This section of the FEDERAL REGISTER

contains regulatory documents having general

applicability and legal effect, most of which

are keyed to and codified in the Code of

Federal Regulations, which is published under

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

The Code of Federal Regulations is sold by

the Superintendent of Documents. Prices of

new books are listed in the first FEDERAL

REGISTER issue of each week.

Rules and Regulations Federal Register

8613

Vol. 62, No. 38

Wednesday, February 26, 1997

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96–NM–71–AD; Amendment

39–9945; AD 97–05–01]

RIN 2120–AA64

Airworthiness Directives; Boeing

Model 747–200, –300, and –400 Series

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final rule.

SUMMARY: This amendment adopts a

new airworthiness directive (AD),

applicable to certain Boeing Model 747–

200, –300, and –400 series airplanes,

that requires repetitive inspections to

detect cracking of the front spar web of

the center section of the wing, and

repair, if necessary. This amendment is

prompted by reports of fatigue cracking

found in the front spar web. The actions

specified by this AD are intended to

prevent the leakage of fuel into the

forward cargo bay, as a result of fatigue

cracking in the front spar web, which

could result in a potential fire hazard.

DATES: Effective April 2, 1997.

The incorporation by reference of

certain publications listed in the

regulations is approved by the Director

of the Federal Register as of April 2,

1997.

ADDRESSES: The service information

referenced in this AD may be obtained

from Boeing Commercial Airplane

Group, P.O. Box 3707, Seattle,

Washington 98124–2207. This

information may be examined at the

Federal Aviation Administration (FAA),

Transport Airplane Directorate, Rules

Docket, 1601 Lind Avenue, SW.,

Renton, Washington; or at the Office of

the Federal Register, 800 North Capitol

Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Tamara Dow, Aerospace Engineer,

Airframe Branch, ANM–120S, FAA,

Seattle Aircraft Certification Office,

1601 Lind Avenue, SW., Renton,

Washington; telephone (206) 227–2771;

fax (206) 227–1181.

SUPPLEMENTARY INFORMATION: A

proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) to

include an airworthiness directive (AD)

that is applicable to certain Boeing

Model 747–200, –300, and –400 series

airplanes was published in the Federal

Register on November 18, 1996 (61 FR

58669). That action proposed to require

repetitive HFEC inspections to detect

cracking of the front spar web along the

tangent point of the pocket fillet radii.,

and repair, if necessary.

Interested persons have been afforded

an opportunity to participate in the

making of this amendment. Due

consideration has been given to the

comments received.

Support for the Proposal

Three commenters support the

proposed AD.

Request to Extend Initial Compliance

Time

One commenter requests that the

proposal be revised to extend the

compliance time for the initial

inspection from the proposed 12 months

to 18 months. The commenter requests

this extension so that affected operators

will be able to perform the inspection

during a regularly scheduled

maintenance visit. The extent of the

work involved in the proposed

inspection, and any necessary repair,

cannot be accomplished at a line

station, but must be accomplished when

the airplane would be located at a main

base where special equipment and

trained personnel would be readily

available. The commenter states that the

adoption of the proposed compliance

time of 12 months would require

operators to schedule special times for

the accomplishment of the inspection,

at additional expense and downtime.

Further, this commenter states that

the wing center section front spar web

is inspected currently on some affected

airplanes under the Supplemental

Structural Inspection Document (SSID)

program, which was mandated most

recently by AD 94–15–18, amendment

39–8989 (59 FR 41233, August 11,

1994). There have been no reports of

cracks found in this front spar web area

during these required inspections.

Additionally, the commenter states that,

since June 1995, at least 3 airplanes in

its fleet have undergone either NDT or

visual inspections, and no cracks or

other problems were found on the

subject front spar web. The commenter

requests that the FAA take this

experience into consideration and

extend the proposed compliance

threshold as requested.

The FAA does not concur. Leakage of

fuel into the forward cargo bay, as a

result of fatigue cracking in the front

spar web, is a significant safety issue,

and the FAA has determined that the

inspection threshold, as proposed, is

warranted. The FAA considered not

only these safety issues in developing

an appropriate compliance time for this

action, but the recommendations of the

manufacturer, the availability of any

necessary repair parts, and the practical

aspect of accomplishing the required

inspection within an interval of time

that parallels normal scheduled

maintenance for the majority of affected

operators.

The FAA points out that the

manufacturer recommended that the

inspections begin within 18 months

after the release of Boeing Service

Bulletin 747–57A2298, Revision 1, on

September 12, 1996; that interval

corresponds to most operators’

scheduled ‘‘C’’ checks. The FAA took

this recommendation into account, as

well as the time that would be necessary

to complete the rulemaking process, and

found that a 12-month initial

compliance time should fall well within

the time that the majority of operators

have regular maintenance visits

scheduled.

As for the results of inspections

previously performed on the affected

area, the FAA points out that this AD

action was based on reports from two

operators who did find cracking in the

wing center section front spar web on at

least three airplanes; the longest crack

found was 17 inches. While those cracks

were found on Model 747–100 series

airplanes, the FAA maintains that

similar cracking is likely to develop on

Model 747–200, –300, and –400 series

airplanes up to line number 744 because

those models have the same web

thickness and similar loading as the

Model 747–100.
8614 Federal Register / Vol. 62, No. 38 / Wednesday, February 26, 1997 / Rules and Regulations

In light of these factors, the FAA has

determined that the 12-month initial

compliance time, as proposed, is

appropriate. The FAA points out that, if

operators already have accomplished

the initial inspection within the last 12

months prior to the effective date of the

AD, they are given ‘‘credit’’ for that

inspection as compliance with the

initial inspection requirement of the

AD. The final rule has been revised to

clarify this point.

Request To Extend Repetitive

Inspection Intervals

One commenter requests that the

proposal be revised to extend the

repetitive inspection interval from the

proposed 1,400 cycles to 2,000 cycles.

The commenter, a U.S. operator, states

that it already has inspected several of

the airplanes in its fleet and has found

no cracking. In addition, the commenter

points out that the inspection area will

be visually inspected at regular intervals

to detect corrosion as part of the Boeing

747 Corrosion Prevention and Control

Program, which was mandated by AD

90–25–05, amendment 39–6790 (55 FR

49268, November 27, 1990).

The FAA does not concur, since the

commenter provided no technical

justification for an extension. The

repetitive interval of 1,400 cycles is

based on damage tolerance and crack

growth analyses that the manufacturer

performed. Additionally, the interval

was calculated based on accomplishing

high frequency eddy current (HFEC)

inspections, and the effectiveness of

those inspections in detecting cracking.

The FAA acknowledges that visual

inspections to detect corrosion of the

area are mandated by AD 90–25–05;

however, the HFEC inspections required

by this AD will provide a much higher

level of precision than visual

inspections, and will be able to detect

cracking far earlier than could be

discovered by visual inspections alone.

Request To Revise Method of Counting

Accumulated Cycles

One commenter requests that the

proposal be revised to include a

provision specifying that pressurization

cycles of 2.0 psi or less need not be

counted as a flight cycle when

determining the number of flight cycles

relative to the proposed compliance

thresholds. The commenter states that

cabin pressure is the main contributor to

stresses in the center section front spar

web, but a cabin pressure of 2.0 psi

would result in stresses of less than onefourth the normal operating level.

Further, with a maximum cabin

pressure at 2.0 psi, the fatigue damage

per cycle would be reduced by a factor

of approximately 100.

The FAA does not concur with the

commenter’s request. The FAA

considers that flights with less than 2.0

psi cabin pressure may contribute a

negligible amount of fatigue damage to

the front spar web of the wing center

section. However, a pressurization cycle

of 2.0 psi or less is a typical pressure

used during flight training, and is not

typical of normal operation of the

affected airplanes. The FAA does not

consider it appropriate to include

various provisions in an AD applicable

to a unique use of an affected airplane.

Paragraph (e) of this final rule provides

for the approval of alternative methods

of compliance to address these types of

unique circumstances.

Conclusion

After careful review of the available

data, including the comments noted

above, the FAA has determined that air

safety and the public interest require the

adoption of the rule with the one change

described previously. The FAA has

determined that this change will neither

increase the economic burden on any

operator nor increase the scope of the

AD.

Cost Impact

There are approximately 485 Model

747–200, –300, and –400 series

airplanes of the affected design in the

worldwide fleet. The FAA estimates that

105 airplanes of U.S. registry will be

affected by this AD, that it will take

approximately 48 work hours per

airplane to accomplish the required

inspections, and that the average labor

rate is $60 per work hour. Based on

these figures, the cost impact of the AD

on U.S. operators is estimated to be

$302,400, or $2,880 per airplane, per

inspection.

The cost impact figure discussed

above is based on assumptions that no

operator has yet accomplished any of

the 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 adopted herein will

not have substantial direct effects on the

States, on the relationship between the

national government and the States, or

on the distribution of power and

responsibilities among the various

levels of government. Therefore, in

accordance with Executive Order 12612,

it is determined that this final rule does

not have sufficient federalism

implications to warrant the preparation

of a Federalism Assessment.

For the reasons discussed above, I

certify that this action (1) is not a

‘‘significant regulatory action’’ under

Executive Order 12866; (2) is not a

‘‘significant rule’’ under DOT

Regulatory Policies and Procedures (44

FR 11034, February 26, 1979); and (3)

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 final evaluation has

been prepared for this action and it is

contained in the Rules Docket. A copy

of it may be obtained from the Rules

Docket at the location provided under

the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation

safety, Incorporation by reference,

Safety.

Adoption of the Amendment

Accordingly, pursuant to the

authority delegated to me by the

Administrator, the Federal Aviation

Administration amends part 39 of the

Federal Aviation Regulations (14 CFR

part 39) as follows:

PART 39—AIRWORTHINESS

DIRECTIVES

1. The authority citation for part 39

continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13 [Amended]

2. Section 39.13 is amended by

adding the following new airworthiness

directive:

97–05–01 Boeing: Amendment 39–9945.

Docket 96–NM–71–AD.

Applicability: Model 747–200, –300, and

–400 series airplanes, up to and including

line number 744, 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 (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 prevent the leakage of fuel into the

forward cargo bay through fatigue cracks in

the front spar web, which could result in a

potential fire hazard, accomplish the

following:
Federal Register / Vol. 62, No. 38 / Wednesday, February 26, 1997 / Rules and Regulations 8615

(a) Perform a high frequency eddy current

(HFEC) inspection to detect cracking of the

front spar web of the center section of the

wing, in accordance with Boeing Alert

Service Bulletin 747–57A2298, Revision 1,

dated September 12, 1996, at the time

specified in paragraph (a)(1) or (a)(2) of this

AD, as applicable.

(1) For airplanes that have accumulated

12,000 to 17,999 total landings as of the

effective date of this AD: Perform the initial

inspection within 12 months after the

effective date of this AD, unless previously

accomplished within the last 12 months.

Perform this inspection again prior to the

accumulation of 18,000 total landings or

within 1,400 landings, whichever occurs

later; after accomplishing the initial

inspection, and thereafter at intervals not to

exceed 1,400 landings.

(2) For all other airplanes: Perform the

initial inspection prior to the accumulation

of 18,000 total landings or within 12 months

after the effective date of this AD, whichever

occurs later. Repeat this inspection thereafter

at intervals not to exceed 1,400 landings.

(b) Except as provided by paragraph (c) of

this AD, if any cracking is detected during an

inspection required by paragraph (a) of this

AD, prior to further flight, repair in

accordance with paragraph (b)(1) or (b)(2) of

this AD, as applicable. Thereafter repeat the

HFEC inspection required by paragraph (a) of

this AD at intervals not to exceed 1,400

landings.

(1) If any vertical crack is found that is less

than 10 inches in length, repair in

accordance with Boeing Alert Service

Bulletin 747–57A2298, Revision 1, dated

September 12, 1996.

(2) If any vertical crack is found that is 10

inches or greater in length; or if any crack is

found that has extended in a diagonal

direction (regardless of length); or if any

crack is found that would affect an existing

repair; repair in accordance with a method

approved by the Manager, Seattle Aircraft

Certification Office (ACO), FAA, Transport

Airplane Directorate.

(c) In lieu of accomplishing the procedures

specified in paragraph (b) of this AD: If a

crack in the front spar web is detected during

an HFEC inspection required by paragraph

(a) of this AD, prior to further flight,

operators may accomplish the procedures for

an optional HFEC inspection to confirm

cracking, as described in paragraph III.D.2. of

the Accomplishment Instructions of Boeing

Alert Service Bulletin 747–57A2298,

Revision 1, dated September 12, 1996.

(1) If this optional inspection is

accomplished and cracking is not confirmed,

thereafter repeat the HFEC inspection

specified in paragraph (a) of this AD at

intervals not to exceed 1,400 landings.

(2) If this optional inspection is

accomplished and confirms cracking, prior to

further flight, repair the cracking in

accordance with paragraph (b)(1) or (b)(2) of

this AD, as applicable.

(d) For airplanes that are required to

perform an initial HFEC inspection in

accordance with paragraph (a)(1) of this AD:

Within 30 days after accomplishing the

initial inspection, submit a report of

inspection results, negative or positive, that

includes the information identified in

paragraphs (d)(1) through (d)(5) of this AD,

to the Manager, Seattle Aircraft Certification

Office, FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton, Washington

98055–4056; fax (206) 227–1181. Information

collection requirements contained in this

regulation have been approved by the Office

of Management and Budget (OMB) under the

provisions of the Paperwork Reduction Act of

1980 (44 U.S.C. 3501 et seq.) and have been

assigned OMB Control Number 2120–0056.

(1) Airplane serial number.

(2) Total number of landings accumulated.

(3) Total number of hours time-in-service

accumulated.

(4) Location, size and orientation of each

crack.

(5) Whether fuel leakage resulted from the

crack.

(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 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.

(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.

(g) The actions shall be done in accordance

with Boeing Alert Service Bulletin 747–

57A2298, Revision 1, dated September 12,

1996. This incorporation by reference was

approved by the Director of the Federal

Register in accordance with 5 U.S.C. 552(a)

and 1 CFR part 51. Copies may be obtained

from Boeing Commercial Airplane Group,

P.O. Box 3707, Seattle, Washington 98124–

2207. Copies may be inspected at the FAA,

Transport Airplane Directorate, 1601 Lind

Avenue, SW., Renton, Washington; or at the

Office of the Federal Register, 800 North

Capitol Street, NW., suite 700, Washington,

DC.

(h) This amendment becomes effective on

April 2, 1997.

Issued in Renton, Washington, on February

19, 1997.

James V. Devany,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 97–4555 Filed 2–25–97; 8:45 am]

BILLING CODE 4910–13–U

14 CFR Part 39

[Docket No. 95–NM–51–AD; Amendment

39–9946; AD 97–05–02]

RIN 2120–AA64

Airworthiness Directives; Empresa

Brasileira de Aeronautica S.A.

(EMBRAER) Model EMB–120 Series

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final rule.

SUMMARY: This amendment adopts a

new airworthiness directive (AD),

applicable to certain EMBRAER Model

EMB–120 series airplanes, that requires

removal of the upper channel fairings

and their shims; and rework of the

riveting holes, the aileron sealing canvas

(aerodynamic seals), and the protective

covers of the trim tab hinge fittings of

the aileron and elevator. This

amendment is prompted by reports of

binding of the aileron due to water

freezing between the upper channel

fairings and the surface of the leading

edge of the aileron. The actions

specified by this AD are intended to

prevent water from freezing these areas,

which could result in binding of the

aileron and subsequent reduced

controllability of the airplane.

DATES: Effective April 2, 1997.

The incorporation by reference of

certain publications listed in the

regulations is approved by the Director

of the Federal Register as of April 2,

1997.

ADDRESSES: The service information

referenced in this AD may be obtained

from Embraer, Empresa Brasileira De

Aeronautica S/A, Sao Jose Dos Campos,

Brazil. This information may be

examined at the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, Rules Docket,

1601 Lind Avenue, SW., Renton,

Washington; or at the FAA, Small

Airplane Directorate, Atlanta Aircraft

Certification Office, Campus Building,

1701 Columbia Avenue, Suite 2–160,

College Park, Georgia; or at the Office of

the Federal Register, 800 North Capitol

Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Curtis Jackson, Aerospace Engineer,

Airframe Branch, ACE–117A, FAA,

Small Airplane Directorate, Atlanta

Aircraft Certification Office, Campus

Building, 1701 Columbia Avenue, Suite

2–160, College Park, Georgia 30337–

2748; telephone (404) 305–7358; fax

(404) 305–7348.

SUPPLEMENTARY INFORMATION: A

proposal to amend part 39 of the Federal