[Federal Register Volume 59, Number 174 (Friday, September 9, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-22075]


[[Page Unknown]]

[Federal Register: September 9, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-ANE-20; Amendment 39-9019; AD 94-18-06]

 

Airworthiness Directives; Textron Lycoming LTS101 Series 
Turboshaft and LTP101 Series Turboprop Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to Textron Lycoming LTS101 series turboshaft and LTP101 
series turboprop engines. This action requires a one-time removal of 
321 No. 2 bearings with serial numbers from suspect manufacturing lots, 
and replacement with serviceable parts. This amendment is prompted by 
reports of three in-service bearing failures. The actions specified in 
this AD are intended to prevent engine power loss and inflight engine 
shutdown due to No. 2 bearing failure, which could result in possible 
loss of the aircraft.

DATES: Effective September 26, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of September 26, 1994.
    Comments for inclusion in the Rules Docket must be received on or 
before November 8, 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. 94-ANE-20, 12 New England 
Executive Park, Burlington, MA 01803-5299.
    The service information referenced in this AD may be obtained from 
Textron Lycoming, Stratford Division, 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; or at the Office of the Federal Register, 800 North 
Capitol Street, NW., suite 700, Washington, DC.

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) 
238-7148, fax (617) 238-7199.

SUPPLEMENTARY INFORMATION: The Federal Aviation Administration (FAA) 
has received reports of three in-service bearing failures on Textron 
Lycoming LTS101 series turboshaft engines. Investigation revealed that 
three manufacturing lots totaling 321 No. 2 bearings were manufactured 
with roller cages either undercut or staked improperly, thereby 
increasing the bearing cage stress levels. The bearings from the 
incident engines exhibited circumferential fractures spanning across 
the cage cross web sections. The bearings were the winged design, which 
incorporates features to improve lubrication.
    The FAA has determined through analysis that the fractures were 
caused due to high cycle fatigue, as no material defects have been 
found. The failures were caused by an increased stress level at the 
cross web area, the location of maximum tensile stress of the cage, 
with crack initiation at the corners of the cross web. Textron Lycoming 
has determined that two manufacturing lots, with 100 bearings and 147 
bearings each, were undercut at the inner diameter (ID) of cage roller 
pockets to remove burrs after broaching. This undercutting operation 
removed up to 0.020 inch from the cross web area thickness, about 25% 
of the total thickness. The two bearing failures were from the lot of 
100 undercut-cage bearings. In addition, Textron Lycoming has found 
that a separate lot of 74 bearings had cage cross webs deformed as the 
result of an improperly fitted spacer of a staking tool. This 
condition, if not corrected, could result in engine power loss and 
inflight engine shutdown due to No. 2 bearing failure, which could 
result in possible loss of the aircraft.
    The FAA has reviewed and approved the technical contents of Textron 
Lycoming Alert Service Bulletin (ASB) No. A-LT101-72-50-0163, Revision 
1, dated March 8, 1994, that describes procedures for removal and 
replacement of affected No. 2 bearings.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Textron Lycoming LTS101 series turboshaft and 
LTP101 series turboprop engines of the same type design, this 
airworthiness directive (AD) is being issued to prevent engine power 
loss and inflight engine shutdown due to No. 2 bearing failure. This AD 
requires a one-time removal of 321 No. 2 bearings with serial numbers 
from suspect manufacturing lots, and replacement with serviceable 
parts. For engines installed on single-engine aircraft and twin-engine 
aircraft with two affected bearings, the bearings must be removed and 
replaced prior to further flight. For engines installed on all other 
aircraft, the bearings must be removed and replaced prior to the next 
25 hours time in service (TIS). This timetable is empirically based on 
the early failure times, on the unpredictable nature of the high cycle 
fatigue mode, and on the lack of advance warning of failure. At this 
time, the FAA has not determined an analytically predicted failure 
time. The compliance timetable of prior to further flight for the 
single-engine aircraft or twin-engine aircraft with two affected 
bearings provides for more conservatism based on the possibility of 
complete loss of engine power. The actions are required to be 
accomplished in accordance with the alert service bulletin described 
previously.
    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD 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 94-ANE-20.'' The postcard will be date stamped and 
returned to the commenter.
    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and is not a ``significant regulatory action'' 
under Executive Order 12866. It has been determined further that this 
action involves an emergency regulation under DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979). If it is determined 
that this emergency regulation otherwise would be significant under DOT 
Regulatory Policies and Procedures, a final regulatory evaluation will 
be prepared and placed in the Rules Docket. A copy of it, if filed, may 
be obtained from the Rules Docket at the location provided under the 
caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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:

    94-18-06 Textron Lycoming: Amendment 39-9019. Docket 94-ANE-20.

    Applicability: Textron Lycoming LTS101 series turboshaft and 
LTP101 series turboprop engines incorporating No. 2 bearings, Part 
Number (P/N) 4-301-362-01 that have serial numbers 3-740 through 3-
839, 3-1288 through 3-1361, and 4-534 through 4-680. These engines 
are installed on but not limited to Aerospatiale AS350 and SA-366 
series, Bell 222 series, and MBB BK117 series helicopters; and 
Airtractor AT302, Piaggio P166, Cessna 421 (STC), and Page Thrush 
airplanes.

    Note: Affected bearings, or kits P/N T05K21714, incorporating 
those bearings, would have been shipped from Textron Lycoming or an 
approved Service Facility after September 20, 1993.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent engine power loss and inflight engine shutdown due to 
No. 2 bearing failure, which could result in possible loss of the 
aircraft, accomplish the following:
    (a) For engines installed on single-engine aircraft and twin-
engine aircraft with both engines having affected bearings, prior to 
further flight remove No. 2 bearings in accordance with Textron 
Lycoming Alert Service Bulletin (ASB) No. A-LT101-72-50-0163, 
Revision 1, dated March 8, 1994, and replace with serviceable parts.
    (b) For engines installed on all other aircraft, within 25 hours 
time in service (TIS) after the effective date of this airworthiness 
directive (AD) remove No. 2 bearings in accordance with Textron 
Lycoming ASB No. A-LT101-72-50-0163, Revision 1, dated March 8, 
1994, and replace with serviceable parts.
    (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 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.

    (d) The removal and replacement of the No. 2 bearings shall be 
done in accordance with the following service document: 

------------------------------------------------------------------------
                                            Revision                    
           Document No.             Pages                    Date       
------------------------------------------------------------------------
Textron Lycoming ASB No. A-LT101-      1-3         1  Mar. 8, 1994.     
 72-50-0163.                                                            
Total pages: 3.                                                         
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    This incorporation by reference was approved by the Director of the 
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 
Copies may be obtained from Textron Lycoming, Stratford Division, 550 
Main Street, Stratford, CT 06497. Copies may be inspected at the FAA, 
New England Region, Office of the Assistant Chief Counsel, 12 New 
England Executive Park, Burlington, MA; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
    (e) This amendment becomes effective on September 26, 1994.

    Issued in Burlington, Massachusetts, on August 30, 1994.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 94-22075 Filed 9-8-94; 8:45 am]
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