[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]


=======================================================================
-----------------------------------------------------------------------

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).

-----------------------------------------------------------------------

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: ``9-ane-
[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 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