DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION

14 CFR Part 39

[Docket No. FAA-2009-0811; Directorate Identifier 2008-NE-41-AD]
RIN 2120-AA64

AIRWORTHINESS DIRECTIVES; Rolls-Royce Corporation (RRC) AE 3007A
Series Turbofan 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 adopt a new airworthiness directive (AD)  for
RRC  AE 3007A  series turbofan  engines.  This  proposed AD  would require
removing or  performing initial  and repetitive  eddy current  inspections
(ECIs)  or  surface wave  ultrasonic  testing (SWUT)  inspections  on high
-pressure turbine (HPT) stage 2  wheels for cracks. This proposed  AD also
reduces  the approved  life limits  of certain  HPT stage  2 wheels.  This
proposed AD results  from reports of  cracked HPT stage  2 wheels. We  are
proposing this AD to prevent uncontained failure of the HPT stage 2  wheel
and damage to the airplane.

DATES: We must receive any comments on this proposed AD by March 22, 2010.

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.

You can get  the service information  identified in this  proposed AD from
Rolls-Royce Corporation, P.O.  Box 420, Speed  Code U15, Indianapolis,  IN
46206-0420, e-mail: indy.pubs.services@rolls- royce.com.

FOR  FURTHER INFORMATION  CONTACT: Kyri  Zaroyiannis, Aerospace  Engineer,
Chicago Aircraft  Certification Office,  Small Airplane  Directorate, FAA,
2300    E.    Devon    Ave.,    Des    Plaines,    IL    60018;    e-mail:
kyri.zaroyiannis@faa.gov; telephone (847) 294-7836; fax (847) 294-7834.

SUPPLEMENTARY INFORMATION:

COMMENTS INVITED

We invite you to  send us any written  relevant data, views, or  arguments
regarding this  proposal. Send  your comments  to an  address listed under
ADDRESSES. Include "Docket No. FAA-2009-0811; Directorate Identifier  2008
-NE-41-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 Web site, anyone can find and read the comments in any of our dockets,
including, if provided,  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).

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

On September 8,  2008, we issued  emergency AD 2008-19-51  that applied to
RRC AE 3007A series turbofan engines. That AD required performing  initial
and repetitive eddy current inspections (ECIs) on HPT stage 2 wheels  that
have accumulated 6,500  or more cycles-since-new  (CSN). That AD  resulted
from reports of  HPT stage 2  wheels that had  cracks in the  bores of the
wheels.  This condition,  if not  corrected, could  result in  a  possible
uncontained failure of the HPT stage 2 wheel, which could cause damage  to
the airplane.

ACTIONS SINCE AD 2008-19-51 WAS ISSUED

After we issued emergency AD 2008-19-51, we determined that the cracks  in
the HPT stage 2 wheel bores are caused by a thermally-induced high  stress
in the disk  bore, which was  not identified at  the time of  the original
certification. We performed a new risk assessment for cracking in the bore
of the  HPT stage  2 wheel  using the  FAA methodology  guidelines in  FAA
Advisory Circular 39-8 and the results of the inspections from AD  2008-19
-51. The risk assessment takes into account physical characteristics about
the cracks that were not available  when we issued AD 2008-19-51. The  new
risk  assessment,  in  combination  with  a  sufficient  number  of  early
inspections,  showed that  the risk  profile was  not rapidly  increasing,
which  was  a  concern when  we  issued  AD 2008-  19-51.  Using  this new
information, we determined we could change the compliance requirements for
the ECI  while still  maintaining a  level of  safety consistent  with the
intent  of  the original  AD  2008-19-51. We  changed  the new  compliance
schedule to  an interval  of 150  cycles-in- service  (CIS) between  wheel
populations. The intervals  for the wheel  populations were based  on CSN,
and  they  varied  because  of the  distribution  of  the  affected wheels
throughout the fleet at that time. A distribution based on CSN resulted in
a compliance  schedule that  inspected the  fleet from  the highest  time,
highest risk wheels to the lowest time, lowest risk wheels. It allowed  us
to control the overall risk consistent with the intent of AD 2008-19-51.

We also determined that a requirement to perform the ECI by a certain  CIS
is by itself  sufficient to maintain  the level of  safety consistent with
the intent of the original  AD 2008-19-51. Because of that  determination,
we no longer prohibit installing any engine that had an HPT stage 2  wheel
with  more than  6,500 CSN  unless the  wheel was  inspected. Instead,  we
modified that requirement to apply only to HPT stage 2 wheels removed from
service as a result of complying  with AD 2008-26-06 or emergency AD  2008
-19-51.

Finally, we specified the part numbers (P/Ns) for the affected HPT stage 2
wheels to ensure proper identification.

On December 12,  2008, we issued  AD 2008-26-06 as  an immediately adopted
rule to  mandate a  short-term program  (90 days)  to ensure the continued
airworthiness of the product. That AD published in the Federal Register on
December 24, 2008 (73 FR 78927).

ACTIONS SINCE AD 2008-26-06 WAS ISSUED

A  few  months  after  we issued  AD  2008-26-06  we  received reports  of
additional cracks  in the  HPT stage  2 wheels.  A revised risk assessment
that included these additional reports indicated that we needed to require
a higher inspection rate. For this reason, we issued Emergency AD  2009-08
-51 on April 10, 2009. That AD also provides instructions for an  optional
SWUT inspection. We then published a final rule; request for comments  (74
FR 22091, May 12,  2009) to make the  emergency actions applicable to  all
persons.

We are  now proceeding  through the  normal rule  making process to ensure
full public comment on our proposed  actions. In this proposed AD, we  are
still requiring the same removal from service or ECI or SWUT  inspections,
but we are expanding the scope of the compliance schedule to more  engines
by including wheels  with lower CSN.  We are also  including a requirement
for  repetitive inspections.  In addition,  we have  identified by  serial
number a group of HPT stage 2 wheels that were repaired while  in-service;
because of  this repair  those wheels  can only  be inspected  by the  ECI
method. We have also determined that the engine cycle life limit (ECLL) of
the  HPT  stage 2  wheels,  P/N 23075345  and  23084520, covered  by  this
proposed AD should be reduced to 23,000 CSN and that the ECLL of all other
part number  HPT stage  2 wheels  covered by  this proposed  AD should  be
reduced to 20,000 CSN on the effective date of this AD.

The occurrence of cracked HPT stage 2 wheels has been shown by statistical
analysis of field data  to have a causal  link to a manufacturing  process
that led to incomplete shot peening on the drive arm fillets (shaft  inner
diameter fillet)  of the  wheel. Improvements  to the  fixed manufacturing
process have addressed this  incomplete peening condition. Therefore,  HPT
stage 2 wheels that have been determined to have been fully shot peened in
the drive arm fillet are excluded from the inspection requirements of this
proposed AD.

RELEVANT SERVICE INFORMATION

We have reviewed and approved the technical contents of:

RRC Alert Service Bulletin AE  3007A-A-72-367, Revision 2, dated June  22,
2009, that describes  procedures for ECI  of the HPT  stage 2 wheel  on AE
3007A series engines.

RRC Service Bulletin  AE 3007A-72-368, Revision  2, dated April  28, 2009,
that describes the procedures for SWUT inspection of the HPT stage 2 wheel
on AE 3007A series turbofan engines.

RRC Service Bulletin AE 3007A-72-369, Revision 2, dated November 5,  2009,
that describes the procedures for SWUT inspection of the HPT stage 2 wheel
on AE 3007A series turbofan engines.

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. We are proposing this AD, which would require:

Removing from service any engine with certain P/N HPT stage 2 wheels  that
have  a  CSN specified  in  Table 1  of  this AD  by  the compliance  time
specified in Table 1 of this AD; or

Performing an ECI  or SWUT inspection  on certain P/N  HPT stage 2  wheels
that have a  CSN specified in  Table 1 of  this AD by  the compliance time
specified in Table 1 of this AD; and

Performing repetitive ECI  or SWUT inspections  of the HPT  stage 2 wheels
within 3,000 cycles-since-last inspection.

You must use the service  information described previously to perform  the
actions required by this AD.

INTERIM ACTION

These  actions are  interim actions  and we  may take  further rulemaking
actions in the future.

COSTS OF COMPLIANCE

We estimate that this proposed  AD would affect 1402 engines  installed on
airplanes of U.S. registry.  We also estimate that  it would take about  2
work-hours per engine to perform both the proposed ECI and proposed  SWUT.
The average labor rate is $85 per work-hour. No parts are required for the
inspection. We estimate the prorated life lost per stage 2 wheel is  about
$13,177.  Based  on these  figures,  we estimate  the  total cost  of  the
proposed  AD  to  U.S.  operators  to  be  $18,712,494.  This  estimate is
exclusive of any warranty coverage.

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. You may get a copy of this summary at the address listed
under ADDRESSES.

LIST OF SUBJECTS IN 14 CFR PART 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference,
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 adding the  following new airworthiness
directive: