[Federal Register Volume 77, Number 37 (Friday, February 24, 2012)]
[Proposed Rules]
[Pages 11017-11019]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-4286]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-1095; Directorate Identifier 2009-NE-40-AD]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney (PW) Models PW4074 and 
PW4077 Turbofan Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to supersede an existing airworthiness directive 
(AD) that applies to all PW PW4074 and PW4077 turbofan engines. The 
existing AD currently requires removing the 15th stage high pressure 
compressor (HPC) disk within 12,000 cycles since new (CSN) or using a 
drawdown removal plan for disks that exceed 12,000 CSN. Since we issued 
that AD, we received a request from an operator that we clarify our 
inspection schedule for 15th stage HPC disks. This proposed AD would 
clarify that 15th stage HPC disks that have accumulated more than 9,685 
CSN require a borescope inspection (BSI) or eddy current inspection 
(ECI) of the disk outer rim front rail for cracks prior to accumulating 
12,000 CSN. We are proposing this AD to prevent cracks from propagating 
into the disk bolt holes, which could result in a failure of

[[Page 11018]]

the 15th stage HPC disk, uncontained engine failure, and damage to the 
airplane.

DATES: We must receive comments on this proposed AD by April 24, 2012.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE., Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this AD, contact Pratt & 
Whitney, 400 Main St., East Hartford, CT 06108; phone: 860-565-7700; 
fax: 860-565-1605. 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 proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (phone: 800-647-5527) is in the ADDRESSES 
section. Comments will be available in the AD docket shortly after 
receipt.

FOR FURTHER INFORMATION CONTACT: Ian Dargin, Aerospace Engineer, Engine 
Certification Office, FAA, 12 New England Executive Park, Burlington, 
MA 01803; phone: 781-238-7178; fax: 781-238-7199; email: 
[email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2010-1095; 
Directorate Identifier 2009-NE-40-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because 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 we 
receive about this proposed AD.

Discussion

    On June 24, 2011, we issued AD 2011-14-07, amendment 39-16742 (76 
FR 47056, August 4, 2011), for all PW PW4074 and PW4077 turbofan 
engines with 15th stage HPC disks, part number (P/N) 55H615, installed. 
That AD requires removing the 15th stage HPC disk within 12,000 CSN or, 
for any disks that exceed 12,000 CSN after the effective date of this 
AD, using a drawdown plan that includes a BSI or ECI of the disk outer 
rim front rail for cracks. That AD resulted from multiple shop findings 
of cracked 15th stage HPC disks. We issued that AD to prevent cracks 
from propagating into the disk bolt holes, which could result in a 
failure of the 15th stage HPC disk, uncontained engine failure, and 
damage to the airplane.

Actions Since Existing AD Was Issued

    Since we issued AD 2011-14-07 (76 FR 47056, August 4, 2011), we 
received a request from an operator that we clarify our inspection 
schedule for 15th stage HPC disks that have accumulated more than 
9,685, but less than 12,000 CSN, on the effective date of the AD. The 
operator indicated that AD 2011-14-07 did not require a BSI or ECI for 
15th stage HPC disks that had more than 9,685, but less than 12,000 
CSN, on the effective date of the AD. Based on the comment, we reviewed 
the AD and found that this new AD action was necessary to ensure that 
the disc was inspected before accumulating 12,000 CSN. This proposed AD 
would ensure that inspection will occur.

Relevant Service Information

    We reviewed and approved the technical contents of Pratt & Whitney 
Service Bulletin (SB) PW4G-112-72-309, Revision 1, dated July 1, 2010. 
The SB describes procedures for performing a BSI or ECI for cracks in 
the front rail of the outer rim of the 15th stage HPC disk.

FAA's Determination

    We are proposing this AD because we evaluated all the relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design.

Proposed AD Requirements

    This proposed AD would retain all requirements of AD 2011-14-07 (76 
FR 47056, August 4, 2011). This proposed AD would also clarify that 
15th stage HPC disks that have accumulated more than 9,685, but less 
than 12,000 CSN, require a BSI or ECI of the disk outer rim front rail 
for cracks prior to accumulating 12,000 CSN.

Costs of Compliance

    We estimate that this proposed AD would affect 44 engines installed 
on airplanes of U.S. registry. Prorated parts life would cost about 
$66,000 per 15th stage HPC disk. Based on these figures, we estimate 
the total cost of the proposed AD to U.S. operators to be $2,904,000. 
The new requirements of this proposed AD add no additional economic 
burden.

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

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Procedures (44 FR 11034, February 26, 1979),
    (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.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA 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 airworthiness directive 
(AD) 2011-14-07, Amendment 39-16742 (76 FR 47056, August 4, 2011), and 
adding the following new AD:

Pratt & Whitney: Docket No. FAA-2010-1095; Directorate Identifier 
2009-NE-40-AD.

(a) Comments Due Date

    The FAA must receive comments on this AD action by April 24, 
2012.

(b) Affected ADs

    This AD supersedes AD 2011-14-07, Amendment 39-16742.

(c) Applicability

    This AD applies to Pratt & Whitney (PW) PW4074 and PW4077 
turbofan engines with 15th stage high-pressure compressor (HPC) 
disks, part number (P/N) 55H615, installed.

(d) Unsafe Condition

    This AD results from multiple shop findings of cracked 15th 
stage HPC disks. We are issuing this AD to prevent cracks from 
propagating into the disk bolt holes, which could result in a 
failure of the 15th stage HPC disk, uncontained engine failure, and 
damage to the airplane.

(e) Compliance

    Comply with this AD within the compliance times specified, 
unless already done. To perform the inspections, use paragraph 1.A. 
or 1.B. of the Accomplishment Instructions ``For Engines Installed 
on the Aircraft'' or 1.A. or 1.B. of the Accomplishment Instructions 
``For Engines Removed from the Aircraft,'' of PW Service Bulletin 
PW4G-112-72-309, Revision 1, dated July 1, 2010.
    (1) For 15th stage HPC disks that have 9,865 or fewer cycles 
since new (CSN) on the effective date of this AD, remove the disk 
from service before accumulating 12,000 CSN.
    (2) For 15th stage HPC disks that have accumulated more than 
9,865 CSN on the effective date of this AD, do the following:
    (i) Remove the disk from service at the next piece-part 
exposure, not to exceed 2,135 cycles-in-service (CIS) after the 
effective date of this AD.
    (ii) Perform a borescope inspection (BSI) or eddy current 
inspection (ECI) of the front rail of the disk outer rim according 
to the following schedule:
    (A) Within 2,400 cycles-since-last fluorescent penetrant 
inspection or ECI, or
    (B) Within 1,200 cycles-since-last BSI, or
    (C) Before accumulating 12,000 CSN, or
    (D) Within 55 CIS after the effective date of this AD, whichever 
occurs latest.
    (3) If the BSI from paragraph (e)(2)(ii) of this AD indicates 
the presence of a crack in the disk outer rim front rail, but you 
cannot visually confirm a crack, perform an ECI within 5 CIS after 
the BSI.
    (4) If you confirm a crack in the front rail of the disk outer 
rim using any inspection method, remove the disk from service before 
further flight.

(f) Alternative Methods of Compliance (AMOCs)

    The Manager, Engine Certification Office, FAA, has the authority 
to approve AMOCs for this AD, if requested using the procedures 
found in 14 CFR 39.19.

(g) Related Information

    (1) For more information about this AD, contact Ian Dargin, 
Aerospace Engineer, Engine Certification Office, FAA, 12 New England 
Executive Park, Burlington, MA 01803; phone: (781) 238-7178; fax: 
(781) 238-7199; email: [email protected].
    (2) Pratt & Whitney Service Bulletin PW4G-112-72-309 Revision 1, 
dated July 1, 2010, pertains to the subject of this AD. Contact 
Pratt & Whitney, 400 Main St., East Hartford, CT 06108; phone: 860-
565-7700; fax: 860-565-1605, for a copy of this service information.
    (3) You may review copies of the referenced service information 
at the FAA, Engine & Propeller Directorate, 16 New England Executive 
Park, Burlington, MA. For information on the availability of this 
material at the FAA, call 781-238-7125.

    Issued in Burlington, Massachusetts, on February 15, 2012.
Peter A. White,
Manager, Engine & Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 2012-4286 Filed 2-23-12; 8:45 am]
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