[Federal Register Volume 60, Number 2 (Wednesday, January 4, 1995)]
[Proposed Rules]
[Pages 393-395]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-64]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-ANE-64]


Airworthiness Directives; Textron Lycoming LTS101 Series 
Turboshaft and LTP101 Series Turboprop 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 Textron Lycoming LTS101 series 
turboshaft and LTP101 series turboprop engines. This proposal would 
require replacement of cast material axial compressor rotors with 
wrought material axial compressor rotors that have improved fatigue 
characteristics and material properties. This proposal is prompted by 
36 reports of axial compressor blade failures on cast rotors. The 
actions specified by the proposed AD are intended to prevent engine 
power loss and inflight engine shutdown.

DATES: Comments must be received by February 3, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Assistant Chief Counsel, Attention: 
Rules Docket No. 94-ANE-64, 12 New England Executive Park, Burlington, 
MA 01803-5299. Comments may be inspected at this location between 8:00 
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 Textron Lycoming, 550 Main Street, Stratford, CT 06497. 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: Eugene Triozzi, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (617) 
238-7131, 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. 
[[Page 394]] 
    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 94-ANE-64.'' 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. 94-ANE-64, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    The Federal Aviation Administration (FAA) has determined that cast 
material axial compressor rotors in Textron Lycoming LTS101 series 
turboshaft and LTP101 series turboprop engines are susceptible to high 
cycle fatigue (HCF) failure. The FAA has received 36 reports of axial 
compressor blade failures on cast material axial compressor rotors 
installed in these engines. Metallurgical evaluation of these failed 
rotors found that cracks originated from porosity, inclusions, or 
pitting erosion. This condition, if not corrected, can result in engine 
power loss and inflight engine shutdown.
    Statistical analysis shows decreasing failure probability with 
increasing rotor time in service. In addition, engine testing has 
identified blade excitation frequencies that occur within the engine 
operating range that could contribute to HCF failure. The wrought rotor 
design has improved material properties and increased HCF margin. This 
proposed airworthiness directive (AD) requires replacement of cast 
material axial compressor rotors with wrought material axial compressor 
rotors.
    The FAA has reviewed and approved the technical contents of Textron 
Lycoming Service Bulletin No. LT 101-72-30-0088, Revision 5, dated 
September 25, 1992, that describes procedures and schedules for 
replacing cast material axial compressor rotors with wrought material 
axial compressor rotors.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require replacing cast material axial compressor 
rotors with wrought material axial compressor rotors that have improved 
fatigue characteristics and material properties. The actions would be 
required to be accomplished in accordance with the service bulletin 
described previously.
    There are approximately 200 engines of the affected design in the 
worldwide fleet. The FAA estimates that 100 engines installed on 
aircraft of U.S. registry would be affected by this proposed AD, that 
it would take approximately 50 work hours per engine to accomplish the 
proposed actions, and that the average labor rate is $60 per work hour. 
Required parts would cost approximately $6,500 per engine, on a 
prorated cost basis. Based on these figures, the total cost impact of 
the proposed AD on U.S. operators is estimated to be $955,000.
    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 ``major rule'' under Executive Order 12291; (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. 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:

Textron Lycoming: Docket No. 94-ANE-64.

    Applicability: Textron Lycoming LTS101 turboshaft and LTP101 
turboprop engines installed on but not limited to Aerospatiale AS 
350 and SA366G, Bell 222, and Messerschmitt Bolkow-Blohm (MBB) BK117 
helicopters; Piaggio P166-DL3 and Airtractor AT302 airplanes.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent engine power loss and inflight engine shutdown, 
accomplish the following:
    (a) Remove from service Part Numbers (P/N) 4-101-006-20, -21, -
24, -26, -35, -36, and -40 cast material axial compressor rotors, as 
follows:
    (1) For axial compressor rotors P/N 4-101-006-35 with serial 
number suffix ``E,'' remove in accordance with Textron Lycoming 
Service Bulletin (SB) No. LT 101-72-30-0088, Revision 5, dated 
September 25, 1992, within 50 hours time in service (TIS), or 60 
days after the effective date of this AD, whichever occurs first.
    (2) For axial compressor rotors P/N 4-101-006-35 with serial 
number suffix other than ``E,'' and all other axial compressor 
rotors with P/N listed in paragraph (a) of this airworthiness 
directive (AD), remove in accordance with Textron Lycoming SB No. LT 
101-72-30-0088, Revision 5, dated September 25, 1992, as follows:
    (i) For axial compressor rotors that have accumulated 600 hours 
or less TIS since new, remove within 100 hours TIS, or 120 days 
after the effective date of this AD, whichever occurs first.
    (ii) For axial compressor rotors that have accumulated more than 
600 but less than or equal to 1,200 hours TIS since new, remove 
within 300 hours TIS, or 240 days after the effective date of this 
AD, whichever occurs first.
    (iii) For axial compressor rotors that have accumulated more 
than 1,200 but less than or equal to 2,400 hours TIS since new, 
remove within 600 hours TIS, or 360 days after the effective date of 
this AD, whichever occurs first.
    (iv) For axial compressor rotors that have accumulated more than 
2,400 hours TIS since new, remove within 1,200 hours TIS, or 720 
days after the effective date of this AD, whichever occurs first.
    (3) Replace with a serviceable wrought material axial compressor 
rotor P/N 4-101-006-28, -32, -39, or -41, as applicable, in 
accordance with Textron Lycoming SB No. LT 101-72-30-0088, Revision 
5, dated September 25, 1992.
    (b) 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 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 [[Page 395]] compliance with this 
airworthiness directive, if any, may be obtained from the Engine 
Certification Office.

    (c) Special flight permits may be issued in accordance with 
sections 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 December 27, 1994.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 95-64 Filed 1-3-95; 8:45 am]
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