
[Federal Register Volume 76, Number 57 (Thursday, March 24, 2011)]
[Rules and Regulations]
[Pages 16526-16530]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-6719]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-0452; Directorate Identifier 98-ANE-80-AD; 
Amendment 39-16639; AD 2011-07-02]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney JT8D-209, -217, -217A, 
-217C, and -219 Series Turbofan Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are superseding an existing airworthiness directive (AD) 
for the products listed above. That AD currently requires initial and 
repetitive torque inspections of the 3rd stage and 4th stage low-
pressure turbine (LPT) blades for shroud notch wear and replacement of 
the blade if wear limits are exceeded. That AD also requires replacing 
LPT-to-exhaust case bolts and nuts with bolts and nuts made of Tinidur 
material. This new AD requires the same torque inspection, blade, and 
Tinidur nut replacement actions, but requires replacement of the LPT-
to-exhaust case bolts with longer bolts made of Tinidur material. This 
AD also requires installation of crushable sleeve spacers on the bolts. 
This AD was prompted by nine reports of failure of Tinidur material 
LPT-to-exhaust case bolts, as a result of blade failure, since AD 2005-
02-03 became effective. We are issuing this AD to prevent turbine blade 
failures that could result in uncontained engine debris and damage to 
the airplane.

DATES: This AD is effective April 28, 2011. The Director of the Federal 
Register approved the incorporation by reference of certain 
publications listed in the AD as of April 28, 2011.

ADDRESSES: For service information identified in this AD, contact Pratt 
& Whitney, 400 Main St., East Hartford, CT 06108; phone: (860) 565-
8770, fax: (860) 565-4503. You may review copies of the referenced 
service information at the FAA, Engine & Propeller Directorate, 12 New 
England Executive Park, Burlington, MA. For information on the 
availability of this material at the FAA, call 781-238-7125.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this AD, the regulatory evaluation, 
any comments received, and other information. The address for the 
Docket Office (phone: 800-647-5527) is Document Management Facility, 
U.S. Department of Transportation, Docket Operations, M-30, West 
Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., 
Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Ian Dargin, Aerospace Engineer, Engine 
Certification Office, FAA, Engine and Propeller Directorate, 12 New 
England Executive Park; Burlington, MA 01803; phone: 781-238-7178; fax: 
781-238-7199; e-mail: ian.dargin@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to supersede AD 2005-02-03, Amendment 39-13948 (70 FR 3867, 
January 27, 2005). That AD applies to the specified products. The NPRM 
published in the Federal Register on July 1, 2010 (75 FR 38052). That 
NPRM proposed the same torque inspection, blade, and LPT-to-exhaust 
case retaining nut replacement actions as the superseded AD, but would 
also require replacement of the LPT-to-exhaust case bolts with longer 
bolts made of Tinidur material. That NPRM also proposed to require 
installation of crushable sleeve spacers on the LPT-to-exhaust case 
bolts.

Comments

    We gave the public the opportunity to participate in developing 
this AD. We have considered the comments received.

Request to Include Other FAA-Approved Methods

    One commenter, American Airlines, requested that paragraph (s) of 
the proposed AD be revised to include other FAA-approved methods not 
published in the OEM's engine manual.
    We agree and changed paragraph (t) to state: ``For the purpose of 
this AD, ``refurbished'' is defined as restoration of the shrouds and/
or blade re-twist per the JT8D-200 Engine Manual, Part No. 773128, or 
per an operator's approved manual system.''

[[Page 16527]]

Request To Allow Compliance to Alert Service Bulletin (ASB) Revision 5 
or Revision 6

    One commenter, Delta Airlines, requested that we allow compliance 
using either PW ASB No. JT8D A6224, Revision 5, dated June 11, 2004, or 
Revision 6, dated May 3, 2007. They stated that their experience with 
back-to-back testing both with and without notch gauge support did not 
show any measurable differences. Revision 6 introduced the notch gauge 
support.
    We do not agree. Revision 6 of the ASB provides an improved method 
of inspection that ensures that the arm of the inspection tool is 
parallel to the engine center line during the inspection. This yields 
more accurate inspection results. We do allow previous credit using 
Revision 5 of the ASB for performing an initial inspection before the 
effective date of the AD. We did not change the AD.

Request To Change ``Modified'' to ``As-Cast''

    One commenter, Turborreactores S.A. de C.V., stated that in Table 
4, item 5, the term ``Modified'' should be changed to ``As-Cast'' to 
correctly identify the blades.
    We do not agree. PW Service Bulletin No. JT8D 6090 is referenced in 
ASB No. JT8D A6224. PW Service Bulletin No. JT8D 6090 released both a 
new ``as-cast'' blade and instructions for a field modification of 
existing blades, which could result in ``modified'' blades in the 
field. We did not change the AD.

Suggestion That Proposed AD Does Not Address Root Cause

    One commenter, Scandinavian Airlines System, suggested that the 
proposed AD does not address the root cause of LPT failures, which they 
state is stage 3/stage 4 LPT turbine blades shroud wear and subsequent 
high-cycle fatigue. They suggested that the proposed AD will probably 
improve containment with the new design of longer case bolts with 
crushable sleeves, but they will not eliminate the root cause of LPT 
failures.
    We do not agree. This AD addresses the stage 3 and stage 4 turbine 
blade shroud notch wear with initial and repetitive torque inspections. 
The longer Tinidur material LPT case bolts with crushable spacers will 
prevent bolt fractures and/or case ripping near the flange, and will 
result in only a 2.02 pound weight increase. We did not change the AD.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
the AD with the change described previously. We have determined that 
this change will neither increase the economic burden on any operator 
nor increase the scope of the AD.

Costs of Compliance

    We estimate that this AD will affect 1,143 engines installed on 
airplanes of U.S. registry. We also estimate that it will take about 1 
work-hour per engine to perform the 3rd and 4th stage LPT blade 
inspection, and 1.5 work-hours per engine to replace the LPT-to-exhaust 
case bolts and nuts and install the crushable sleeve spacers. Required 
bolts, nuts, and sleeve spacers will cost about $4,576 per engine. We 
anticipate that 61 engines will also require blade replacement each 
year. Required blades will cost about $131,560 per engine. The average 
labor rate is $85 per work-hour. Based on these figures, we estimate 
the total cost of the AD to U.S. operators to be $13,617,671.

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 AD will not have federalism 
implications under Executive Order 13132. This AD will 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 this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866;
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and
    (3) Will not affect intrastate aviation in Alaska, and
    (4) 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.

List of Subjects in 14 CFR Part 39

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

Adoption of the Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The FAA amends Sec.  39.13 by removing airworthiness directive (AD) 
2005-02-03, Amendment 39-13948 (70 FR 3867, January 27, 2005), and 
adding the following new AD:

2011-07-02 Pratt & Whitney: Amendment 39-16639. Docket No. FAA-2010-
0452; Directorate Identifier 98-ANE-80-AD.

Effective Date

    (a) This airworthiness directive (AD) is effective April 28, 
2011.

Affected ADs

    (b) This AD supersedes AD 2005-02-03, Amendment 39-13948.

Applicability

    (c) This AD applies to Pratt & Whitney (PW) JT8D-209, -217, -
217A, -217C, and -219 series turbofan engines. These engines are 
installed on, but not limited to, Boeing 727 series and McDonnell 
Douglas MD-80 series airplanes.

Unsafe Condition

    (d) This AD results from nine reports of failure of Tinidur 
material LPT-to-exhaust case bolts, as a result of blade failure, 
since AD 2005-02-03 became effective. We are issuing this AD to 
prevent turbine blade failures that could result in uncontained 
engine debris and damage to the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified unless the 
actions have already been done.

[[Page 16528]]

Requirements of AD 2005-02-03

Initial Torque Inspection for JT8D-209, -217, and -217A Engines

    (f) For JT8D-209, -217, and -217A engines, perform the initial 
torque inspection of 3rd and 4th stage LPT blades for shroud notch 
wear. Use the procedures described in Accomplishment Instructions, 
Part 1, Paragraphs 1 through 3, of PW Alert Service Bulletin (ASB) 
No. JT8D A6224, Revision 6, dated May 3, 2007, at the applicable 
threshold in the following Table 1:

               Table 1--Initial Torque Inspection Threshold for JT8D-209, -217, and -217A Engines
----------------------------------------------------------------------------------------------------------------
                                       Hours time-in-service (TIS) as of March 3,
              Blade type               2005 (the effective date of AD 2005-02-03)       Inspection threshold
----------------------------------------------------------------------------------------------------------------
(1) New pre-Service Bulletin (SB) No.  Any number................................  Within 6,000 hours TIS.
 5867 (small notch) 3rd stage turbine
 blades.
(2) Refurbished pre-SB No. 5867        (i) Fewer than 3,000......................  Within 4,000 hours TIS.
 (small notch) 3rd stage turbine
 blades.
                                       (ii) 3,000 or more........................  Within 6,000 hours TIS, or
                                                                                    within 1,000 hours TIS from
                                                                                    March 3, 2005, whichever
                                                                                    occurs first.
(3) New post-SB No. 5867 (large        Any number................................  Within 10,000 hours TIS.
 notch) 3rd stage turbine blades.
(4) Refurbished post-SB No. 5867       (i) Fewer than 6,000......................  Within 7,000 hours TIS.
 (large notch) 3rd stage turbine
 blades.
                                       (ii) 6,000 or more........................  Within 8,000 hours TIS, or
                                                                                    within 1,000 hours TIS from
                                                                                    March 3, 2005, whichever
                                                                                    occurs first.
(5) New pre-SB No. 6029 (small notch)  Any number................................  Within 6,000 hours TIS.
 4th stage turbine blades.
(6) Refurbished pre-SB No. 6029        (i) Fewer than 3,000......................  Within 4,000 hours TIS.
 (small notch) 4th stage turbine
 blades.
                                       (ii) 3,000 or more........................  Within 6,000 hours TIS, or
                                                                                    within 1,000 hours TIS from
                                                                                    March 3, 2005, whichever
                                                                                    occurs first.
(7) New post-SB No. 6029 or new post-  Any number................................  Within 10,000 hours TIS.
 SB No. 6308 (large notch) 4th stage
 turbine blades.
(8) Refurbished post-SB No. 6029 or    (i) Fewer than 6,000......................  Within 7,000 hours TIS.
 refurbished post-SB No. 6308 (large
 notch) 4th stage turbine blades.
                                       (ii) 6,000 or more........................  Within 8,000 hours TIS, or
                                                                                    within 1,000 hours TIS from
                                                                                    March 3, 2005, whichever
                                                                                    occurs first.
----------------------------------------------------------------------------------------------------------------

Repetitive Torque Inspections for JT8D-209, -217, and -217A Engines

    (g) For JT8D-209, -217, and -217A engines, perform repetitive 
torque inspections of 3rd and 4th stage LPT blades for shroud notch 
wear. Use the procedures described in Accomplishment Instructions, 
Part 1, Paragraph 1 of PW ASB No. JT8D A6224, Revision 6, dated May 
3, 2007, at the applicable intervals in the following Table 2 and 
Table 3:

         Table 2--3rd Stage Repetitive Torque Inspection Intervals for JT8D-209, -217, and -217A Engines
----------------------------------------------------------------------------------------------------------------
      Inspection torque readings                   Number of readings                       Disposition
----------------------------------------------------------------------------------------------------------------
Greater than or equal to 15 LB-IN      All.......................................  Repeat torque inspection
 (1.695 N.m).                                                                       within 1,000 hours TIS since
                                                                                    last inspection.
Less than 15 LB-IN (1.695 N.m) but     One or more...............................  Repeat torque inspection
 greater than or equal to 10 LB-IN                                                  within 500 hours TIS since
 (1.130 N.m).                                                                       last inspection.
Less than 10 LB-IN (1.130 N.m) but     One to three..............................  Repeat torque inspection
 greater than or equal to 5 LB-IN                                                   within 125 hours TIS since
 (0.565 N.m).                                                                       last inspection.
Less than 10 LB-IN (1.130 N.m) but     Four or more..............................  Remove engine from service
 greater than or equal to 5 LB-IN                                                   within 20 hours TIS since
 (0.565 N.m).                                                                       last inspection.
Less than 5 LB-IN (0.565 N.m)........  One or more...............................  Remove engine from service
                                                                                    within 20 hours TIS since
                                                                                    last inspection.
----------------------------------------------------------------------------------------------------------------


         Table 3--4th Stage Repetitive Torque Inspection Intervals for JT8D-209, -217, and -217A Engines
----------------------------------------------------------------------------------------------------------------
      Inspection torque readings                   Number of readings                       Disposition
----------------------------------------------------------------------------------------------------------------
Greater than or equal to 15 LB-IN      All.......................................  Repeat torque inspection
 (1.695 N.m).                                                                       within 1,000 hours TIS since
                                                                                    last inspection.
Less than 15 LB-IN (1.695 N.m) but     One or more...............................  Repeat torque inspection
 greater than or equal to 10 LB-IN                                                  within 500 hours TIS since
 (1.130 N.m).                                                                       last inspection.
Less than 10 LB-IN (1.130 N.m) but     One to six................................  Repeat torque inspection
 greater than or equal to 5 LB-IN                                                   within 125 hours TIS since
 (0.565 N.m).                                                                       last inspection.
Less than 10 LB-IN (1.130 N.m) but     Seven or more.............................  Remove engine from service
 greater than or equal to 5 LB-IN                                                   within 20 hours TIS since
 (0.565 N.m).                                                                       last inspection.
Less than 5 LB-IN (0.565 N.m)........  One or more...............................  Remove engine from service
                                                                                    within 20 hours TIS since
                                                                                    last inspection.
----------------------------------------------------------------------------------------------------------------


[[Page 16529]]

     (h) Subsequent repeat inspection intervals must not exceed the 
previous inspection interval.

JT8D-209, -217, and -217A Engines Removed From Service

    (i) JT8D-209, -217, and -217A engines removed from service may 
be returned to service after a detailed inspection and repair or 
replacement of all blades of the failed stage, that exceed Engine 
Manual limits, is done. Information on repairing or replacing 
turbine blades can be found in Sections 72-53-12 through 72-53-13 of 
the JT8D-200 Engine Manual, Part No. 773128.

Initial Inspection for JT8D-217C and -219 Engines

    (j) For JT8D-217C and -219 engines, perform the initial torque 
inspection of 4th stage LPT blades for shroud notch wear. Use the 
procedures described in Accomplishment Instructions, Part 2, 
Paragraphs 1 through 3 of PW ASB No. JT8D A6224, Revision 6, dated 
May 3, 2007, at the applicable threshold in the following Table 4:

                   Table 4--Initial Torque Inspection Threshold for JT8D-217C and -219 Engines
----------------------------------------------------------------------------------------------------------------
              Blade type                         TIS as of March 3, 2005                Inspection threshold
----------------------------------------------------------------------------------------------------------------
(1) New pre-SB No. 6090 (small notch)  Any number................................  Within 5,000 hours TIS.
 4th stage turbine blades.
(2) Refurbished pre-SB No. 6090        (i) Fewer than 3,000......................  Within 4,000 hours TIS.
 (small notch) 4th stage turbine
 blades.
                                       (ii) 3,000 or more........................  Within 5,000 hours TIS, or
                                                                                    within 1,000 hours TIS from
                                                                                    March 3, 2005, whichever
                                                                                    occurs first.
(3) New post-SB No. 6090, new post-SB  Any number................................  Within 10,000 hours TIS.
 No. 6402, or new post-SB No. 6412
 (large notch) 4th stage turbine
 blades.
(4) Refurbished ``As-Cast'' post-SB    Any number................................  Within 7,000 hours TIS.
 No. 6090, post-SB No. 6402, or post-
 SB No. 6412 (large notch) 4th stage
 turbine blades.
(5) Refurbished ``Modified'' post-SB   (i) Fewer than 3,000......................  Within 4,000 hours TIS.
 No. 6090, post-SB No. 6402, or post-
 SB No. 6412 (large notch) 4th stage
 turbine blades.
                                       (ii) 3,000 or more........................  Within 7,000 hours TIS, or
                                                                                    within 1,000 hours TIS from
                                                                                    March 3, 2005, whichever
                                                                                    occurs first.
----------------------------------------------------------------------------------------------------------------

Repetitive Torque Inspections for JT8D-217C and -219 Engines

    (k) For JT8D-217C and -219 engines, perform repetitive torque 
inspections of 4th stage LPT blades for shroud notch wear. Use the 
procedures described in Accomplishment Instructions, Part 2, 
Paragraph 1 of PW ASB No. JT8D A6224, Revision 6, dated May 3, 2007, 
at the applicable intervals in the following Table 5:

                 Table 5--Repetitive Torque Inspection Intervals for JT8D-217C and -219 Engines
----------------------------------------------------------------------------------------------------------------
      Inspection torque readings                   Number of readings                       Disposition
----------------------------------------------------------------------------------------------------------------
Greater than or equal to 15 LB-IN      All.......................................  Repeat torque inspection
 (1.695 N.m).                                                                       within 1,000 hours TIS since
                                                                                    last inspection.
Less than 15 LB-IN (1.695 N.m) but     One or more...............................  Repeat torque inspection
 greater than or equal to 10 LB-IN                                                  within 500 hours TIS since
 (1.130 N.m).                                                                       last inspection.
Less than 10 LB-IN (1.130 N.m) but     One to six................................  Repeat torque inspection
 greater than or equal to 5 LB-IN                                                   within 125 hours TIS since
 (0.565 N.m).                                                                       last inspection.
Less than 10 LB-IN (1.130 N.m) but     Seven or more.............................  Remove engine from service
 greater than or equal to 5 LB-IN                                                   within 20 hours TIS since
 (0.565 N.m).                                                                       last inspection.
Less than 5 LB-IN (0.565 N.m)........  One or more...............................  Remove engine from service
                                                                                    within 20 hours TIS since
                                                                                    last inspection.
----------------------------------------------------------------------------------------------------------------

     (l) Subsequent repeat inspection intervals must not exceed the 
previous inspection interval.

JT8D-217C and -219 Engines Removed From Service

    (m) JT8D-217C and -219 engines removed from service may be 
returned to service after a detailed inspection and repair or 
replacement of all blades of the failed stage, that exceed Engine 
Manual limits, is done. Information on repairing or replacing 
turbine blades can be found in Sections 72-53-12 through 72-53-13 of 
the JT8D-200 Engine Manual, Part No. 773128.

Other Criteria for All Engine Models Listed in This AD

    (n) Whenever a refurbished or used blade is intermixed with new 
blades in a rotor, use the lowest initial inspection threshold that 
is applicable.
    (o) The initial torque inspection or the repetitive inspection 
intervals for a particular stage may not be reset, unless the blades 
for that stage are refurbished or replaced.
    (p) Whenever a used (service run) blade is reinstalled in a 
rotor, the previous used time should be subtracted from the initial 
torque inspection threshold.

What This AD Changes

LPT-to-Exhaust Case Bolts and Nuts Replacement, and Crushable Sleeve 
Spacer Installation

    (q) At next accessibility to the LPT-to-Exhaust Case bolts and 
nuts, do the following:
    (1) Replace the bolts with part number (P/N) MS9557-26 bolts; 
and
    (2) Replace the nuts with P/N 375095 nuts or P/N 490270 nuts; 
and
    (3) Install crushable sleeve spacers, P/N 822903, under the head 
of the bolts.
    (r) Guidance on replacing the bolts and nuts and installing the 
crushable sleeve spacers can be found in PW ASB No. JT8D A6494, 
Revision 1, dated January 26, 2010.

Previous Credit

    (s) Initial inspections performed before the effective date of 
this AD using PW ASB No. JT8D A6224, Revision 5, dated June 11, 
2004, or Revision 6, dated May 3, 2007, satisfy the initial 
inspection requirements of this AD.

[[Page 16530]]

Definitions

    (t) For the purpose of this AD, ``refurbished'' is defined as 
restoration of the shrouds and/or blade re-twist per the JT8D-200 
Engine Manual, Part No. 773128, or per an operator's approved manual 
system.
    (u) For the purpose of this AD, ``As-Cast'' refers to blades 
that were machined from new castings, and ``Modified'' refers to 
blades that were derived from the pre-SB No. 6090 configuration.
    (v) For the purpose of this AD, ``accessibility to the LPT-to-
exhaust case bolts'' refers to when the inner turbine fan ducts are 
removed.

Alternative Methods of Compliance

    (w) The Manager, Engine Certification Office, has the authority 
to approve alternative methods of compliance (AMOCs) for this AD if 
requested using the procedures found in 14 CFR 39.19. AMOCs approved 
for the initial and repetitive inspection requirements of AD 2005-
02-03 are approved as AMOCs for this AD.

Related Information

    (x) For information about this AD, contact Ian Dargin, Aerospace 
Engineer, Engine Certification Office, FAA, Engine and Propeller 
Directorate, 12 New England Executive Park; Burlington, MA 01803; 
phone: 781-238-7178; fax: 781-238-7199; e-mail: ian.dargin@faa.gov.

Material Incorporated by Reference

    (y) You must use Pratt & Whitney Alert Service Bulletin No. JT8D 
A6224, Revision 6, dated May 3, 2007, to perform the torque 
inspections required by this AD.
    (1) The Director of the Federal Register approved the 
incorporation by reference of this service bulletin in accordance 
with 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) For service information identified in this AD, contact Pratt 
& Whitney, 400 Main St., East Hartford, CT 06108; phone: 860-565-
8770, fax: 860-565-4503, for a copy of this service information.
    (3) You may review copies of the service information at the FAA, 
New England Region, 12 New England Executive Park, Burlington, MA. 
For information on the availability of this material at the FAA, 
call 781-238-7125.
    (4) You may also review copies of the service information that 
is incorporated by reference at the National Archives and Records 
Administration (NARA). For information on the availability of this 
material at an NARA facility, call 202-741-6030, or go to http://www.archives.gov/federal_register/code_of _federal_regulations/
ibr_locations.html.

    Issued in Burlington, Massachusetts on March 14, 2011.
Peter A. White,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 2011-6719 Filed 3-23-11; 8:45 am]
BILLING CODE 4910-13-P


