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

2033

Vol. 60, No. 4

Friday, January 6, 1995

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94–NM–224–AD]

Airworthiness Directives; Boeing

Model 747 Series Airplanes Equipped

With General Electric Model CF6–80C2

Series Engines or Pratt & Whitney

Model PW4000 Series Engines

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

modification of the nacelle strut and

wing structure, inspections and checks

to detect discrepancies, and correction

of discrepancies. This proposal is

prompted by the development of a

modification of the strut and wing

structure that improves the fail-safe

capability and durability of the strut-towing attachments, and reduces reliance

on inspections of those attachments.

The actions specified by the proposed

AD are intended to prevent failure of the

strut and subsequent loss of the engine.

DATES: Comments must be received by

March 3, 1995.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 94–NM–

224–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: Tim

Backman, Aerospace Engineer, Airframe

Branch, ANM–121S, FAA, Transport

Airplane Directorate, Seattle Aircraft

Certification Office, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056;

telephone (206) 227–2776; 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 94–NM–224–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.

94–NM–224–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

The FAA has received numerous

reports of fatigue cracking and/or

corrosion in the strut-to-wing

attachments on Boeing Model 747 series

airplanes. In two cases, cracking

resulted in the failure of a strut load

path and the subsequent loss of the

number 3 engine and strut. In both

cases, catastrophic accidents occurred

when the number 3 engine and strut

separated from the wing of the airplane

and struck the number 4 engine, causing

it to separate from the airplane.

Investigation into the cause of these

accidents and other reported incidents

has revealed that fatigue cracks and

corrosion in the strut-to-wing

attachments, if not detected and

corrected in a timely manner, can result

in failure of the strut and subsequent

separation of the engine from the

airplane. Investigation also has revealed

that the structural fail-safe capability of

the strut-to-wing attachment is

inadequate on these airplanes.

The FAA has previously issued 3

airworthiness directives (AD’s) that

address various problems associated

with the strut attachment assembly on

Model 747 series airplanes equipped

with General Electric Model CF6–80C2

series engines or Pratt & Whitney Model

PW4000 series engines. These AD’s

have required, among other things,

inspection of the strut, midspar fittings,

diagonal brace, and midspar fuse pins.

Explanation of Service Information

Boeing recently has developed a

modification of the strut-to-wing

attachment structure installed on certain

Model 747 series airplanes equipped

with General Electric Model CF6–80C2

series engines or Pratt & Whitney Model

PW4000 series engines that significantly

improves the load-carrying capability

and durability of the strut-to-wing

attachments. Such improvement also

will substantially reduce the possibility

of fatigue cracking and corrosion

developing in the attachment assembly.

The FAA has reviewed and approved

Boeing Alert Service Bulletin 747–

54A2156, dated December 15, 1994,

which describes procedures for

modification of the nacelle strut and

wing structure. This modification

entails the following:

1. Providing a new fail-safe load path

by installing a new dual side load fitting

to the strut and the underwing structure

and the associated wing back-up fitting,

front spar post, and side links;

2. Installing a new titanium dual side

load fitting to the strut aft bulkhead and
2034 Federal Register / Vol. 60, No. 4 / Friday, January 6, 1995 / Proposed Rules

new 15–5 stainless steel midspar

fittings;

3. Replacing the aft bulkhead

assembly and overhaul of the spring

beam;

4. Improving the strut-to-wing

attachments by replacing the upper link

and the diagonal brace;

5. Reworking the rib of wing station

(WS)1140; and

6. Modifying the electrical wiring and

hydraulics by rerouting certain wire

bundles around the new dual side load

fitting and installing new hydraulic

tubes.

This alert service bulletin specifies

that the modification of the nacelle strut

and wing structure is to be

accomplished prior to, or concurrently

with, the terminating actions described

in the service bulletins listed in

paragraph I.C., Table 2, ‘‘Prior or

Concurrent Service Bulletins,’’ on page

7 of this alert service bulletin. These

terminating actions include the

following:

1. Replacement of the diagonal brace,

midspar, and upper link fuse pins with

new third generation 15–5 corrosion

resistant steel fuse pins;

2. Inspection and replacement of the

bearings on the lower spar fitting of the

outboard engine strut with new

bearings;

3. Installation of improved bushings

in the strut-to-wing attach fittings; and

4. Inspection and rework of

improperly torqued fasteners.

Paragraph III, NOTES 8, 9, 10, and 11

of the Accomplishment Instructions on

page 91 of the alert service bulletin also

describe procedures for inspections and

checks to detect discrepancies of the

adjacent structure, and correction of any

discrepancies.

Explanation of the Provisions of the

Proposed AD

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 modification of the nacelle strut

and wing structure, inspections and

checks to detect discrepancies in the

adjacent structure, and correction of

discrepancies. The actions would be

required to be accomplished in

accordance with the alert service

bulletin described previously.

The FAA has determined that long

term continued operational safety will

be better assured by design changes to

remove the source of the problem, rather

than by repetitive inspections. Long

term inspections may not be providing

the degree of safety assurance necessary

for the transport airplane fleet. This,

coupled with a better understanding of

the human factors associated with

numerous continual inspections, has led

the FAA to consider placing less

emphasis on inspections and more

emphasis on design improvements. The

proposed modification requirement is in

consonance with these considerations.

Accomplishment of the modification

of the nacelle strut and wing structure

would terminate the inspections

currently required by the following

AD’s:

AD No. Amendment No.

Federal

Register

citation

Date of

publication

93–17–07 ............................................................................................................................................... 39–8678 58 FR 45827 Aug. 31, 1993.

93–03–14 ............................................................................................................................................... 39–8518 58 FR 14513 Mar. 18, 1993.

92–24–51 ............................................................................................................................................... 39–8439 57 FR 60118 Dec. 18, 1992.

As a result of recent communications

with the Air Transport Association

(ATA) of America, the FAA has learned

that, in general, some operators may

misunderstand the legal effect of AD’s

on airplanes that are identified in the

applicability provision of the AD, but

that have been altered or repaired in the

area addressed by the AD. The FAA

points out that all airplanes identified in

the applicability provision of an AD are

legally subject to the AD. If an airplane

has been altered or repaired in the

affected area in such a way as to affect

compliance with the AD, the owner or

operator is required to obtain FAA

approval for an alternative method of

compliance with the AD, in accordance

with the paragraph of each AD that

provides for such approvals. A note has

been included in this notice to clarify

this requirement.

Cost Estimate

There are approximately 257 Model

747 series airplanes equipped with

General Electric Model CF6–80C2 series

engines or Pratt & Whitney Model

PW4000 series engines of the affected

design in the worldwide fleet. The FAA

estimates that 36 airplanes of U.S.

registry would be affected by this

proposed AD.

The proposed modification would

take approximately 6,253 work hours

per airplane to accomplish, at an

average labor cost of $60 per work hour.

The manufacturer would incur the cost

of labor, on a prorated basis, with 20

years being the expected life of these

airplanes. The total cost impact of the

proposed AD on U.S. operators is based

on the median age for the fleet of Model

747 series airplanes equipped with

General Electric Model CF6–80C2 series

engines or Pratt & Whitney Model

PW4000 series engines, which is

estimated to be 5 years. Required parts

would be supplied by the manufacturer

at no cost to the operators. Based on

these figures, the total cost impact of the

proposed AD on U.S. operators is

estimated to be $3,376,620, or $93,795

per airplane.

This cost impact figure does not

reflect the cost of the terminating

actions described in the service

bulletins listed in paragraph I.C., Table

2, ‘‘Prior or Concurrent Service

Bulletins,’’ on page 7 of Boeing Alert

Service Bulletin 747–54A2156, dated

December 15, 1994, that are proposed to

be accomplished prior to, or

concurrently with, the modification of

the nacelle strut and wing structure.

Since some operators may have

accomplished certain modifications on

some or all of the airplanes in its fleet,

while other operators may not have

accomplished any of the modifications

on any of the airplanes in its fleet, the

FAA is unable to provide a reasonable

estimate of the cost of accomplishing

the terminating actions described in the

service bulletins listed in Table 2 of the

Boeing alert service bulletin. As

indicated earlier in this preamble, the

FAA invites comments specifically on

the overall economic aspects of this

proposed rule. Any data received via

public comments to this notice will aid

the FAA in developing an accurate

accounting of the cost impact of the

rule.

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.

The FAA recognizes that the

obligation to maintain aircraft in an

airworthy condition is vital, but

sometimes excessive. Because AD’s
Federal Register / Vol. 60, No. 4 / Friday, January 6, 1995 / Proposed Rules 2035

require specific actions to address

specific unsafe conditions, they appear

to impose costs that would not

otherwise be borne by operators.

However, because of the general

obligation of operators to maintain

aircraft in an airworthy condition, this

appearance is deceptive. Attributing

those costs solely to the issuance of this

AD is unrealistic because, in the interest

of maintaining safe aircraft, prudent

operators would accomplish the

required actions even if they were not

required to do so by the AD.

A full cost-benefit analysis has not

been accomplished for this proposed

AD. As a matter of law, in order to be

airworthy, an aircraft must conform to

its type design and be in a condition for

safe operation. The type design is

approved only after the FAA makes a

determination that it complies with all

applicable airworthiness requirements.

In adopting and maintaining those

requirements, the FAA has already

made the determination that they

establish a level of safety that is costbeneficial. When the FAA, as in this

proposed AD, makes a finding of an

unsafe condition, this means that the

original cost-beneficial level of safety is

no longer being achieved and that the

proposed actions are necessary to

restore that level of safety. Because this

level of safety has already been

determined to be cost-beneficial, a full

cost-benefit analysis for this proposed

AD would be redundant and

unnecessary.

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. App. 1354(a), 1421

and 1423; 49 U.S.C. 106(g); and 14 CFR

11.89.

§ 39.13 [Amended]

2. Section 39.13 is amended by

adding the following new airworthiness

directive:

Boeing: Docket 94–NM–224–AD.

Applicability: Model 747 series airplanes

having line positions 679 through 1046

inclusive, equipped with General Electric

Model CF6–80C2 series engines or Pratt &

Whitney Model PW4000 series engines;

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 use the authority

provided in paragraph (d) 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 prevent failure of the strut and

subsequent loss of the engine, accomplish the

following:

(a) Within 80 months after the effective

date of this AD, accomplish the modification

of the nacelle strut and wing structure in

accordance with Boeing Alert Service

Bulletin 747–54A2156, dated December 15,

1994. All of the terminating actions described

in the service bulletins listed in paragraph

I.C., Table 2, ‘‘Prior or Concurrent Service

Bulletins,’’ on page 7 of Boeing Alert Service

Bulletin 747–54A2156, dated December 15,

1994, must be accomplished in accordance

with those service bulletins prior to, or

concurrently with, the accomplishment of

the modification of the nacelle strut and wing

structure required by this paragraph.

(b) Perform the inspections and checks

specified in paragraph III, NOTES 8, 9, 10,

and 11 of the Accomplishment Instructions

on page 91 of Boeing Alert Service Bulletin

747–54A2156, dated December 15, 1994,

concurrently with the modification of the

nacelle strut and wing structure required by

paragraph (a) of this AD. Prior to further

flight, correct any discrepancies in

accordance with the alert service bulletin.

(c) Accomplishment of the modification of

the nacelle strut and wing structure in

accordance with Boeing Alert Service

Bulletin 747–54A2156, dated December 15,

1994, constitutes terminating action for the

inspections required by the following AD’s:

AD No. Amendment No.

Federal

Register citation

Date of

publication

93–17–07 ............................................................................................................................................... 39–8678 58 FR 45827 Aug. 31, 1993.

93–03–14 ............................................................................................................................................... 39–8518 58 FR 14513 Mar. 18, 1993.

92–24–51 ............................................................................................................................................... 39–8439 57 FR 60118 Dec. 18, 1992.

(d) 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.

(e) 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.
2036 Federal Register / Vol. 60, No. 4 / Friday, January 6, 1995 / Proposed Rules

Issued in Renton, Washington, on

December 30, 1994.

S.R. Miller,

Acting Manager, Transport Airplane

Directorate, Aircraft Certification Service.

[FR Doc. 95–307 Filed 1–5–95; 8:45 am]

BILLING CODE 4910–13–U

14 CFR Part 39

[Docket No. 94–NM–28–AD]

Airworthiness Directives; Boeing

Model 767 Series Airplanes Equipped

With General Electric CF6–80C2 Series

Engines

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Notice of proposed rulemaking

(NPRM).

SUMMARY: This document proposes the

supersedure of an existing airworthiness

directive (AD), applicable to certain

Boeing Model 767 series airplanes, that

currently requires tests, inspections, and

adjustments of the thrust reverser

system. This action would add

requirements for installation of a

terminating modification on airplanes

equipped with General Electric CF6–

80C2 series engines, and repetitive

operational checks of the electromechanical brake and the cone brake of

the center drive unit following

accomplishment of the modification.

This action also would remove airplanes

equipped with Rolls-Royce RB211–524

series engines from the applicability of

the existing AD. This proposal is

prompted by the identification of a

modification that ensures that the level

of safety inherent in the original type

design of the thrust reverser system is

further enhanced. The actions specified

by the proposed AD are intended to

prevent possible discrepancies that exist

in the current thrust reverser control

system, which could result in an

inadvertent deployment of a thrust

reverser during flight.

DATES: Comments must be received by

March 3, 1995.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), Transport

Airplane Directorate, ANM–103,

Attention: Rules Docket No. 94–NM–

28–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:

Lanny Pinkstaff, Aerospace Engineer,

Propulsion Branch, ANM–140S, FAA,

Transport Airplane Directorate, Seattle

Aircraft Certification Office, 1601 Lind

Avenue, SW., Renton, Washington

98055–4056; telephone (206) 227–2684;

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 94–NM–28–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.

94–NM–28–AD, 1601 Lind Avenue,

SW., Renton, Washington 98055–4056.

Discussion

On October 7, 1991, the FAA issued

AD 91–22–02, amendment 39–8062 (56

FR 51638, October 15, 1991), applicable

to Boeing Model 767 series airplanes

equipped with Rolls-Royce RB211–524

series engines or General Electric CF6–

80C2 series engines, to require tests,

inspections, and adjustments of the

thrust reverser system. That action was

prompted by an ongoing design review,

resulting from an accident investigation

from which it had been determined that,

prior to the accident, the airplane

apparently experienced an

uncommanded in-flight deployment of a

thrust reverser. Deployment of a thrust

reverser in flight could result in reduced

controllability of the airplane. The

requirements of that AD are intended to

ensure the integrity of the fail-safe

features of the thrust reverser system by

preventing possible discrepancies in the

thrust reverser control system that can

result in the inadvertent deployment of

a thrust reverser during flight.

Since the issuance of AD 91–22–02,

the FAA issued AD 94–17–03,

amendment 39–8998 (59 FR 41647,

August 15, 1994). AD 94–17–03 was

issued to require inspections,

adjustments, and functional checks of

the thrust reverser system; installation

of a terminating modification; and

repetitive operational checks of the

gearbox locks and the air motor brake

following accomplishment of the

terminating modification on Model 767

series airplanes equipped with RollsRoyce RB211–524 series engines. In the

preamble to AD 94–17–03, the FAA

stated it would consider superseding

AD 91–22–02 to remove the

requirements for Model 767 series

airplanes equipped with Rolls-Royce

RB211–524 series engines from that AD,

to specify that those requirements are

contained in AD 94–17–03, and to

require accomplishment of a

terminating modification for Model 767

series airplanes equipped with General

Electric CF6–80C2 series engines. This

action proposes such requirements.

Explanation of Relevant Service

Information

Since the issuance of AD 91–22–02,

the FAA has reviewed and approved

Boeing Service Bulletin 767–78–0047,

Revision 3, dated July 28, 1994. The

original issue of the service bulletin was

cited in AD 91–22–02 as the appropriate

source of service information for

performing various tests, inspections,

and adjustments required by that AD.

Revision 3 of the service bulletin revises

certain procedures specified in the

Accomplishment Instructions of earlier

revisions of the service bulletin. (The

FAA has referenced this latest revision

of the service bulletin as the appropriate

source of service information for

accomplishment of those actions after

the effective date of this proposed AD.)

The FAA also has reviewed and

approved Boeing Service Bulletin 767–

78–0063, Revision 2, dated April 28,