Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 91-ANE-51; Amendment 39-8987; AD 94-15-16]

Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan

Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to Pratt & Whitney JT9D series turbofan engines, that

requires a one-time modification and overhaul of engine control system

accessories. This amendment is prompted by multiple engine surge and

power loss events caused by deterioration of internal components of

engine control system accessories. The actions specified by this AD are

intended to prevent the loss of engine compressor surge margin caused

by the deterioration of engine control system accessories, resulting in

an engine surge, and subsequent power loss or inflight engine shutdown.

DATES: Effective October 14, 1994.

The incorporation by reference of certain publications listed in

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

of October 14, 1994.

ADDRESSES: The service information referenced in this AD may be

obtained from Pratt & Whitney, Publications Department, 400 Main

Street, East Hartford, CT 06108. This information may be examined at

the Federal Aviation Administration (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: 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 Pratt & Whitney (PW) JT9D series

turbofan engines was published in the Federal Register on January 5,

1993 (58 FR 275). That action proposed to require a one-time

modification and overhaul of engine control system accessories to

prevent loss of engine compressor surge margin caused by the

deterioration of engine control system accessories, resulting in an

engine surge, and subsequent power loss or inflight engine shutdown.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

Several commenters question the need for the Federal Aviation

Administration (FAA) to issue an AD to improve the inflight engine

shutdown rate. The commenters cite section 39.1 of the Federal Aviation

Regulations (14 CFR 39.1) which requires that an AD be issued when an

unsafe condition exists in a product and is likely to exist or develop

in other products of the same design. The commenters further state that

an inflight engine shutdown on a multi-engine aircraft is not a safety

event but an operational restriction. The FAA does not concur. A

decrease in engine component reliability can pose a potentially unsafe

condition due to excessive inflight engine shutdown or surge rates.

After a review of the inflight engine shutdown and surge rates, the FAA

determined that certain populations of engines had a heightened

susceptibility to engine surge, but in many instances engine surge

events did not result in an actual inflight engine shutdown. For this

reason it is not sufficient to consider only inflight engine shutdown

rates. Other measures of overall engine reliability were also

considered, including component mean time between failure and

unscheduled removal rates. The requirements of this AD will help

preclude an incident where multiple engines on the same aircraft surge,

with or without a resultant inflight engine shutdown. The FAA has

received 12 reports of multiple engine surge events occurring during

critical phases of flight such as takeoff and climb-out; therefore, the

FAA has determined that an unsafe condition exists in a product that is

likely to exist or develop in other products of the same type design

and, accordingly, AD action is warranted.

One commenter states that the AD should be revised to require

incorporation of its provisions into an operator's existing FAA-

approved maintenance program, and that once incorporated into the

program, the AD would no longer be applicable. In addition, the

commenter suggests that the FAA Flight Standards District Offices

should administer the maintenance program. The FAA does not concur.

This AD will restore engine component reliability through incorporation

of certain design upgrades. These upgrades are necessary due to design

deficiencies of these components. This AD will not require periodic

maintenance, but only a one-time incorporation of certain service

bulletin (SB) upgrades. The FAA has, however, approved guidance titled,

``Guidance Criteria for Overhaul,'' which is incorporated as a separate

document into the latest revisions to the components' maintenance

manuals (MM). This document essentially provides for incorporation of

the SB's required by this AD, and also requires replacement of all

disposable packings and seals. The guidance provides suggested

maintenance intervals consistent with mean time between failure rates

for each component.

Several commenters request as an alternate means of compliance to

the modification required by PW SB No. 5889, that the FAA include in

this AD the tap and torque procedure described in the applicable engine

MM. The FAA does not concur. The tap and torque procedure has not

provided consistent fault-proof installation of engine main fuel pumps.

Revision 6 to PW SB No. 5889 introduces the improved QAD ring with the

necessary featural changes to alleviate the possibility of a

maintenance-induced error during the installation of an engine main

fuel pump. The FAA has incorporated Revision 6 into this AD.

One commenter states that rather than specifying ``Time Since Last

Overhaul'' the AD should read ``Time Since Limited Overhaul.'' The FAA

does not concur. The intervals specified in this AD are based on time

since a complete overhaul accomplished in accordance with the

components' MM. Previous revisions to the components' MM's did not

include a defined procedure for limited overhaul. Therefore, there is

no standard by which the FAA can evaluate whether the limited overhaul

procedures will accomplish the necessary design upgrades, and the

commenter does not include supporting data. The latest revisions to the

components' MM's, in the section titled ``Guidance Criteria for

Overhaul,'' defines what is required to perform a limited overhaul on

these components. If an operator satisfies these minimum criteria and

has data to demonstrate low inflight engine shutdown and surge rates,

the operator may apply for an alternate means of compliance with this

AD.

One commenter states that Hamilton Standard (HS) SB No. JFC68 73-19

should be referred to as a ``General'' SB in order to avoid confusion.

The FAA concurs and the final rule has been changed accordingly.

One commenter states that HS SB No. JFC68-3 73-150 requires

installation of components that are then replaced during accomplishment

of HS SB No. JFC68-3 73-151, and that HS SB No. JFC68-4 73-50 requires

installation of components that are then replaced during accomplishment

of HS SB No. JFC68-4 73-51. The commenter questions if it is acceptable

to install the most recent parts. The FAA concurs. The reliability

aspects of the requirements of HS SB No. JFC68-3 73-150 and HS SB No.

JFC68-3 73-151, and HS SB No. JFC68-4 73-50 and HS SB No. JFC68-4 73-

51, are similar. Accomplishment of HS SB No. JFC68-3 73-151 and HS SB

No. JFC68-4 73-51 in lieu of HS SB No. JFC68-3 73-150 and HS SB No.

JFC68-4 73-50, respectively, constitute an acceptable alternate means

of compliance for this AD.

One commenter states that HS MM 73-21-01, Revision 19, is dated

January 15, 1992, not June 15, 1991. The FAA concurs and has changed

the AD accordingly.

One commenter states that HS SB No. 75-49 requires components to be

reidentified to L47, not L30. The FAA concurs and has changed the AD

accordingly.

One commenter states that HS SB No. 75-27 has not been revised. The

FAA concurs and has changed the AD accordingly.

Several commenters address that HS Engine Vane Control (EVC)3-5 is

not applicable to the PW Model JT9D-7Q engine. The FAA concurs and has

changed the AD accordingly.

Several commenters state that TRW (formerly Argo-Tech) SB 73-43

does not include the PW Models JT9D-20 or -20J engines and question if

compliance will be required for these models. The FAA concurs. PW has

released SB No. 6127, dated September 10, 1993, that includes the PW

JT9D-20 and -20J engine models. This SB in turn makes reference to

Argo-Tech SB No. 73-43, which calls for modification of the PW Models

JT9D-20 and -20J fuel pump to accommodate the new QAD ring. The FAA has

changed the AD accordingly to include this SB.

One commenter states that soft-time requirements would be

preferable to hard time requirements for one-time overhaul and

modification of engine accessories. The FAA does not concur. Most

significantly, many operators have decided to postpone accessory

upgrades recommended by PW. The FAA's analysis indicates that

postponing these upgrades has a cumulative effect which has resulted in

a degradation of component reliability and loss of engine surge margin.

The FAA conducted an industry-wide survey and determined that there is

a direct correlation between accessory build standard and engine surge

rate. There is also a direct correlation between time between accessory

overhaul and loss of engine surge margin due to the degradation of the

accessories. The one-time overhaul and modifications required by this

AD have been established based on the FAA's review of inflight engine

shutdown and surge rates. The FAA recommends that following

accomplishment of the one-time overhaul and modifications required by

this AD, all operators establish a soft-time overhaul interval for

maintenance of engine accessories in accordance with the ``Guidance

Criteria for Overhaul'' incorporated into the components' MM's.

One commenter states that the AD does not clearly state that the

overhaul requirement for the accessories is a one-time overhaul. The

FAA concurs and has changed the AD accordingly to emphasize that this

overhaul is a one-time requirement only.

One commenter questions why the threshold for overhaul is 12,000

hours time in service (TIS) for the EVC and 10,000 hours for the Engine

Vane and Bleed Control (EVBC). The commenter states that the EVBC is

more reliable than the EVC. The FAA does not concur. The fleet survey

provided data on mean time failure rates from which the overhaul

intervals specified in this AD were derived. Based on this review, the

FAA has determined that maximum time between overhauls should be 12,000

hours TIS for EVC's and 10,000 hours TIS for EVBC's. If an operator can

provide enhanced reliability data through improved maintenance

procedures, the FAA may consider this data as an acceptable alternate

means of compliance for this AD.

One commenter states that the AD does not account for operators'

responsiveness to vendor recommended modifications and that the AD

requires immediate incorporation of SB's assigned a low to medium

priority by the Original Equipment Manufacturer. The FAA does not

concur. The FAA conducted a fleet survey which showed that most

operators lacked adequate accessory build standards and that this

inadequacy had a direct effect on engine surge and inflight shutdown

rates. Furthermore, those operators that have incorporated the

modifications required by this AD, satisfy the intent of this AD, and

no further action is required. Regarding the SB's priority, the FAA has

determined that all the required SB's have a significant effect on

engine surge margin regardless of SB category.

One commenter states that the AD is contradictory about previous

accomplishment. The commenter references paragraphs (a)(3), (a)(4),

(b)(3), (b)(4), (c)(3), (c)(4) of the AD. The FAA does not concur.

These paragraphs state that previous accomplishment for overhaul is

based on Time Since Overhaul, and extend credit to those operators who

have already accomplished overhaul provided they are within the

prescribed intervals specified by the AD. As to the paragraphs

requiring modifications, if the operator has implemented all the SB's

referenced in the AD, then the operator has accomplished previously the

modification requirements of this AD.

One commenter states that the AD will require all their components

to be overhauled and modified by the calendar end date of January 31,

1995, based on the operator's maintenance program, which will require

overhaul of all components disassembled to the extent required for

these modifications. The FAA does not concur. An individual operator's

FAA-approved maintenance program may dictate that the components must

be overhauled by a certain date, but for other operators there may be

instances where certain components may remain in service past the

calendar-end date. In the NPRM, paragraphs (a)(3), (b)(3), (c)(3), and

(d)(3) stated that certain components must be overhauled prior to a

certain TIS, or January 31, 1995, whichever occurs later. Since

publication of that NPRM, the FAA has determined to extend the

compliance end date to July 31, 1995, due to the time required to

adequately address all comments and publish the final rule.

One commenter states that the AD would require, based on current

aircraft utilization, the majority of Fuel Control Units to be modified

within 250 days after the effective date of this AD. The FAA concurs.

The FAA has determined that the drawdown intervals defined in this AD

constitute an acceptable minimum standard of airworthiness for the PW

JT9D fuel control.

One commenter states that monitoring of engine condition is not

taken into account as a compliance option in the AD. The FAA concurs.

However, this data could be used as substantiation for an alternate

means of compliance.

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.

The FAA estimates that approximately 300 engines of the affected

design installed on aircraft of U.S. registry will be affected by this

AD, that it will take approximately 30 work hours per engine to

accomplish the required actions, and that the average labor rate is $55

per work hour. Required parts will cost approximately $13,100 per

engine. Based on these figures, the total cost impact of the AD on U.S.

operators is estimated to be $4,425,000.

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 activity'' under Executive Order 12866;

(2) is not a ``significant rule'' under DOT Regulatory Policies and

Procedures (44 FR 11034, February 26, 1979); and (3) will not have a

significant economic impact, positive or negative, on a substantial

number of small entities under the criteria of the Regulatory

Flexibility Act. A final evaluation has been prepared for this action

and it is contained in the Rules Docket. A copy of it may be obtained

from the Rules Docket at the location provided under the caption

ADDRESSES.

List of Subjects in 14 CFR Part 39

Air Transportation, Aircraft, Aviation safety, Incorporation by

reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration amends part 39 of

the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 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 adding the following new

airworthiness directive:

94-15-16 Pratt & Whitney: Amendment 39-8987. Docket 91-ANE-51.

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

7AH, -7H, -7F, -7J, -20, -20J, -59A, -70A, and -7Q turbofan engines

installed on but not limited to Boeing 747 series, McDonnell Douglas

DC-10 series, and Airbus A300 series aircraft.

Compliance: Required as indicated, unless accomplished

previously.

To prevent the loss of engine compressor surge margin caused by

the deterioration of engine control system accessories, resulting in

an engine surge, and subsequent power loss or inflight engine

shutdown, accomplish the following:

(a) Perform a one-time overhaul and modification of the main

fuel controls as follows:

(1) For main fuel controls with either 12,000 hours or more time

since overhaul (TSO) on the effective date of this AD or with an

undocumented TSO, or for those main fuel controls that have never

been overhauled and have either 12,000 hours or more time since new

(TSN) on the effective date of this AD or an undocumented TSN,

overhaul in accordance with the applicable Hamilton Standard (HS)

Maintenance Manual (MM) listed in Table 1 of this AD, and modify in

accordance with the applicable HS Service Bulletins (SB) listed in

Table 2 of this AD, at the earliest of: the next shop visit; 3,000

hours time in service (TIS) after the effective date of this AD; or

July 31, 1995.

(2) For main fuel controls with more than 10,000 hours but less

than 12,000 hours TSO, or TSN if never overhauled, on the effective

date of this AD, overhaul in accordance with the applicable HS MM

listed in Table 1 of this AD, and modify in accordance with the

applicable HS SB's listed in Table 2 of this AD, not later than

3,000 hours TIS after the effective date of this AD, or by July 31,

1995, whichever occurs first.

(3) For main fuel controls with 10,000 hours or less TSO, or TSN

if never overhauled, on the effective date of this AD, overhaul in

accordance with the applicable HS MM listed in Table 1 of this AD,

not later than 12,000 hours TSO or TSN, or by July 31, 1995,

whichever occurs later.

(4) For main fuel controls with 10,000 hours or less TSO, or TSN

if never overhauled, on the effective date of this AD, modify in

accordance with the applicable HS SB's listed in Table 2 of this AD,

not later than 12,000 hours TSO or TSN, or by July 31, 1995,

whichever occurs first.

Table 1.--Engine Accessory Overhaul Reference List

----------------------------------------------------------------------------------------------------------------

Accessory description Hamilton standard maint. manual No. Temporary revision No.

----------------------------------------------------------------------------------------------------------------

Main fuel controls:

JFC68-3...................... 73-21-01, Revision 19, dated January 15, 73-54, dated June 15, 1992.

1992.

JFC68-4...................... 73-21-02, Revision 10, dated January 15, 73-31, dated June 15, 1992.

1992.

JFC68-6...................... 73-21-03, Revision 10, dated September 15, N/A.

1992.

Engine vane controls:

EVC3-2 and EVC3-4............ 75-31-01, Revision 20, dated July 1, 1992.. 75-26, dated July 15, 1993.

EVC3-5....................... 75-32-01, Revision 9, dated June 15, 1986.. 75-5, dated July 1, 1992.

Engine vane and bleed controls:

GTA9-1 and GTA9-2............ 75-34-01, Revision 11, dated August 15, N/A.

1992.

----------------------------------------------------------------------------------------------------------------

Table 2.--Hamilton Standard Main Fuel Control Unit (FCU) Service

Bulletin Incorporation List

------------------------------------------------------------------------

FCU model JFC68-3, JT9D- FCU model JFC68-4, JT9D- FCU model JFC68-6,

3A, -7 series engines 20, -20J series engines JT9D-59A, -70A, -7Q

series engines

------------------------------------------------------------------------

73-150 (L160), Revision 73-50 (L94), Revision 73-23 (L30), Revision

1, dated 8-15-91. 2, dated 12-13-93. 1, dated 8-15-91.

73-139 (L152), 73-42 (L87), Original, N/A.

Original, dated 2-27- dated 2-27-76.

76.

73-129 (L143), Revision 73-36 (L81), Revision 73-3 (L14), Original,

3, dated 7-1-77. 3, dated 7-1-77. dated 1-7-77.

73-128 (L142), Revision 73-35 (L80), Revision N/A.

1, dated 8-29-75. 1, dated 8-29-75.

73-127 (L141), Revision 73-33 (L79), Revision N/A.

2, dated 10-31-78. 2, dated 10-31-78.

73-122 (L137), Revision 73-29 (L75), Revision N/A.

1, dated 9-27-77. 1, dated 9-27-77.

73-121 (L136), 73-28 (L74), Original, N/A.

Original, dated 5-29- dated 5-29-74.

74.

73-117 (L133), Revision 73-24 (L71), Revision N/A.

3, dated 10-15-74. 2, dated 10-15-74.

73-111 (L128), Revision 73-21 (L69), Revision N/A.

1, dated 10-27-76. 1, dated 10-27-76.

N/A.................... N/A.................... 73-27 (L33), Revision

1, dated 9-27-82.

73-19, General, 73-19, General, 73-19, General,

Revision 1, dated 9-20- Revision 1, dated 9-20- Revision 1, dated 9-

86. 86. 20-86.

------------------------------------------------------------------------

(b) Perform a one-time overhaul and modification of engine vane

controls as follows:

(1) For engine vane controls with either 12,000 hours or more

TSO on the effective date of this AD or with an undocumented TSO, or

for those engine vane controls that have never been overhauled and

have either 12,000 hours or more TSN on the effective date of this

AD or an undocumented TSN, overhaul in accordance with the

applicable HS MM listed in Table 1 of this AD, and modify in

accordance with the applicable HS SB's listed in Table 3 of this AD,

at the earliest of: the next shop visit; 3,000 hours time in service

(TIS) after the effective date of this AD; or July 31, 1995.

(2) For engine vane controls with more than 10,000 hours but

less than 12,000 hours TSO, or TSN if never overhauled, on the

effective date of this AD, overhaul in accordance with the

applicable HS MM listed in Table 1 of this AD, and modify in

accordance with the applicable HS SB's listed in Table 3 of this AD,

not later than 3,000 hours TIS after the effective date of this AD,

or by July 31, 1995, whichever occurs first.

(3) For engine vane controls with 10,000 hours or less TSO, or

TSN if never overhauled, on the effective date of this AD, overhaul

in accordance with the applicable HS MM listed in Table 1 of this

AD, not later than 12,000 hours TSO or TSN, or by July 31, 1995,

whichever occurs later.

(4) For engine vane controls with 10,000 hours or less TSO, or

TSN if never overhauled, on the effective date of this AD, modify in

accordance with the applicable HS SB's listed in Table 3 of this AD

not later than 12,000 hours TSO or TSN, or by July 31, 1995,

whichever occurs first.

Table 3.--Hamilton Standard Engine Vane Control (EVC) Recommended

Service Bulletin Incorporation List

------------------------------------------------------------------------

EVC3-2 model JT9D-3A, - EVC3-4 model JT9D-20, - EVC3-5 model JT9D-59A,

7 series engines 20J series engines -70A series engines

------------------------------------------------------------------------

75-48 (L46), Revision 75-27 (L33), Revision 75-9 (L10), Revision

1, dated 8-6-91. 1, dated 8-19-91. 1, dated 8-21-91.

75-45 (L43), Revision 75-24 (L30), Revision 75-6 (L7), Revision 1,

1, dated 8-16-91. 1, dated 8-19-91. dated 8-20-91.

75-43 (L42), Revision 75-23 (L29), Original, 75-5, Original, dated

2, dated 4-25-91. dated 3-31-88. 3-31-88.

75-41 (L41), Revision 75-22 (L28), Revision 75-4 (L5), Revision 2,

3, dated 8-16-91. 1, dated 8-19-91. dated 8-20-91.

75-42, Revision 1, N/A.................... N/A.

dated 8-16-91.

75-37 (L40), Revision 75-19 (L27), Revision 75-2 (L4), Revision 1,

3, dated 8-16-91. 3, dated 8-19-91. dated 11-8-79.

75-36, Revision 1, 75-20, Original dated 9- N/A.

dated 9-1-78. 1-78.

75-31 (L35), Original, 75-14 (L22), Original, N/A.

dated 5-23-75. dated 5-23-75.

75-28 (L33), Original, 75-11 (L20), Original, N/A.

dated 1-3-75. dated 1-3-75.

75-27 (L32), Original, 75-10 (L19), Original, N/A.

dated 9-10-74. dated 9-10-74.

75-49 (L47), Original, 75-28 (L34), Original, N/A.

dated 5-13-91. dated 5-13-91.

------------------------------------------------------------------------

(c) Perform a one-time overhaul and modification of engine vane

and bleed controls as follows:

(1) For engine vane and bleed controls with either 10,000 hours

or more TSO on the effective date of this AD or with an undocumented

TSO, or for those engine vane and bleed controls that have never

been overhauled and have either 10,000 hours or more TSN on the

effective date of this AD or an undocumented TSN, overhaul in

accordance with the applicable HS MM listed in Table 1 of this AD,

and modify in accordance with the applicable HS SB's listed in Table

4 of this AD, at the earliest of: the next shop visit; 3,000 hours

TIS after the effective date of this AD; or July 31, 1995.

(2) For engine vane and bleed controls with more than 8,000

hours but less than 10,000 hours TSO, or TSN if never overhauled, on

the effective date of this AD, overhaul in accordance with the

applicable HS MM listed in Table 1 of this AD, and modify in

accordance with the applicable HS SB's listed in Table 4 of this AD,

not later than 3,000 hours TIS after the effective date of this AD,

or by July 31, 1995, whichever occurs first.

(3) For engine vane and bleed controls with 8,000 hours or less

TSO, or TSN if never overhauled, on the effective date of this AD,

overhaul in accordance with the applicable HS MM listed in Table 1

of this AD, not later than 10,000 hours TSO or TSN, or by July 31,

1995, whichever occurs later.

(4) For engine vane and bleed controls with 8,000 hours or less

TSO, or TSN if never overhauled, on the effective date of this AD,

modify in accordance with the applicable HS SB's listed in Table 4

of this AD, not later than 10,000 hours TSO or TSN, or by July 31,

1995, whichever occurs first.

Table 4.--Hamilton Standard Engine Vane Bleed Control (EVBC) (GTA9)

Required Service Bulletin Incorporation List

JT9D-59A, -70A, -7Q, Series Engines

------------------------------------------------------------------------

Service bulletin Revision Date

------------------------------------------------------------------------

GTA9-75-26 (L21).............................. 1............ 8-21-91

GTA9-75-19 (L14).............................. 1............ 8-21-91

GTA9-75-17 (L13).............................. Original..... 3-31-88

GTA9-75-16 (L12).............................. Original..... 3-20-88

GTA9-75-9 (L8)................................ 3............ 8-15-92

------------------------------------------------------------------------

(d) Perform a one-time overhaul and modification of main fuel

gear pumps as follows:

(1) For main fuel gear pumps with either 8,000 hours or more TSO

on the effective date of this AD or with an undocumented TSO, or for

those main fuel gear pumps that have never been overhauled and have

either 8,000 hours or more TSN on the effective date of this AD or

an undocumented TSN, overhaul in accordance with either Argo-Tech

(AT) Overhaul Manual (OM) No. 73-11-01 or No. 73-11-02, as

applicable, and modify in accordance with the applicable TRW, AT,

and Pratt & Whitney (PW) SB's listed in Table 5 of this AD, at the

earliest of: the next shop visit; 3,000 hours TIS after the

effective date of this AD; or July 31, 1995.

(2) For main fuel gear pumps with more than 6,000 hours but less

than 8,000 hours TSO, or TSN if never overhauled, on the effective

date of this AD, overhaul in accordance with either AT OM No. 73-11-

01 or No. 73-11-02, as applicable, and modify in accordance with the

applicable TRW, AT, and PW SB's listed in Table 5 of this AD, not

later than 3,000 hours TIS after the effective date of this AD, or

by July 31, 1995, whichever occurs first.

(3) For main fuel gear pumps with 6,000 hours or less TSO, or

TSN if never overhauled, on the effective date of this AD, overhaul

in accordance with either AT OM No. 73-11-01 or No. 73-11-02, as

applicable, not later than 8,000 hours TSO or TSN, or by July 31,

1995, whichever occurs later.

(4) For main fuel gear pumps with 6,000 hours or less TSO, or

TSN if never overhauled, on the effective date of this AD, modify in

accordance with the applicable TRW, AT and PW SB's listed in Table 5

of this AD, not later than 8,000 hours TSO or TSN, or by July 31,

1995, whichever occurs first.

Table 5.--TRW, AT, and PW Main Fuel Gear Pump Required Service Bulletin

Incorporation List

------------------------------------------------------------------------

JT9D-3A, -7, -20, -20J series

engines JT9D-59A, -70A, -7Q series engines

------------------------------------------------------------------------

TRW 73-28 (-26), Revision 2, dated N/A.

4-15-77.

TRW 73-29 (-27), Revision 1, dated TRW 73-5 (-9), Original, dated 4-30-

9-1-80. 81.

TRW 73-31 (-29), Original, dated 9- N/A.

1-79.

TRW 73-32 (-30), Revision 3, dated N/A.

4-1-85.

AT 73-36 (-32), Revision 1, dated N/A.

10-1-88.

AT 73-43, Original, dated 12-15-89. N/A.

N/A................................ TRW 73-8 (-12) Original, dated 9-1-

82.

PW 5889, Revision 6, dated 12-20-93 N/A.

PW 6127, Original, dated 9-10-93... N/A.

------------------------------------------------------------------------

(e) For the purpose of this AD, a shop visit is defined as an

engine removal where engine maintenance entails separation of pairs

of mating engine flanges or the removal of a disk, hub, or spool.

(f) 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 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.

(g) 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.

(h) The overhauls and modifications shall be done in accordance

with the following service bulletins:

----------------------------------------------------------------------------------------------------------------

SB No. Pages Revision Date

----------------------------------------------------------------------------------------------------------------

TRW SB No. 73-28........................ 1......................... 2......................... 4-15-77

2......................... 1......................... 1-15-77

3......................... 2......................... 4-15-77

4......................... 1......................... 1-15-77

4A........................ 2......................... 4-15-77

5-7....................... 1......................... 1-15-77

8......................... 2......................... 4-15-77

9-10...................... 1......................... 1-15-77

Total Pages: 10

TRW SB No. 73-29........................ 1......................... 1......................... 9-1-80

2......................... Original.................. 3-1-79

3......................... 1......................... 9-1-80

4......................... Original.................. 3-1-79

Total Pages: 4

TRW SB No. 73-31........................ 1-3....................... Original.................. 9-1-79

Total Pages: 3

TRW SB No. 73-32........................ 1-3....................... 3......................... 4-1-85

4......................... 1......................... 6-15-81

Total Pages: 4

Argo-Tech SB No. 73-36.................. 1-3....................... 1......................... 10-1-88

Total Pages: 3

Argo-Tech SB No. 73-43.................. 1......................... Original.................. 12-15-89

Total Pages: 4

TRW SB No. 73-8......................... 1-4....................... Original.................. 9-1-82

Total Pages: 4

TRW SB No. 73-5......................... 1-3....................... Original.................. 4-30-81

Total Pages: 3

PW SB No. 5889.......................... 1......................... 6......................... 12-20-93

2......................... 5......................... 9-21-92

3-5....................... Original.................. 12-21-89

6......................... 4......................... 5-7-92

7-8....................... Original.................. 12-21-89

9-11...................... 3......................... 10-4-91

12........................ 1......................... 1-24-90

13........................ 4......................... 5-7-92

14-18..................... Original.................. 12-21-89

19........................ 6......................... 12-20-93

20........................ 4......................... 5-7-92

Total Pages: 20

PW SB No. 6127.......................... 1-14...................... Original.................. 9-10-93

Total Pages: 14

HS SB No. GTA9-75-26.................... 1-3....................... 1......................... 8-21-91

4-6....................... Original.................. 5-9-90

Total Pages: 6

HS SB No. GTA9-75-19.................... 1-4....................... 1......................... 8-21-91

Total Pages: 4

HS SB No. GTA9-75-17.................... 1-3....................... Original.................. 3-31-88

Total Pages: 3

HS SB No. GTA9-75-16.................... 1-3....................... Original.................. 3-20-88

Total Pages: 3

HS SB No. GTA9-75-9..................... 1-2....................... 3......................... 8-15-92

3-7....................... 2......................... 8-21-91

Total Pages: 7

HS SB No. 75-9.......................... 1-2....................... 1......................... 8-20-91

2A/2B..................... 1......................... 8-20-91

3-6....................... Original.................. 5-9-90

Total Pages: 7

HS SB No. 75-6.......................... 1-3....................... 1......................... 8-20-91

Total Pages: 3

HS SB No. 75-5.......................... 1-3....................... Original.................. 3-31-88

Total Pages: 3

HS SB No. 75-4.......................... 1-3....................... 2......................... 8-20-91

4-7....................... 1......................... 10-15-84

Total Pages: 7

HS SB No. 75-2.......................... 1-7....................... 1......................... 11-8-79

Total Pages: 7

HS SB No. 75-28......................... 1-4....................... Original.................. 5-13-91

Total Pages: 4

HS SB No. 75-27......................... 1-6....................... Original.................. 8-19-91

Total Pages: 5

HS SB No. 75-24......................... 1-3....................... 1......................... 8-19-91

Total Pages: 3

HS SB No. 75-23......................... 1-3....................... Original.................. 3-31-88

Total Pages: 3

HS SB No. 75-22......................... 1-2....................... 1......................... 8-19-91

2A/2B..................... 1......................... 8-19-91

3-6....................... Original.................. 4-30-84

Total Pages: 6

HS SB No. 75-19......................... 1-2....................... 3......................... 8-19-91

2A/2B..................... 3......................... 8-19-91

3-7....................... 2......................... 11-8-79

Total Pages: 7

HS SB No. 75-20......................... 1-3....................... Original.................. 9-1-78

Total Pages: 3

HS SB No. 75-14......................... 1-4....................... Original.................. 5-23-75

Total Pages: 4

HS SB No. 75-11......................... 1-3....................... Original.................. 1-3-75

Total Pages: 3

HS SB No. 75-10......................... 1-5....................... Original.................. 9-10-74

Total Pages: 5

HS SB No. 75-49......................... 1-4....................... Original.................. 5-13-91

Total Pages: 4

HS SB No. 75-48......................... 1-2....................... 1......................... 8-16-91

3-6....................... Original.................. 5-9-90

Total Pages: 6

HS SB No. 75-45......................... 1-4....................... 1......................... 8-16-91

Total Pages: 4

HS SB No. 75-43......................... 1-4....................... 2......................... 4-25-91

Total Pages: 4

HS SB No. 75-42......................... 1-2....................... 1......................... 8-16-91

Total Pages: 2

HS SB No. 75-41......................... 1-3....................... 3......................... 8-16-91

4-7....................... 2......................... 12-20-90

Total Pages: 7

HS SB No. 75-37......................... 1-2....................... 3......................... 8-16-91

2A/2B..................... 3......................... 8-16-91

3-7....................... 2......................... 12-12-79

Total Pages: 8

HS SB No. 75-36......................... 1-3....................... Revision 1................ 9-1-78

Total Pages: 3

HS SB No. 75-31......................... 1-4....................... Original.................. 5-23-75

Total Pages: 4

HS SB No. 75-28......................... 1-3....................... Original.................. 1-3-75

Total Pages: 3

HS SB No. 75-27......................... 1-5....................... Original.................. 9-10-74

Total Pages: 6

HS General SB No. 73-19................. 1-3....................... 1......................... 9-20-86

4......................... Original.................. 12-15-84

5-6....................... 1......................... 9-20-86

Total Pages: 6

HS SB No. 73-27......................... 1-2....................... 1......................... 9-27-82

3-4....................... Original.................. 2-10-82

5......................... 1......................... 9-27-82

Total Pages: 5

HS SB No. 73-23......................... 1-2....................... 1......................... 8-15-91

2A/2B..................... 1......................... 8-15-91

3-5....................... Original.................. 4-30-81

Total Pages: 5

HS SB No. 73-3.......................... 1-5....................... Original.................. 1-7-77

Total Pages: 5

HS SB No. 73-50......................... 1-2....................... 2......................... 12-13-92

2A/2B..................... 1......................... 8-15-91

3......................... Original.................. 4-30-81

4-5....................... 2......................... 12-13-92

Total Pages: 5

HS SB No. 73-42......................... 1-3....................... Original.................. 2-27-76

Total Pages: 3

HS SB No. 73-36......................... 1......................... 3......................... 7-1-77

2......................... 1......................... 11-5-76

3......................... 3......................... 7-1-77

4......................... 2......................... 4-20-77

5......................... 3......................... 7-1-77

Total Pages: 5

HS SB No. 73-35......................... 1-2....................... 1......................... 8-29-75

3-4....................... Original.................. 4-22-75

5-6....................... 1......................... 8-29-75

7......................... Original.................. 4-22-75

Total Pages: 7

HS SB No. 73-33......................... 1......................... 2......................... 10-31-78

2......................... 1......................... 3-5-76

3-4....................... 2......................... 10-31-78

5......................... 1......................... 3-5-76

Total Pages: 5

HS SB No. 73-29......................... 1-3....................... 1......................... 9-27-77

4-5....................... Original.................. 2-7-75

6-7....................... 1......................... 9-27-77

Total Pages: 7

HS SB No. 73-28......................... 1-5....................... Original.................. 5-29-74

Total Pages: 5

HS SB No. 73-24......................... 1-2....................... 2......................... 10-15-74

3-5....................... Original.................. 11-16-73

Total Pages: 5

HS SB No. 73-21......................... 1-8....................... 1......................... 10-27-76

Total Pages: 8

HS SB No. 73-150........................ 1-2B...................... 1......................... 8-15-91

3-5....................... Original.................. 4-30-81

Total Pages: 5

HS SB No. 73-139........................ 1-3....................... Original.................. 2-27-76

Total Pages: 3

HS SB No. 73-129........................ 1......................... 3......................... 7-1-77

2......................... Original.................. 2-21-75

3......................... 3......................... 7-1-77

4......................... 2......................... 4-20-77

5......................... 3......................... 7-1-77

Total Pages: 5

HS SB No. 73-128........................ 1-3....................... 1......................... 8-29-75

4......................... Original.................. 4-22-75

5......................... 1......................... 8-29-75

6-7....................... Original.................. 4-22-75

Total Pages: 7

HS SB No. 73-127........................ 1......................... 2......................... 10-31-78

2......................... Original.................. 3-12-75

3-6....................... 2......................... 10-31-78

Total Pages: 6

HS SB No. 73-122........................ 1......................... 1......................... 9-27-77

2......................... Original.................. 2-7-75

3......................... 1......................... 9-27-77

4-5....................... Original.................. 2-7-75

6-7....................... 1......................... 9-27-77

Total Pages: 7

HS SB No. 73-121........................ 1-5....................... Original.................. 5-29-74

Total Pages: 5

HS SB No. 73-117........................ 1-2....................... 3......................... 10-15-74

3-5....................... Original.................. 11-16-73

Total Pages: 5

HS SB No. 73-111........................ 1-8....................... 1......................... 10-27-76

Total Pages: 8

----------------------------------------------------------------------------------------------------------------

This incorporation by reference was approved by the Director of

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

part 51. Copies may be obtained from Pratt & Whitney, Technical

Publications Department, M/S 132-30, 400 Main Street, East Hartford,

CT 06108. 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.

(i) This amendment becomes effective on October 14, 1994.

Issued in Burlington, Massachusetts, on July 28, 1994.

Jay J. Pardee,

Manager, Engine and Propeller Directorate, Aircraft Certification

Service.

[FR Doc. 94-19354 Filed 8-12-94; 8:45 am]

BILLING CODE 4910-13-P