[Federal Register Volume 59, Number 156 (Monday, August 15, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-19354]


[[Page Unknown]]

[Federal Register: August 15, 1994]


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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