[Federal Register Volume 64, Number 144 (Wednesday, July 28, 1999)]
[Proposed Rules]
[Pages 40789-40790]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-19322]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NE-10-AD]
RIN 2120-AA64
Airworthiness Directives; AlliedSignal Inc. TFE731 Turbofan
Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain AlliedSignal Inc. high
pressure compressor (HPC) impellers installed on TFE731 series turbofan
engines. This proposal would require replacing the HPC impeller with a
serviceable impeller that has been eddy-current inspected. This
proposal is prompted by an incident of an uncontained impeller failure
due to cracking in the seal relief area of the HPC impeller. The
actions specified by the proposed AD are intended to prevent fatigue
cracking of the HPC impeller, which could result in an uncontained
failure of the impeller, an in-flight engine shutdown, and damage to
the airplane.
DATES: Comments must be received by September 27, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Regional
Counsel, Attention: Rules Docket No.99-NE-10-AD, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may also be sent
via the Internet using the following address: ``adcomment@faa.gov.'' 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 AlliedSignal Aerospace Services Attn: Data Distribution,
M/S 64-3/2101-201, P.O. Box 29003, Phoenix, AZ 85038-9003; telephone
(602) 365-2493, fax (602) 365-5577. 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 notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 99-NE-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-NE-10-AD, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion
The Federal Aviation Administration (FAA) has determined that on
May 10, 1998, a high pressure compressor (HPC) impeller, part number
(P/N) 3073394-1, separated and exited from an AlliedSignal Inc. 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
AlliedSignal 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. This condition, if not corrected,
could result in fatigue cracking of the HPC impeller, which could
result in an uncontained failure of the impeller, an in-flight engine
shutdown, and damage to the airplane.
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 replacing the HPC
impellers, P/Ns 3073393-1, 3073394-1, 3073433-1, and 3073434-1 with
impellers that have been inspected using a specialized eddy
[[Page 40790]]
current inspection. At present, only AlliedSignal is properly trained
and equipped to perform this inspection that requires specialized
training and tooling. Within the near future, the FAA expects to
approve a revision to ASB TFE731-A72-3641 which will include a
reference to the eddy-current procedure document and additional
facilities that are properly trained and equipped to perform this
specialized inspection. The Final Rule will incorporate the revised
ASB.
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 fatigue cracking of the HPC impeller, which
could result in an uncontained failure of the impeller, an in-flight
engine shutdown, and damage to the airplane. This AD requires 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. These replacements must be done in accordance with the SB
described previously.
There are approximately 2,105 engines of the affected design in the
worldwide fleet. The FAA estimates that 1,537 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 to be $996,660.
The regulations proposed herein would 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
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
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:
AlliedSignal Inc.: Docket No. 99-NE-10-AD.
Applicability: AlliedSignal Inc. TFE731 series turbofan engines
with high pressure compressor (HPC) impeller part numbers (P/Ns)
3073393-1, 3073394-1, 3073433-1, and 3073434-1 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 fatigue cracking of the HPC impeller, which could
result in an uncontained failure of the impeller, an in-flight
engine shutdown, and damage to the airplane, accomplish the
following:
(a) Replace the HPC impeller, P/N's 3073393-1, 3073394-1,
3073433-1, and 3073434-1, in accordance with Section 2.A. of the
Accomplishment Instructions of AlliedSignal Alert Service Bulletin
(ASB) TFE731-A72-3641, dated November 24, 1998, 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, replace the HPC impeller,
P/N's 3073393-1, 3073394-1, 3073433-1, and 3073434-1, in accordance
with Section 2.A. of the Accomplishment Instructions of AlliedSignal
SB TFE731-A72-3641, dated November 24, 1998, whenever either of the
following conditions are met:
(1) At every CZI, or
(2) When accessing the HPC module and the impeller has
accumulated more than 1,000 cycles since the last 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) Installation of HPC impellers having
P/N's 3073398-X, 3073435-X, and 3075171-X, where ``X'' represents
any dash number, constitutes terminating action for the inspection
requirements of this AD.
Note 2: Installation of HPC impellers having P/N's 3070274-1 and
3072639-1, which are subject to AD 82-23-03 R1, are not considered
eligible parts for terminating action.
(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. Operators shall submit their request through an appropriate
FAA Principal Maintenance Inspector, who may add comments and then
send it to the Manager, Los Angeles Aircraft Certification Office.
Note 3: Information concerning the existence of approved
alternative methods of compliance with this airworthiness directive,
if any, may be obtained from the Los Angeles Aircraft Certification
Office.
(f) Special flight permits may be issued in accordance with
Secs. 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 July 22, 1999.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 99-19322 Filed 7-27-99; 8:45 am]
BILLING CODE 4910-13-P
