Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 92-ANE-33; Amendment 39-9038; AD 93-19-02R1]

Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan

Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule, request for comments.

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SUMMARY: This amendment revises an existing airworthiness directive

(AD), applicable to Pratt & Whitney (PW) JT9D series turbofan engines,

that currently requires eddy current inspection and modification of the

diffuser case rear rail, and removal, if necessary, of the diffuser

case. This amendment corrects an error in paragraph numbering in the

compliance section and allows modification of diffuser cases in

accordance with previous revisions of a PW Service Bulletin as an

alternative means of compliance. This amendment is prompted by comments

received after issuance of AD 93-19-02. The actions specified by this

AD are intended to prevent diffuser case rupture and an uncontained

engine failure.

DATES: Effective on October 17, 1994.

The incorporation by reference of certain publications listed in

the regulations was approved by the Director of the Federal Register as

of October 18, 1993 (58 FR 51212, October 1, 1993).

Comments for inclusion in the Rules Docket must be received on or

before November 29, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), New England Region, Office of the Assistant Chief

Counsel, Attention: Rules Docket No. 92-ANE-33, 12 New England

Executive Park, Burlington, MA 01803-5299.

The service information referenced in this AD may be obtained from

Pratt & Whitney, 400 Main Street, East Hartford, CT 06108. This

information may be examined at the FAA, New England Region, Office of

the Assistant Chief 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.

FOR FURTHER INFORMATION CONTACT: Daniel Kerman, Aerospace Engineer,

Engine Certification Office, FAA, Engine and Propeller Directorate, 12

New England Executive Park, Burlington, MA 01803-5299; telephone (617)

238-7130, fax (617) 238-7199.

SUPPLEMENTARY INFORMATION: On September 16, 1993, the Federal Aviation

Administration (FAA) issued AD 93-19-02, Amendment 39-8695 (58 FR

51212, October 1, 1993), as a final rule with request for comments that

superseded AD 86-11-04, to define initial inspection requirements that

will allow for transition to more stringent repetitive on-wing eddy

current inspections of the diffuser case rear rail for cracking. AD 93-

19-02 also requires ultrasonic and metallographic inspections of the

shell wall, and ultrasonic inspection of the rear rail at the Boss 6

location to determine weld size. In the previous AD, 86-11-04, diffuser

cases were allowed to remain in service with weld repairs of up to 4

inches in length. In AD 93-19-02, diffuser cases with weld repairs in

the rear rail of greater than or equal to 1.5 inches in axial length at

Boss 6 must be replaced. In addition, AD 93-19-02 requires a one-time

X-ray inspection of the rear rail and sides of bosses for weld quality.

This inspection is necessary since in the last two failures, weld

defects were undetected by the inspections required by AD 86-11-04.

Also, diffuser cases with rear rails that have been weld-repaired must

incorporate the modifications described in PW SB No. 5805, Revision 6,

dated September 15, 1993. Finally, an optional terminating action to

the inspections and modifications of AD 93-19-02 is available with the

installation of a new, improved diffuser case in accordance with PW SB

No. 6105, Revision 2, dated May 14, 1993.

AD 93-19-02 was prompted by reports of 2 additional diffuser case

failures. Both failures occurred within significantly shorter time

intervals since last inspection than that specified in AD 86-11-04. In

an effort to better understand the diffuser case failure mode, a rig

test was performed. This test examined crack initiation and growth

rates in weld-repaired versus non-weld-repaired diffuser cases. Results

of the test established that cracks initiate and propagate more rapidly

in weld-repaired diffuser cases. In addition, weld repairs at the Boss

6 location were determined to have even greater potential for rapid

crack growth and resultant diffuser case failure. That condition, if

not corrected, could result in diffuser case rupture and an uncontained

engine failure.

Although AD 93-19-02 was issued as a final rule without prior

notice and an opportunity for public comment, the FAA requested comment

on the AD. Due consideration has been given to the comments received.

One commenter states that paragraph (c)(3) of AD 93-19-02 refers

incorrectly to paragraphs (d) and (f), as those paragraphs are

applicable to those diffuser cases that have been weld-repaired. The

FAA concurs. Paragraph (c)(3) of this Revision to AD 93-19-02 has been

changed to refer to paragraphs (e), (g), (h), (i), (j), (k), and (l).

These paragraphs are applicable to those diffuser cases that have not

been weld-repaired.

One commenter states that paragraph (o) of AD 93-19-02 requires

modifications to the diffuser case in accordance with PW Service

Bulletin (SB) No. 5805, Revision 6, dated September 15, 1993. The

commenter maintains that modifications performed in accordance with the

earlier revisions to this SB should be considered in compliance with

this AD. The FAA concurs. All previous revisions of PW SB No. 5805

differ from Revision 6 only in editorial clarifications or corrections

of typographical errors and do not impact the intent of the document.

Modifications performed to the diffuser case in accordance with the

previous revisions of PW SB No. 5805 constitute an acceptable alternate

means of compliance to paragraph (o) of this AD.

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 revision 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.

The FAA has reviewed and approved the technical contents of PW SB

No. 5805, Revision 6, dated September 15, 1993, that describes

procedures for modification of the rear rail by detaching the diffuser

case rear rail from the strut boss, thus extending the serviceable life

of the diffuser case by reducing crack initiation and propagation

rates; PW Alert Service Bulletin (ASB) No. 6076, Revision 1, dated

August 20, 1992, that describes ultrasonic and metallographic

inspection of the shell wall, and ultrasonic inspection of the rear

rail at the Boss 6 location to determine weld size; PW SB No. 6088,

dated August 5, 1992, that describes an X-ray inspection of the rear

rail and sides of bosses for detection of poor weld quality; PW SB No.

5591, Revision 7, dated August 25, 1992, that describe initial and

repetitive on-wing eddy current inspections of the diffuser case rear

rail; and PW SB No. 6105, Revision 2, dated May 14, 1993, that

describes installation of a new, improved diffuser case.

Additional information regarding weld repair requirements for the

diffuser case rear rail is contained in PW JT9D Engine Manual, Part

Number 686028, dated September 1, 1993.

Since an unsafe condition has been identified that is likely to

exist or develop on other PW JT9D series turbofan engines of this same

type design, this AD revises AD 93-19-02 to correct an error in

paragraph numbering in the compliance section and allow modification of

diffuser cases in accordance with previous revisions of PW SB No. 5805

as an alternative means of compliance to paragraph (o) of this AD. The

actions are required to be accomplished in accordance with the service

bulletins described previously.

Since a situation exists that requires the immediate adoption of

this regulation, it is found that notice and opportunity for prior

public comment hereon are impracticable, and that good cause exists for

making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves

requirements affecting flight safety and, thus, was not preceded by

notice and an opportunity for public comment, comments are invited on

this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All

communications received on or before the closing date for comments will

be considered, and this rule may be amended in light of the comments

received. Factual information that supports the commenter's ideas and

suggestions is extremely helpful in evaluating the effectiveness of the

AD action and determining whether additional rulemaking action would be

needed.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the rule that might

suggest a need to modify the 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 that

summarizes each FAA-public contact concerned with the substance of this

AD 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 92-ANE-33.'' The postcard will be date stamped and

returned to the commenter.

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.

The FAA has determined that this regulation is an emergency

regulation that must be issued immediately to correct an unsafe

condition in aircraft, and is not a ``significant regulatory action''

under Executive Order 12866. It has been determined further that this

action involves an emergency regulation under DOT Regulatory Policies

and Procedures (44 FR 11034, February 26, 1979). If it is determined

that this emergency regulation otherwise would be significant under DOT

Regulatory Policies and Procedures, a final regulatory evaluation will

be prepared and placed in the Rules Docket. A copy of it, if filed, 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. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing Amendment 39-8695 (58 FR

51212, October 1, 1993) and by adding a new airworthiness directive,

Amendment 39-9038, to read as follows:

93-19-02 R1 Pratt & Whitney: Amendment 39-9038. Docket 92-ANE-33.

Revises AD 93-19-02, Amendment 39-8695.

Applicability: Pratt & Whitney (PW) JT9D-3A, -7, -7H, -7A, -7AH,

-7F, -7J, -20, and -20J turbofan engines installed on but not

limited to Boeing 747 series, Airbus A300 series, and McDonnell

Douglas DC-10 series aircraft.

Compliance: Required as indicated, unless accomplished

previously.

To prevent diffuser case rupture and an uncontained engine

failure, accomplish the following:

(a) For those diffuser cases that have not been inspected in

accordance with PW Alert Service Bulletin (ASB) No. 6076, Revision

1, dated August 20, 1992, initially inspect the diffuser case for

cracks in accordance with the intervals and requirements described

in paragraphs (d), (f), (g), (i), (j), (k), or (l) of this AD, as

applicable.

(b) For those diffuser cases that have not been inspected in

accordance with PW ASB No. 6076, Revision 1, dated August 20, 1992,

inspect the diffuser case rear rail along the shell wall at Boss 6

for weld repair size in accordance with PW ASB No. 6076, Revision 1,

dated August 20, 1992, at the next M flange separation of the high

pressure turbine case after the effective date of this AD. Diffuser

cases with weld repairs in the rear rail along the shell wall of

axial length greater than or equal to 1.5 inches at Boss 6 must not

be returned to service. If the weld length is less than 1.5 inches,

inspect in accordance with the new criteria, improved technique,

intervals, and requirements defined in the Accomplishment

Instructions of PW Service Bulletin (SB) No. 5591, Revision 7, dated

August 25, 1992.

Note: Additional information regarding weld repair requirements

for the diffuser case rear rail is contained in PW JT9D Engine

Manual, Part Number 686028, dated September 1, 1993.

(c) For those diffuser cases that have been inspected in

accordance with PW ASB No. 6076, Revision 1, dated August 20, 1992,

accomplish the following:

(1) For diffuser cases that have weld repairs in the rear rail

along the shell wall at Boss 6 of axial length greater than or equal

to 1.5 inches, remove from service and replace with a serviceable

part prior to further flight.

(2) For diffuser cases that have weld repairs in the rear rail

along the shell wall at Boss 6 of axial length less than 1.5 inches,

initially inspect the diffuser case for cracks in accordance with

the intervals and requirements described in paragraphs (d), (f),

(g), (i), (j), (k), or (l) of this AD, as applicable.

(3) For diffuser cases that have no weld repairs in the rear

rail along the shell wall at Boss 6, initially inspect the diffuser

case for cracks in accordance with the intervals and requirements

described in paragraphs (e), (g), (h), (i), (j), (k), or (l) of this

AD, as applicable.

(d) For those diffuser cases that have been inspected in

accordance with PW SB No. 5591, Revision 4, dated March 6, 1986,

that contained rear rails with no cracks at any boss location at the

last ECI, and have a weld repair in the rear rail along the shell

wall at Boss 6, perform an initial ECI of the diffuser case rear

rail for cracks in accordance with the new criteria and improved

technique defined in the Accomplishment Instructions of PW SB No.

5591, Revision 7, dated August 25, 1992, as follows:

(1) For diffuser cases with greater than 275 cycles in service

(CIS) since the last ECI performed in accordance with PW SB No.

5591, Revision 4, dated March 6, 1986, on the effective date of this

AD, perform an ECI in accordance with the new criteria and improved

technique defined in the Accomplishment Instructions PW SB No. 5591,

Revision 7, dated August 25, 1992, prior to accumulating 500 CIS

since the last ECI performed in accordance with PW SB No. 5591,

Revision 4, dated March 6, 1986, or prior to accumulating 75 CIS

after the effective date of this AD, whichever occurs first.

(2) For diffuser cases with less than or equal to 275 CIS since

the last ECI performed in accordance with PW SB No. 5591, Revision

4, dated March 6, 1986, on the effective date of this AD, perform an

ECI in accordance with the new criteria and improved technique

defined in the Accomplishment Instructions of PW SB No. 5591,

Revision 7, dated August 25, 1992, prior to accumulating 350 CIS

since the last ECI performed in accordance with PW SB No. 5591,

Revision 4, dated March 6, 1986.

(e) For those diffuser cases that have been inspected in

accordance with PW SB No. 5591, Revision 4, dated March 6, 1986,

that contained rear rails with no cracks at any boss location at the

last ECI, and have no weld repairs in the rear rail along the shell

wall at Boss 6, perform an ECI of the diffuser case rear rail for

cracks in accordance with the new criteria and improved technique

defined in the Accomplishment Instructions of PW SB No. 5591,

Revision 7, dated August 25, 1992, prior to accumulating 500 CIS

since the last ECI performed in accordance with PW SB No. 5591,

Revision 4, dated March 6, 1986.

(f) For those diffuser cases that have been inspected in

accordance with PW SB No. 5591, Revision 4, dated March 6, 1986,

that contained rear rails with ``A'' cracks at Boss 6 at the last

ECI, and have a weld repair in the rear rail along the shell wall at

Boss 6, perform an ECI of the diffuser case rear rail for cracks in

accordance with the new criteria and improved technique defined in

the Accomplishment Instructions of PW SB No. 5591, Revision 7, dated

August 25, 1992, prior to accumulating 300 CIS since the last ECI

performed in accordance with PW SB No. 5591, Revision 4, dated March

6, 1986, or prior to accumulating 60 CIS after the effective date of

this AD, whichever occurs first.

(g) For those diffuser cases that have been inspected in

accordance with PW SB No. 5591, Revision 4, dated March 6, 1986,

that contained rear rails with ``A'' cracks at any boss location

other than at Boss 6 at the last ECI, with or without weld repairs

in the rear rail along the shell wall at Boss 6, perform an ECI of

the diffuser case rear rail for cracks in accordance with the new

criteria and improved technique defined in the Accomplishment

Instructions of PW SB No. 5591, Revision 7, dated August 25, 1992,

prior to accumulating 300 CIS since the last ECI performed in

accordance with PW SB No. 5591, Revision 4, dated March 16, 1986.

(h) For those diffuser cases that have been inspected in

accordance with PW SB No. 5591, Revision 4, dated March 6, 1986,

that contained rear rails with ``A'' cracks at Boss 6 at last ECI,

and have no weld repairs at Boss 6, perform an ECI of the diffuser

case rear rail for cracks in accordance with the new criteria and

improved technique defined in the Accomplishment Instructions of PW

SB No. 5591, Revision 7, dated August 25, 1992, prior to

accumulating 300 CIS since the last ECI performed in accordance with

PW SB No. 5591, Revision 4, dated March 6, 1986.

(i) For those diffuser cases that have been inspected in

accordance with PW SB No. 5591, Revision 4, dated March 6, 1986, and

contained rear rails with ``B'' cracks at Boss 6 at last ECI, with

or without weld repairs in the rear rail along the shell wall at

Boss 6, remove from service and replace with a serviceable part

prior to accumulating 5 CIS after the effective date of this AD.

(j) For those diffuser cases that have been inspected in

accordance with PW SB No. 5591, Revision 4, dated March 6, 1986, and

contained rear rails with ``B'' cracks at any boss location other

than Boss 6 at last ECI, with or without weld repairs in the rear

rail along the shell wall at Boss 6, perform an ECI of the diffuser

case rear rail for cracks in accordance with the new criteria and

improved technique defined in the Accomplishment Instructions of PW

SB No. 5591, Revision 7, dated August 25, 1992, prior to

accumulating 75 CIS since the last ECI performed in accordance with

PW SB No. 5591, Revision 4, dated March 6, 1986.

(k) For those diffuser cases that have been inspected in

accordance PW SB No. 5591, Revision 4, dated March 6, 1986, and

contained rear rails with ``C'' cracks at Boss 6 at last ECI, with

or without weld repairs in the rear rail along the shell wall at

Boss 6, remove from service and replace with a serviceable part

prior to further flight.

(l) For those diffuser cases that have been inspected in

accordance with PW SB No. 5591, Revision 4, dated March 6, 1986, and

contain rear rails with ``C'' cracks at any boss location other than

Boss 6 at last ECI, with or without weld repairs in the rear rail

along the shell wall at Boss 6, remove from service and replace with

a serviceable part as follows:

(1) For shell wall cracks of greater than or equal to 2 inches,

remove from service and replace with a serviceable part prior to

further flight.

(2) For shell wall cracks of less than 2 inches, remove from

service and replace with a serviceable part within 5 CIS after the

effective date of this AD.

(m) Thereafter, perform repetitive ECI of the diffuser case rear

rail for cracks in accordance with the new criteria, improved

technique, intervals, requirements, and removal from service

criteria defined in the Accomplishment Instructions of PW SB No.

5591, Revision 7, dated August 25, 1992.

(n) For those diffuser cases that have been weld repaired at any

boss location, at the next K flange separation of the diffuser case

after the effective date of this AD, perform a one-time x-ray

inspection of the diffuser case rear rail and sides of all bosses

for weld quality in accordance with PW SB No. 6088, dated August 5,

1992, prior to installation of the diffuser case. Remove any weld

defects within the inspection zone in accordance with PW SB No.

6088, dated August 5, 1992, prior to installation of the diffuser

case.

(o) For those diffuser cases with rear rails that have been weld

repaired at any boss location, incorporate the modifications

described in PW SB No. 5805, Revision 6, dated September 15, 1993,

at the next removal of the diffuser case for repair after the

effective date of this AD.

(p) Installation of an improved diffuser case in accordance with

PW SB No. 6105, Revision 2, dated May 14, 1993, constitutes

terminating action to the inspections and modifications required by

this AD.

(q) 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. The

request should be forwarded through an appropriate FAA Principal

Maintenance Inspector, who may add comments and then send it to the

Manager, Engine Certification Office.

Note: Information concerning the existence of approved

alternative methods of compliance with this airworthiness directive,

if any, may be obtained from the Engine Certification Office.

(r) Except for diffuser cases that have cracks that require

removal prior to further flight, special flight permits may be

issued in accordance with Secs. 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. For diffuser cases that have cracks that require

removal prior to further flight, on aircraft that are eligible for

an engine-inoperative ferry, special flight permits may be issued in

accordance with Secs. 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 with

one engine inoperative.

(s) The inspections and modifications shall be done in

accordance with the following PW service bulletins:

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Document No. Pages Revision Date

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SB No. 5591.......................................... 1-3 7................. Aug. 25, 1992.

4-9 6................. Aug. 14, 1992.

10 7................. Aug. 25, 1992.

11-12 6................. Aug. 14, 1992.

13 7................. Aug. 25, 1992.

14-15 6................. Aug. 14, 1992.

16 7................. Aug. 25, 1992.

17-19 6................. Aug. 14, 1992.

Total pages: 19

SB No. 5805.......................................... 1-4 6................. Sept. 15, 1993.

5 Original.......... Apr. 20, 1988.

6-72 6................. Sept. 15, 1993.

Total pages: 72

ASB No. 6076......................................... 1-5 1................. Aug. 20, 1992.

6-19 Original.......... July 31, 1992.

Total pages: 19

SB No. 6088.......................................... 1-11 Original.......... Aug. 5, 1992.

Total pages: 11

SB No. 6105.......................................... 1 2................. May 14, 1993.

2-7 Original.......... Jan. 15, 1993.

8 1................. Apr. 14, 1993.

9 2................. May 14, 1993.

10-15 Original.......... Jan. 15, 1993.

16 2................. May 14, 1993.

17-18 Original.......... Jan. 15, 1993.

19 2................. May 14, 1993.

20-46 Original.......... Jan. 15, 1993.

47 1................. Apr. 14, 1993.

48 2................. May 14, 1993.

49-56 Original.......... Jan. 15, 1993.

Total pages: 56

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This incorporation by reference was approved previously by the Director

of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR

part 51 as of October 18, 1993 (58 FR 51212, October 1, 1993). Copies

may be inspected at the FAA, New England Region, Office of the

Assistant Chief 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.

(t) This amendment becomes effective on October 17, 1994.

Issued in Burlington, Massachusetts, on September 22, 1994.

Mark C. Fulmer,

Acting Manager, Engine and Propeller Directorate, Aircraft

Certification Service.

[FR Doc. 94-24070 Filed 9-29-94; 8:45 am]

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