[Federal Register Volume 59, Number 7 (Tuesday, January 11, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-00587]
[[Page Unknown]]
[Federal Register: January 11, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 93-ANE-31]
Airworthiness Directives; Rolls-Royce, plc Spey Series Turbofan
Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to Rolls-Royce, plc (R-R) Spey series
turbofan engines. This document proposes to supersede Telegraphic AD
T89-02-52, which superseded Telegraphic AD T88-22-51. Telegraphic AD
T88-22-51 reduced cyclic life limits for seventh stage high pressure
compressor (HPC) disk from 40,000 total part cycles in service (TPC) to
35,000 TPC for the R-R Spey Model 506-14 and -14D engines. Telegraphic
AD T89-02-52 currently requires repetitive inspections or further
reduced cyclic life limits for seventh stage HPC disks. This proposal
would increase the AD's effectivity to include additional R-R Spey
engine models, eliminate the option for repetitive inspections, and
further reduce the cyclic life limits. This proposal is prompted by
further investigation into disk bore cracking that was caused by
corrosion. The actions specified by the proposed AD are intended to
prevent a seventh stage HPC disk burst due to cracking attributed to
corrosion, which may result in an uncontained engine failure.
DATES: Comments must be received by February 10, 1994.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 93-ANE-31, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may be inspected at
this location between 8 a.m. and 4:30 p.m., Monday through Friday,
except Federal holidays.
The service information referenced in this AD may be obtained from
the Service Manager, Spey engines, Rolls-Royce, plc, East Kilbride,
Glasgow G74 4PY, Scotland. 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: 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:
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 93-ANE-31.'' 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. 93-ANE-31, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion:
The Civil Aviation Authority (CAA), which is the airworthiness
authority of the United Kingdom, notified the Federal Aviation
Administration (FAA) that an unsafe condition may exist on Rolls-Royce,
plc (R-R) Spey series turbofan engines. The CAA advises that they have
received a report of a three-inch crack extending radially outward from
the bore on a seventh stage high pressure compressor (HPC) disk
installed in a R-R Spey Model 506-14D engine. The crack originated from
a corrosion pit that apparently had been present at the disk's entry
into service. Investigation indicated that failure of the engine due to
disk burst was imminent. That condition, if not corrected, could result
in a seventh stage HPC disk burst due to cracking attributed to
corrosion, which may result in an uncontained engine failure.
This engine model is manufactured in the United Kingdom and is type
certificated for operation in the United States under the provisions of
Sec. 21.29 of the Federal Aviation Regulations and the applicable
bilateral airworthiness agreement. Pursuant to this bilateral
airworthiness agreement, the CAA has kept the FAA informed of the
situation described above. The FAA has examined the findings of the
CAA, reviewed all available information, and determined that
airworthiness directive (AD) action is necessary for products of this
type design that are certificated for operation in the United States.
On October 20, 1988, the FAA issued Telegraphic AD T88-22-51, which
reduced cyclic life limits for seventh stage HPC disks from 40,000
total part cycles in service (TPC) to 35,000 TPC for the R-R Spey Model
506-14 and -14D engines. On January 26, 1989, the FAA issued
Telegraphic AD T89-02-52, which supersedes Telegraphic AD T88-22-51,
and currently requires repetitive inspections or further reduced cyclic
life limits for seventh stage HPC disks.
Since the issuance of these two previous AD's, further
investigation of the cracked disk revealed that the crack originated
from a corrosion pit that could have been present at the disk's entry
into service. A testing program investigated the effects of corrosion
on seventh stage HPC disks, and as a result of this investigation, disk
cyclic life has been reevaluated, assuming the possible presence of
corrosion at entry into service. To account for the possible presence
of corrosion, this proposed AD would further reduce the cyclic life
limit, and would require removing from service seventh stage HPC disks
that exceed the revised cyclic life limits following the schedule
established in this AD.
This revised limit reduces the cyclic life limit below the point
that intermediate, repetitive inspections are practical; therefore,
this AD does not provide for repetitive inspections. In addition, this
AD would increase the effectivity to include additional R-R Spey engine
models not affected by the previous Telegraphic AD's.
Rolls-Royce issued Mandatory Service Bulletin No. Sp72-1034,
Revision 1, dated May 4, 1990, that describes the revised cyclic life
limits for seventh stage HPC disks, and the additional R-R Spey engine
models affected. The CAA classified this service bulletin as mandatory
in order to assure the airworthiness of these R-R Spey series turbofan
engines in the United Kingdom.
Since an unsafe condition has been identified that is likely to
exist or develop on other R-R Spey series turbofan engines of this same
type design installed on aircraft registered in the United States, the
proposed AD would supersede Telegraphic AD T89-02-52 to increase the
AD's effectivity to include additional R-R Spey engine models,
eliminate the option for repetitive inspections of seventh stage HPC
disks, further reduce the cyclic life limits, and require removing from
service disks that exceed the revised cyclic life limits following the
schedule established in this AD. The actions are required to be
accomplished in accordance with the service bulletin described
previously.
The FAA estimates that 173 engines installed on aircraft of U.S.
registry would be affected by this proposed AD, and that it would not
take any additional work hours per engine to accomplish the proposed
actions. Replacement parts, prorated for the reduced life, would cost
approximately $1,718 per engine. Based on these figures, the total cost
impact of the proposed AD on U.S. operators is estimated to be
$297,214.
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 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:
Rolls-Royce, plc: Docket No. 93-ANE-31
Applicability: Rolls-Royce, plc (R-R) Spey 506-14 series, 511-14
series, and 555-15 series turbofan engines installed on but not
limited to British Aerospace BAC 1-11 and Fokker F28 aircraft.
Compliance: Required as indicated, unless accomplished
previously.
To prevent a seventh stage high pressure compressor (HPC) disk
burst due to cracking attributed to corrosion, which may result in
an uncontained engine failure, accomplish the following:
(a) For seventh stage HPC disks that on the effective date of
this airworthiness directive (AD) exceed the revised cyclic life
limits described in R-R Service Bulletin (SB) Sp72-1034, Revision 1,
dated May 4, 1990, remove from service and replace with a
serviceable part within 60 days after the effective date of this AD.
(b) For seventh stage HPC disks that on the effective date of
this AD do not exceed the revised cyclic life limits described in R-
R SB Sp72-1034, Revision 1, dated May 4, 1990, remove from service
and replace with a serviceable part: either prior to exceeding the
revised cyclic life limits, or within 60 days after the effective
date of this AD, whichever occurs later.
(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. The
request should be forwarded through an 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.
(d) Special flight permits may be issued in accordance with FAR
21.197 and 21.199 to operate the airplane to a location where the
requirements of this AD can be accomplished.
Issued in Burlington, Massachusetts, on December 29, 1993.
Jay J. Pardee,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 94-00587 Filed 01-10-94; 8:45 am]
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