[Federal Register Volume 62, Number 182 (Friday, September 19, 1997)]
[Rules and Regulations]
[Pages 49137-49140]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-24798]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-ANE-07; Amendment 39-10135; AD 97-19-14]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan 
Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to Pratt & Whitney JT8D series turbofan engines, that 
currently requires inspections of low pressure turbine (LPT) blade sets 
for blade shroud crossnotch wear, and removal, if necessary. In 
addition, the current AD requires, as a terminating action to the 
inspections, installation of improved LPT containment hardware, and 
installation of an improved No. 6 bearing scavenge pump bracket 
bushing. This amendment keeps the compliance actions of the current AD 
intact but changes the compliance time for LPT containment hardware 
installation from the current calendar end-date to December 31, 1998, 
for engines that contain suspect 4th stage hubs identified by serial 
number. This amendment is prompted by a report of a fourth stage hub 
manufacturing defect that led to the failure of the hub and subsequent 
release of LPT blades. The actions specified by this AD are intended to 
prevent damage to the aircraft resulting from engine debris following 
an LPT blade, shaft, or hub failure.

DATES: Effective October 24, 1997.
    The incorporation by reference of PW Alert Service Bulletin No. 
A6131, Revision 1, dated May 16, 1995; PW Alert Service Bulletin No. 
A6131, Revision 2, dated July 28, 1997; PW Alert Service Bulletin No. 
A6274, Original, dated November 7, 1996; and PW Alert Service Bulletin 
No. A6274, Revision 1, dated December 9, 1996, is approved by the 
Director of the Federal Register as of October 24, 1997.
    The incorporation by reference of all other publications listed in 
the regulations was previously approved as of November 14, 1994 (59 FR 
51842, October 13, 1994).

ADDRESSES: The service information referenced in this AD may be 
obtained from Pratt & Whitney, 400 Main St., East Hartford, CT 06108; 
telephone (860) 565-6600, fax (860) 565-4503. This information may be 
examined at the Federal Aviation Administration (FAA), New England 
Region, Office of the Assistant Chief Counsel, 12 New England Executive 
Park, Burlington, MA 01803-5299; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Christopher Spinney, Aerospace 
Engineer, Engine Certification Office, FAA, Engine and Propeller 
Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; 
telephone (781) 238-7175, fax (781) 238-7199.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 94-20-08, 
Amendment 39-9036 (59 FR 51842, October 15, 1994), applicable to Pratt 
& Whitney (PW) JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -17, 
and -17R series turbofan engines, was published in the Federal Register 
on April 1, 1997 (62 FR 15437). That action proposed to require 
inspections of low pressure turbine (LPT) blade sets for blade shroud 
crossnotch wear, and removal, if necessary. In addition, the current AD 
requires, as a terminating action to the inspections, installation of 
improved LPT containment hardware, and installation of an improved No. 
6 bearing scavenge pump bracket bushing. The proposal would have 
reduced the compliance time for LPT containment hardware installation 
from the current calendar end-date to December 31, 1998.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due

[[Page 49138]]

consideration has been given to the comments received.
    Eight commenters state that the more stringent compliance times 
should only be applicable to those engines that have a suspect 4th 
stage LPT hub installed. Otherwise, the proposed AD imposes an undue 
burden to operators, since the proposed AD does not specifically 
address the threat of the 4th stage hub suspect population. The 
commenters offer several alternatives, such as withdrawal of the NPRM, 
writing a stand alone AD, changing the compliance paragraph, and adding 
a paragraph to NPRM Docket No. 96-ANE-32. The FAA concurs with the 
comments and is changing the compliance paragraph accordingly. This 
final rule contains a new compliance schedule, which is intended to 
meet the threat of an blade release due to the failure of the 4th stage 
LPT hub. The threat of a 4th hub failure has been isolated to a suspect 
population of hubs listed in PW Alert Service Bulletin No. A6274, 
Revision 1, dated December 9, 1996.
    Two commenters state that the third stage turbine air sealing ring 
should not have the more stringent compliance times, as the third stage 
turbine air sealing ring does not affect 4th stage LPT containment, 
which is why the compliance end-date is being moved up. The FAA 
concurs. The third stage turbine air sealing ring does not contribute 
to the containment of 4th stage LPT blades, therefore the FAA has 
removed the more stringent compliance times for the third stage turbine 
air sealing ring in this final rule. The FAA has also relaxed the 
compliance time for the improved No. 6 bearing scavenge pump bracket 
bushing, as this part also does not contribute to the containment of 
4th stage LPT blades released due to a 4th stage hub fracture.
    One commenter states that the AD cannot be complied with on 
schedule as the replacement hardware is not available. The FAA does not 
concur. The manufacturer has advised the FAA that there are no current 
or foreseen shortages of hardware that will slow down operators' 
ability to comply with the AD.
    One commenter states that the proposed rule should be withdrawn, as 
the risk is within acceptable limits without any further action and the 
actions described in NPRM Docket No. 96-ANE-32 are adequate to prevent 
future occurrences of uncontained failures from this cause. The FAA 
does not concur. While not yet published, the actions proposed in NPRM 
Docket No. 96-ANE-32 would, if adopted, minimize the threat of an 
uncontained blade release due to a hub fracture. The FAA has also 
evaluated the risk and crack growth analysis data and field experience 
for the 4th stage LPT hub and the data supports the conclusion that the 
failure mechanism is the loss of a 4th stage LPT blade and that the hub 
field management program must address non-containment of the LPT blade 
as well as the inspection of the LPT hub for cracks. The FAA feels the 
added measure of security offered by the improved containment is 
warranted in this case. However, the FAA agrees the more aggressive 
containment schedule should only apply to those hubs at highest risk of 
failing and releasing a blade as outlined in the compliance section 
described in previous responses to comments.
    One commenter states that accomplishment of the actions described 
in PW ASB No. A6131, Revision 1, dated May 16, 1995, should be an 
acceptable alternative method of compliance to the AD's reference of 
the Original version of the ASB. The FAA concurs and has added 
reference to Revision 1 to the compliance section of this final rule.
    One commenter states concern that the same containment hardware 
will be required for engines required to accomplish the actions 
described in AD 94-20-09 covering ``A'' model engines. The FAA does not 
concur. The suspect hubs are not approved for installation on ``A'' 
model engines; therefore, a similar condition does not exist for the 
``A'' models.
    Three commenters support the rule as proposed.
    In addition, the FAA has reviewed and approved the technical 
contents of PW ASB No. A6274, Revision 1, dated December 9, 1996, and 
Original, dated November 7, 1996, that describe procedures for 
repetitive inspections of affected LPT hubs; and PW ASB No. A6131, 
Revision 2, dated July 28, 1997, that describes procedures for 
installation of the improved No. 6 bearing scavenge pump bracket 
bushing.
    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 the changes to the AD would neither 
increase the scope of the required actions over the current AD, nor 
increase the economic burden on operators over the costs of complying 
with the current AD. While the new AD alters the compliance times, 
operators should still be able to perform the required actions at 
scheduled maintenance. Therefore the FAA has determined that this new 
AD will result in no additional economic impact.
    The regulations adopted herein will not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a 
significant economic impact, positive or negative, on a substantial 
number of small entities under the criteria of the Regulatory 
Flexibility Act. A final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air Transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

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

    Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-9036 (59 FR 
51842, October 15, 1994) and by adding a new airworthiness directive to 
read as follows:

97-19-14 Pratt & Whitney: Amendment 39-10135. Docket 97-ANE-07. 
Supersedes AD 94-20-08, Amendment 39-9036.

    Applicability: Pratt & Whitney (PW) JT8D-1, -1A, -1B, -7, -7A, -
7B, -9, -9A, -11, -15, -17, and -17R turbofan engines, installed on 
but not limited to Boeing 737 and 727 series aircraft, and McDonnell 
Douglas DC-9 series aircraft.


[[Page 49139]]


    Note 1: This airworthiness directive (AD) applies to each engine 
identified in the preceding applicability provision, regardless of 
whether it has been modified, altered, or repaired in the area 
subject to the requirements of this AD. For engines that have been 
modified, altered, or repaired so that the performance of the 
requirements of this AD is affected, the owner/operator must request 
approval for an alternative method of compliance in accordance with 
paragraph (d) of this AD. The request should include an assessment 
of the effect of the modification, alteration, or repair on the 
unsafe condition addressed by this AD; and, if the unsafe condition 
has not been eliminated, the request should include specific 
proposed actions to address it.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent damage to the aircraft resulting from engine debris 
following a low pressure turbine (LPT) blade, shaft, or hub failure, 
accomplish the following:
    (a) For engines that do not contain fan exhaust inner front duct 
segment assemblies that are installed in accordance with PW Alert 
Service Bulletin (ASB) No. 6039, Revision 3, dated October 15, 1993, 
or earlier revisions of PW ASB No. 6039, and either PW honeycomb 
third stage outer airseal Part Number (P/N) 801931, 802097, 797594, 
or 798279; or Pyromet Industries, Inc., honeycomb third stage outer 
airseal P/N PI9336; or McClain International, Inc., honeycomb third 
stage outer airseal P/N M2433; or a turbine case shield assembly 
installed in accordance with PW ASB No. 6039, Revision 3, dated 
October 15, 1993, or earlier revisions of PW ASB No. 6039; or a 
third stage blade set that has third stage turbine blades that were 
installed in accordance with PW SB No. 5331, dated October 27, 1982, 
accomplish the following:
    (1) Conduct initial and repetitive inspections on installed 
third and fourth stage LPT blade sets, and remove and replace with 
serviceable blade sets, as necessary, in accordance with Part 1 of 
the Accomplishment Instructions of PW ASB No. A5913, Revision 6, 
dated October 15, 1993; or PW ASB No. A5913, Revision 5, dated 
August 10, 1992; or PW ASB No. A5913, Revision 4, dated February 20, 
1992, as follows:
    (i) Initially inspect the blade shroud crossnotches of the third 
stage LPT blade set when specified in paragraphs (a)(1)(i)(A) or 
(a)(1)(i)(B) of this AD, whichever occurs later. Engines that 
contain a third stage blade set that have third stage turbine blades 
that were installed per the requirements specified in PW Service 
Bulletin (SB) No. 5331, dated October 27, 1982, do not require the 
third stage blade set inspection.
    (A) Inspect within 6,000 cycles or 6,000 hours time in service, 
whichever occurs first, since new, since the last blade shroud 
crossnotch inspection specified in Section 72-53-12 of PW JT8D 
Engine Manual P/N 481672, or since last blade shroud crossnotch 
repair that was accomplished per the requirements specified in 
Section 72-53-12 of PW JT8D Engine Manual P/N 481672; or
    (B) Inspect within 1,000 cycles or 1,000 hours time in service 
since November 14, 1994, whichever occurs first.
    (ii) Initially inspect the blade shroud crossnotches of the 
fourth stage LPT blade set when specified in paragraph (a)(1)(ii)(A) 
or (a)(1)(ii)(B) of this AD, whichever occurs later. Engines that 
contain fan exhaust inner front duct segment assemblies that were 
installed per the requirements of PW ASB No. 6039, Revision 3, dated 
October 15, 1993, or earlier revisions of PW ASB No. 6039, do not 
require the fourth stage blade set inspection.
    (A) Inspect within 6,000 cycles or 6,000 hours time in service, 
whichever occurs first, since new, since the last blade shroud 
crossnotch inspection specified in Section 72-53-13 of PW JT8D 
Engine Manual P/N 481672, or since last blade shroud crossnotch 
repair that was accomplished per the requirements specified in 
Section 72-53-13 of PW JT8D Engine Manual P/N 481672; or
    (B) Inspect within 1,000 cycles or 1,000 hours time in service 
since November 14, 1994, whichever occurs first.
    (iii) Thereafter, inspect the third and fourth stage LPT blade 
sets in accordance with the procedures and intervals specified in PW 
ASB No. A5913, Revision 6, dated October 15, 1993;
    (2) At the next shop visit after the effective date of this AD, 
install the improved inner front fan exhaust duct and associated 
hardware in accordance with Part A of the Accomplishment 
Instructions of PW ASB A6110, Revision 1, dated October 15, 1993, as 
follows:
    (i) For engines that have a 4th stage LPT hub installed with a 
serial number listed in PW ASB A6274, Table A, dated November 7, 
1996, or Revision 1, dated December 9, 1996, install the improved 
inner front fan exhaust duct before December 31, 1998, or 8,000 
hours time in service since November 14, 1994, or 7,000 cycles in 
service since November 14, 1994, whichever occurs first.
    (ii) For engines that do not have a 4th stage LPT hub installed 
with a serial number listed in PW ASB A6274, Table A, dated November 
7, 1996, or Revision 1, dated December 9, 1996, install the improved 
inner front fan exhaust duct before December 31, 1999, or 8,000 
hours time in service since November 14, 1994, or 7,000 cycles in 
service since November 14, 1994, whichever occurs latest.
    (3) At the next access to the third stage turbine air sealing 
ring, install the improved third stage turbine air sealing ring and 
associated hardware in accordance with Part B of the Accomplishment 
Instructions of PW ASB A6110, Revision 1, dated October 15, 1993. 
The installation of the improved third stage turbine air sealing 
ring must occur no later than December 31, 1999, or 8,000 hours time 
in service since November 14, 1994, or 7,000 cycles in service since 
November 14, 1994, whichever occurs latest.

    Note 2: Third stage turbine outer air seal, P/N M2533, is an 
acceptable alternative to PW P/N 811962 for compliance with this 
paragraph.

    (4) At the next shop visit after the effective date of this AD, 
install the improved No. 6 bearing scavenge pump bracket bushing in 
accordance with the Accomplishment Instructions of PW ASB No. A6131, 
dated August 24, 1993, or Revision 1, dated May 16, 1995, or 
Revision 2, dated July 28, 1997. The installation of the improved 
No. 6 bearing scavenge pump bracket bushing must be accomplished no 
later than December 31, 1999, or 8,000 hours time in service since 
November 14, 1994, or 7,000 cycles since November 14, 1994, 
whichever occurs latest.
    (5) Accomplishment of the installations required by paragraphs 
(a)(2), (a)(3), and (a)(4) of this AD constitutes terminating action 
to the repetitive inspections required by paragraph (a)(1) of this 
AD.
    (b) For engines that do contain fan exhaust inner front duct 
segment assemblies that are installed in accordance with PW ASB No. 
6039, Revision 3, dated October 15, 1993, or earlier revisions of PW 
ASB No. 6039, and either PW honeycomb third stage outer airseal P/N 
801931, 802097, 797594, or 798279; or Pyromet Industries, Inc., 
honeycomb third stage outer airseal P/N PI9336; or McClain 
International, Inc., honeycomb third stage outer airseal P/N M2433; 
or a turbine case shield assembly installed in accordance with PW 
ASB No. 6039, Revision 3, dated October 15, 1993, or earlier 
revisions of PW ASB No. 6039; or a third stage blade set that has 
third stage turbine blades that were installed in accordance with PW 
SB No. 5331, dated October 27, 1982, perform the installations 
required by paragraphs (a)(2), (a)(3), and (a)(4) of this AD, at the 
times specified in those respective paragraphs.
    (c) For the purpose of this AD, a shop visit is defined as an 
engine removal, where engine maintenance entails separation of pairs 
of major mating engine flanges or the removal of a disk, hub, or 
spool at a maintenance facility that is capable of compliance with 
the instructions of this AD, regardless of other planned 
maintenance, except for field maintenance type activities performed 
at this maintenance facility in lieu of performing them on-wing or 
at another peripheral facility.
    (d) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Engine Certification Office. 
Operators shall forward their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Engine Certification Office.

    Note 3: Information concerning the existence of approved 
alternative method of compliance with this AD, if any, may be 
obtained from the Engine Certification Office.

    (e) 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.
    (f) The actions required by this AD shall be done in accordance 
with the following PW service documents:

[[Page 49140]]



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            Document No.                Pages           Revision                          Date                  
----------------------------------------------------------------------------------------------------------------
ASB No. A5913......................         1-12  6...................  October 15, 1993.                       
Total pages: 12.                                                                                                
ASB No. A6110......................         1-59  1...................  October 15, 1993.                       
Total pages: 59.                                                                                                
ASB No. A6131......................         1-13  Original............  August 24, 1993.                        
Total pages: 13.                                                                                                
ASB No. A6131......................         1-14  1...................  May 16, 1995.                           
Total pages: 14.                                                                                                
ASB No. A6131......................         1-21  2...................  July 28, 1997.                          
Total pages: 21.                                                                                                
ASB No. A6274......................         1, 2  1...................  December 9, 1996.                       
                                            3, 4  Original............  November 7, 1996.                       
                                               5  1...................  December 9, 1996.                       
                                            6-22   Original...........  November 7, 1996.                       
                                              23  1...................  December 9, 1996.                       
Total pages: 23.                                                                                                
ASB No. A6274......................         1-23  Original............  November 7, 1996.                       
Attachment NDIP-889................         1-39  Original............  November 1, 1996.                       
Total pages: 62.                                                                                                
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    This incorporation by reference of PW ASB No. A5913, Revision 6, 
dated October 15, 1993; and PW ASB No. A6110, Revision 1, dated 
October 15, 1993; was previously approved by the Director of the 
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 
51 as of November 14, 1994 (59 FR 51842, October 13, 1994). Copies 
may be obtained from Pratt & Whitney, 400 Main St., East Hartford, 
CT 06108; telephone (860) 565-6600, fax (860) 565-4503. Copies may 
be inspected at the FAA, New England Region, Office of the 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.
    (g) This amendment becomes effective on October 24, 1997.

    Issued in Burlington, Massachusetts, on September 10, 1997.
Mark C. Fulmer,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 97-24798 Filed 9-18-97; 8:45 am]
BILLING CODE 4910-13-U