[Federal Register Volume 59, Number 135 (Friday, July 15, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-17068]


[[Page Unknown]]

[Federal Register: July 15, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 92-ANE-23; Amendment 39-8916; AD 94-10-09]

 

Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan 
Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to Pratt & Whitney (PW) JT9D series turbofan engines, that 
requires initial and repetitive inspections of the sixth stage low 
pressure turbine (LPT) inner airseal, and modification of the sixth 
stage LPT inner airseal to reduce the potential for two failure modes. 
This amendment is prompted by reports of thermal mechanical 
interference inducing low cycle fatigue (LCF) cracks at two locations 
on the sixth stage LPT inner airseal, resulting in five uncontained 
failures. The actions specified by this AD are intended to prevent an 
uncontained failure of the sixth stage LPT inner airseal, which can 
result in damage to the aircraft.

DATES: Effective September 13, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of September 13, 1994.

ADDRESSES: The service information referenced in this AD may be 
obtained from Pratt & Whitney, Publication 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 June 7, 1993 
(58 FR 31920). That action proposed to require initial and repetitive 
on-wing borescope or eddy current inspections of the sixth stage low 
pressure turbine (LPT) inner airseal rear retaining wing, initial and 
repetitive on-wing eddy current inspections of the sixth stage LPT 
inner airseal knife edges, rework of the sixth stage inner airseal 
knife edges, which is a terminating action to the repetitive knife edge 
inspections, and rework of the sixth stage LPT inner airseal rear 
retaining wing, in accordance with the following service bulletins 
(SB's):
    PW SB No. 5978, Revision 3, dated May 20, 1992; PW SB No. 5979, 
Revision 2, dated April 28, 1992; PW SB No. 5847, Revision 2, dated 
October 31, 1990; and PW SB No. 5745, Revision 2, dated October 24, 
1990.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comment received.
    The comment requests the inclusion of PW SB No. 6054, Revision 1, 
dated April 24, 1992, in the proposed rule. This SB describes 
installation of a new 6th stage LPT inner airseal as a terminating 
action to the required inspections and rework. The FAA concurs. This 
final rule includes the option of installing a new, improved 6th stage 
LPT inner airseal, in accordance with PW SB No. 6054, Revision 1, dated 
April 24, 1992, as a terminating action to the inspections and rework 
required by this AD.
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes described 
previously. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.
    There are approximately 602 Pratt & Whitney Model JT9D-59A, -70A, -
7Q, and -7Q3 turbofan engines of the affected design in the worldwide 
fleet. The FAA estimates that 121 engines installed on aircraft of U.S. 
Registry would be affected by this proposed AD, that it would take 
approximately 153 work hours per engine to accomplish the required 
actions, and that the average labor rate is $55 per work hour. The FAA 
estimates that approximately 50% of affected engines have already 
incorporated the knife edge modification described in PW SB No. 5847, 
Revision 2, dated October 31, 1990, and that approximately 5% of 
affected engines have already incorporated the retaining wing 
modification described in PW SB No. 5745, Revision 2, dated October 24, 
1990. The average utilization of these engines is 2 cycles per day, and 
the program duration is estimated to be 20 years. Based on these 
figures, the total cost impact of the proposed AD on U.S. operators is 
estimated to be $981,479 over a 20 year period.
    The regulations adopted herein will not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under 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:

94-10-09 Pratt & Whitney: Amendment 39-8916. Docket 92-ANE-23.

    Applicability: Pratt & Whitney (PW) Model JT9D-59A, -70A, -7Q, 
and -7Q3 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 an uncontained failure of the sixth stage low 
pressure turbine (LPT) inner airseal, which can result in damage to 
the aircraft, accomplish the following:
    (a) For engines that have not had the sixth stage LPT inner 
airseal reworked in accordance with PW Service Bulletin (SB) No. 
5847, Revision 2, dated October 31, 1990, eddy current inspect the 
sixth stage LPT inner airseal knife edges for cracks in accordance 
with the Accomplishment Instructions of PW SB No. 5979, Revision 2, 
dated April 28, 1992, and remove cracked sixth stage LPT inner 
airseals, as follows:
    (1) For sixth stage LPT inner airseals identified by Part Number 
(P/N) in PW SB No. 5979, Revision 2, dated April 28, 1992, with 
greater than 2,500 cycles since new (CSN) on the effective date of 
this AD, accomplish an initial eddy current inspection prior to 
accumulating more than 250 cycles in service (CIS) after the 
effective date of this AD, or within 1,000 CIS since the last in-
shop fluorescent penetrant inspection, whichever occurs later.
    (2) For sixth stage LPT inner airseals listed by P/N in PW SB 
No. 5979, Revision 2, dated April 28, 1992, with less than or equal 
to 2,500 CSN on the effective date of this AD, accomplish an initial 
eddy current inspection prior to accumulating more than 2,750 CSN, 
or within 1,000 CIS since the last in-shop fluorescent penetrant 
inspection, whichever occurs later.
    (3) For sixth stage LPT inner airseals that meet the continue in 
service criteria described in PW SB No. 5979, Revision 2, dated 
April 28, 1992, thereafter eddy current inspect the sixth stage LPT 
inner airseal knife edges for cracks in accordance with the 
Accomplishment Instructions of PW SB No. 5979, Revision 2, dated 
April 28, 1992, at intervals not to exceed 1,000 CIS since the last 
eddy current inspection in accordance with this AD.
    (4) Remove cracked sixth stage LPT inner airseals that do not 
meet the continue in service criteria described in PW SB No. 5979, 
Revision 2, dated April 28, 1992, and replace with a new, or 
serviceable sixth stage LPT inner airseal that has been reworked in 
accordance with paragraph (b) of this AD.
    (b) Rework the sixth stage LPT inner airseal knife edge 
diameters in accordance with the Accomplishment Instructions of PW 
SB 5847, Revision 2, dated October 31, 1990, at the next shop visit 
after the effective date of this AD where the LPT module is 
accessible, or not later than January 1, 1996, whichever occurs 
first. Accomplishment of this rework constitutes a terminating 
action to the initial and repetitive inspection requirements of 
paragraph (a)(1), (a)(2), and (a)(3) of this AD.
    (c) Eddy current or borescope inspect sixth stage LPT inner 
airseal rear retaining wings for cracks in accordance with the 
Accomplishment Instructions of PW SB No. 5978, Revision 3, dated May 
20, 1992, and remove cracked sixth stage LPT inner airseals, as 
follows:
    (1) For sixth stage LPT inner airseals identified by P/N in PW 
SB No. 5978, Revision 3, dated May 20, 1992, with greater than 500 
CSN on the effective date of this AD, accomplish an initial eddy 
current or borescope inspection prior to accumulating more than 250 
CIS after the effective date of this AD, or 500 CIS since the last 
in-shop fluorescent penetrant inspection, whichever occurs later.
    (2) For sixth stage LPT inner airseals identified by P/N in PW 
SB No. 5978, Revision 3, dated May 20, 1992, with less than or equal 
to 500 CSN on the effective date of this AD, accomplish an initial 
eddy current or borescope inspection prior to accumulating 750 CSN, 
or 500 CIS since the last in-shop fluorescent penetrant inspection, 
whichever occurs later.
    (3) For sixth stage LPT inner airseals that meet the continue in 
service criteria described in PW SB No. 5978, Revision 3, dated May 
20, 1992, thereafter eddy current or borescope inspect the sixth 
stage LPT inner airseal retaining wing for cracks at intervals 
specified in accordance with the Accomplishment Instructions of PW 
SB No. 5978, Revision 3, dated May 20, 1992.
    (4) Remove cracked sixth stage LPT inner airseals that do not 
meet the continue in service criteria described in PW SB No. 5979, 
Revision 2, dated April 28, 1992, and replace with a new, or 
serviceable sixth stage LPT inner airseal that has been reworked in 
accordance with paragraph (b) of this AD.
    (b) Rework the sixth stage LPT inner airseal knife edge 
diameters in accordance with the Accomplishment Instructions of PW 
SB 5847, Revision 2, dated October 31, 1990, at the next shop visit 
after the effective date of this AD where the LPT module is 
accessible, or not later than January 1, 1996, whichever occurs 
first. Accomplishment of this rework constitutes a terminating 
action to the initial and repetitive inspection requirements of 
paragraph (a)(1), (a)(2), and (a)(3) of this AD.
    (c) Eddy current or borescope inspect sixth stage LPT inner 
airseal rear retaining wings for cracks in accordance with the 
Accomplishment Instructions of PW SB No. 5978, Revision 3, dated May 
20, 1992, and remove cracked sixth stage LPT inner airseals, as 
follows: (1) For sixth stage LPT inner airseals identified by P/N in 
PW SB No. 5978, Revision 3, dated May 20, 1992, with greater than 
500 CSN on the effective date of this AD, accomplish an initial eddy 
current or borescope inspection prior to accumulating more than 250 
CIS after the effective date of this AD, or 500 CIS since the last 
in-shop fluorescent penetrant inspection, whichever occurs later. 
(2) For sixth stage LPT inner airseals identified by P/N in PW SB 
No. 5978, Revision 3, dated May 20, 1992, with less than or equal to 
500 CSN on the effective date of this AD, accomplish an initial eddy 
current or borescope inspection prior to accumulating 750 CSN, or 
500 CIS since the last in-shop fluorescent penetrant inspection, 
whichever occurs later. (3) For sixth stage LPT inner airseals that 
meet the continue in service criteria described in PW SB No. 5978, 
Revision 3, dated May 20, 1992, thereafter, eddy current or 
borescope inspect the sixth stage LPT inner airseal retaining wing 
for cracks at intervals specified in accordance with the 
Accomplishment Instructions of PW SB No. 5978, Revision 3, dated May 
20, 1992. (4) Remove cracked sixth stage LPT inner airseals that do 
not meet the continue in service criteria described in PW SB No. 
5978, Revision 3, dated May 20, 1992, and replace with a new, or 
serviceable sixth stage LPT inner airseal that has been reworked in 
accordance with paragraph (d) of this AD.
    (5) Thereafter, inspect initially, reinspect, and remove from 
service, if necessary, the replacement sixth stage LPT inner 
airseals in accordance with paragraph (c)(1), (c)(2), (c)(3), and 
(c)(4) of this AD.
    (d) Rework the sixth stage LPT inner airseal rear retaining wing 
in accordance with the Accomplishment Instructions of PW SB 5745, 
Revision 2, dated October 24, 1990, at the next shop visit after the 
effective date of this AD where the LPT module is accessible, or not 
later than January 1, 1996, whichever occurs first.
    NOTE: Rework of the sixth stage LPT inner airseal rear retaining 
wing in accordance with paragraph (d) of this AD does not exempt 
sixth stage LPT inner airseals from initial and repetitive 
inspections in accordance with paragraph (c)(1), (c)(2), (c)(3) of 
this AD.
    (e) Installation of a new, improved 6th stage LPT inner airseal, 
in accordance with PW SB No. 6054, Revision 1, dated April 24, 1992, 
constitutes terminating action to the inspections and rework 
required by this AD.
    (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 appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Engine Certification Office.
    NOTE: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Engine Certification Office.
    (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 airplane to a location where 
the requirements of this AD can be accomplished.
    (h) The inspections and modifications shall be done in 
accordance with the following service bulletins: 

----------------------------------------------------------------------------------------------------------------
                  Document No.                      Pages        Revision                    Date               
----------------------------------------------------------------------------------------------------------------
PW SB No. 5978..................................          1  3...............  May 20, 1992.                    
                                                          2  Original........  December 19, 1990.               
                                                        3-4  2...............  April 28, 1992.                  
                                                       5-11  1 October 10,                                      
                                                              1991..                                            
                                                         12  3 October 10,                                      
                                                              1991..                                            
                                                      13-18  1...............  October 10, 1991.                
                                                         19  3...............  May 20, 1991.                    
                                                      20-33  1...............  October 10, 1991.                
                                                         34  2...............  April 28, 1992.                  
Total Pages: 34.                                                                                                
PW SB No. 5979..................................          1  2...............  April 28, 1992.                  
                                                          2  Original........  December 20, 1990.               
                                                        3-4  1...............  September 27, 1991.              
                                                       5-33  Original........  December 19, 1990.               
                                                         34  1...............  September 27, 1991.              
                                                      35-36  Original........  December 19, 1990.               
                                                         37  2...............  April 28, 1992.                  
Total Pages: 37.                                                                                                
PW SB No. 5847 1-4 2 October 31, 1990...........                                                                
                                                          5  Original........  April 11, 1989.                  
                                                          6  2...............  October 31, 1990.                
                                                          7  Original........  April 11, 1989.                  
                                                          8  2...............  October 11, 1989.                
                                                          9  Original........  April 11, 1989.                  
                                                         10  2...............  October 11, 1989.                
Total Pages: 10.                                                                                                
PW SB No. 5745..................................        1-9  2...............  October 24, 1990.                
Total Pages: 9.                                                                                                 
PW SB No. 6054..................................        1-4  1...............  April 24, 1992.                  
                                                        5-7  Original........  November 6, 1991.                
                                                          8  1...............  April 24, 1992.                  
                                                       9-16  Original........  November 6, 1991.                
Total Pages: 16.                                                                                                
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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, Publication 
Department, 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 September 13, 1994.
    Issued in Burlington, Massachusetts, on July 7, 1994.
Michael H. Borfitz,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 94-17068 Filed 7-14-94; 8:45 am]
BILLING CODE 4910-13-P