Skip to Content

Proposed Rule

Airworthiness Directives; Honeywell International, Inc. LTP 101 Series Turboprop and LTS101 Series Turboshaft Engines

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble


Federal Aviation Administration, DOT.


Notice of proposed rulemaking (NPRM).


This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Honeywell International, Inc. (formerly AlliedSignal, Inc. and Textron Lycoming) LTP 101 series turboprop and LTS101 series turboshaft engines. This proposal would require a new life limitation and removal of rigid tube fuel manifold assemblies and replacement with serviceable assemblies. This proposal is prompted by reports of cracking and fuel leakage of rigid tube fuel manifolds. The actions specified by the proposed AD are intended to prevent engine fuel leakage due to low-cycle fatigue (LCF) cracking of the rigid Start Printed Page 14347tube fuel manifold, which could result in an in-flight fire.


Comments must be received by May 11, 2001.


Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-NE-16-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: “” Comments sent via the Internet must contain the docket number in the subject line. Comments may be inspected at this location between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays.

Start Further Info


Robert Baitoo, Aerospace Engineer, Los Angeles Aircraft Certification Office, FAA, Transport Airplane Directorate, 3960 Paramount Blvd., Lakewood, CA 90712-4137; telephone (562) 627-5245; fax (562) 627-5210.

End Further Info End Preamble Start Supplemental 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 action 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 action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 99-NE-16-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRM's

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-16-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Events Leading to This Proposed AD

The FAA has received reports of approximately 48 instances of fuel leakage from rigid tube fuel manifolds since 1990. None of the reported instances involved fires. The engine manufacturer has determined that the leaks were caused by cracking of the rigid tubes in fuel manifolds due to low-cycle fatigue (LCF). This condition, if not corrected, could result in engine fuel leakage due to LCF cracking of the rigid tube fuel manifold, which could result in an in-flight fire.

FAA's Determination and Explanation of Proposed Rule

The FAA has examined all available data, including relevant service information, and determined that an unsafe condition exists or is likely to develop on other products of this same type design.

Accordingly, this proposed AD would require the removal of certain rigid tube fuel manifolds with part numbers (P/N's) specified in this proposed rule, before exceeding the new cyclic life limits.

Since an unsafe condition has been identified that is likely to exist or develop on other Honeywell International, Inc. LPT 101 series turboprop and LTS101 series turboshaft engines of the same type design with the affected fuel manifolds installed, the proposed AD would establish life limits for the rigid tube fuel manifolds.

Economic Analysis

There are approximately 1600 engines of the affected design in the worldwide fleet. The FAA estimates that 670 engines installed on aircraft of U.S. registry would be affected by this proposed AD, that it would take approximately 2 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 $6,000 per engine. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $4,100,400.

Regulatory Impact

This proposed rule does not have federalism implications, as defined in Executive Order 13132, because it does 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 proposed rule.

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 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 has been prepared for this action and 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.

Start List of Subjects

List of Subjects in 14 CFR Part 39

  • Air transportation
  • Aircraft
  • Aviation safety
  • Safety
End List of Subjects

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:

Start Part


1. The authority citation for part 39 continues to read as follows:

Start Authority

Authority: 49 U.S.C. 106(g), 40113, 44701.

End Authority

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

Honeywell International, Inc.: Docket No. 99-NE-16-AD.

Applicability: This proposed airworthiness directive (AD) is applicable to Honeywell International, Inc. (formerly AlliedSignal Inc. and Textron Lycoming) LTP 101 series turboprop and LTS101 series turboshaft engines with the following part numbers (P/N's) rigid tube fuel manifolds installed: Start Printed Page 14348

Table 1.—P/N's of Affected Rigid Tube Fuel Manifolds


These engines are installed on, but not limited to Aerospatiale AS350, Eurocopter MBB-BK117 and HH-65A, Bell 222, Page Thrush, Air Tractor AT-302, Piaggio P. 166-DL3, Riley International R421, and Pacific Aero 08-600 aircraft.

Note 1:

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 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: Compliance with this AD is required as specified below, unless already done. To prevent engine fuel leakage due to low-cycle fatigue (LCF) cracking of the rigid tube fuel manifold, which could result in an in-flight fire, do the following:

(a) Replace fuel manifolds that have accumulated the following gas generator rotor (Ng) cycles-since-new (CSN) on the effective date of this AD or Ng cycles-in-service (CIS) on the effective date of this AD since all tubes were replaced:

Table 2.—Fuel Tube Replacement Schedule

Ng CSN, or Ng CIS Since Total Tube ReplacementReplacement schedule
(1) 2,750 or lessBefore accumulating 3,000 total Ng cycles.
(2) More than 2,750Within 250 CIS after the effective date of this AD.
(3) Unknown(i) Within 2,000 CIS after the effective date of this AD, or
(ii) At the next engine removal, or
(iii) At the removal of the fuel manifold for cause, whichever is first.

New Life Limitation

(b) Do not install fuel manifolds with P/N's that are listed in Table 1 of this AD after the effective date of this AD if they meet ANY of the following conditions:

(1) The manifold has accumulated 3,000 or more total Ng cycles; OR

(2) The manifold has had partial tube replacements; OR

(3) The manifold has an unknown number of Ng cycles.

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, Los Angeles Aircraft Certification Office (LAACO). Operators shall submit their request through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, LAACO.

Note 2:

Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the LAACO.

Special Flight Permits

(d) Special flight permits may be issued in accordance with §§ 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.

Start Signature

Issued in Burlington, Massachusetts, on March 2, 2001.

David A. Downey,

Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.

End Signature End Part End Supplemental Information

[FR Doc. 01-5737 Filed 3-9-01; 8:45 am]