Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines

[Federal Register Volume 64, Number 28 (Thursday, February 11, 1999)]
[Rules and Regulations]
[Pages 6784-6786]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-3038]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-28-AD; Amendment 39-11029; AD 99-04-05]
RIN 2120-AA64


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 certain Pratt & Whitney (PW) JT9D series turbofan 
engines, that requires a fluorescent penetrant inspection (FPI) of the 
rear skirt of the diffuser case for cracks, and, if necessary, blending 
down to minimum wall thickness to remove cracks and subsequent FPI to 
determine if cracks have been removed, polishing, and shotpeening. If 
the cracks are shown by subsequent FPI not to have been removed, this 
AD requires removing the diffuser case from service and replace with a 
serviceable part. This amendment is prompted by a report of a diffuser 
case rupture during takeoff roll that resulted in damage to the 
aircraft. The actions specified by this AD are intended to prevent 
diffuser case rupture due to cracks, which can result in an uncontained 
engine failure and damage to the aircraft.

DATES: Effective April 12, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of April 12, 1999.

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 Regional 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: 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: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD)

[[Page 6785]]

that is applicable to certain Pratt & Whitney (PW) JT9D series turbofan 
engines was published in the Federal Register on August 31, 1998 (63 FR 
46200). That action proposed to require fluorescent penetrant 
inspection (FPI) of the rear skirt of the diffuser case for cracks, 
and, if necessary, blending down to minimum wall thickness, to remove 
cracks, subsequent FPI to determine if cracks have been removed, and 
polishing and shotpeening. If the cracks are shown by subsequent FPI 
not to have been removed, the proposed AD would require removing the 
diffuser case from service for possible weld repair or replacement with 
serviceable parts. The actions would be required to be accomplished in 
accordance with PW Service Bulletin (SB) No. JT9D-6329, dated May 20, 
1998.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    One commenter states that the proposed AD only requires blending 
out if an indication of a crack is found. The AD should be amended to 
require blending out of all tooling and other surface marks at piece-
part exposure, whether or not cracks are found, in order to remove the 
danger of them becoming crack initiation sites at a future date. The 
FAA does not concur. The referenced SB explains that scratches and 
toolmarks can lead to cracking. The criteria in the SB also state any 
questionable indications be marked as a crack. Although surface tooling 
mark conditions may exist in other locations on the diffuser case, 
there has been no field experience to indicate that an unsafe condition 
exists in other locations.
    The same commenter states the proposed AD concentrates solely on 
the area around the dog bone bosses. With a highly stressed part such 
as a diffuser casing, attention should be paid to the whole component 
and the AD should be amended to reflect this. The FAA concurs in part. 
Paragraph (a) of the AD has been changed to reflect the intent of the 
SB to perform an FPI of the rear skirt of the diffuser case with 
particular attention to the area around the dogbone location because it 
is a high stress area. At this time, however, the FAA has determined 
that it is not necessary to require an FPI of the entire diffuser case. 
The JT9D Engine Manual (Part Number (P/N) 777210) Inspection -01 Task 
72-41-03-22-000 contains a full diffuser case FPI as a prerequisite 
procedure for visual and dimensional inspection per SPOP 82. That 
inspection procedure also contains cautionary note to pay particular 
attention to the rear rail.
    Two commenters have no objection to the proposed 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 as proposed.
    There are approximately 566 engines of the affected design in the 
worldwide fleet. The FAA estimates that 157 engines installed on 
aircraft of U.S. registry will be affected by this AD, that it will 
take approximately 68 work hours per engine to accomplish the required 
actions, and that the average labor rate is $60 per work hour. Based on 
these figures, the total cost impact of the AD on U.S. operators is 
estimated to be $640,560.
    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 adding the following new 
airworthiness directive:

99-04-05  Pratt & Whitney: Amendment 39-11029 Docket 98-ANE-28-AD.

    Applicability: Pratt & Whitney (PW) Model JT9D-7Q, -7Q3, -59A, 
and -70A turbofan engines, with diffuser cases, part numbers (P/Ns) 
772173, 772173-001, 772173-002, 782222, 782222-001, and 782222-002, 
installed. These engines are installed on but not limited to Boeing 
747 series, McDonnell Douglas DC-10 series, and Airbus A300 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 (c) 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 rupture due to cracks, which can result 
in an uncontained engine failure and damage to the aircraft, 
accomplish the following:
    (a) At the next piece-part exposure of the diffuser case after 
the effective date of this AD, accomplish the following in 
accordance with PW Service Bulletin (SB) No. JT9D-6329, dated May 
20, 1998:
    (1) Perform a fluorescent penetrant inspection (FPI) for cracks 
in accordance with the procedures and criteria stated in the SB of 
the diffuser case rear skirt paying particular attention to areas 
around the dog bone-shaped bosses identified in the SB.
    (2) If no indications of cracks are found in accordance with the 
procedures and criteria stated in the SB, no further action is 
required.
    (3) If indications of cracks are found in accordance with the 
procedures and criteria stated in the SB, remove the diffuser case 
from service, replace with a serviceable part, or blend the cracks 
as needed down to the minimum wall thickness to remove cracks in 
accordance with the procedures and criteria stated in the SB.
    (4) After blending down in accordance with the procedures and 
criteria stated in the SB, perform a subsequent etch and FPI for 
cracks, as follows:
    (i) If no indications of cracks are found in accordance with the 
procedures and criteria stated in the SB, polish and shot-peen the 
area around each dog bone boss in accordance with the procedures and 
criteria stated in the SB.
    (ii) If indications of cracks are found in accordance with the 
procedures and criteria

[[Page 6786]]

stated in the SB, remove the diffuser case from service and replace 
with a serviceable part.
    (b) For the purpose of this AD, piece-part exposure is defined 
as when the part is considered completely disassembled when done in 
accordance with the disassembly instructions in the engine 
manufacturer's manual, to give access to the dog bone-shaped bosses 
in the diffuser case rear skirt.
    (c) 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 request 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.

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

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            Document No.               Pages              Date
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JT9D 6329..........................       1-42  May 20, 1998.
    Total Pages: 42.
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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, 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 
Regional 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.
    (f) This amendment becomes effective on April 12, 1999.

    Issued in Burlington, Massachusetts, on February 1, 1999.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 99-3038 Filed 2-10-99; 8:45 am]
BILLING CODE 4910-13-P

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