[Federal Register Volume 63, Number 239 (Monday, December 14, 1998)]
[Proposed Rules]
[Pages 68708-68710]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-33027]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-42-AD]
RIN 2120-AA64


Airworthiness Directives; AlliedSignal Inc. (formerly Textron 
Lycoming) ALF502R-5 and ALF502R-3A Model 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 AlliedSignal Inc. ALF502R-5 and 
ALF502R-3A model turbofan engines. This proposal would require 
incorporation of an improved fan core inlet anti-ice system. This 
proposal is prompted by reports of uncommanded reduction of engine 
thrust (rollback) and loss of thrust control in icing conditions. The 
actions specified by the proposed AD are intended to prevent ice 
accretion on the fan core inlet stator vane surfaces, which can result 
in engine rollback and loss of thrust control in icing conditions.

DATES: Comments must be received by February 12, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

[[Page 68709]]

Administration (FAA), New England Region, Office of the Regional 
Counsel, Attention: Rules Docket No. 98-ANE-42-AD, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may also be sent 
via the Internet using the following address: ``9-ad-
[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 Engines, Inc., P.O. Box 5218, Phoenix, AZ 
85072-2181, 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: Eugene Triozzi, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7148, fax (781) 238-7199.

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 98-ANE-42-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    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. 98-ANE-42-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    The Federal Aviation Administration (FAA) has received reports of 
uncommanded reduction of engine thrust (rollback), and loss of thrust 
control on AlliedSignal Inc. (formerly Textron Lycoming) ALF502R-5 
model turbofan engines. 12 rollback events have been recorded to date, 
which all occurred in icing conditions at altitudes above 26,000 feet, 
and generally near areas of weather conditions that can be described as 
the anvil area of thunderstorm clouds. Seven events involved 
simultaneous rollbacks of multiple engines on the four-engine British 
Aerospace (BAe) 146 airplane.
    The FAA Transport Airplane Directorate (TAD) issued Airworthiness 
Directive (AD) 94-07-09, effective on April 15, 1994, to require 
airplane altitude restrictions and operating procedures, to prevent 
engine rollbacks during flight in icing conditions. Following two 
additional rollback events during aircraft operation in icing 
conditions above 26,000 feet, the FAA TAD issued emergency AD 96-14-09 
effective on July 2, 1997, to supersede AD 94-07-09. AD 96-14-09 
carried over the earlier AD's altitude restrictions, and revised the 
Aircraft Flight Manual (AFM) airplane operating procedures.
    The FAA Engine Certification Office (ECO) has reviewed the results 
of engine investigations, component icing tests, and in-flight engine 
icing tests of the present ALF502R-5 engine, which showed that 
accretion of ice may occur in the ALF502R-5 engine fan core inlet at 
stator vane surfaces, under specific icing conditions identified as ice 
crystals, which are likely to be encountered in weather occurring 
within the approved engine operating envelope. This ice accretion 
adversely restricts airflow to the engine core, causing rollback, 
progressing to further ice accretion and worsening rollback severity. 
This condition, if not corrected, can result in engine rollback and 
loss of thrust control.
    The FAA ECO has reviewed the results of analyses, component tests, 
and in-flight engine testing of modifications of the ALF502R-5 engine, 
to incorporate an improved fan core inlet anti-ice system. These data 
show the engine modifications to be acceptable to prevent adverse ice 
accretion and engine rollback in icing conditions. The FAA ECO has 
reviewed and approved the technical contents of AlliedSignal Inc. 
Service Bulletin (SB) No. ALF/LF 72-1020, Revision 2, dated September 
30, 1998, that describes procedures for installation of the improved 
fan core inlet anti-ice system. Installation of modified ALF502 engines 
onto BAe 146 aircraft also requires incorporation of two airframe 
modifications, contained in BAe Regional Aircraft SB 26-40-01601A, 
dated March 25, 1998, and SB 71-68-01581A, Revision 1, dated March 25, 
1998.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, this 
proposed AD would require installation of an improved fan core inlet 
anti-ice system, at the next shop visit, but no later than December 31, 
2002.
    The compliance end date of not later than December 31, 2002, was 
determined based on safety analysis considering the projected ALF502R-5 
engine fleet rollback rate and projected cumulative unmodified engine 
operating hours.
    The requirement for compliance at next shop visit was determined 
based upon average engine hourly usage between shop visits, and the 
corresponding modification incorporation rate assumed by the safety 
analysis. The shop visit requirement, rather than a specific hourly 
usage, was intended to allow modifications to occur concurrently with 
periodic maintenance.
    The actions would be required to be accomplished in accordance with 
the SBs described previously.
    The FAA TAD is considering new rulemaking to allow BAe 146-100A, -
200A and -300A aircraft, equipped with all four engines modified, to be 
excluded from the altitude restrictions and operating procedures of AD 
96-14-09. To be considered for that exclusion, modifications of the 
aircraft associated with the engine modifications, changes to 
limitations placards, and revisions of the AFM, will be required to be 
accomplished on the aircraft in accordance with the previously 
mentioned BAe SBs, BAe SB 71-72-30473A, and certain FAA approved AFM 
revisions.
    There are approximately 982 engines of the affected design in the 
worldwide fleet. The FAA estimates that 100 engines installed on 
aircraft of U.S.

[[Page 68710]]

registry would be affected by this proposed AD, that it would take 
approximately 30 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 $75,000 per engine. Based on these 
figures, the cost impact for incorporation of engine modifications 
required by the proposed AD on U.S. operators is estimated to be 
$7,680,000.
    In addition to the above engine modifications, further aircraft 
modifications specified by BAe SB No. 71-68-01581A, and BAe SB No. 26-
40-01601A, Revision 1, are required prior to installation of modified 
engines onto BAe 146 aircraft. The FAA estimates that 20 aircraft of 
U.S. registry would be affected by this proposed AD, that it would take 
approximately 33 work hours per aircraft to accomplish the proposed 
actions, and that the average labor rate is $60 per work hour. Required 
parts would cost approximately $2,400 per aircraft. Based on these 
figures, the cost impact for incorporation of aircraft modifications 
required by the proposed AD on U.S. operators is estimated to be 
$87,600.
    Based on these figures, the total cost impact of the proposed AD on 
U.S. operators is estimated to be $7,767,600.
    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. 98-ANE-42-AD.

    Applicability: AlliedSignal Inc. (formerly Textron Lycoming) 
ALF502R-5 and ALF502R-3A model turbofan engines, installed on but 
not limited to British Aerospace (BAe) 146100A, -200A and -300A 
series aircraft.

    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 (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: Required as indicated, unless accomplished 
previously.
    To prevent uncommanded reduction of engine thrust and loss of 
thrust control in icing conditions, accomplish the following:
    (a) At the next engine shop visit, but not later than December 
31, 2002, install an improved fan core inlet anti-ice system in 
accordance with Accomplishment Instructions, Paragraphs 2.B. through 
2.I.(1-4), of AlliedSignal Inc. Service Bulletin (SB) No. ALF/LF 72-
1020, Revision 2, dated September 30, 1998. In order to install 
engines with the required modifications onto BAe 146-100A, -200A and 
-300A series aircraft, accomplish BAe Regional Aircraft SB No. 2640-
01601A, dated March 25, 1998, and BAe Regional Aircraft SB No. 71-
68-01581A, Revision 1, dated March 25, 1998.
    (b) For the purpose of this AD, an engine shop visit is defined 
as maintenance that includes separation of either the fan module or 
the combustor turbine module from the remainder of the engine.
    (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, Engine 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, Certification Office.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Engine Certification Office.

    (d) 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 December 7, 1998.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service
[FR Doc. 98-33027 Filed 12-11-98; 8:45 am]
BILLING CODE 4910-13-P