[Federal Register Volume 59, Number 231 (Friday, December 2, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-28374]
[[Page Unknown]]
[Federal Register: December 2, 1994]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 91-ANE-39; Amendment 39-9065; AD 94-23-03]
Airworthiness Directives; Pratt & Whitney JT8D 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 (PW) JT8D series turbofan engines, that
requires installation and periodic inspection of temperature indicators
installed on the No. 4 and 5 bearing compartment scavenge oil tube and
performance of any necessary corrective action. This amendment is
prompted by reports of high pressure turbine (HPT) shaft fractures
caused by oil fires that resulted from internal leakage of thirteenth
stage compressor discharge air into the No. 4 and 5 bearing
compartment. The actions specified by this AD are intended to prevent
fracture of the HPT shaft, which can result in uncontained release of
engine fragments, engine fire, inflight engine shutdown, or possible
aircraft damage.
DATES: Effective January 31, 1995.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of January 31, 1995.
ADDRESSES: The service information referenced in this AD may be
obtained from Pratt & Whitney, Technical Publications Department, M/S
132-30, 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: Mark A. Rumizen, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (617)
238-7137, fax (617) 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) that is applicable to Pratt & Whitney (PW) JT8D series
turbofan engines, was published as a notice of proposed rulemaking
(NPRM) in the Federal Register on January 24, 1992 (57 FR 2857). That
action proposed to require the installation and periodic inspection of
temperature indicators (temp tabs) installed on the No. 4 and 5 bearing
compartment scavenge oil tube, performance of any necessary corrective
action, and to require the installation of No. 4 and 5 bearing
compartment hardware modifications for certain engines.
On July 19, 1993, the FAA issued a Supplemental NPRM (58 FR 40083,
July 27, 1993) that reopened the comment period, due to comments
received and the determination that the bearing compartment hardware
modifications do not adequately prevent internal leakage of thirteenth
stage compressor discharge air into the No. 4 and 5 bearing
compartment. That Supplemental NPRM proposed to require installation of
improved temperature indicators to extend the compliance time for
installation of temperature indicators, and to eliminate the
requirement to perform No. 4 and 5 bearing compartment hardware
modifications, in accordance with PW Alert Service Bulletin (ASB) No.
5944, Revision 2, dated June 8, 1992, and ASB No. 6053, Revision 7,
dated May 24, 1993.
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 PW JT8D-Std series turbofan engines
installed in Boeing 727 series aircraft should be exempt from the
requirements of the AD based on the absence of uncontained engine
failures over the last 16 years for those engines. The FAA concurs. The
FAA has determined that the risk of uncontained engine failures on PW
JT8D-Std series turbofan engines installed in Boeing 727 series
aircraft has been reducing as newer model engines with improved
containment capability have been accumulating an increasing percentage
of fleet operating hours. Based on this determination, the FAA has
concluded that a mandatory requirement to install the temperature
indicators on these engines cannot be justified. Therefore, this final
rule has been revised to remove from the applicability PW JT8D-Std
series engines.
One commenter states that the repetitive inspections and associated
record keeping should be incorporated into the operators' FAA-approved
maintenance program. The FAA does not concur. The FAA has determined
that it is necessary to keep the repetitive inspections under the AD
and separate from the routine-approved maintenance program to
distinguish this activity as being critical to flight safety. In
addition, this AD represents an interim program until installation of
the HPT containment hardware in PW JT8D-200 series turbofan engines has
been accomplished in accordance with AD 93-23-10.
Two commenters state that the temp tab installation requirement
should be extended beyond the current 90 days. The FAA does not concur.
The FAA has provided ample notice of this requirement and extension of
the installation grace period will increase the probability of a No. 4
and 5 bearing compartment fire and possible shaft fracture. In
addition, this 90 day grace period represents an increase from 65 days
proposed in the NPRM.
Two commenters state that the repetitive inspection interval should
be changed from 65 hours time in service (TIS) to a longer interval or
an interval based on calendar time. The FAA does not concur. Extension
of this interval will increase the probability of a No. 4 and 5
compartment fire to an unacceptable level. This interval represents a
maximum limit, and shorter intervals can be selected to be consistent
with calendar time maintenance schedules.
One commenter states that temp tabs are unreliable and are subject
to oil contamination and false indications, and that the program should
be delayed until a new indicating method is developed. The FAA does not
concur. The temp tab configuration specified in this rule and
associated PW SB represent an improved version that incorporates a
sealant which is applied over the indicator and prevents oil
saturation. In addition, a procedure to determine if oil saturation has
occurred is included in the associated PW SB. PW has developed a more
costly mechanical pop-up indicator that is resistant to oil
contamination. Introduction of this indicator is currently under
evaluation and it may be available as an alternate means of compliance
at a future date.
Two commenters state that the cost impact does not take into
account the expense of maintaining the temp tab indicators and the
costs of troubleshooting false indications, and that, therefore, the
total cost estimate for compliance with the AD should be increased to
reflect these indirect costs. The FAA does not concur. The economic
analysis reflects the direct cost of compliance with the requirements
of the AD actions that the FAA has determined are necessary to correct
an unsafe condition likely to exist on engines of this type design. The
FAA has determined that adherence to the temp tab indicator
installation instructions provided in PW SB No. 5944 will allow for
reliable installation of the indicators. Once installed correctly, the
temp tab indicators will provide warning of potentially catastrophic
and costly abnormal engine conditions.
One commenter states that the temp tab indicator part numbers
should not be stated in the AD. The commenter maintains that the AD
would then still be applicable for improved indicators with new part
numbers when they are introduced. The FAA does not concur. A new
revision to PW SB No. 5944 would be required to introduce new part
numbers for new temp tab indicators, and the FAA may approve the new
revision and installation of these new temp tab indicators as an
alternative method of compliance.
One commenter states that utilizing oil system condition monitoring
and checks should allow for an increased temp tab indicator inspection
interval. The FAA does not concur. The FAA has determined that the temp
tab indicators are the most effective indicator of No. 4 and 5 bearing
compartment overtemperature conditions. However, other oil system
checks, such as oil consumption monitoring, breather pressure, and oil
pressure, can be used to assist in the troubleshooting process and help
identify bearing compartment overtemperature conditions.
One commenter agrees with the rule as proposed.
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 2,432 PW JT8D-200 series engines of the
affected design in the worldwide fleet. The FAA estimates that 1,044
engines installed on aircraft of U.S. registry will be affected by this
AD, that it will take approximately 1.5 work hours per engine to
accomplish the required actions, and that the average labor rate is $55
per work hour. Based on these figures, the total cost impact of the AD
on U.S. operators is estimated to be $85,883.
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. 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:
94-23-03 Pratt & Whitney: Amendment 39-9065. Docket 91-ANE-39.
Applicability: Pratt & Whitney (PW) JT8D-209, -217, -217A, -
217C, and -219 turbofan engines that have not installed high
pressure turbine (HPT) containment hardware in accordance with AD
93-23-10. These engines are installed on but not limited to
McDonnell Douglas MD-80 series and Boeing 727 series aircraft.
Compliance: Required as indicated, unless accomplished
previously.
To prevent fracture of the HPT shaft, which can result in
uncontained release of engine fragments, engine fire, inflight
engine shutdown, or possible aircraft damage, accomplish the
following:
(a) Install and inspect one or two temperature indicators, part
number (P/N) 810486, or a single or double set of P/N 809129 and P/N
809130 temperature indicators, on the No. 4 and 5 bearing
compartment scavenge oil tube, as follows:
(1) Install temperature indicators on the No. 4 and 5 bearing
compartment scavenge oil tube in accordance with Section 2.A.(1) of
the Accomplishment Instructions of PW Alert Service Bulletin (ASB)
No. 5944, Revision 2, dated June 8, 1992, within 90 days after the
effective date of this airworthiness directive (AD).
(2) Visually inspect temperature indicators within 65 hours TIS
of installation. Thereafter, inspect at intervals not to exceed 65
hours TIS since last inspection.
(3) If upon inspection, the color of any temperature indicator
window(s) has turned completely black, perform troubleshooting and
diagnostic testing and corrective action as required, in accordance
with Section 2.A.(2)(c) and (d) or (f) and (g), as applicable, of
the Accomplishment Instructions of PW ASB No. 5944, Revision 2,
dated June 8, 1992. Prior to returning the engine to service,
replace any temperature indicator that has turned black and inspect
in accordance with paragraph (a)(2) and (a)(3) of this AD.
(b) For aircraft installations utilizing one P/N 810486
indicator or one set of P/N 809129 and 809130 indicators, and
inspection reveals a missing indicator, inspect the remaining
temperature indicator, if applicable, to determine if the indicator
window has turned completely black. If the indicator window has
turned completely black, perform troubleshooting and diagnostic
testing, and corrective action as required, in accordance with
paragraph (a)(3) of this AD. If the indicator window has not turned
completely black or if there are no additional indicators installed,
then install a new indicator in accordance with Section 2.A.(1) of
the Accomplishment Instruction of PW ASB No. 5944, Revision No. 2,
dated June 8, 1992, prior to return to service, and visually inspect
the temperature indicator within 65 hours TIS since installation.
Thereafter, inspect at intervals not to exceed 65 hours TIS since
last inspection in accordance with paragraphs (a)(2) and (a)(3) of
this AD.
(c) For aircraft installations utilizing two P/N 810486
indicators or two sets of P/N 809129 and 809130 indicators, and
inspection reveals a missing indicator(s), inspect the remaining
temperature indicator(s), if applicable, to determine if the
indicator window has turned completely black. If the indicator
window has turned completely black, perform troubleshooting and
diagnostic testing, and corrective action as required, in accordance
with paragraph (a)(3) of this AD. If the indicator window has not
turned completely black, install a new indicator(s) in accordance
with Section 2.A.(1) of the Accomplishment Instructions of PW ASB
No. 5944, Revision 2, dated June 8, 1992, prior to return to
service, and visually inspect the temperature indicator within 65
hours TIS since installation. Thereafter, inspect at intervals not
to exceed 65 hours TIS since last inspection in accordance with
paragraphs (a)(2) and (a)(3) of this AD.
(d) Report the data elements identified in Appendix E of the
Accomplishment Instructions of PW ASB No. 5944, Revision 2, dated
June 8, 1992, whenever an overtemperature condition is observed on
any color temperature indicator which is the result of an internal
engine problem only and not resulting from an external cause
corrected by the published troubleshooting procedures. Data elements
should be reported within 30 days of determining that the
overtemperature condition is the result of an internal engine
problem, to the Manager, Engine Certification Office, Engine and
Propeller Directorate, Aircraft Certification Service, FAA, 12 New
England Executive Park, Burlington, MA 01803-05299; fax (617) 238-
7199. The reporting requirements of this AD terminate six months
from the effective date of the AD.
(e) Information collection requirements contained in this
regulation have been approved by the Office of Management and Budget
under the provisions of the Paperwork Reduction Act of 1980 (Pub. L.
96-511) and have been assigned OMB control number 2120-0056.
(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 Engine Certification Office.
(g) Special flight permits may be issued in accordance with
Secs. 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.
(h) The installations and inspections shall be done in
accordance with the following service bulletin:
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Document No. Pages Revision Date
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PW ASB No. 5944............. 1-44 2 June 8, 1992.
Total pages: 44
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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, Technical
Publications Department, M/S 132-30, 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 January 31, 1995. Issued
in Burlington, Massachusetts, on November 3, 1994.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 94-28374 Filed 12-1-94; 8:45 am]
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