[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: 94-00586]
[[Page Unknown]]
[Federal Register: January 11, 1994]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 93-ANE-43]
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 Spey series
turbofan engines. This proposal would require a one-time inspection of
stage 1 and stage 2 high pressure turbine (HPT) and low pressure
turbine (LPT) steel disks for cracks and corrosion pitting. This
proposal is prompted by a report of a stage 7 high pressure compressor
steel disk found cracked due to corrosion. The actions specified by the
proposed AD are intended to prevent an HPT or LPT steel turbine disk
burst due to cracking attributed to corrosion, which may result in an
uncontained engine failure.
DATES: Comments must be received by March 14, 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-43, 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 the proposed rule 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-43.'' 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-43, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion
The Civil Aviation Authority (CAA), which is the airworthiness
authority for the United Kingdom, recently 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 of a steel stage 7 high pressure
compressor disk installed in an R-R Spey 506-14D engine. The crack had
originated from a corrosion pit that apparently had been present at the
disk's entry into service. Subsequent investigation revealed that
engine failure due to disk burst was imminent.
The CAA has determined that steel stage 1 and stage 2 high pressure
turbine (HPT) and low pressure turbine (LPT) disks could also contain
corrosion pitting that could have been present since original
manufacture. Rolls-Royce, plc has informed the FAA that all turbine
disks installed in Spey engine models type certificated in the United
States are made of steel. This condition, if not corrected, could
result in an HPT or LPT steel turbine disk burst due to cracking
attributed to corrosion, which may result in an uncontained engine
failure.
Testing and further analysis indicate that to ensure that steel
stage 1 and stage 2 HPT and LPT disks do not operate under prolonged
exposure to levels of corrosion greater than the overhaul manual
limits, at least one inspection is required after 40% of the disk
cyclic life is expended in order for the disk to continue in service
and to reliably attain full disk cyclic life. Rolls-Royce, plc has
issued Service Bulletin No. Sp72-1044, dated September 1992, that
specifies a one-time inspection of steel stage 1 and stage 2 HPT and
LPT disks for cracks and corrosion pitting. 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.
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 AD action
is necessary for products of this type design that are certificated for
operation in the United States.
Since an unsafe condition has been identified that is likely to
exist or develop on other R-R Spey series turbofan engines of the same
type design registered in the United States, the proposed AD would
require a one-time inspection of steel stage 1 and stage 2 HPT and LPT
disks for cracks and corrosion pitting once the disks have completed at
least 40% of their published Group ``A'' cyclic life limits as
specified in the applicable overhaul manual. These disks must be
inspected in accordance with the applicable overhaul manual during the
engine's next shop visit for either HPT or LPT overhaul after the
effective date of this AD. Accomplishment of this inspection will allow
stage 1 and stage 2 HPT and LPT disks to complete the remainder of
their current published cyclic life limits.
The FAA estimates that 173 engines installed on aircraft of U.S.
registry would be affected by this proposed AD and that the average
labor rate is $55 per work hour. The FAA estimates that it would take
no additional work hours per engine to accomplish the proposed actions
to the HPT's as the inspection is performed during scheduled overhauls.
Approximately 80% of the engines will require an additional 25 work
hours of extra access, inspection, and rebuild time to perform the
required LPT inspection. Based on these figures, the total cost impact
of the proposed AD on U.S. operators is estimated to be $189,750.
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-43.
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 series and Fokker F28 series
aircraft.
Compliance: Required as indicated, unless accomplished
previously.
To prevent a high pressure turbine (HPT) or low pressure turbine
(LPT) steel turbine disk burst due to cracking attributed to
corrosion, which may result in an uncontained engine failure,
accomplish the following:
(a) Perform a one-time inspection for cracks and corrosion
pitting in steel stage 1 and stage 2 HPT disks that on the effective
date of this airworthiness directive (AD) have completed 40% or more
of their published Group ``A'' lives, in accordance with the
procedures and schedule described in R-R Service Bulletin (SB) No.
Sp72-1044, dated September 1992, at the next shop visit after the
effective date of this AD.
(b) Perform a one-time inspection for cracks and corrosion
pitting in steel stage 1 and stage 2 HPT disks that on the effective
date of this AD have completed less than 40% of their published
Group ``A'' lives, in accordance with the procedures and schedule
described in R-R SB No. Sp72-1044, dated September 1992, at the
first shop visit after completing 40% of their published Group ``A''
lives.
(c) Perform a one-time inspection for cracks and corrosion
pitting in steel stage 1 and stage 2 LPT disks that on the effective
date of this AD have completed 40% or more of their published Group
``A'' lives, in accordance with the procedures and schedule
described in R-R SB No. Sp72-1044, dated September 1992, at the next
shop visit after the effective date of this AD.
(d) Perform a one-time inspection for cracks and corrosion
pitting in steel stage 1 and stage 2 LPT disks that on the effective
date of this AD have completed less than 40% of their published
Group ``A'' lives, in accordance with the procedures and schedule
described in R-R SB No. Sp72-1044, dated September 1992, at the
first shop visit after completing 40% of their published Group ``A''
lives.
(e) Replace with a serviceable part, disks that do not meet the
inspection requirements described in section 72-50 of the applicable
R-R Spey Engine Overhaul Manual, prior to return to service.
(f) Mark disks that meet the inspection requirements described
in section 72-50 of the applicable R-R Spey Engine Overhaul Manual
in accordance with R-R SB No. Sp72-1044, dated September 1992, prior
to return to service.
(g) For the purpose of this AD, a shop visit is defined as an
engine removal where engine maintenance entails removal of either
HPT or LPT disks for the purposes of scheduled disk inspections.
(h) 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.
(i) 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 27, 1993.
Jay J. Pardee,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 94-00586 Filed 01-10-94; 8:45 am]
BILLING CODE 4910-13-P
