[Federal Register Volume 62, Number 235 (Monday, December 8, 1997)]
[Proposed Rules]
[Pages 64523-64525]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-31967]


      
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 Proposed Rules
                                                 Federal Register
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
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  Federal Register / Vol. 62, No. 235 / Monday, December 8, 1997 / 
Proposed Rules  

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-ANE-38]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney JT9D-7R4 Series 
Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of 
comment period.

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SUMMARY: This notice revises an earlier proposed airworthiness 
directive (AD), applicable to Pratt & Whitney (PW) JT9D-7R4 series 
turbofan engines, that would have required removal of web material at 
ten bosses on the diffuser case assembly, inspections, shotpeening of 
the area, and remarking the diffuser case assemblies with a new part 
number. That proposal was prompted by reports of cracks in the aft 
corners of the bosses. This action revises the proposed rule by adding 
initial and repetitive on-wing eddy current inspections (ECI) of the 
affected bosses for cracks, and replacement, if found cracked, with 
serviceable parts. In addition, this action revises the initial 
accomplishment time for the previously proposed actions. Finally, this 
action adds further etches, fluorescent penetrant inspections (FPIs), 
x-ray inspections, and shotpeening to the shop requirements, and 
provides an optional terminating action in the form of a redesigned 
diffuser case. The actions specified by this proposed AD are intended 
to prevent diffuser case assembly rupture, which could result in an 
uncontained engine failure, engine fire, and damage to the aircraft.

DATES: Comments must be received by February 6, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 95-ANE-38, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may also be sent 
via the Internet using the following address: ``9-ad-
[email protected]''. Comments sent via the Internet must contain 
the docket number in the subject line. Comments may be inspected at 
this location between 8:00 a.m. and 4:30 p.m., Monday through Friday, 
except Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from Pratt & Whitney, Publications Department, Supervisor 
Technical Publications Distribution, M/S 132-30, 400 Main St., East 
Hartford, CT 06108; telephone (860) 565-7700, fax (860) 565-4503. This 
information may be examined at the FAA, New England Region, Office of 
the Assistant Chief Counsel, 12 New England Executive Park, Burlington, 
MA.

FOR FURTHER INFORMATION CONTACT: Tara Goodman, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7130, fax (781) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications should identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 95-ANE-38.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, New England Region, Office of the Assistant Chief Counsel, 
Attention: Rules Docket No. 95-ANE-38, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to add an airworthiness directive (AD), applicable to 
Pratt & Whitney (PW) JT9D-7R4 series turbofan engines, was published as 
a notice of proposed rulemaking (NPRM) in the Federal Register on 
August 23, 1995 (60 FR 43730). That NPRM would have required removing 
webs of material at ten bosses on the diffuser case assembly, 
performing a fluorescent penetrant inspection (FPI) and x-ray 
inspection of the reworked area, performing furnace stress relief if a 
local stress relief had been previously accomplished, shotpeening the 
reworked area, and remarking the diffuser case assemblies with a new 
part number. That NPRM was prompted by reports of cracks at the aft 
corners of bosses on the diffuser case assembly. No engine failures 
have resulted from these cracks. The cracks occur in webs of material 
at 10 diffuser case bosses that were a result of a machining operation 
during original manufacture. The webs of material create stress 
concentrations that can cause a crack to start. That condition, if not 
corrected, could result in diffuser case assembly rupture, which could 
result in an uncontained engine failure, engine fire, and damage to the 
aircraft.
    Since the issuance of that NPRM, the FAA received three comments 
regarding the actions proposed by this AD.
    One commenter states basic concurrence with the intent of the AD, 
but recommends a change in the accomplishment time, from the next shop 
visit, not to exceed 6,000 cycles in service (CIS) after the effective 
date of this AD, to the next diffuser module

[[Page 64524]]

disassembly after the effective date of this AD. The commenter states 
that the original accomplishment time causes an undue scheduling 
burden, and estimates that an additional $469,608 will be incurred 
without the revision to the accomplishment time. The FAA concurs. The 
FAA has revised the accomplishment time, and has added initial and 
repetitive on-wing and shop eddy current inspections (ECI) of the 
bosses to mitigate any additional safety risk incurred by the extension 
of the accomplishment time.
    One commenter recommends a change to the work hours estimate in the 
economic analysis. The commenter states that 44 work hours of labor are 
necessary to perform the actions required by this AD, instead of the 20 
work hours specified in the NPRM, and indicates that 44 work hours is 
more consistent with the maintenance environment of airlines and repair 
facilities. The FAA concurs, and has revised the economic analysis 
accordingly, but has increased the work hours estimate further in this 
supplemental NPRM to include the time required to accomplish the 
additional actions proposed in this supplemental NPRM.
    In addition, since issuance of the NPRM, the FAA has determined the 
need to enhance the AD by adding further etches, fluorescent penetrant 
inspections (FPIs), x-ray inspections, and shotpeening to the shop 
requirements. The FAA estimates that an additional two hours of labor 
will be necessary to access and perform the enhanced inspection of the 
diffuser case. The FAA also has determined the need to clarify, based 
on overhaul shop concerns regarding repairable diffuser cases, that 
cracks under the rail are acceptable as long as total weld bead length 
is less than 1.5 inches. This supplemental NPRM has been revised 
accordingly to incorporate these changes.
    Finally, this supplemental NPRM references PW Service Bulletin (SB) 
No. JT9D-7R4-72-527, Revision 3, dated April 16, 1997, Revision 2, 
dated July 12, 1996, and Revision 1, dated May 3, 1996, that describes 
the on-wing ECIs required by this AD, and SB No. JT9D-7R4-72-469, 
Revision 3, dated January 24, 1996, that describes the new shop 
procedures required by this AD. In addition, installation of diffuser 
case, part number 815736, in accordance with the requirements of PW SB 
No. JT9D-7R4-72-533, dated August 29, 1996, constitutes terminating 
action for this AD.
    Since these changes expand the scope of the originally proposed 
rule, the FAA has determined that it is necessary to reopen the comment 
period to provide additional opportunity for public comment.
    There are approximately 690 engines of the affected design in the 
worldwide fleet. The FAA estimates that 137 engines would be affected 
by this proposed AD, that it would take approximately 46 work hours per 
engine to accomplish the proposed actions, and that the average labor 
rate is $60 per work hour. Based on these figures, the total cost 
impact of the proposed AD on U.S. operators is estimated to be 
$378,120.
    The regulations proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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 adding the following new 
airworthiness directive:

Pratt & Whitney: Docket No. 95-ANE-38.

    Applicability: Pratt & Whitney (PW) JT9D-7R4 series turbofan 
engines, installed on but not limited to Airbus A300, A310 series, 
and Boeing 747, 767 series aircraft.

    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 (g) 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 diffuser case assembly rupture, which could result in 
an uncontained engine failure, engine fire, and damage to the 
aircraft, accomplish the following:
    (a) For assembled diffuser case assembly, Part Numbers (P/Ns) 
789996, 789996-002, 789996-003, 790541, 790541-002, 790541-003, 
798379, 798379-003, 798379-004, 5000366-002, 5000366-021, 5000366-
022, 5004770-01, 5004770-022, and 5004770-023, perform initial on-
wing eddy current inspection (ECI) or initial and repetitive 
fluorescent penetrant inspection (FPI) or ECI shop inspections of 
the diffuser case bosses in accordance with PW Service Bulletin (SB) 
No. JT9D-7R4-72-527, Revision 3, dated April 16, 1997, or Revision 
2, dated July 12, 1996, or Revision 1, dated May 3, 1996, within 250 
cycles in service (CIS) after the effective date of this AD, as 
follows:
    (1) For assembled diffuser cases in the shop, that have not been 
previously inspected in accordance with any one of the requirements 
of the SBs cited in paragraph (a) of this AD, perform an initial FPI 
or ECI of both rear corners of all 10 diffuser case mounting bosses 
and 2 case mount pads in accordance with any one of the SBs cited in 
paragraph (a) of this AD, or,
    (i) If cracks are found, perform repairs in accordance with the 
applicable Engine Manual, Chapter/Section 72-41-02, Repair-28.
    (ii) Thereafter, perform inspections within 650 CIS since last 
inspection, in accordance with any one of the SBs cited in paragraph 
(a) of this AD.
    (2) For assembled diffuser cases that are installed on-wing, 
that have not been previously inspected in accordance with any of 
the requirements of this AD, perform an initial ECI of both rear 
corners of boss six, located at the six o'clock position, in 
accordance with any one of the SBs cited in paragraph (a) of this 
AD:

[[Page 64525]]

    (i) If a crack indication is found, borescope or FPI the area 
where the crack was indicated, in accordance with any one of the SBs 
cited in paragraph (a) of this AD. Depending on the crack size, 
accomplish the following:
    (A) The diffuser case may continue in service provided it is 
inspected at intervals not to exceed 50 CIS since last borescope 
inspection, if the circumferential crack dimension ``B'', is less 
than 0.5 inches long, and the axial crack dimension ``A'' is less 
than 0.8 inches long, in accordance with any one of the SBs cited in 
paragraph (a) of this AD.
    (B) The diffuser case may continue in service for a maximum of 5 
CIS, if the axial crack dimension ``A'' is equal to or greater than 
0.8 inches but less than or equal to 1.0 inch, in accordance with 
any one of the SBs cited in paragraph (a) of this AD.
    (C) Remove from service prior to further flight the diffuser 
case when the axial crack dimension ``A'' is greater than 1.0 inch, 
in accordance with any one of the SBs cited in paragraph (a) of this 
AD.
    (ii) Diffuser cases with no cracks at boss six, perform an ECI 
at intervals not to exceed 650 CIS since the last boss 6 inspection, 
in accordance with any one of the SBs cited in paragraph (a) of this 
AD.
    (b) At the next diffuser module disassembly when all hardware is 
stripped off the diffuser case, but not to exceed 6,000 CIS after 
the effective date of this AD, inspect diffuser cases, P/Ns 790541, 
798379, 789996, 5004770-01, or 5000366-02, for existence of web 
material at ten boss locations, in accordance with PW SB No. JT9D-
7R4-72-469, Revision 3, dated January 24, 1996.
    (1) Rework the diffuser case assembly in accordance with PW SB 
No. JT9D-7R4-72-469, Revision 3, dated January 24, 1996. This rework 
removes web material at 10 boss locations.
    (2) Perform an etch and an ultra-high fluorescent penetrant 
inspection (FPI) of the reworked areas in accordance with PW SB No. 
JT9D-7R4-72-469, Revision 3, dated January 24, 1996, to ensure that 
there are no crack indications.
    (3) If a crack indication is discovered, repair, and perform an 
ECI and an FPI in accordance with Engine Manual Section 72-41-02, 
Repair-28, or remove the diffuser case from service and replace with 
a serviceable part.
    (4) Perform an x-ray inspection of the reworked areas (all 10 
boss locations and 2 mount pad locations) in accordance with PW SB 
No. JT9D-7R4-72-469, Revision 3, dated January 24, 1996, to ensure 
that there are no crack indications. Additionally, the x-ray 
inspection is performed to assure that there are no cracks, 
incomplete fusion, incomplete penetration, voids, porosity, or 
inclusions from previous local weld repairs. If any of these defects 
are discovered, repair per PW JT9D-7R4 Engine Manual, Section 72-41-
02, Repair-28, or remove the diffuser case from service and replace 
with a serviceable part.
    (5) Determine if local stress relief was performed previously, 
and if weld repairs have been performed at any of the boss locations 
described in the above SB, through reviewing maintenance records. If 
maintenance records cannot be located, or maintenance records 
indicate that a weld repair with no stress relief or a weld repair 
with a local stress relief that has been performed at any of the 10 
boss locations or 2 mount pad locations, perform furnace stress 
relief and FPI of the diffuser case assemblies in accordance with PW 
SB No. JT9D-7R4-72-469, Revision 3, dated January 24, 1996.
    (6) Shotpeen the reworked areas in accordance with PW SB No. 
JT9D-7R4-72-469, Revision 3, dated January 24, 1996.
    (7) Remark the diffuser case assembly with a new part number in 
accordance with PW SB No. JT9D-7R4-72-469, Revision 3, dated January 
24, 1996.
    (c) At the next shop visit, but not to exceed 6,000 CIS after 
the effective date of this AD, for diffuser case assembly, P/Ns 
790541-002, 790541-003, 798379-003, 798379-004, 789996-002, 789996-
003, 5000366-021, 5000366-022, 5004770-022, and 5004770-023, that 
have been previously reworked to remove web material at any boss 
locations prior to the effective date of this AD in accordance with 
the original issue of PW SB No. JT9D-7R4-72-469, dated October 2, 
1992, accomplish the following:
    (1) Unless maintenance records indicate that x-ray inspections 
were performed at the last shop visit where diffuser case repairs 
were accomplished at the 10 boss locations, prior to the effective 
date of this AD, in accordance with PW JT9D-7R4 Engine Manual, 
Section 72-41-02, Repair-28, perform an x-ray inspection of all 10 
boss locations and 2 mount pad locations in accordance with the x-
ray requirements of PW JT9D-7R4 Engine Manual, Section 72-41-02, 
Repair-28.
    (2) Determine if any previous weld repairs have been performed 
at any of the boss locations described in the above SB through 
reviewing maintenance records. If maintenance records cannot be 
located, or maintenance records indicate that a weld repair with no 
stress relief or with a local stress relief has been performed at 
any of the boss locations, perform furnace stress relief, FPI, and 
shotpeen diffuser case assemblies in accordance with PW SB No. JT9D-
7R4-72-469, Revision 3, dated January 24, 1996.
    (d) For the purpose of this AD, shop visit is defined as 
separation of diffuser case at ``K'' and ``M'' flanges.
    (e) For the purpose of this AD, an assembled diffuser case in 
the shop is defined as a diffuser case either mounted or dismounted 
from the engine, but with external hardware removed to perform the 
inspections.
    (f) Installation of diffuser case, P/N 815736, in accordance 
with the requirements of PW SB No. JT9D-7R4-72-533, dated August 29, 
1996, constitutes terminating action for this AD.
    (g) 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 submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Engine Certification Office.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Engine Certification Office.

    (h) 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.

    Issued in Burlington, Massachusetts, on November 28, 1997.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 97-31967 Filed 12-5-97; 8:45 am]
BILLING CODE 4910-13-U