[Federal Register Volume 66, Number 85 (Wednesday, May 2, 2001)]
[Proposed Rules]
[Pages 21896-21898]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-10890]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NE-53-AD]
RIN 2120-AA64


Airworthiness Directives; Honeywell International Inc. TFE731-2, 
-3, and -4 Series Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The Federal Aviation Administration (FAA) proposes to 
supersede two existing airworthiness directives (ADs), applicable to 
Honeywell International Inc. (formerly AlliedSignal Inc. and Garrett 
Turbine Engine Co.) TFE731-2, -3, and -4 series turbofan engines. Those 
AD's currently require removing certain fan rotor discs from service in 
accordance with a drawdown schedule, and establishing new fan rotor 
disc life limits. This proposal would require stricter life limits for 
certain fan rotor discs. This proposal is prompted by the availability 
of an improved fan rotor disc and by a reduction in the probability of 
fan rotor disc failure by terminating the life of the older, high-
stressed, fan rotor disc. The actions specified in the proposed AD are 
intended to prevent failure of the fan disc due to fatigue cracking in 
the dovetail slots, which could result in in-flight engine shutdown, 
uncontained engine failure, and damage to the airplane.

DATES: Comments must be received by July 2, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Regional 
Counsel, Attention: Rules Docket No. 2000-NE-53-AD, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may also be sent 
via the Internet using the following address: ``[email protected]''. 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. The service information referenced in the proposed 
rule may be obtained from Honeywell Engines and Systems (formerly 
AlliedSignal Inc. and Garrett Turbine Engine Co.) Technical 
Publications and Distribution, M/S 2101-201, P.O. Box 52170, Phoenix, 
AZ 85072-2170; telephone: (602) 365-2493 (General Aviation), (602) 365-
5535 (Commercial Aviation), fax: (602) 365-5577 (General Aviation), 
(602) 365-2832 (Commercial Aviation). This information may be examined 
at the FAA, New England Region, Office of the Regional Counsel, 12 New 
England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT: Joseph Costa, Aerospace Engineer, Los 
Angeles Aircraft Certification Office, FAA, Transport Airplane 
Directorate, 3960 Paramount Blvd., Lakewood CA 90712-4137; telephone: 
(562) 627-5246; fax: (562) 627-5210.

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 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 2000-NE-53-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. 2000-NE-53-AD, 12 New

[[Page 21897]]

England Executive Park, Burlington, MA 01803-5299.

Discussion

    On May 22, 1986, the FAA issued AD 86-11-05, Amendment 39-5325 (51 
FR 2025, June 4, 1986), and on August 26, 1996, the FAA issued AD 96-
18-13, Amendment 39-9737 (61 FR 47806, September 11, 1996). These AD's 
require removing certain fan rotor discs from service in accordance 
with drawdown schedules based on the fan rotor disc's accumulated 
cycles-since-new (CSN). These AD's also establish new fan rotor disc 
life cycle limits at 4,100 CSN or 4,600 CSN, depending on the 
respective disc part number. That action was prompted after additional 
analyses revealed that stress levels in the dovetail slots of the 
affected fan rotor discs were higher than initially calculated. The 
requirements of that AD are intended to prevent failure of the fan disc 
due to fatigue cracking in the dovetail slots, resulting in in-flight 
engine shutdown, uncontained engine failure, and damage to the 
airplane. In addition, to further reduce the probability of a fatigue 
failure and separation of in-service fan rotor discs, the FAA issued AD 
96-05-03, Amendment 39-9529 (61 FR 10881, March 18, 1996) and AD 96-04-
01, Amendment 39-9512 (61 FR 7690, February 29, 1996), which require 
initial and repetitive eddy current inspections of the dovetail slots. 
Within the past ten years, 400 fan discs have been removed from service 
for unacceptable eddy current inspection indications. Service 
experience has shown that the crack detection capability of this eddy 
current inspection procedure remains between 80-90 percent. Since AD 
86-11-05, AD 96-18-13, AD 96-05-03, and AD 96-04-01 were issued, the 
FAA has determined that approximately 1,400 affected fan rotor discs 
remain in service, and has concluded that an accelerated removal 
schedule of affected fan rotor discs at next access or prior to 
December 31, 2002, is necessary to further reduce the probability of 
fan rotor disc failures.

Manufacturer's Service Information

    The FAA has reviewed and approved the technical contents of 
Honeywell International Inc. Alert Service Bulletin TFE731-A72-3668, 
dated October 25, 2000, that describes fan rotor disc replacement 
procedures, and references other documents for instructions on 
replacement, with the redesigned fan rotor discs.

FAA's Determination of an Unsafe Condition and Proposed Actions

    Since an unsafe condition has been identified that is likely to 
exist or develop on other Honeywell International Inc. (formerly 
AlliedSignal Inc. and Garrett Turbine Engine Co.) TFE731-2, -3, and -4 
series turbofan engines of this same type design, the proposed AD would 
require replacing fan rotor discs part numbers (P/N's) 3072162-All, 
3072816-All, 3073436-All, 3073539-All, and 3074529-All (where All 
denotes all dash numbers).

Economic impact

    There are approximately 1,400 engines with affected discs in the 
worldwide fleet. The FAA estimates that 1,100 engines installed on 
aircraft of U.S. registry would be affected by this proposed AD. The 
FAA also estimates that it would take approximately one work hour per 
engine to accomplish the proposed action during a normally scheduled 
fan rotor disc removal period, and approximately six work hours per 
engine to accomplish the proposed action during an unscheduled fan 
rotor disc removal period, and that the average labor rate is $60 per 
work hour. Required parts would cost approximately $20,400 per engine. 
Based on these figures, the total cost impact of the proposed AD on 
U.S. operators is estimated to be $22,509,000.

Regulatory Impact

    This proposed rule does not have federalism implications, as 
defined in Executive Order 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 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 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 (FAA) 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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Amendment 39-5325 (51 FR 
2025, June 4, 1986) and Amendment 39-9737, (61 FR 47806, September 11, 
1996) and by adding a new airworthiness directive, to read as follows:

Honeywell International Inc.:  Docket No. 2000-NE-53-AD. Supersedes 
AD 86-11-05, Amendment 39-5325 and AD 96-18-13, Amendment 39-9737.

    Applicability: This airworthiness directive (AD) is applicable 
to Honeywell International Inc. (formerly AlliedSignal Inc. and 
Garrett Turbine Engine Co.) TFE731-2, -3, and -4 series turbofan 
engines, with fan rotor discs part numbers (P/N's) 3072162-All, 
3072816-All, 3073436-All, 3073539-All, and 3074529-All (where All 
denotes all dash numbers). These engines are installed on, but not 
limited to, Avions Marcel Dassault Falcon 10, 50, and 100 series; 
Learjet 31, 35, 36, and 55 series; Lockheed-Georgia 1329-23 and -25 
series; Israel Aircraft Industries 1124 series and 1125 Westwind 
series; Cessna Model 650, Citations III, VI, and VII; Raytheon 
British Aerospace HS-125 series; and Sabreliner NA-265-65 airplanes.

    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 indicated, unless already 
done.
    To prevent failure of the fan disc due to fatigue cracking in 
the dovetail slots, which could result in in-flight engine shutdown,

[[Page 21898]]

uncontained engine failure, and damage to the airplane, do the 
following:
    (a) Remove fan rotor discs P/N's 3072162-All, 3072816-All, 
3073436-All, 3073539-All, and 3074529-All (where All denotes all 
dash numbers), and replace with serviceable fan rotor discs at next 
access to the fan rotor disc, at the next scheduled fan rotor disc 
inspection, or prior to December 31, 2002, whichever occurs 
earliest. Fan rotor disc replacement information is available in 
Honeywell International Inc. Alert Service Bulletin TFE731-A72-3668, 
dated October 25, 2000.

Definitions

    (b) For the purpose of this AD, the following definitions apply:
    (1) Access to the fan rotor disc is whenever the fan shaft is 
unstretched.
    (2) A serviceable disc is a disc that does not have a P/N listed 
in this AD.

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 
Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 
21.197 and 21.199) to operate the airplane to a location where the 
requirements of this AD can be accomplished.

    Issued in Burlington, Massachusetts, on April 24, 2001.
Donald E. Plouffe,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 01-10890 Filed 5-1-01; 8:45 am]
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