[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