aviation

Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking.

SUMMARY: This action proposes to

modify Jet Route 41 (J–41) by altering J–

41 between the Lee County, FL, Very

High Frequency Omnidirectional Range/

Tactical Air Navigation (VORTAC) and

the Seminole, FL, VORTAC. The FAA is

proposing this modification of J–41 to

increase system capacity, enhance

safety, and improve the management of

air traffic operations in the west Florida

area.

DATES: Comments must be received on

or before September 18, 1998.

ADDRESSES: Send comments on the

proposal in triplicate to: Manager, Air

Traffic Division, ASO–500, Docket No.

97–ASO–19, Federal Aviation

Administration, P.O. Box 20636,

Atlanta, GA 30320.

The official docket may be examined

in the Rules Docket, Office of the Chief

Counsel, Room 916G, 800 Independence

Avenue, SW., Washington, DC,

weekdays, except Federal holidays,

between 8:30 a.m. and 5:00 p.m.

An informal docket may also be

examined during normal business hours

at the Office of the Regional Air Traffic

Division.

FOR FURTHER INFORMATION CONTACT:

Patricia Crawford, Airspace and Rules

Division, ATA–400, Office of Air Traffic

Airspace Management, Federal Aviation

Administration, 800 Independence

Avenue, SW., Washington, DC 20591;

telephone: (202) 267–8783.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested parties are invited to

participate in this proposed rulemaking

by submitting such written data, views,

or arguments as they may desire.

Comments that provide the factual basis

supporting the views and suggestions

presented are particularly helpful in

developing reasoned regulatory

decisions on the proposal. Comments

are specifically invited on the overall

regulatory, aeronautical, economic,

environmental, and energy-related

aspects of the proposal.

Communications should identify the

airspace docket number and be

submitted in triplicate to the address

listed above. Commenters wishing the

FAA to acknowledge receipt of their

comments on this notice must submit

with those comments a self addressed,

stamped postcard on which the

following statement is made:

‘‘Comments to Airspace Docket No. 97–

ASO–19.’’ The postcard will be date/

time stamped and returned to the

commenter. All communications

received on or before the specified

closing date for comments will be

considered before taking action on the

proposed rule. The proposal contained

in this notice may be changed in light

of comments received. All comments

submitted will be available for

examination in the Rules Docket both

before and after the closing date for

comments. A report summarizing each

substantive public contact with FAA

personnel concerned with this

rulemaking will be filed in the docket.

Availability of NPRM’s

An electronic copy of this document

may be downloaded, using a modem

and suitable software, from the FAA

regulations section of the Fedworld

electronic bulletin board service

(telephone: 703–321–3339) or the

Federal Register’s electronic bulletin

board service (telephone: 202–512–

1661). Internet users may reach the

Federal Register’s web page at

http:www.access.gpo.govsu—docs for

access to recently published rulemaking

documents.

Any person may obtain a copy of this

Notice of Proposed Rulemaking (NPRM)

by submitting a request to the Federal

Aviation Administration, Office of Air

Traffic Airspace Management, 800

Independence Avenue, SW.,

Washington, DC 20591, or by calling

(202) 267-8783. Communications must

identify the notice number of this

NPRM. Persons interested in being

placed on a mailing list for future

NPRM’s should also request a copy of

Advisory Circular No. 112A, which

describes the application procedure.

The Proposal

The FAA is proposing to amend 14

CFR part 71 (part 71) by altering the

route of J–41 between the Lee County,

FL, VORTAC and the Seminole, FL,

VORTAC. Currently, aircraft landing in

the Tampa and Sarasota/Fort Myers

areas are routed over the St. Petersburg,

FL, VORTAC, which also serves as a

major navigational aid for transitioning

aircraft into southern Florida. Due to the

volume of air traffic utilizing the St.

Petersburg VORTAC, it would be

advantageous to segregate aircraft