[Federal Register Volume 65, Number 8 (Wednesday, January 12, 2000)]
[Proposed Rules]
[Pages 1831-1833]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-601]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NE-61-AD]
RIN 2120-AA64


Airworthiness Directives; Rolls-Royce plc Tay 650-15 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 Tay 650-15 series 
turbofan engines. This proposal would establish cyclic life limits for 
stage 1 high pressure turbine (HPT) and stage 1 low pressure turbine 
(LPT) disks operating under new flight plan profiles. This proposal is 
prompted by reports that on some engines disk cracks in the stage 1 HPT 
and stage 1 LPT could initiate and propagate at a faster rate than 
forecast under the flight plan profiles originally published at the 
time the engine design was certified. The actions specified by the 
proposed AD are intended to prevent crack initiation and propagation 
leading to turbine disk failure, which could result in an uncontained 
engine failure and damage to the aircraft.

DATES: Comments must be received by March 13, 2000.

ADDRESSES: Submit comments to the Federal Aviation Administration 
(FAA), New England Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 99-NE-61-AD, 12 New England Executive Park, 
Burlington, MA 01803-5299. Comments may also be submitted to the Rules 
Docket by using the following Internet address: ``9-ane-
[email protected]''. Comments may be inspected at this location between 
8:00 a.m. and 4:30 p.m., Monday through Friday, except Federal 
holidays.

FOR FURTHER INFORMATION CONTACT: James Lawrence, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone 781-
238-7176, fax 781-238-7199.

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

[[Page 1832]]

they may desire. Communications should identify the Rules Docket number 
and be submitted 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 99-NE-61-AD.'' 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 Regional Counsel, 
Attention: Rules Docket No. 99-NE-61-AD, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    The Civil Aviation Authority (CAA), which is the airworthiness 
authority for the United Kingdom (UK), recently notified the Federal 
Aviation Administration (FAA) that an unsafe condition may exist on 
Rolls-Royce plc (R-R) Tay 650-15 series turbofan engines. The CAA 
advises that on engines installed on Fokker F.28 Mark 0100 (F100) 
series airplanes cracks could initiate and propagate at a faster rate 
than forecast under the flight plan profiles originally published at 
the time the engine design was certified. These published flight plan 
profiles, A and B, provide cyclic life limits for affected engine 
components, specifically the stage 1 high pressure turbine (HPT), part 
numbers (P/Ns) JR32013 and JR33838, and stage 1 low pressure turbine 
(LPT) disks, P/N JR32318A. Rolls-Royce has developed two new flight 
plan profiles, C and D, and published life limits for the stage 1 HPT 
and stage 1 LPT disks associated with operating under those new flight 
plan profiles. The FAA has determined that three domestic engines must 
be categorized as having operated under flight plan profiles C and D, 
as described in the R-R Tay Engine Manual, 70-01-10, pages 1-10. 
Engines operating under flight plan profiles C and D have faster HPT 
and LPT disk crack initiation and propagation rates than engines 
operated under flight plan profiles A or B. Therefore, the FAA has 
determined that the stage 1 HPT and stage 1 LPT disks must be removed 
from these three domestic engines at lower cyclic life limits than if 
operated under flight plan profiles A or B. This condition, if not 
corrected, could result in crack initiation and propagation leading to 
turbine disk failure, which could result in an uncontained engine 
failure and damage to the aircraft.

CAA Airworthiness Directive (AD) Differences with This Proposed 
Rule

    The CAA issued AD 004-07-99 on July 20, 1999, in order to assure 
the airworthiness of R-R Tay 650-15 series turbofan engines in the UK. 
The CAA AD published a drawdown plan which allows operators with 
engines near or slightly over the reduced life limit to remove those 
disks from service in a scheduled, but safe manner. The three engines 
operated on aircraft of US registry do not have disks that are 
approaching the new, lower cyclic life limits, therefore, this proposed 
rule does not contain a drawdown schedule, but only establishes the 
cyclic life limits for the new flight plan profiles.

Bilateral Airworthiness Agreement

    This engine model is manufactured in the UK and is type 
certificated for operation in the United States under the provisions of 
Sec. 21.29 of the Federal Aviation Regulations (14 CFR 21.29) 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.

Proposed Actions

    Since an unsafe condition has been identified that is likely to 
exist or develop on other engines of the same type design registered in 
the United States, the proposed AD would establish life limits for 
stage 1 HPT and stage 1 LPT disks operated under the new flight plan 
profiles, C and D, require removing from service stage 1 HPT and stage 
1 LPT disks prior to reaching new, lower cyclic life limits, and 
replacing those disks with serviceable parts.

Economic Analysis

    There are approximately 242 engines of the affected design in the 
worldwide fleet. The FAA estimates that 3 engines installed on aircraft 
of U.S. registry would be affected by this proposed AD, that the 
prorated life reduction would cost $26,658 per engine. Based on these 
figures, the total cost impact of the proposed AD on U.S. operators is 
estimated to be $79,974.

Regulatory Impact

    This proposal does not have federalism implications, as defined in 
Executive Order No. 13132, because it would not have a substantial 
direct effect 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. Accordingly, 
the FAA has not consulted with state authorities prior to publication 
of this proposal.
    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 
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. 106(g), 40113, 44701.

[[Page 1833]]

Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Rolls-Royce plc: Docket No. 99-NE-61-AD.

    Applicability: Rolls-Royce plc (R-R) Tay 650-15 series turbofan 
engines, with stage 1 high pressure turbine (HPT) disks, part 
numbers (P/Ns) JR32013 and JR33838, and stage 1 low pressure turbine 
(LPT) disks, 
P/N JR32318A. These engines are installed on but not limited to 
Fokker F.28 Mark 0100 (F100) series aircraft.

    Note 1: This airworthiness directive (AD) applies to each engine 
identified in the preceding applicability provision, regardless of 
whether it has been modified, altered, or repaired in the area 
subject to the requirements of this AD. For engines that have been 
modified, altered, or repaired so that the performance of the 
requirements of this AD is affected, the owner/operator must request 
approval for an alternative method of compliance in accordance with 
paragraph (c) of this AD. The request should include an assessment 
of the effect of the modification, alteration, or repair on the 
unsafe condition addressed by this AD; and, if the unsafe condition 
has not been eliminated, the request should include specific 
proposed actions to address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent crack initiation and propagation leading to turbine 
disk failure, which could result in an uncontained engine failure 
and damage to the aircraft, accomplish the following:

Flight Plan Profile C

    (a) Remove from service stage 1 HPT disks, P/Ns JR32013 and 
JR33838, and stage 1 LPT disks, P/N JR32318A, operated under flight 
plan profile C, as defined in the R-R Tay Engine Manual, 70-01-10, 
pages 1-10, prior to accumulating 18,000 cycles-since-new (CSN), and 
replace with serviceable parts.

Flight Plan Profile D

(b) Remove from service stage 1 HPT disks, P/Ns JR32013 and JR33838, 
and stage 1 LPT disks, P/N JR32318A, operated under flight plan profile 
D, as defined in the R-R Tay Engine Manual, 70-01-10, pages 1-10, prior 
to accumulating 14,250 CSN, and replace with serviceable parts.

Alternative Methods of Compliance

    (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 (ECO). 
Operators shall submit their request through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, ECO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the ECO.

Ferry Flights

    (d) 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.

    Issued in Burlington, Massachusetts, on January 5, 2000.
Thomas A. Boudreau,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 00-601 Filed 1-11-00; 8:45 am]
BILLING CODE 4910-13-U