31340 Federal Register / Vol. 63, No. 110 /Tuesday, June 9, 1998 /Rules and Regulations

Issued in Burlington, Massachusetts, on

May 29, 1998.

Jay J. Pardee,

Manager, Engine and Propeller Directorate,

Aircraft Certification Service.

[FR Doc. 98–15088 Filed 6–8–98; 8:45 am]

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97–ANE–05; Amendment 39–

10563; AD 98–12–07]

RIN 2120–AA64

Airworthiness Directives; Pratt &

Whitney JT8D Series Turbofan Engines

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final rule.

SUMMARY: This amendment supersedes

an existing airworthiness directive (AD),

applicable to Pratt & Whitney JT8D

series engines, that currently requires a

determination of the utilization rate and

coating type of the 7th, 8th, 9th, 10th,

11th, and 12th stage high pressure

compressor (HPC) disks, and removal,

inspection for corrosion, and recoating

of those HPC disks based on utilization

rate. This amendment shortens the

inspection interval for certain low

utilization disks. This amendment is

prompted by reports of an additional

uncontained 9th stage HPC disk failure

due to corrosion pitting. The actions

specified by this AD are intended to

prevent fracture of the HPC disks, which

can result in uncontained release of

engine fragments, inflight engine

shutdown, and airframe damage.

DATES: Effective August 10, 1998.

The incorporation by reference of

Pratt & Whitney Alert Service Bulletin

No. 6038, Revision 5, dated August 17,

1994, as listed in the regulations, was

approved previously by the Director of

the Federal Register as of November 28,

1994 (59 FR 49175, September 27,

1994).

ADDRESSES: The service information

referenced in this AD 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

Federal Aviation Administration (FAA),

New England Region, Office of the

Regional Counsel, 12 New England

Executive Park, Burlington, MA 01803–

5299; or at the Office of the Federal

Register, 800 North Capitol Street, NW.,

suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Christopher Spinney, Aerospace

Engineer, Engine Certification Office,

FAA, Engine and Propeller Directorate,

12 New England Executive Park,

Burlington, MA 01803–5299; telephone

(781) 238–7175, fax (781) 238–7199.

SUPPLEMENTARY INFORMATION: A

proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39)

by superseding airworthiness directive

(AD) 94–20–01, Amendment 39–9020

(59 FR 49175, September 27, 1994),

applicable to Pratt & Whitney (PW)

JT8D–1, –1A, –1B, –7, –7A, –7B, –9,

–9A, –11, –15, –15A, –17, –17A, –17R,

and –17AR turbofan engines was

published in the Federal Register on

September 17, 1997 (62 FR 48800). That

action proposed the same record search

and inspection program but on a more

conservative inspection schedule, and

that low utilization disks, regardless of

the disk coating, would have to be

inspected at an interval of 7 years since

new, replate, or corrosion (YRSNRC) in

accordance with the engine manual.

Currently, the inspection interval for

low utilization disks is based on the

disk coating and the maximum

inspection interval ranges from 9 to 11

YRSNRC depending on the part number

and the type of coating. The high

utilization disk inspection interval

remained unchanged.

Interested persons have been afforded

an opportunity to participate in the

making of this amendment. Due

consideration has been given to the

comments received.

Four commenters, comprising of 3

operators and the manufacturer, state

that the proposed superseding rule

should be withdrawn, based on the

manufacturer’s risk analysis, the lack of

a defined unsafe condition, the lack of

technical substantiation of the rule, and

the belief that the current management

plan is adequate to address the HPC

disk corrosion issue. The FAA does not

concur. The National Transportation

Safety Board (NTSB) has determined

from their investigation of the December

1995 accident that the most probable

cause of the HPC disk failure was a

fatigue crack which originated at a

corrosion pit. The failed disk was last

stripped of its protective coating and

replated 8 years prior to the failure. The

current AD and management plan

requires reinspection of the disk at 10

year intervals. Therefore, the unsafe

condition has been identified as the

failure of a low utilization HPC disk

prior to its currently mandated

inspection interval. Risk analysis is

used to develop a management plan to

lower the probability of future events

from occurring and cannot preclude a

future event from occurring. The FAA

establishes its confidence in the

manufacturer’s risk assessment by

thoroughly reviewing the assumptions

and modeling involved in developing

the risk values. Although the FAA

concurs that the manufacturer’s risk

assessment produces risk values that fall

within typically acceptable limits, the

FAA concludes that a more conservative

corrective action is necessary. The

acceptable risk limits are meant to be

limits, and not typical values for

allowable future risk. Establishing 7

years as the maximum inspection

interval provides lowered risk without

an onerous effect on the inspection and

removal schedule, and, therefore,

represents a desirable tradeoff.

Furthermore, the reduced interval

captures the concern of allowing a

maximum inspection 25% in excess (10

years) of the recently-observed failure (8

years). While studies have determined

that low utilization engines are more

susceptible to corrosion because of the

longer intervals between engine

overhauls and the increased time spent

stationary, subject to condensation, the

FAA has determined that the statistical

modeling of the onset and growth of a

corrosion pit does not provide the level

of confidence for the FAA to accept a

longer interval. Therefore, the 7 year

inspection interval was determined by

the circumstances of the December 1995

accident. The disk failed 8 years after

replating, therefore in order to lower the

risk of a similar event 7 years was

chosen as the maximum inspection

interval. This provides an adequate

margin of safety against an incident

occurring 8 years after replating.

Three commenters state that the

economic analysis is inadequate, as the

costs don’t take into account required

early shop visits, costs associated with

aircraft down time, and industry’s

inability to perform engine overhauls

due to shortages of engine parts. The

FAA does not concur as these costs do

not directly stem from the AD’s required

actions. This AD does not require any

additional action over and above the

original AD; however, the FAA has

chosen to adopt the original economic

analysis for inclusion in this revision.

The indirect costs associated with

performing the maintenance actions

required by this AD are not directly

related to this proposed rule, and,

therefore, are not addressed in the

economic analysis for this rule. A full

cost analysis for each AD, including

such indirect costs, is not necessary

since the FAA has already performed a

cost benefit analysis when adopting the
Federal Register / Vol. 63, No. 110 /Tuesday, June 9, 1998 /Rules and Regulations 31341

part 33, airworthiness requirements to

which these engines were originally

certificated. A finding that an AD is

warranted means that the original

design no longer achieves the level of

safety specified by those airworthiness

requirements, and that other required

actions are necessary, as in this case,

stripping, corrosion inspecting and

recoating or removing HPC disks.

Because the original level of safety was

already determined to be cost beneficial,

these additional requirements needed to

return the engine to that level of safety

do not add any additional regulatory

burden, and, therefore, a full cost

analysis would be redundant and

unnecessary.

Two commenters state that the years

since last inspection (YRSLI) criteria has

been removed from the AD. The FAA

concurs with the following exception.

The years since last corrosion

inspection was in the original AD as a

one-time relief to operators who may

have recently installed a disk and had

not replated, but had performed a

corrosion inspection. It was intended as

a one-time only category for a disk and

is not intended for repetitive

inspections. The FAA concludes,

however, that the original intent of

YRSLI should remain intact and will

change the compliance accordingly, but

has reduced in this final rule the

compliance interval of YRSLI by 3 years

to be consistent with the 3 year

compliance interval reduction for years

since new, replated, or corrosion

inspected (YRSNRC).

One commenter states that the mixed

utilization disks category has been

removed from the AD, as high

utilization disks that become low

utilization disks in the current AD

receive a 40% time credit for the years

they are operated as high utilization

disks. The FAA concurs and has added

to this final rule the time credit for disks

that are operated as high utilization

disks and then become low utilization

disks. Low utilization disks that become

high utilization disks must remain in

the low utilization category until

replated, and thus receive no time credit

for time spent as a high utilization disk.

One commenter states that engines

will require immediate removal upon

publication of the AD. The FAA does

not concur. The FAA has considered the

impact on industry from immediate

removals of engines upon publication of

the AD. Since this superseding AD

contains the requirements of the current

AD, only engines that are not currently

in compliance with AD 94–20–01

should require immediate removal upon

publication of this AD. Engines that fall

outside of the new reinspection interval

are given a reasonable drawdown period

before compliance is required.

Operators finding that immediate

removal of engines is required may

apply for relief through the procedures

contained in the AD allowing for

approval of an alternate method of

compliance or an adjustment to the

compliance time.

One commenter states that they will

follow the FAA-approved data

contained in the PW Centralized and

Coordinated Telecommunications

Utility System (CACTUS) wire dated

January 1, 1997. The FAA does not

concur. Operators are reminded that

PW’s CACTUS wire is not FAAapproved data. It is simply PW’s method

of communicating their

recommendations to their operators.

Further, FAA approval of maintenance

plans does not constitute approval of an

alternate method of complying with

actions required by an AD. The

exclusive procedure for seeking

approval of an alternate method of

compliance is provided in the AD.

One commenter requests that

previous alternative methods of

compliance (AMOCs) should be

applicable to this AD. The FAA concurs

in part. The AMOCs to this AD are not

intended to be different from the AD

which it is superseding; however, the

intervals for compliance are being

adjusted by this AD. Therefore,

approved AMOCs to AD 94–20–01 are

approved for this AD, but adjustments

to compliance times which were

approved for 94–20–01 are not approved

for this AD.

One commenter requests clarification

of partial year calculations. The FAA

concurs in part. The FAA agrees that a

partial year calculation of utilization

rate is acceptable if a disk enters service

at a time other than an operator’s

calculation interval. However, the FAA

does not concur that a note is necessary

in the AD to clarify this as it would

unduly add to the complexity of the AD

and that individual questions of this

nature can best be handled on an

individual basis.

Five commenters concur with the rule

as proposed.

New part numbers compressor disks

have been introduced by PW and

approved for use by the FAA. However,

these disks also require a corrosion

inspection for all of the same reasons

stated in the NPRM and this AD. Not

adding the additional part numbers to

the NPRM was an unintentional

oversight. Since the introduction of the

new part numbers was only introduced

last year, no drawdown interval is

specified or required. The addition of

paragraph (d)(5) in the final rule poses

no undo burden on operators and meets

the intent of the NPRM.

In addition, the FAA has clarified the

phrasing in the compliance section of

this AD to better explain the

requirements for corrosion inspections.

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 changes

described previously. The FAA has

determined that these changes will

neither increase the economic burden

on any operator nor increase the scope

of the AD.

There are approximately 11,119

engines of the affected design in the

worldwide fleet. The FAA estimated

that 6,815 engines installed on aircraft

of U.S. registry were affected by AD 94–

20–01, and 2 work hours would be

necessary to determine the utilization

rate and type of surface treatment. Based

on domestic fleetwide data, the FAA

estimated that approximately 8.7% or

593 engines were considered to have

low utilization rates. Approximately 8.6

work hours would be required to

remove these engines from the aircraft,

500 work hours to tear down, deblade,

and to reassemble the engine, and 8.6

work hours to reinstall the reassembled

engines. For the purposes of this cost

analysis only, the FAA has

conservatively estimated that 69% of

the removed low utilization engines

would require replacing the disks

inspected. The FAA assumed that 3

disks per engine may require

replacement, and the cost of a new disk

would be approximately $7,000. The

average labor rate is $60 per work hour.

Based on these figures, the total cost

impact of AD 94–20–01 on U.S.

operators was estimated to be

$14,279,542. The cost increase between

AD 94–20–01 and this superseding AD

is based on the increased inspections of

some low utilization disks. The FAA

estimates 31% of the low utilization

disks require an additional inspection.

The cost of these additional inspections

is estimated to be $4,426,658.

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
31342 Federal Register / Vol. 63, No. 110 /Tuesday, June 9, 1998 /Rules and Regulations

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

removing amendment 39–9029 (59 FR

49175, September 27, 1994) and by

adding a new airworthiness directive,

Amendment 39–10563, to read as

follows:

98–12–07 Pratt & Whitney: Amendment 39–

10563. Docket 97–ANE–05. Supersedes

AD 94–20–01, Amendment 39–9029.

Applicability: Pratt & Whitney (PW) JT8D–

1, –1A, –1B, –7, –7A, –7B, –9, –9A, –11, –15,

–15A, –17, –17A, –17R, and –17AR turbofan

engines installed on but not limited to Boeing

737 and 727 series, and McDonnell Douglas

DC–9 series aircraft.

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 (j)

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 fracture of the high pressure

compressor (HPC) disks, which can result in

uncontained release of engine fragments,

inflight engine shutdown, and airframe

damage, accomplish the following:

(a) Within four months of the effective date

of this AD, determine the fleet and sub-fleet

average engine utilization rate for the 12

months of operations prior to August 17,

1994, the issue date of PW Alert Service

Bulletin (ASB) No. 6038, Revision 5, in

accordance with paragraph 2.A of PW ASB

No. 6038, Revision 5, dated August 17, 1994.

(1) For fleet or sub-fleet average utilization

rates that are equal to or greater than 1,300

hours per year, and equal to or greater than

900 cycles per year, perform the following:

(i) For engines or stage 7 through stage 12

HPC disks that were added to a fleet or

subfleet after November 28,1994, and that

were previously designated as low utilization

disks in accordance with PW ASB No. 6038,

Revision 5, dated August 17, 1994, comply

with the requirements of paragraph (d) of this

AD.

(ii) Designate all other stage 7 through stage

12 HPC disks as high utilization disks and

comply with the requirements of paragraph

(b) of this AD.

(2) For fleet or sub-fleet average utilization

rates that are less than 1,300 hours per year

or less than 900 cycles per year, within four

months after the effective date of this AD,

determine the utilization rate for each stage

7 through stage 12 HPC disk in accordance

with paragraph 2.B.(1) of PW ASB No. 6038,

Revision 5, dated August 17, 1994.

(i) For each stage 7 through stage 12 HPC

disk with an initial utilization rate equal to

or greater than 1,300 hours per year, and

equal to or greater than 900 cycles per year,

designate this disk as a high utilization disk

and inspect in accordance with paragraph (c)

of this AD.

(ii) For each stage 7 through stage 12 HPC

disk with an initial utilization rate less than

1,300 hours per year or less than 900 cycles

per year, designate this disk as a low

utilization disk and inspect in accordance

with paragraph (d) of this AD.

(iii) For each stage 7 through stage 12 HPC

disk with an unknown initial utilization rate,

designate this disk as a low utilization disk

and inspect in accordance with paragraph (d)

of this AD.

Note 2: Once a disk is designated as low

utilization, then it must retain this

designation for the life of the disk or until

recoated.

(iv) For recoated or new disks, designate

these disks as high utilization disks and

inspect in accordance with paragraph (c) of

this AD.

(b) For high average utilization fleets and

sub-fleets, excluding those disks identified in

paragraph (a)(1)(i) of this AD, perform the

following for each stage 7 through stage 12

HPC disk in that fleet or sub-fleet:

(1) Inspect, and recoat or replace if

necessary, at the next part accessibility of the

disk, in accordance with paragraph 2.D.(1)(b)

and Chart A of PW ASB No. 6038, Revision

5, dated August 17, 1994.

(2) Recalculate the fleet or sub-fleet average

utilization rate at 12 month intervals after the

previous date of utilization determination in

accordance with paragraph 2.B of PW ASB

No. 6038, Revision 5, dated August 17, 1994.

(i) For fleet or sub-fleet average utilization

rates that are equal to or greater than 1,300

hours per year, and equal to or greater than

900 cycles per year, continue to designate all

stage 7 through stage 12 HPC disks as high

utilization disks and comply with the

requirements of paragraph (b) of this AD.

(ii) For fleet or sub-fleet average utilization

rates that are less than 1,300 hours per year

or less than 900 cycles per year, within four

months of compliance with paragraph (b)(2)

of this AD, determine the utilization rate for

each stage 7 through stage 12 HPC disk in

accordance with paragraph 2.B.(1) of PW

ASB No. 6038, Revision 5, dated August 17,

1994, as follows:

(A) For each stage 7 through stage 12 HPC

disk with a utilization rate equal to or greater

than 1,300 hours per year, and equal to or

greater than 900 cycles per year, designate

this disk as a high utilization disk and

inspect in accordance with paragraph (c) of

this AD.

(B) For each stage 7 through stage 12 HPC

disk with a utilization rate less than 1,300

hours per year or less than 900 cycles per

year, designate this disk as a low utilization

disk and inspect in accordance with

paragraph (d) of this AD.

(C) For each stage 7 through stage 12 HPC

disk with an unknown utilization rate,

designate this disk as a low utilization disk

and inspect in accordance with paragraph (d)

of this AD.

Note 3: Once a disk is designated as low

utilization, then it must retain this

designation for the life of the disk or until

recoated.

(c) For high utilization stage 7 through

stage 12 HPC disks, perform the following:

(1) Inspect, and recoat or replace if

necessary, at the next part accessibility of the

disk, in accordance with paragraph 2.D.(1)(b)

and Chart A of PW ASB No. 6038, Revision

5, dated August 17, 1994.

(2) Calculate the disk utilization rate at 12

month intervals after the previous date of

utilization determination, or after installation

of new or recoated disks, in accordance with

paragraph 2.B.(3) of PW ASB No. 6038,

Revision 5, dated August 17, 1994.

(i) For stage 7 through stage 12 HPC disks

designated as high utilization in accordance

with (c)(2), comply with the requirements of

paragraph (c)(1) of this AD.

(ii) For stage 7 through stage 12 HPC disks

designated as low utilization in accordance

with (c)(2), comply with the requirements of

paragraph (d) of this AD.

(d) For low utilization stage 7 through stage

12 HPC disks, perform the following:

(1) For Nickel Cadmium coated disks listed

by Part Number (P/N) in Chart B of PW ASB

No. 6038, Revision 5, dated August 17, 1994,

and Aluminide coated disks listed by P/N in

Chart C of PW ASB 6038, Revision 5, dated

August 17, 1994, strip protective coating,

corrosion inspect, and recoat or remove from

service in accordance with PW JT8D Engine

Manual, P/N 481672, at the time intervals

specified in Table A or Table B of this AD,

whichever occurs later.
Federal Register / Vol. 63, No. 110 /Tuesday, June 9, 1998 /Rules and Regulations 31343

TABLE A.—YEARS SINCE NEW, RECOATED, OR CORROSION INSPECTION (YRSNRC) INTERVAL FOR LOW UTILIZATION

DISKS—NICAD COATED DISKS FROM CHART B OF PW ASB NO. 6038, REVISION 5, DATED AUGUST 17, 1994, AND

ALUMINIDE COATED DISKS FROM CHART C OF PW ASB NO. 6038, REVISION 5, DATED AUGUST 17, 1994

Years since new, recoated or corrosion inspected (YRSNRC) Remove to inspect and recoat or

replace

Less than or equal to 5 .......................................................................................................................................... By 7 YRSNRC.

Greater than 5 but less than or equal to 6 ............................................................................................................ Within 24 months.

Greater than 6 but less than or equal to 7 ............................................................................................................ Within 18 months.

Greater than 7 but less than or equal to 8 ............................................................................................................ Within 15 months.

Greater than 8 but less than or equal to 9 ............................................................................................................ Within 12 months.

Greater than 9 but less than or equal to 10 .......................................................................................................... Before reaching 10 YRSNRC.

Greater than 10 ...................................................................................................................................................... Before further flight.

TABLE B.—YEARS SINCE LAST NON-CORROSION INSPECTION (YRSLI) INTERVAL FOR LOW UTILIZATION DISKS—NICAD

COATED DISKS FROM CHART B OF PW ASB NO. 6038, REVISION 5, DATED AUGUST 17, 1994, AND ALUMINIDE

COATED DISKS FROM CHART C OF PW ASB NO. 6038, REVISION 5, DATED AUGUST 17, 1994

Years since last non-corrosion inspection prior to November 28, 1994 (YRSLI) Remove to inspect and

recoat or replace

Less than or equal to 3 ................................................................................................................................................... By 5 YRSLI.

Greater than 3 but less than or equal to 5 ..................................................................................................................... Within 24 months.

Greater than 5 but less than or equal to 6 ..................................................................................................................... Within 18 months.

Greater than 6 but less than or equal to 7 ..................................................................................................................... Within 12 months.

Greater than 7 but less than or equal to 8 ..................................................................................................................... Before reaching 8 YRSLI.

Greater than 8 ................................................................................................................................................................. Before further flight.

(2) For Nickel Cadmium coated disks listed by P/N in Chart C of PW ASB No. 6038, Revision 5, dated August 17, 1994, strip

protective coating, corrosion inspect, and recoat or remove from service in accordance with PW JT8D Engine Manual, P/N 481672,

at the time intervals specified in Table C or Table D of this AD, whichever occurs later.

TABLE C.—YRSNRC INSPECTION INTERVAL FOR LOW UTILIZATION DISKS—NICAD COATED DISKS FROM CHART C OF

PW ASB NO. 6038, REVISION 5, DATED AUGUST 17, 1994

Years since new, recoated or corrosion inspected (YRSNRC) Remove to inspect and recoat or

replace

Less than or equal to 5 .......................................................................................................................................... By 7 YRSNRC.

Greater than 5 but less than or equal to 6 ............................................................................................................ Within 24 months.

Greater than 6 but less than or equal to 7 ............................................................................................................ Within 21 months.

Greater than 7 but less than or equal to 8 ............................................................................................................ Within 18 months.

Greater than 8 but less than or equal to 9 ............................................................................................................ Within 15 months.

Greater than 9 but less than or equal to 10 .......................................................................................................... Within 12 months.

Greater than 10 but less than or equal to 11 ........................................................................................................ Before reaching 11 YRSNRC.

Greater than 11 ...................................................................................................................................................... Before further flight.

TABLE D.—YRSLI INSPECTION INTERVAL FOR LOW UTILIZATION DISKS—NICAD COATED DISKS FROM CHART C OF PW

ASB NO. 6038, REVISION 5, DATED AUGUST 17, 1994

Years since last non-corrosion inspection prior to November 28, 1994 (YRSLI) Remove to inspect and

recoat or replace

Less than or equal to 4 ................................................................................................................................................... By 6 YRSLI.

Greater than 4 but less than or equal to 6 ..................................................................................................................... Within 24 months.

Greater than 6 but less than or equal to 7 ..................................................................................................................... Within 18 months.

Greater than 7 but less than or equal to 8 ..................................................................................................................... Within 12 months.

Greater than 8 but less than or equal to 9 ..................................................................................................................... Before reaching 9 YRSLI.

Greater than 9 ................................................................................................................................................................. Before further flight.

(3) For Aluminide coated disks listed by P/N in Chart B of PW ASB No. 6038, Revision 5, dated August 17, 1994, strip protective

coating, corrosion inspect, and recoat or remove from service in accordance with PW JT8D Engine Manual, P/N 481672, at the time

intervals specified in Table E or Table F of this AD, whichever occurs later.

TABLE E.—YRSNRC INSPECTION INTERVAL FOR LOW UTILIZATION DISKS ALUMINIDE COATED DISKS FROM CHART B OF

PW ASB NO. 6038, REVISION 5, DATED AUGUST 17, 1994

Years since new, recoated or corrosion inspected (YRSNRC) Remove to inspect and

recoat or replace

Less than or equal to 5 ................................................................................................................................................... By 7 YRSNRC.
31344 Federal Register / Vol. 63, No. 110 /Tuesday, June 9, 1998 /Rules and Regulations

TABLE E.—YRSNRC INSPECTION INTERVAL FOR LOW UTILIZATION DISKS ALUMINIDE COATED DISKS FROM CHART B OF

PW ASB NO. 6038, REVISION 5, DATED AUGUST 17, 1994—Continued

Years since new, recoated or corrosion inspected (YRSNRC) Remove to inspect and

recoat or replace

Greater than 5 but less than or equal to 6 ..................................................................................................................... Within 24 months.

Greater than 6 but less than or equal to 7 ..................................................................................................................... Within 18 months.

Greater than 7 but less than or equal to 8 ..................................................................................................................... Within 12 months.

Greater than 8 but less than or equal to 9 ..................................................................................................................... Before reaching 9

YRSNRC.

Greater than 9 ................................................................................................................................................................. Before further flight.

TABLE F.—YRSLI INSPECTION INTERVAL FOR LOW UTILIZATION DISKS ALUMINIDE COATED DISKS FROM CHART B OF PW

ASB NO. 6038, REVISION 5, DATED AUGUST 17, 1994

Years since last non-corrosion inspection prior to November 28, 1994 (YRSLI) Remove to inspect and

recoat or replace

Less than or equal to 2 ................................................................................................................................................... By 4 YRSLI.

Greater than 2 but less than or equal to 4 ..................................................................................................................... Within 24 months.

Greater than 4 but less than or equal to 5 ..................................................................................................................... Within 18 months.

Greater than 5 but less than or equal to 6 ..................................................................................................................... Within 12 months.

Greater than 6 but less than or equal to 7 ..................................................................................................................... Before reaching 7 YRSLI.

Greater than 7 ................................................................................................................................................................. Before further flight.

(4) For all other low utilization stage 7

through stage 12 HPC disks, strip protective

coating, corrosion inspect, and recoat or

remove from service in accordance with the

PW JT8D Engine Manual, P/N 481672, prior

to 7 years since new, recoated, or corrosion

inspected (YRSNRC).

(5) For disks that are categorized as high

utilization and subsequently entered low

utilization service, YRSNRC can be adjusted

as follows and applied to Table A, Table C,

and Table E of this AD:

(i) Adjusted YRSNRC = (0.60) × (years

utilized at a rate greater than or equal to

1,300 hours per year, and greater than or

equal to 900 cycles per year) + (years

classified as low utilization).

(ii) Once a disk enters low utilization

service it must remain in that category and

an adjustment to YRSNRC cannot be made

for any subsequent high utilization operation.

(iii) Years Since Last Non-Corrosion

Inspection prior to November 18, 1994

(YRSLI) is a one-time interval only and

cannot be used as a repetitive interval.

(e) For stage 7 through stage 12 HPC disks

that have been recoated in accordance with

paragraphs (b)(1), (c)(1), or (d)(1) of this AD,

designate these disks as high utilization and

perform the following:

(1) For disks installed in an engine that is

part of a high utilization fleet, comply with

the requirements of paragraph (b) of this AD.

(2) For disks installed in an engine that is

part of a low utilization fleet, comply with

the requirements of paragraph (c) of this AD.

(f) For the purpose of this AD, recoat of an

HPC disk is defined as removal and

application of new plating or coating in

accordance with Sections 72–36–41, Repair

02; 72–36–42, Repair 02; 72–36–43, Repair

03; 72–36–44, Repair 03; 72–36–45, Repair

03; or 72–36–46, Repair 03, as applicable, of

PW JT8D Engine Manual P/N 481672.

(g) For the purpose of this AD, a corrosion

inspection is defined as performing an

inspection in accordance with PW Engine

Manual 481672, section 72–36–41,

inspection 01 for stage 7 disks, section 72–

36–42, inspection 02, for 8th stage disks,

section 72–36–43, inspection 02 for 9th stage

disks, section 72–36–44, inspection 02 for

10th stage disks, section 72–36–45,

inspection 02 for 11th stage disks, section

72–36–46, inspection 02 for 12th stage disks.

(h) For the purpose of this AD, part

accessibility is defined as the removal of the

disk from the engine and deblading of that

disk.

(i) For the purpose of this AD, a sub-fleet

is defined as any individual aircraft or any

portion of an operator’s fleet that operates in

a separate and unique route structure,

characterized by different flight lengths,

frequencies, or geographic location.

(j) 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 requests through an appropriate FAA

Principal Maintenance Inspector, who may

add comments and then send it to the

Manager, Engine Certification Office.

Alternate methods of compliance approved

for AD 94–20–01 are approved for this AD;

adjustments to compliance times approved

for AD 94–20–01 are not approved for this

AD.

Note 4: Information concerning the

existence of approved alternative methods of

compliance with this airworthiness directive,

if any, may be obtained from the Engine

Certification Office.

(k) 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.

(l) The actions required by this AD shall be

done in accordance with the following PW

ASB:

Document No. Pages Revision Date

PW ASB No. 6038 ........................................................................................ 1 5 ......................................... August 17, 1994.

2 Original ............................... August 5, 1991.

3 5 ......................................... August 17, 1994.

4–6 4 ......................................... July 13, 1994.

7–26 5 ......................................... August 17, 1994.

Appendix A .................................................................................................... 27–41 5 ......................................... August 17, 1994.

Appendix B NDIP–803 .................................................................................. 1–33 4 ......................................... July 13, 1994.

Appendix to NDIP–803 .................................................................................. 1–2 4 ......................................... July 13, 1994.

Total Pages: 76.
Federal Register / Vol. 63, No. 110 /Tuesday, June 9, 1998 /Rules and Regulations 31345

The incorporation by reference of PW ASB

No. 6038, Revision 5, dated August 17, 1994,

was approved previously by the Director of

the Federal Register as of November 28, 1994

(59 FR 49175, September 27, 1994). Copies

may be obtained from Pratt & Whitney, 400

Main St., East Hartford, CT 06108; telephone

(860) 565–6600, fax (860) 565–4503. Copies

may be inspected at the FAA, New England

Region, Office of the Regional Counsel, 12

New England Executive Park, Burlington,

MA; or at the Office of the Federal Register,

800 North Capitol Street, NW., suite 700,

Washington, DC.

(m) This amendment becomes effective on

August 10, 1998.

Issued in Burlington, Massachusetts, on

May 29, 1998.

Jay J. Pardee,

Manager, Engine and Propeller Directorate,

Aircraft Certification Service.

[FR Doc. 98–15086 Filed 6–8–98; 8:45 am]

BILLING CODE 4910–13–U

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96–NM–184–AD; Amendment

39–10573; AD 98–12–18]

RIN 2120–AA64

Airworthiness Directives; Airbus Model

A320–111, –211, and –231 Series

Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final rule.

SUMMARY: This amendment adopts a

new airworthiness directive (AD),

applicable to certain Airbus Model

A320–111, –211, and –231 series

airplanes, that requires repetitive

inspections for cracking in the transition

and pick-up angles in the lower part of

the center fuselage area, and corrective

action, if necessary. This amendment

also provides for an optional

terminating modification for the

repetitive inspection requirements. This

amendment is prompted by the issuance

of mandatory continuing airworthiness

information by a foreign civil

airworthiness authority. The actions

specified by this AD are intended to

detect and correct fatigue cracking in

the transition and pick-up angles of the

lower part of the center fuselage, which

could result in reduced structural

integrity of the wing-fuselage support

and fuselage pressure vessel.

DATES: Effective July 14, 1998.

The incorporation by reference of

certain publications listed in the

regulations is approved by the Director

of the Federal Register as of July 14,

1998.

ADDRESSES: The service information

referenced in this AD may be obtained

from Airbus Industrie, 1 Rond Point

Maurice Bellonte, 31707 Blagnac Cedex,

France. 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:

Norman B. Martenson, Manager,

International Branch, ANM–116, FAA,

Transport Airplane Directorate, 1601

Lind Avenue, SW., Renton, Washington

98055–4056; telephone (425) 227–2110;

fax (425) 227–1149.

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 Airbus

Model A320–111, –11, and –231 series

airplanes was published in the Federal

Register on November 19, 1997 (62 FR

61704). That action proposed to require

repetitive inspections for cracking in the

transition and pick-up angles in the

lower part of the center fuselage area,

and corrective action, if necessary. That

action also proposed to provide for an

optional terminating modification for

the repetitive inspection requirements.

Comments

Interested persons have been afforded

an opportunity to participate in the

making of this amendment. Due

consideration has been given to the

comments received.

Two commenters support the

proposed rule.

One commenter supports the intent of

the proposed rule, but identifies a

redundancy that appears in paragraph

(a)(2)(i)(A) of the proposed AD. The

commenter notes that the repetitive

inspection requirements of this

paragraph specify accomplishment of

both a visual and a rotating probe (eddy

current) inspection, whereas the original

requirement was only for an eddy

current inspection. Since the eddy

current inspection provides a greater

detailed inspection than a visual

inspection, the commenter states that

the visual inspection should not be

necessary. The FAA concurs and has

revised paragraph (a)(2)(i)(A) of the final

rule accordingly.

Additionally, paragraphs (a)(1)(i)(B),

(a)(1)(ii), and (a)(2)(i)(B) of the final rule

have been revised to cite only Revision

2 of Airbus Service Bulletin A320–53–

1027 for accomplishment of certain

actions. Revision 2 contains no

substantive differences from the original

or Revision 1 of the service bulletin. A

‘‘NOTE’’ has been added to the final

rule to give credit to operators who may

have previously accomplished the

required actions in accordance with

these earlier versions of the service

bulletin.

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 change

previously described. 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

The FAA estimates that 24 airplanes

of U.S. registry will be affected by this

AD.

It will take approximately 9 work

hours per airplane to accomplish the

required inspections, at an average labor

rate of $60 per work hour. Based on

these figures, the cost impact of the

inspections required by this AD on U.S.

operators is estimated to be $12,960, or

$540 per airplane, per inspection cycle.

It will take approximately 10 work

hours per airplane to accomplish the

required modification, at an average

labor rate of $60 per work hour.

Required parts will cost approximately

$2,895 per airplane. Based on these

figures, the cost impact of the

modification required by this AD on

U.S. operators is estimated to be

$83,880, or $3,495 per airplane.

The cost impact figures discussed

above are 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