AD 95-26-01 ACTIVE

This amendment adopts a new airworthiness directive (AD), applicable to AlliedSignal, Inc. (formerly Textron Lycoming) Models LTS101-650B1, -750B1, -650C, and -750C turboshaft engines, that requires installation of an improved power turbine (PT) rotor and electronic PT rotor overspeed controller as a terminating action to the currently required inspections of AD 88-14-01. This amendment is prompted by reports of additional bearing failures since publication of AD 88-14-01, including one additional uncontained PT disk failure. The actions specified by this AD are intended to prevent PT overspeed and uncontained engine failure.

Final rule.

95-26-01 AlliedSignal, Inc.: Amendment 39-9459. Docket 95-ANE-08.
Applicability: AlliedSignal, Inc. (formerly Textron Lycoming) Model LTS101-650B1, -750B1, -650C, and -750C turboshaft engines installed on Bell Helicopter Textron 222 series and Messerschmitt-Bolkow-Blohm (MBB) BK117 series helicopters. NOTE: This 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 use the authority provided in paragraph (d) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition, or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect ofthe changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any engine from the applicability of this AD.
Compliance: Required as indicated, unless accomplished previously.
To prevent power turbine (PT) overspeed and uncontained engine failure, accomplish the following:
(a) Install the improved PT rotor with retention capability at the next shop visit when the PT rotor is removed after the effective date of this AD, but prior to December 31, 1997, in accordance with the following Textron Lycoming Service Bulletins (SB):

Engine Model
SB No.
Rev.
Date
LTS101-650B1
LTS101B-72-50-0122
4
June 17, 1991
LTS101-750B1 or -650B1
LTS101B-72-50-0116
6
August 14, 1992
LTS101-650C and -750C Series
LTS101C-72-50-0119
2
June 17, 1991

(b) Install the improved electronic PT rotor overspeed controller concurrently with the PT rotor installation required by paragraph (a) of this AD, or at the next airframe 600 hour inspection point after the effective date of this AD, whichever occurs later, in accordance with the following Textron Lycoming SB:

Engine Model
SB No.
Rev.
Date
LTS101-650B1
LTS101B-73-10-0127
2
August 14, 1992
LTS101-750B1
LTS101B-73-10-0127
2
August 14, 1992
LTS101-650C and -750C Series
LTS101C-73-10-0129
3
August 14, 1992

(c) Installation of the improved PT rotor with retention capability and the improved electronic PT rotor overspeed controller in accordance with paragraphs (a) and (b) of this AD constitutes terminating action to the inspection requirements of AD 88-14-01.
(d) 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 compliance with this airworthiness directive, if any, may be obtained from the Engine Certification Office.
(e) 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.
(f) The actions required by this AD shall be done in accordance with the following service bulletins:

Document No.
Pages
Revision
Date
LTS101B-72-50-0122
1-11
4
June 17, 1991
Total Pages: 11.

LTS101B-72-50-0116
1-10
6
August 14, 1992
Total Pages: 10.

LTS101C-72-50-0119
1-11
2
June 17, 1991
Total Pages: 11.

LTS101B-73-10-0127
1-13
2
August 14, 1992
Total Pages: 13.

LTS101C-73-10-0129
1-14
3
August 14, 1992
Total Pages: 14.

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 AlliedSignal Inc., 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.
(g) This amendment becomes effective on April 22, 1996.

On May 26, 1988, the Federal Aviation Administration (FAA) issued airworthiness directive (AD) 88-14-01, Amendment 39-5952 (53 FR 25317, July 6, 1988), to require initial and repetitive inspections of the engine lubrication and bearing systems on AlliedSignal, Inc. (formerly Textron Lycoming) LTS101 series turboshaft engines. That action was prompted by reports of four uncontained power turbine (PT) disk failures. Subsequent investigation revealed that the PT disk failures were caused by bearing failures resulting in PT shaft disengagement from the gear train drive, unloading the PT and causing rotor overspeed. Two other PT disk failures involved No. 4 bearing failure, followed by power pinion gear teeth failure, thereby unloading the PT and causing PT rotor overspeed. This condition, if not corrected, could result in PT overspeed and uncontained engine failure.
Since the issuance of that AD, the FAA has received reports of additional bearing failureswith resultant loss of PT rotor location, including one additional uncontained PT disk failure. In order to minimize the possibility of an uncontained engine failure, the manufacturer has developed an improved PT rotor with retention capability and an improved electronic PT rotor overspeed controller. These improvements are only available for AlliedSignal, Inc. Models LTS101-650B1, -750B1, -650C, and -750C turboshaft engines, installed on Bell Helicopter Textron 222 series and Messerschmitt-Bolkow-Blohm (MBB) BK117 series helicopters.
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that is applicable to AlliedSignal, Inc. (formerly Textron Lycoming) Models LTS101-650B1, -750B1, -650C, and -750C turboshaft engines was published in the Federal Register on May 19, 1995 (60 FR 26846). That action proposed to require installation of an improved PT rotor with retention capability and an electronic PT rotor overspeed controller at the next shop visit when the PT rotor is removed after the effective date of this AD, but prior to December 31, 1997, as a terminating action to the currently required inspections of AD 88-14-01.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.
One commenter states that the requirement to incorporate an electronic PT overspeed controller should be deleted from the AD, as the additional economic impact is not justified from the basis of increased safety, or the basis of reliability in adverse operating conditions. The FAA does not concur. The FAA has determined that the electronic PT overspeed controller will increase flight safety by providing overspeed protection in the event of a No. 4 bearing failure. As stated in the NPRM, the current PT rotor overspeed controller, in two cases of No. 4 bearing failure, has allowed PT rotor overspeed and uncontained PT disk failures.The FAA has also determined that the electronic PT overspeed protection system provides an acceptable level of reliability in adverse environmental operating conditions consistent with that required for engine digital electronic controls.
One commenter states that the pneumatic portion of the PT retention system should be enabled in lieu of installation of the electronic PT overspeed controller, as this would be a more cost effective improvement. The FAA does not concur. The pneumatic portion of the PT retention system would not provide overspeed protection in the event of a No. 4 bearing failure. Available data shows that the pneumatic portion of the PT retention system provides automatic shutdown only in the event of loss of PT rotor axial location.
One commenter states that the requirements of AD 88-14-01 should be continued with no terminating actions, thereby continuing preventive maintenance benefits. The FAA does not concur. The FAA has approved incorporation of applicable ongoing maintenance requirements currently in AD 88-14-01 into the applicable AlliedSignal, Inc. LTS101 engine maintenance manual requirements. The FAA considers that incorporation of these requirements into the maintenance manuals will provide desirable preventive maintenance actions for the AlliedSignal, Inc. LTS101 engine, while the design modifications proposed would alleviate the additional record-keeping burden imposed by AD 88-14-01.
One commenter states that the compliance timetable for incorporation of electronic PT rotor overspeed controller should be revised to allow installation at a scheduled aircraft inspection rather than at the next PT rotor removal. This change is requested because incorporation of electronic PT rotor overspeed controller at the next PT rotor removal may not be logistically supportable due to the increased rate of PT rotor removals resulting from another field management plan. The FAA concurs. Adoption of the revised timetable will minimize the possible logistic impact of the original compliance timetable while still providing the equivalent level of safety proposed by the NPRM.
One commenter states that the proposed AD should apply only for engines that do not incorporate the insertable blade PT rotor. The FAA concurs in part. The PT rotor with retention capability, to be required by the proposed rule, is the same as the insertable blade PT rotor. Therefore, the PT rotor installation required by the proposed rule would be previously accomplished for engines with the insertable blade PT rotor. However, as addressed in a previous comment, the FAA has determined that installation of the electronic PT overspeed controller is required for all engines regardless of the P/N PT rotor installed, in order to provide overspeed protection in the event of a No. 4 bearing failure.
One commenter states that the economic impact of the proposed rule should be revised to reflect installation of aircraft electronics necessary for operation of the electronic overspeed system. The FAA concurs, and has adjusted the economic impact to reflect the associated increase in the cost impact.
After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes described previously. The FAA has determined that these changes will not increase the scope of the AD.
There are approximately 950 engines of the affected design in the worldwide fleet. The FAA estimates that 95 engines installed on aircraft of U.S. registry will be affected by the requirement to install the PT rotor with improved retention, that it will take approximately 10 work hours per engine to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $44,400 per engine. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $4,275,000 for installation of the PT rotor with improved retention.
In addition, the FAA estimates that 576 engines installed on aircraft of U.S. registry will be affected by the requirement to install the electronic PT rotor overspeed controller, that it will take approximately 3 work hours per engine to accomplish the required action, and that the average labor rate is $60 per work hour. Required parts cost for the electronic PT rotor overspeed controller installation is $5,825. Based on these figures, the cost impact of installing the electronic PT rotor overspeed controller would be $3,458,880.
There are approximately 288 aircraft of U.S. registry that would be affected by the requirement to install aircraft electronics necessary for the functioning of the electronic PT rotor overspeed controller. It would take approximately 80 work hours per aircraft to accomplish the proposed actions, and the average labor rate is $60 per work hour. Required parts for the aircraft installation would be approximately $4,531. Based on these figures, the cost impact of installing the aircraft electronics for the electronic PT rotor overspeed controller would be $2,287,328. Therefore, the revised total cost impact of all the actions of the proposed AD on U.S. operators is estimated to be $10,421,208.
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.
For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February26, 1979); and (3) 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it 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 USC 106(g), 40113, 44701. 39.13 - [AMENDED]
2. Section 39.13 is amended by adding the following new airworthiness directive:

The service information referenced in this AD may be obtained from AlliedSignal Inc., 550 Main Street, Stratford, CT 06497. This information may be examined at the Federal Aviation Administration (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.

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.