Federal Register / Vol. 63, No. 117 /Thursday, June 18, 1998 / Proposed Rules 33295

FAA Maintenance Inspector, who may add

comments and then send it to the Manager,

Small Airplane Directorate.

Note 2: Information concerning the

existence of approved alternative methods of

compliance with this AD, if any, may be

obtained from the Small Airplane

Directorate.

(d) Questions or technical information

related to Schempp-Hirth Technical Note

265–8, dated February 11, 1985, should be

directed to Schempp-Hirth Flugzeugbau

GmbH, Krebenstrasse 25, Postfach 1443, D–

73230 Kircheim/Teck, Germany. This service

information may be examined at the FAA,

Central Region, Office of the Regional

Counsel, Room 1558, 601 E. 12th Street,

Kansas City, Missouri 64106.

Note 3: The subject of this AD is addressed

in German AD 85–56, dated March 4, 1985.

Issued in Kansas City, Missouri, on June 9,

1998.

Michael Gallagher,

Manager, Small Airplane Directorate, Aircraft

Certification Service.

[FR Doc. 98–16165 Filed 6–17–98; 8:45 am]

BILLING CODE 4910–13–U

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97–ANE–53–AD]

RIN 2120–AA64

Airworthiness Directives; Pratt &

Whitney PW4000 Series Turbofan

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 Pratt & Whitney (PW) PW4000

series turbofan engines not

incorporating modifications described

in certain PW service bulletins listed in

the applicability section. This proposal

would require high pressure compressor

(HPC) blade tip grinding of the rotor

assembly, installation of aluminum

oxide coated HPC blade tips in stages 9

through 12, modification of HPC 8th

through 14th stage stators, incorporation

of 1st stage high pressure turbine (HPT)

vanes with increased airflow area which

also requires additional HPT hardware

modifications, and incorporation of HPC

13th–15th stage zirconium oxide blade

tips. This proposal is prompted by

reports of HPC surge caused by

excessive HPC rear stage rotor-to-case

clearance. The actions specified by the

proposed AD are intended to prevent

HPC surge, which can result in engine

power loss at a critical phase of flight

such as takeoff or climb.

DATES: Comments must be received by

August 17, 1998.

ADDRESSES: Submit comments in

triplicate to the Federal Aviation

Administration (FAA), New England

Region, Office of the Regional Counsel,

Attention: Rules Docket No. 97–ANE–

53–AD, 12 New England Executive Park,

Burlington, MA 01803–5299. Comments

may also be sent via the Internet using

the following address: ‘‘9-adengineprop@faa.dot.gov’’. Comments

sent via the Internet must contain the

docket number in the subject line.

Comments may be inspected at this

location between 8:00 a.m. and 4:30

p.m., Monday through Friday, except

Federal holidays.

The service information referenced in

the proposed rule may be obtained from

Pratt & Whitney, 400 Main St., East

Hartford, CT 06108; telephone (860)

565–6600, fax (860) 565–4503. This

information may be examined at the

FAA, New England Region, Office of the

Regional Counsel, 12 New England

Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT:

Chris Gavriel, Aerospace Engineer,

Engine Certification Office, FAA, Engine

and Propeller Directorate, 12 New

England Executive Park, Burlington, MA

01803–5299; telephone (781) 238–7147,

fax (781) 238–7199.

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

should 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–ANE–53–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, New England Region, Office of the

Regional Counsel, Attention: Rules

Docket No. 97–ANE–53–AD, 12 New

England Executive Park, Burlington, MA

01803–5299.

Discussion

The Federal Aviation Administration

(FAA) has received reports of certain

Pratt & Whitney (PW) PW4000 series

turbofan engine power loss events

occurring frequently during a critical

phase of flight such as takeoff or climb.

The events have led to the flight crew

conducting rejected takeoffs and to

engine power loss or shutdown events

in flight. A rejected takeoff could result

in the airplane overrunning the runway,

incurring airplane damage, and injuring

airplane occupants. Engine power loss

or shutdown during takeoff also

significantly increases crew workload

during a critical phase of flight. The

investigations into these events revealed

that they were caused by high pressure

compressor (HPC) surge that could

require crew action to recover. Further

investigation revealed that the surge

results from excessive HPC rear stage

rotor-to-case clearance. This condition,

if not corrected, could result in HPC

surge, which can result in engine power

loss at a critical phase of flight such as

takeoff.

The FAA has reviewed and approved

the technical contents of the following

PW Service Bulletins (SB): PW4ENG–

72–484, Revision 3, dated July 1, 1997,

that describes procedures for HPC blade

tip grinding at the rotor assembly and

introduces HPC aluminum oxide blade

tip coating in stages 9 through 15

compatible with tip grinding; PW4ENG–

72–486, Revision 1, dated November 23,

1994, that describes procedures for

modifying HPC 8th through 14th stage

stators; PW4ENG–72–514, Revision 1,

dated August 2, 1996, that describe

procedures for high pressure turbine

(HPT) hardware modifications to

accommodate the incorporation of 1st

stage HPT vanes with increased airflow

area; and PW4ENG–72–575, Revision 1,

dated June 30, 1997, that describes

procedures for incorporating HPC 13th–

15th stage zirconium oxide tips.
33296 Federal Register / Vol. 63, No. 117 /Thursday, June 18, 1998 / Proposed Rules

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 grinding of the HPC blade tips

at the rotor assembly and incorporation

of HPC stage 9 through 12 aluminum

oxide blade tips, modification of HPC

8th through 14th stage stators,

modification of HPT hardware to

accommodate incorporation of 1st stage

HPT vanes with increased airflow area

and incorporation of these vanes, and

incorporation of HPC 13th through 15th

stage zirconium oxide blade tips, within

1,400 cycles in service after the effective

date of this AD, or prior to June 30,

1999, whichever occurs first. The

calendar end-date was based upon

analysis of test data and service

experience data. The actions would be

required to be accomplished in

accordance with the SBs described

previously.

There are approximately 187 engines

of the affected design in the worldwide

fleet. The FAA estimates that there are

currently 61 engines installed on aircraft

of U.S. registry that would be affected

by this proposed AD. Required parts

would cost approximately $20,000 per

engine. Based on these figures, the total

cost impact of the proposed AD,

including labor costs, is estimated to be

$1,220,000.

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:

Pratt & Whitney: Docket No. 97–ANE–53–

AD.

Applicability: Pratt & Whitney (PW) Model

PW4152, PW4056, PW4156, PW4256,

PW4052, PW4158, W4060, PW4160,

PW4460, PW4050, PW4060A, PW4156A,

PW4062, PW4462, PW4060C, and PW4650

turbofan engines, not incorporating at least

one of the modifications described in the PW

service bulletins (SBs) and listed in items (1)

through (6), excluding those engines having

a (-3) identifier next to the engine model

number on the engine data plate. These

engines are installed on but not limited to

Boeing 767 and 747 series aircraft,

McDonnell Douglas MD–11 series aircraft,

and Airbus A310 and A300–600 series

aircraft.

(1) PW4ENG 72–484, Revision 3, dated July

1, 1997, or earlier revisions, PW4ENG 72–

486, Revision 1, dated November 23, 1994, or

original issue.

(2) PW4ENG 72–484, Revision 3, dated July

1, 1997, or earlier revisions, PW4ENG 72–

575, Revision 1, dated June 30, 1997, or

original issue, PW4ENG 72–486, Revision 1,

dated November 23, 1994, or original issue.

(3) PW4ENG 72–514, Revision 1, dated

August 2, 1996, or original issue.

(4) PW4ENG 72–490, Revision 1, dated

August 2, 1994, or original issue.

(5) PW4ENG 72–504, Revision 1, dated

May 9, 1995, or original issue.

(6) PW4ENG 72–572, dated June 16, 1995.

Note 1: This airworthiness directive (AD)

applies to each engine 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 engines 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 (b)

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 high pressure compressor

(HPC) surge, which can result in engine

power loss at a critical phase of flight such

as takeoff, accomplish the following:

(a) Within 1,400 cycles in service (CIS)

after the effective date of this AD, or prior to

June 30, 1999, whichever occurs first,

perform the following modifications:

(1) Incorporate stage 9 through 12

aluminum oxide blade tips and grind HPC

blade tips at the rotor assembly in accordance

with the Accomplishment Instructions of PW

SB No. PW4ENG–72–484, Revision 3, dated

July 1, 1997, concurrently with the

requirements of paragraph (a)(4) of this AD.

(2) Modify HPC 8th–14th stage stators in

accordance with the Accomplishment

Instructions of PW SB No. PW4ENG–72–486,

Revision 1, dated November 23, 1994.

(3) Modify the 1st stage high pressure

turbine (HPT) cooling duct (TOBI Duct),

install a metering plug in the Number 2

bearing thrust balance vent tube, and

incorporate 1st stage HPT vanes with

increased airflow area in accordance with the

Accomplishment Instructions of PW SB No.

PW4ENG–72–514, Revision 1, dated August

2, 1996.

(4) Incorporate HPC 13th–15th stage

zirconium oxide blade tips in accordance

with the Accomplishment Instructions of PW

SB No. PW4ENG–72–575, Revision 1, dated

June 30, 1997.

(b) 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, Engine

Certification Office. Operators shall submit

their request through an appropriate FAA

Principal Maintenance Inspector, who may

add comments and then send it to the

Manager, Engine Certification Office.

Note 2: Information concerning the

existence of approved alternative methods of

compliance with this airworthiness directive,

if any, may be obtained from the Engine

Certification Office.

(c) 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 aircraft to

a location where the requirements of this AD

can be accomplished.

Issued in Burlington, Massachusetts, on

June 11, 1998.

Jay J. Pardee,

Manager, Engine and Propeller Directorate,

Aircraft Certification Service.

[FR Doc. 98–16271 Filed 6–17–98; 8:45 am]

BILLING CODE 4910–13–P