DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION

14 CFR Part 39

[Docket No. FAA-2006-24261; Directorate Identifier 2006-NE-12-AD]
RIN 2120-AA64

AIRWORTHINESS DIRECTIVES; General Electric Company Aircraft
Engines (GEAE) CT7-8A Turboshaft Engines

AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede an existing airworthiness directive
(AD)  for  certain  GEAE  CT7-8A  turboshaft  engines.  That  AD currently
requires  initial  and  repetitive  inspections  of  the  electrical  chip
detectors for the No. 3  bearing. This proposed AD would  require removing
certain GEAE  CT7-8A turboshaft  engines within  6,200 cycles-  since-new.
This proposed  AD results  from investigation  for the  root causes of two
failures of the No. 3 bearing. We are proposing this AD to prevent failure
of the No. 3 bearing due  to contamination by Aluminum Oxide, which  could
result in a possible dual in-flight shutdown of the engines.

DATES: We must receive any comments on this proposed AD by May 19, 2008.

ADDRESSES: Use one of the following addresses to comment on this  proposed
AD.

Federal eRulemaking Portal: Go  to http:// www.regulations.gov and  follow
the instructions for sending your comments electronically.

Mail: Docket Management Facility, U.S. Department of Transportation,  1200
New  Jersey  Avenue,  SE.,  West  Building  Ground  Floor,  Room  W12-140,
Washington, DC 20590-0001.

Hand Delivery: Deliver to  Mail address above between  9 a.m. and 5  p.m.,
Monday through Friday, except Federal holidays.

Fax: (202) 493-2251.

Contact General  Electric Aircraft  Engines CT7  Series Turboprop Engines,
1000 Western  Ave., Lynn,  MA 01910;  telephone (781)  594-3140, fax (781)
594-4805, for the service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT: Christopher Richards, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New
England     Executive     Park,     Burlington,    MA    01803;    e-mail:
christopher.j.richards@faa.gov; telephone  (731) 238-7133;  fax (781)  238
-7199.

SUPPLEMENTARY INFORMATION:

COMMENTS INVITED

We  invite you  to send  any written  relevant data,  views, or  arguments
regarding this  proposal. Send  your comments  to an  address listed under
ADDRESSES.  Include  "Docket  No.  FAA-2006-24261;  Directorate Identifier
2006-NE-12-AD"  in  the subject  line  of your  comments.  We specifically
invite comments  on the  overall regulatory,  economic, environmental, and
energy aspects of the proposed AD. We will consider all comments  received
by  the closing  date and  may amend  the proposed  AD in  light of  those
comments.

We  will  post  all  comments  we  receive,  without  change,  to  http://
www.regulations.gov, including  any personal  information you  provide. We
will also post a report  summarizing each substantive verbal contact  with
FAA personnel concerning  this proposed AD.  Using the search  function of
the DMS  Web site,  anyone can  find and  read the  comments in any of our
dockets, including  the name  of the  individual who  sent the comment (or
signed the  comment on  behalf of  an association,  business, labor union,
etc.). You  may review  the DOT's  complete Privacy  Act Statement  in the
Federal Register published on April 11,  2000 (65 FR 19477-78) or you  may
visit http://www.regulations.gov.

EXAMINING THE AD DOCKET

You   may   examine   the   AD  docket   on   the   Internet   at  http://
www.regulations.gov; or in person at the Docket Operations office  between
9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The  AD
docket contains this proposed AD, the regulatory evaluation, any  comments
received,  and  other  information.  The  street  address  for  the Docket
Operations  office (telephone  (800) 647-5527)  is  the  same as  the Mail
address provided in the ADDRESSES  section. Comments will be available  in
the AD docket shortly after receipt.

DISCUSSION

The FAA proposes to  amend 14 CFR part  39  by superseding AD  2006-06-51,
Amendment 39-14566 (71 FR 19627, April 17, 2006). That AD requires:

Within  25 hours  time-in-service after  the effective  date of  that AD,
inspecting the electrical chip detector assembly.

Staggering the inspection intervals so the chip detectors on both  engines
on the same helicopter are not inspected at the same time.

Thereafter,  within  25  hours  time-since-last  inspection,  performing a
repetitive inspection, and

If the chip detector assembly contains any bearing material, replacing the
engine.

That AD was the result of two failures of the No. 3 bearing in GEAE CT7-8A
turboshaft engines. That  condition, if not  corrected, could result  in a
possible dual in-flight shutdown of the engines.

ACTIONS SINCE AD 2006-06-51 WAS ISSUED

Since we issued  that AD, GEAE  has developed new  procedures for flushing
Aluminum Oxide  hard particle  contamination from  the air  cavity of  the
engine structure's  front frame  after the  manufacturing process  and for
assembling the No.  3 bearing to  the engine. Based  on that new  flushing
procedure, we are proposing to:

Delete the requirements to inspect the electrical chip detector, and

Require removing any engine that has a serial number (SN) listed in  Table
1 of this  proposed AD unless  the front frame  was flushed and  the No. 3
bearing replaced, and

Prohibit installing any  engine that has  a SN listed  in Table 1  of this
proposed AD  unless the  front frame  was flushed  and the  No. 3  bearing
replaced.

RELEVANT SERVICE INFORMATION

We  have reviewed  and approved  the technical  contents  of  GEAE Service
Bulletin (SB) CT7-8  S/B 72-0017, dated  October 18, 2007,  that describes
procedures for  flushing the  engine front  frame and  replacing the No. 3
bearing.

FAA'S DETERMINATION AND REQUIREMENTS OF THE PROPOSED AD

We  have  evaluated all  pertinent  information and  identified  an unsafe
condition that is  likely to exist  or develop on  other products of  this
same type design. For that reason,  we are proposing this AD, which  would
require removing certain GEAE CT7-8A  turboshaft engines, listed by SN  in
this proposed AD, from service within 6,200 cycles- since-new, and,  after
the effective date of the  proposed AD, would prohibit installing  certain
GEAE CT7-8A turboshaft engines, listed by SN in this proposed AD.

COSTS OF COMPLIANCE

We estimate  that this  proposed AD  would affect  29 engines installed on
helicopters of U.S.  registry. We also  estimate that it  would take about
66.0 work-hours per engine to  perform the proposed actions, and  that the
average labor rate is $80  per work-hour. Required parts would  cost about
$3,476 per engine. Based on these  figures, we estimate the total cost  of
the proposed AD to U.S. operators to be $253,924

AUTHORITY FOR THIS RULEMAKING

Title 49 of the United States Code specifies the FAA's authority to  issue
rules on aviation safety. Subtitle I, Section 106, describes the authority
of the FAA  Administrator. Subtitle VII,  Aviation Programs, describes  in
more detail the scope of the Agency's authority.

We are issuing this rulemaking  under the authority described in  Subtitle
VII, Part  A, Subpart  III, Section  44701, "General  requirements." Under
that section, Congress charges the FAA with promoting safe flight of civil
aircraft  in  air  commerce  by  prescribing  regulations  for  practices,
methods, and procedures  the Administrator finds  necessary for safety  in
air  commerce.  This regulation  is  within the  scope  of that  authority
because  it addresses  an unsafe  condition  that  is likely  to exist  or
develop on products identified in this rulemaking action.

REGULATORY FINDINGS

We  have  determined  that  this proposed  AD  would  not  have federalism
implications under Executive Order 13132. This proposed AD would 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.

For the reasons discussed above, I certify that the proposed AD:

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. Would not have a significant economic impact, positive or negative,  on
a  substantial  number  of  small  entities  under  the  criteria  of  the
Regulatory Flexibility Act.

We prepared a regulatory evaluation of the estimated costs to comply  with
this proposed AD. See the ADDRESSES section for a location to examine  the
regulatory evaluation.

LIST OF SUBJECTS IN 14 CFR PART 39

Air transportation, Aircraft, Aviation safety, Safety.

THE PROPOSED AMENDMENT

Under the  authority delegated  to me  by the  Administrator, the  Federal
Aviation Administration proposes to amend 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. The FAA amends Sec.  39.13 by removing Amendment 39-14566 (71 FR 19627,
April 17, 2006)  and by adding  a new airworthiness  directive to read  as
follows: