[Federal Register Volume 59, Number 86 (Thursday, May 5, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-10394]
[[Page Unknown]]
[Federal Register: May 5, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 91-ANE-47; Amendment 39-8878; AD 94-08-06]
Airworthiness Directives; Pratt & Whitney JT9D-7R4 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 JT9D-7R4 series turbofan engines, that
requires initial and repetitive fan blade leading edge inspections, and
either installation of fan blade sets with modified fan blade shrouds
or rework of the fan blade shrouds as a terminating action to the
inspections. This amendment is prompted by reports of flutter-induced
fan blade fractures. The actions specified by this AD are intended to
prevent fan blade fracture and uncontained engine failure, resulting in
possible damage to the aircraft.
DATES: Effective July 5, 1994.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of July 5, 1994.
ADDRESSES: The service information referenced in this AD may be
obtained from Pratt & Whitney, 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: John Fisher, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (617)
238-7149, fax (617) 238-7199.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations to include an airworthiness directive (AD) that is
applicable to Pratt & Whitney (PW) JT9D-7R4 series turbofan engines was
published in the Federal Register on June 2, 1993 (58 FR 31356). That
action proposed to require initial and repetitive on-wing or shop fan
blade leading edge inspections to check for leading edge damage in
accordance with PW Service Bulletin (SB) No. 72-255, Revision 5, dated
January 8, 1990; and to require fan blade set replacement or optional
rework of the fan blade shrouds in accordance with PW SB No. 72-309,
Revision 9, dated June 12, 1991. Though the NPRM referenced PW SB No.
72-309, Revision 9, dated June 12, 1991, this final rule incorporates
the later Revision 10, dated September 2, 1993, which is substantially
unchanged from Revision 9. Rework of the fan blade shrouds in
accordance with PW SB No. 72-309, Revision 9, dated June 12, 1991, is
an acceptable alternate means of compliance for paragraphs (c) and (d)
of this AD.
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 comment states that the proposed 90-day requirement for
initializing the inspection program poses a significant hardship and
economic impact due to difficulty in scheduling engine maintenance.
This comment requests extending the initializing period to 180 days.
The Federal Aviation Administration (FAA) agrees that the proposed
initial 90-day eddy current inspection requirement may be burdensome to
some operators. The FAA has therefore added a visual inspection as an
option to the eddy current inspection in this final rule. This visual
inspection offers greater flexibility in scheduling as it can easily be
performed in the field. The FAA does not concur, however, in extending
the initializing period to 180 days, as this time period does not offer
an adequate level of safety based on risk analysis results. This final
rule establishes an interval of 200 cycles in service (CIS) before
visual or eddy current inspection that should enable operators to
initialize the inspection program with minimum disruption to scheduling
without reducing flight safety. Also, the FAA has added guidance
emphasizing the manner in which the visual inspection should be
performed.
One comment requests eliminating the reference in paragraphs (a)
and (b) of the proposed rule to the leading edge refurbishment
described in PW Service Bulletin (SB) No. 72-117, as the determining
factor for beginning the inspection program. The comment further states
that a previous AD, 90-14-08, already requires the leading edge
refurbishment described in PW SB No. 72-117, and therefore meets the
intent of paragraphs (a) and (b) of the proposed rule. The FAA concurs.
Repetitive leading edge refurbishment as described in PW SB No. 72-117
is already required by AD 90-14-08. The compliance section of this AD
has been changed from the wording in the NPRM to eliminate reference to
leading edge refurbishment, and combines paragraphs (a) and (b) of the
proposed rule into a new paragraph (a) which has the same inspection
requirements and interval of 200 CIS as the repetitive inspections of
paragraph (c) of the proposed rule.
One comment states that the mandatory incorporation of the fan
blade shroud angle rework to 52 degrees as described in PW SB No. 72-
309 should be relaxed from within two years after the effective date of
this AD to the next engine shop visit, thereby reducing the potential
for on-wing maintenance induced error. The FAA does not concur. The FAA
has determined that it is necessary to expeditiously remove fan blades
with the 62 degree shroud configuration, thereby reducing the potential
for operating the fan blade in flutter. The FAA has reviewed a risk
analysis study that indicates that a two-year time period for
incorporating this modification is required to lower the risk
sufficiently to avert future potential uncontained fan blade failures.
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 730 PW JT9D-7R4 series engines of the
affected design in the worldwide fleet. The FAA estimates that 220
engines installed on aircraft of U.S. registry would be affected by
this AD, and that the average labor rate is $55 per work hour. The
inspections required by this AD will take approximately 1.6 work hours
per engine. The blade rework will cost approximately $15,600 per
engine. Based on these figures, the total cost impact of the AD on U.S.
operators is estimated to be $3,451,360.
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 14 CFR part
39 of the Federal Aviation Regulations 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:
94-08-06 Pratt & Whitney: Amendment 39-8878. Docket 91-ANE-47.
Applicability: Pratt & Whitney (PW) JT9D-7R4 series turbofan
engines installed on but not limited to Boeing Models 747 and 767
aircraft, and Airbus Models A300 and A310 aircraft.
Compliance: Required as indicated, unless accomplished
previously.
To prevent fan blade fracture and uncontained engine failure,
resulting in possible damage to the aircraft, accomplish the
following:
(a) Perform an initial visual or eddy current inspection of the
fan blade set leading edges for leading edge damage within 200
cycles in service (CIS) after the effective date of this AD, and
rework or replace fan blades as necessary, in accordance with the
Accomplishment Instructions of PW Service Bulletin (SB) No. 72-255,
Revision 5, dated January 8, 1990. Perform the fan blade leading
edge visual inspections using a strong white light, as well as
fingernails and fingertips when inspecting for nicked, eroded, or
blunt leading edges.
(b) Thereafter, perform repetitive visual or eddy current fan
blade leading edge inspections, at intervals not to exceed 200 CIS,
and rework or replace fan blades as necessary, in accordance with
the Accomplishment Instructions of PW SB No. 72-255, Revision 5,
dated January 8, 1990. Perform the fan blade leading edge visual
inspections using a strong white light, as well as fingernails and
fingertips when inspecting for nicked, eroded, or blunt leading
edges.
(c) For PW Model JT9D-7R4H1 engines, install a new or reworked
fan blade set with a 52 degree shroud angle, in accordance with PW
SB No. 72-309, Revision 10, dated September 2, 1993, within 1 year
after the effective date of this AD.
(d) For PW Models JT9D-7R4D, D1, E, E1, G2, and E4 engines,
install a new or reworked fan blade set with a 52 degree shroud
angle, in accordance with PW SB No. 72-309, Revision 10, dated
September 2, 1993, within 2 years after the effective date of this
AD.
(e) Installation of a new or reworked fan blade set with a 52
degree fan blade shroud angle, in accordance with paragraphs (c) or
(d) of this AD, constitutes a terminating action to the inspection
requirements of paragraphs (a) and (b) of 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 Certification Office.
(g) Special flight permits may be issued in accordance with 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 modification and inspections shall be done in accordance
with the following service bulletins:
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Document No. Pages Revision Date
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PW SB No. 72-255.......................................... 1-2 5 Jan. 8, 1990.
3-4 4 Aug. 25, 1988.
5 5 Jan. 8, 1990.
6-8 3 Aug. 17, 1987.
Total Pages: 8.
PW SB No. 72-309.......................................... 1 10 Sept. 2, 1993.
2 8 Apr. 5, 1989.
3-4 9 Jun. 12, 1991.
5 (\1\) Oct. 2, 1986.
6 1 Nov. 7, 1986.
7 5 Jul. 22, 1987.
8-10 8 Apr. 5, 1989.
11 10 Sept. 2, 1993
12-18 8 Apr. 5, 1989
19-20 10 Sept. 2, 1993
21 8 Apr. 5, 1989
Total Pages: 21.
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\1\Original.
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 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 July 5, 1994.
Issued in Burlington, Massachusetts, on April 5, 1994.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 94-10394 Filed 5-4-94; 8:45 am]
BILLING CODE 4910-13-P