[Federal Register Volume 65, Number 45 (Tuesday, March 7, 2000)]
[Proposed Rules]
[Pages 11942-11944]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-5460]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-ANE-10-AD]
RIN 2120-AA64


Airworthiness Directives; Honeywell International Inc. TFE731-2, 
-3, -4, and -5 Series Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of 
comment period.

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SUMMARY: This notice revises an earlier proposed airworthiness 
directive (AD), applicable to Honeywell International, Inc.(formerly 
AlliedSignal Inc. and Garret Turbine Engine Company) high pressure 
compressor (HPC) impellers installed on TFE731-2, -3, -4, and -5 series 
turbofan engines. That proposal would have required replacing the HPC 
impeller with a serviceable impeller that has been eddy-current 
inspected or with a serviceable impeller of certain part numbers as a 
terminating action. That proposal was prompted by an incident of an 
uncontained impeller failure due to cracking in the seal relief area of 
the HPC impeller. This action revises the proposed rule by eliminating 
the terminating action and adding those impeller PN's to the suspect 
impeller population. This action would also clarify certain portions of 
the proposed AD based on comments that were received from the public. 
The actions specified by this proposed AD are intended to prevent HPC 
impeller failure due to fatigue cracking.

DATES: Comments must be received by May 8, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Regional 
Counsel, Attention: Rules Docket No. 99-ANE-10-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 8:00 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 Honeywell Engines and Systems (formerly AlliedSignal) 
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), fax 
(602) 365-5577 (General Aviation), (602) 365-2832 (Commercial). 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 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.
    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 99-ANE-10-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-ANE-10-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR

[[Page 11943]]

part 39) to add an airworthiness directive (AD), applicable to 
Honeywell International Inc. (formerly AlliedSignal Inc. and Garrett 
Turbine Engine Company) high pressure compressor (HPC) impellers 
installed on TFE731-2, -3, -4, and -5 series turbofan engines, was 
published as a notice of proposed rulemaking (NPRM) in the Federal 
Register on July 28, 1999 (64 FR 40789). That NPRM would have required 
replacing the HPC impeller with a serviceable impeller, which has been 
eddy-current inspected, at the next core zone inspection (CZI) or at 
the next access to the HPC module, and repetitive inspections at each 
subsequent CZI or each subsequent access to the HPC impeller for cause 
if the impeller has more than 1,000 cycles since the last eddy current 
inspection (ECI). That NPRM was prompted by a Federal Aviation 
Administration (FAA) determination that on May 10, 1998, a high 
pressure compressor (HPC) impeller, part number (P/N) 3073394-1, 
separated and exited from a TFE731-3R-1D turbofan engine. This impeller 
had accumulated 9,080 engine cycles since new (CSN) and 5,829 engine 
cycles since rework of the seal relief area in November, 1982, 
performed in accordance with Garrett Turbine Engine Company Service 
Bulletin (SB) TFE731-72-3239 RWK. Fracture analysis revealed a 
subsurface primary origin in the area of the seal relief and that the 
crack propagated through the bore for about 1.0 inch. No melt or 
forging related discrepancies were found at the fatigue origin; 
however, localized alpha grain colonies with an unfavorable fracture 
plane orientation were present. Recent low-temperature fatigue testing 
with a sustained peak hold time (dwell) at higher than engine-operating 
stresses indicate that normal cyclic fatigue lives may be influenced by 
dwell times and an unfavorable titanium macrostructure. The FAA has 
determined that low-cycle fatigue (LCF) cracking in high stressed areas 
of the HPC impeller may lead to an uncontained impeller separation. 
That condition, if not corrected, could result in an HPC impeller 
failure due to fatigue cracking.

Changes to This NPRM

    Since that NPRM was published in the Federal Register, the FAA has 
received a number of comments that change the requirements of the 
original NPRM and the population of applicable HPC impellers was 
increased. The nature and extent of those changes were such that FAA 
has determined that a supplemental NPRM (SNPRM) should be issued.

Manufacturer's Service Information

    The FAA has reviewed and approved the technical contents of 
AlliedSignal Inc. Alert Service Bulletin (ASB) TFE731-A72-3641, dated 
November 24, 1998, that describes procedures for removing, inspecting, 
and, if necessary, replacing HPC impellers, P/N's 3073393-1, 3073394-1, 
3073433-1, 3073434-1 with serviceable impellers. The FAA has 
subsequently reviewed and approved ASB TFE731-A72-3641, Revision 1, 
dated October 20, 1999, that adds P/N's 3073398-All (where All denotes 
all dash numbers), 3073435-All, and 3075171-All.

Proposed Requirements of This AD

    Since an unsafe condition has been identified that is likely to 
exist or develop on other engines of the same type design, this AD is 
being issued to prevent failure of the HPC impeller due to fatigue 
cracks. This AD requires removing and inspecting the HPC impeller, and 
if necessary, replacing the HPC impeller with a serviceable impeller. 
The removal and inspection will be conducted at the next CZI or at the 
next access to the HPC module, and repetitive inspections at each 
subsequent CZI or each subsequent access to the HPC module if the 
impeller has more than 1,000 cycles since the last ECI. These removals, 
inspections, and replacements must be done in accordance with the ASB 
described previously.

Comments About the Original NPRM

    Since the issuance of that NPRM, the FAA has received the following 
four comments:

Request To Eliminate the Terminating Action Paragraph

    The manufacturer comments that paragraph (d) of the proposal should 
be deleted and recommends adding those HPC impellers identified as 
constituting terminating action to the applicability of the AD. During 
further investigation, all HPC impeller designs were found to be at 
risk of fatigue cracking from the same cause, and, therefore, warrant 
the proposed ECI. The FAA agrees. Paragraph (d) has been deleted from 
this supplemental NPRM (SNPRM) and HPC impellers P/N's 3073398-All, 
3073435-All, and 3075171-All have been added to the applicability of 
the AD. At present, therefore, the proposal does not offer any 
terminating action to the required inspections. The FAA may undertake 
further rulemaking to terminate the ECI requirement.

Replace vs. Inspect

    The manufacturer also requests that proposed paragraphs (a) and (b) 
be reworded to state that operators must inspect the HPC impellers 
rather than replace the HPC impellers. The manufacturer believes that 
the use of the word replace may imply that operators must replace the 
HPC impeller with a new impeller at each time an inspection is 
required. The FAA agrees in part. As stated in the NPRM, only Honeywell 
International or persons trained by Honeywell International are 
properly equipped and qualified to perform this specialized ECI. The 
Service Bulletin directs operators to remove the HPC impeller and ship 
the impeller to a facility that can perform the inspection.
    Using the words remove and inspect more accurately describe the 
actions the FAA is requiring of operators. The FAA has added a 
provision to both paragraphs (a) and (b), however, that operators must 
remove and inspect, and if necessary replace, applicable HPC impellers 
with ``serviceable'' impellers, and added a new paragraph (d) that 
defines ``serviceable'' as an impeller which complies with all 
applicable visual, dimensional, and fluorescent penetrant inspections 
requirements for the level of maintenance being accomplished, as 
contained in the Heavy Maintenance Manual and is either an impeller 
with fewer than 1000 engine operation cycles since new or an impeller 
with less than 1000 engine operation cycles since last ECI.

Request To Change Note 2 of the NPRM

    The manufacturer suggests that the words ``Introduction of'' should 
be deleted from proposed Note 2 following proposed paragraph (d). The 
FAA has already deleted paragraph (d) in response to the manufacturer's 
earlier comment, and therefore Note 2 has also been deleted in its 
entirety.

Request To Change the Unsafe Condition Statement

    The manufacturer believes that the unsafe condition statements in 
the preamble and text of the NPRM that describes the intent of the AD 
should be changed. The commenter states that the AD does not prevent 
fatigue cracking of the HPC impeller, but rather is intended to detect 
fatigue cracking of the impeller. The FAA agrees in part. The unsafe 
condition identified as the underlying justification for this AD is 
failure of the HPC impeller due to fatigue cracking. The actions 
required by the AD are not intended to prevent the HPC from cracking, 
but to prevent the HPC impeller from failing, which

[[Page 11944]]

could result in an uncontained engine failure, and damage to the 
airplane. Therefore, the preamble and text of this SNPRM has been 
changed to read that the AD is issued to prevent HPC impeller failure 
due to fatigue cracking.
    Since these changes expand the scope and cost of the originally 
proposed rule, the FAA has determined that it is necessary to reopen 
the comment period to provide additional opportunity for public 
comment.
    There are approximately 7510 engines of the affected design in the 
worldwide fleet. The FAA estimates that 5482 engines installed on 
aircraft of U.S. registry would be affected by this proposed AD, that 
it would take approximately 3 work hours per engine to accomplish the 
proposed actions, and that the average labor rate is $60 per work hour. 
The FAA also estimates that some of the impellers will be replaced, and 
that the impeller will cost about $45,000. Based on these figures, the 
FAA estimates the total cost impact of the proposed AD on U.S. 
operators for the next four years to be $2,201,760.

Regulatory Impact

    The regulations adopted herein will 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. Therefore, it 
is determined that this final rule does not have federalism 
implications under Executive Order (EO) 13132.
    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 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 adding the following new 
airworthiness directive:

Honeywell International Inc. TFE731-2, -3, -4, and -5 Series 
Turbofan Engines: Docket No. 99-ANE-10-AD.

    Applicability: Honeywell International Inc. (formerly 
AlliedSignal Inc. and Garrett Turbine Engine Company) TFE731-2, -3, 
-4, and -5 series turbofan engines with high pressure compressor 
(HPC) impeller part numbers (P/N's) 3073393-1, 3073394-1, 3073433-1, 
3073434-1, 3073398-All (where All denotes all dash numbers), 
3073435-All, and 3075171-All, installed on, but not limited to, 
Avions Marcel Dassault--Breguet Aviation (AMD/BA) Falcon 10, 
Dassault Aviation Mystere--Falcon 50, and 900 series airplanes; 
Dassault Aviation Mystere--Falcon 20 series airplanes, Learjet Inc. 
Models 31, 35, 36, and 55 series airplanes; Lockheed-Georgia 
Corporation 1329-23 and -25 series airplanes; Israel Aircraft 
Industries Ltd. 1124 series and 1125 Westwind series airplanes; 
Cessna Aircraft Co. Model 650 Citation III, VI, and VII series 
airplanes; Raytheon Aircraft Co. HS-125 series airplanes; and 
Sabreliner Corporation NA-265-65 airplanes.


    Note 1: This airworthiness directive (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 (e) 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: Required as indicated, unless accomplished 
previously.
    To prevent failure of the high pressure compressor impeller due 
to fatigue cracking, accomplish the following:
    (a) Remove and inspect the applicable HPC impeller in accordance 
with Section 2.A. of the Accomplishment Instructions of AlliedSignal 
Inc. Alert Service Bulletin (ASB) TFE731-A72-3641, Revision 1, dated 
October 20, 1999, or ASB TFE731-A72-3641 dated November 24, 1998, 
and if necessary, replace the impeller with a serviceable impeller, 
at the earlier of the following:
    (1) At the next core zone inspection (CZI) after the effective 
date of this AD, or
    (2) At the next access to the HPC module after the effective 
date of this AD.
    (b) Thereafter, remove and inspect the applicable HPC impeller 
in accordance with Section 2.A. of the Accomplishment Instructions 
of ASB TFE731--A72-3641 dated November 24, 1998, or ASB TFE731-A72-
3641, Revision 1, dated October 20, 1999, and if necessary, replace 
the impeller with a serviceable impeller, whenever either of the 
following conditions are met:
    (1) At every CZI, or
    (2) At access to the HPC module if the impeller has accumulated 
more than 1,000 cycles since the last Eddy Current Inspection (ECI).
    (c) This AD defines access to the HPC module as whenever the low 
pressure compressor case is removed from the compressor interstage 
diffuser.
    (d) For the purposes of this AD, a serviceable impeller is 
defined as an impeller which complies with all applicable visual, 
dimensional, and fluorescent penetrant inspections requirements for 
the level of maintenance being accomplished, as contained in the 
Heavy Maintenance Manual and is either an impeller with fewer than 
1000 engine operation cycles since new or an impeller with less than 
1000 engine operation cycles since last ECI.
    (e) 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.

    (f) 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 March 1, 2000.
Diane S. Romanosky,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 00-5460 Filed 3-6-00; 8:45 am]
BILLING CODE 4910-13-U