[Federal Register Volume 71, Number 27 (Thursday, February 9, 2006)]
[Proposed Rules]
[Pages 6691-6693]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-1768]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NE-12-AD]
RIN 2120-AA64


Airworthiness Directives; Turbomeca Turmo IV A and IV C Series 
Turboshaft Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede an existing airworthiness 
directive (AD) for Turbomeca Turmo IV A and IV C series turboshaft 
engines. That AD currently requires borescope and eddy current 
inspections or ultrasonic inspections of centrifugal compressor intake 
wheel blades for cracks and evidence of corrosion pitting, and 
replacement with serviceable parts. This proposed AD would require the 
same actions, but would require borescope inspections at more frequent 
intervals for certain engines. This proposed AD results from 
Turbomeca's review of the engines' service experience that determined 
more frequent borescope inspections are required on engines not 
modified to the TU 191, TU 197, or TU 224 standard. We are proposing 
this AD to prevent centrifugal compressor intake wheel blade cracks, 
which can result in engine in-flight power loss, engine shutdown, or 
forced landing.

DATES: We must receive any comments on this proposed AD by April 10, 
2006.

ADDRESSES: Use one of the following addresses to comment on this 
proposed AD:
     By mail: Federal Aviation Administration (FAA), New 
England Region, Office of the Regional Counsel, Attention: Rules Docket 
No. 99-NE-12-AD, 12 New England Executive Park, Burlington, MA 01803-
5299.
     By fax: (781) 238-7055.
     By e-mail: [email protected].
    You can get the service information identified in this proposed AD 
from Turbomeca, 40220 Tarnos, France; telephone 33 05 59 74 40 00, fax 
33 05 59 74 45 15.
    You may examine the AD docket, by appointment, at the FAA, New 
England Region, Office of the Regional Counsel, 12 New England 
Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT: Christopher Spinney, Aerospace 
Engineer, Engine Certification Office, FAA, Engine and Propeller 
Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; 
telephone (781) 238-7175; 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 ``AD Docket No. 99-NE-12-AD'' in the 
subject line of your comments. If you want us to acknowledge receipt of 
your mailed comments, send us a self-addressed, stamped postcard with 
the docket number written on it; we will date-stamp your postcard and 
mail it back to you. We specifically invite comments on the overall 
regulatory, economic, environmental, and energy aspects of the proposed 
AD. If a person contacts us verbally, and that contact relates to a 
substantive part of this proposed AD, we will summarize the contact and 
place the summary in the docket. We will consider all comments received 
by the closing date and may amend the proposed AD in light of those 
comments.

Examining the AD Docket

    You may examine the AD Docket (including any comments and 
serviceinformation), by appointment, between 8 a.m. and 4:30 p.m., 
Monday through Friday, except Federal holidays. See ADDRESSES for the 
location.

Discussion

    On May 20, 2003, the FAA issued AD 2003-11-09, Amendment 39-13168 
(68 FR 31970, May 29, 2003). That AD requires initial and repetitive 
borescope and eddy current inspections or ultrasonic inspections of 
centrifugal compressor intake wheel blades for cracks and evidence of 
corrosion pitting, and, if found cracked or if there is evidence of 
corrosion pitting, replacement with serviceable parts. The Direction 
Generale de L'Aviation Civile (DGAC), which is the airworthiness 
authority for France, notified the FAA that an unsafe condition may 
exist on Turbomeca Turmo IV A and IV C series turboshaft engines. The 
DGAC advises that they have received reports of cracked centrifugal 
compressor intake wheel blades.
    The phenomena of blade cracking occurs in two phases; initiation 
after a single event, such as foreign object damage or surge, and crack 
propagation due to operating at a gas generator speed, between 80 
percent and 83 percent, which sets up a vibration. Although the exact 
cause of the initiation of cracks has not yet been identified, cracks 
could initiate at corrosion pits. The investigation is continuing. This 
condition, if not corrected, could result in centrifugal compressor 
intake wheel blade cracks, which can result in engine in-flight power 
loss, engine shutdown, or forced landing.
    Since AD 2003-11-09 required the removal of the TU 197 standard 
within 6 months after the AD's effective date of July 3, 2003, the TU 
197 standard is no longer allowed. The compliance time in this proposed 
AD requires removing the TU 197 standard before further flight.

Actions Since AD 2003-11-09 Was Issued

    Since AD 2003-11-09 was issued, Turbomeca reevaluated the engines' 
service experience and reduced the borescope inspection interval for 
engines not modified to the TU 191, TU 197, or TU 224 standard, from 
250 flight hours-since-last inspection to 200 flight hours-since-last 
inspection. Also,

[[Page 6692]]

Turbomeca eliminated the TU 197 standard as a valid modification.

Relevant Service Information

    We have reviewed and approved the technical contents of Turbomeca 
Mandatory Service Bulletin (MSB) A249 72 0100, Update No. 5, dated 
February 25, 2005, that describes procedures for the centrifugal 
compressor intake wheel blade borescope inspections. The DGAC 
classified this MSB as mandatory and issued AD F-2005-037, dated March 
2, 2005, in order to ensure the airworthiness of these engines in 
France.

Bilateral Agreement Information

    This engine model is manufactured in France and is type 
certificated for operation in the United States under the provisions of 
Section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and 
the applicable bilateral airworthiness agreement. In keeping with this 
bilateral airworthiness agreement, the DGAC has kept the FAA informed 
of the situation described above. We have examined the findings of the 
DGAC, reviewed all available information, and determined that AD action 
is necessary for products of this type design that are certificated for 
operation in the United States.

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. Therefore, we are proposing this AD, which 
would require:
     For engines modified to the TU 197 standard but not to the 
TU 191 standard or TU 224 standard, before further flight, removing the 
TU 197 standard and installing the TU 224 standard.
     Initial and repetitive borescope and eddy current or 
ultrasonic inspections of centrifugal compressor intake wheel blades 
for cracks and evidence of corrosion pitting.
     Removing centrifugal compressor intake wheel blades 
confirmed cracked or pitted.
    The proposed AD would require that you do these actions using the 
service information described previously.

Costs of Compliance

    We estimate that this proposed AD would affect 36 Turbomeca Turmo 
IV A and IV C series turboshaft engines installed on helicopters of 
U.S. registry. We also estimate that it would take about 41 work hours 
per engine to perform the proposed inspections, including disassembling 
and assembling engines, and that the average labor rate is $65 per work 
hour. A replacement centrifugal compressor assembly costs about 
$21,651. Based on these figures, the cost per inspection and 
replacement is estimated to be $24,316. Based on these figures, we 
estimate the total cost of the proposed AD to U.S. operators to be 
$875,390.

Special Flight Permits Paragraph Removed

    Paragraph (e) of the current AD, AD 2003-11-09, contains a 
paragraph pertaining to special flight permits. Even though this 
proposed AD does not contain a similar paragraph, we have made no 
changes with regard to the use of special flight permits to operate the 
helicopter to a repair facility to do the work required by this AD. In 
July 2002, we published a new Part 39 that contains a general authority 
regarding special flight permits and airworthiness directives; see 
Docket No. FAA-2004-8460, Amendment 39-9474 (69 FR 47998, July 22, 
2002). Thus, when we now supersede ADs we will not include a specific 
paragraph on special flight permits unless we want to limit the use of 
that general authority granted in section 39.23.

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 
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. 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 summary of the costs to comply with this proposal and 
placed it in the AD Docket. You may get a copy of this summary by 
sending a request to us at the address listed under ADDRESSES. Include 
``AD Docket No. 99-NE-12-AD'' in your request.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, 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 39-13168 (68 FR 
31970, May 29, 2003) and by adding a new airworthiness directive, to 
read as follows:

Turbomeca: Docket No. 99-NE-12-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this airworthiness directive (AD) action by April 10, 
2006.

Affected ADs

    (b) This AD supersedes AD 2003-11-09, Amendment 39-39-13168.

Applicability

    (c) This AD applies to Turbomeca Turmo IV A and IV C series 
turboshaft engines. These engines are installed on but not limited 
to Aerospatiale SA 330--PUMA helicopters.

Unsafe Condition

    (d) This AD results from Turbomeca's review of the engines' 
service experience that determined more frequent borescope 
inspections are required on engines not modified to the TU 191, TU 
197, or TU 224 standard. The actions specified in this AD are

[[Page 6693]]

intended to prevent centrifugal compressor intake wheel blade 
cracks, which can result in engine in-flight power loss, engine 
shutdown, or forced landing.

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.

Engine Modification Before Further Flight

    (f) For engines modified to the TU 197 standard but not to the 
TU 191 or TU 224 standard, before further flight, remove the TU 197 
standard and install the TU 224 standard.

Initial Inspections

    (g) For all engines, borescope-inspect, and either eddy current-
inspect (ECI) or ultrasonic-inspect (UI) the centrifugal compressor 
intake wheel blades using paragraphs 2.B.(1)(a) through 2.B.(1)(g) 
of Turbomeca Mandatory Service Bulletin A249 72 0100, Update No. 5, 
dated February 25, 2005, and the criteria in the following Table 1:

                                          Table 1.--Inspection Criteria
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                                        Then borescope-inspect       Were traces of       Then confirm corrosion
   If engine modification level is:     centrifugal compressor     corrosion found at    by performing ECI or UI
                                         intake wheel blades:    borescope-inspection?           within:
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(1) Pre TU 191 and Pre TU 224........  Within 200 flight hours- (i) Yes................  Six months-or 50 flight
                                        since-last inspection.                            hours-since-borescope
                                                                                          inspection, whichever
                                                                                          occurs first.
                                                                (ii) No................  Two hundred flight
                                                                                          hours-since-borescope
                                                                                          inspection.
(2) Post TU 191 or Post TU 224.......  Within 1,000 flight      (i) Yes................  Six months-or 50 flight
                                        hours-since-last                                  hours-since-borescope
                                        inspection.                                       inspection, whichever
                                                                                          occurs first.
                                                                (ii) No................  One thousand flight
                                                                                          hours-since-borescope
                                                                                          inspection.
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    (h) Thereafter, perform repetitive inspections using the 
criteria in Table 1 of this AD.
    (i) Remove centrifugal compressor intake wheel blades confirmed 
cracked or pitted.

Alternative Methods of Compliance

    (j) The Manager, Engine Certification Office, has the authority 
to approve alternative methods of compliance for this AD if 
requested using the procedures found in 14 CFR 39.19.

Related Information

    (k) Direction Generale de L'Aviation Civile airworthiness 
directive F-2005-037, dated March 2, 2005, also addresses the 
subject of this AD.

    Issued in Burlington, Massachusetts, on February 3, 2006.
Peter A. White,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. E6-1768 Filed 2-8-06; 8:45 am]
BILLING CODE 4910-13-P