[Federal Register Volume 62, Number 235 (Monday, December 8, 1997)]
[Rules and Regulations]
[Pages 64517-64519]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-31966]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-ANE-31-AD; Amendment 39-10233; AD 97-25-09]
RIN 2120-AA64


Airworthiness Directives; Allison Engine Company Model 250-C40B 
Turboshaft Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to Allison Engine Company Model 250-C40B turboshaft 
engines. This action requires installation of a placard requiring 
pilots to record torque level and time in service operating above 86% 
engine torque until the defective parts have been replaced, no later 
than December 31, 2000, or when certain maintenance actions are 
accomplished, or when certain operational restrictions are exceeded, 
whichever occurs earliest. This amendment is prompted by a report from 
Allison Engine Company of a manufacturing defect in certain helical 
power takeoff gearshaft assemblies, identified by serial numbers. The 
actions specified in this AD are intended to prevent fatigue failure of 
the helical power takeoff gearshaft assembly, which could result in a 
loss of engine power and inflight engine shutdown.

DATES: Effective December 23, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of December 23, 1997.
    Comments for inclusion in the Rules Docket must be received on or 
before February 6, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Regional 
Counsel, Attention: Rules Docket No. 97-ANE-31-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.
    The service information referenced in this AD may be obtained from 
Allison Engine Company, P.O. Box 420, Speed Code U-15, Indianapolis, IN 
46206-0420; telephone: (317) 230-6674. This information may be examined 
at the FAA, New England Region, Office of the Regional Counsel, 12 New 
England Executive Park, Burlington, MA; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: John Tallarovic, Aerospace Engineer, 
Chicago Aircraft Certification Office, FAA, Small Airplane Directorate, 
ACE-118C, 2300 East Devon Avenue, Des Plaines, IL 60018; telephone 
(847) 294-8180, fax (847) 294-7834.

SUPPLEMENTARY INFORMATION: The Federal Aviation Administration (FAA) 
received a report from Allison Engine Company of a manufacturing defect 
discovered in certain helical power takeoff gearshaft assemblies, part 
number (P/N) 23056617, installed on Model 250-C40B turboshaft engines. 
The manufacturing defect was discovered while measuring the depth of 
the case hardening of the gear. The manufacturing defect was caused by 
excessive removal of case hardened material from the gear during 
manufacturing. This condition, if not corrected, could result in 
fatigue failure of the helical power takeoff gearshaft assembly, which 
could result in a loss of engine power and inflight engine shutdown.
    The FAA has reviewed and approved the technical contents of Allison 
Alert Commercial Engine Bulletin (CEB) No. A-72-5009, dated May 21, 
1997, that lists by serial number (S/N) 49 affected engines, gearboxes, 
and gears. This CEB also describes procedures for replacement of 
affected helical power takeoff gearshaft assemblies with serviceable 
parts.
    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 a loss of engine power and inflight engine 
shutdown. This AD requires installation of a placard requiring pilots 
to record torque and time in service operating above 86% engine torque 
until replacement of defective helical power takeoff gearshaft 
assemblies with serviceable parts, and then the placard can be removed. 
The compliance times were determined based upon an analysis of the 
effect of gearbox assembly torque loading on component life. The 
actions are required to be accomplished in accordance with the CEB 
described previously.
    The operational limitations imposed by this AD have been 
coordinated with the Rotorcraft Directorate.

[[Page 64518]]

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD 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 97-ANE-31-AD.'' The postcard will be date stamped and 
returned to the commenter.
    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and is not a ``significant regulatory action'' 
under Executive Order 12866. It has been determined further that this 
action involves an emergency regulation under DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979). If it is determined 
that this emergency regulation otherwise would be significant under DOT 
Regulatory Policies and Procedures, a final regulatory evaluation will 
be prepared and placed in the Rules Docket. A copy of it, if filed, may 
be obtained from the Rules Docket at the location provided under the 
caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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:

97-25-09  Allison Engine Company: Amendment 39-10233. Docket 97-ANE-
31-AD.

    Applicability: Allison Engine Company Model 250-C40B turboshaft 
engines, with engines, gearboxes, and gears identified by serial 
number (S/N) in Allison Alert Commercial Engine Bulletin (CEB) No. 
A-72-5009, dated May 21, 1997. The 250-C40B engine is installed on 
and limited to the twin-engine Bell Helicopter Textron 430 series 
helicopters.

    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 (g) 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 failure of the helical power takeoff 
gearshaft assembly, which could result in a loss of engine power and 
inflight engine shutdown, accomplish the following for part number 
(P/N) 23056617, identified by S/N in Allison Alert CEB No. A-72-
5009, dated May 21, 1997:
    (a) Prior to further flight, install the following placard on 
the instrument panel in clear view of the pilot, ``RECORD TORQUE AND 
TIME ABOVE 86% ENGINE TORQUE.'' The placard shall be manufactured of 
a material that cannot be easily defaced or erased, and the 
lettering shall be block-style and at least \1/8\ inches in height. 
Additionally, the color and lettering must contrast with the 
background (color of placard material) such that it is legible.
    (b) Remove from service affected helical power takeoff gearshaft 
assemblies, P/N 23056617, and replace with serviceable parts, in 
accordance with Allison Alert CEB No. A-72-5009, dated May 21, 1997, 
when the first of the following conditions exists:
    (1) At the time of turbine overhaul; or
    (2) During gearbox disassembly for any reason; or
    (3) If any of the operational restrictions listed in paragraph 
(c) of this AD are exceeded; or
    (4) No later than December 31, 2000.
    (c) After the effective date of this AD, observe the following 
operational restrictions at all times, until paragraph (b) of this 
AD is complied with by installing serviceable helical power takeoff 
gearshaft assemblies:
    (1) Total operational time accumulated on the suspect helical 
power takeoff gearshaft assemblies may not exceed 1,750 hours time 
in service (TIS). Engines are to be operated in the torque sharing 
mode only.
    (2) Operation of the engine at power between 86% torque and 93% 
torque is limited to one hour prior to reaching 1,750 hours TIS.
    (3) Operation of the engine above 93% torque will require 
replacement of the helical power takeoff gearshaft assemblies. Any 
previously recorded time (Electronic Control Unit (ECU)), Integrated 
Instrument Display System ((IIDS) or Log Book) must be accounted 
for. Operators will be allowed four hours of operation at torque 
levels less than 86% torque to ferry the aircraft to a maintenance 
facility for replacement of the assembly unless any of the following 
have been exceeded:
    (i) Operation of the engine between 93% torque and 105% torque 
for more than six minutes requires replacement of the assembly 
before further flight.
    (ii) Operation of the engine between 105% torque and 110% torque 
for more than ninety seconds requires replacement of the assembly 
before further flight.
    (d) Revise the limitations section of the FAA-approved 
Rotorcraft Flight Manual (RFM) by inserting a copy of this AD. 
Thereafter, except as provided in paragraph (g) of this AD, no 
alternative limitations may be approved for affected helical power 
takeoff gearshaft assemblies, P/N 23056617.
    (e) After replacing parts in accordance with paragraph (b) of 
this AD, remove the placard

[[Page 64519]]

and the AD required by paragraphs (a) and (d) of this AD.
    (f) For the purposes of this AD, a serviceable helical power 
takeoff gearshaft assembly is one not identified by S/N in Allison 
Alert CEB No. A-72-5009, dated May 21, 1997.
    (g) 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, Chicago Aircraft Certification 
Office. Operators shall submit their requests through an appropriate 
FAA Principal Maintenance Inspector, who may add comments and then 
send it to the Manager, Chicago Aircraft 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 Chicago Aircraft Certification 
Office.

    (h) 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) and paragraph (c)(3) of this AD to operate 
the aircraft to a location where the requirements of this AD can be 
accomplished.
    (i) The actions required by this AD shall be done in accordance 
with the following Allison Alert CEB:

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            Document No.               Pages              Date          
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A-72-5009...........................      1-5  May 21, 1997.            
Total pages: 5.                                                         
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This incorporation by reference was approved by the Director of the 
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 
51. Copies may be obtained from Allison Engine Company, P.O. Box 
420, Speed Code U-15, Indianapolis, IN 46206-0420; telephone: (317) 
230-6674. Copies may be inspected at the FAA, New England Region, 
Office of the Assistant Chief Counsel, 12 New England Executive 
Park, Burlington, MA; or at the Office of the Federal Register, 800 
North Capitol Street, NW., suite 700, Washington, DC.
    (j) This amendment becomes effective on December 23, 1997.

    Issued in Burlington, Massachusetts, on November 28, 1997.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 97-31966 Filed 12-5-97; 8:45 am]
BILLING CODE 4910-13-U