[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]
=======================================================================
-----------------------------------------------------------------------
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.
-----------------------------------------------------------------------
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:
------------------------------------------------------------------------
Document No. Pages Date
------------------------------------------------------------------------
JT9D 6329.......................... 1-42 May 20, 1998.
Total Pages: 42.
------------------------------------------------------------------------
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