[Federal Register Volume 71, Number 80 (Wednesday, April 26, 2006)]
[Proposed Rules]
[Pages 24613-24615]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-3922]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-23742; Directorate Identifier 2005-NE-53-AD]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney JT9D-7R4G2 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 Pratt & Whitney (PW) JT9D-7R4G2 turbofan engines. This proposed AD 
would require replacing the old configuration 2nd stage high pressure 
turbine (HPT) air seal assembly with a new design 2nd stage HPT air 
seal assembly that increases cooling air flow. This proposed AD results 
from a report of an uncontained failure of the 2nd stage air seal 
assembly, caused by the air seal assembly brace disengaging from the 
air seal, due to insufficient cooling air flow. We are proposing this 
AD to prevent uncontained failure of the 2nd stage HPT air seal 
assembly, leading to engine in-flight shutdown and damage to the 
airplane.

DATES: We must receive any comments on this proposed AD by June 26, 
2006.

ADDRESSES: Use one of the following addresses to comment on this 
proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590-0001.
     Fax: (202) 493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

[[Page 24614]]

    You can get the service information identified in this proposed AD 
from Pratt & Whitney, 400 Main St., East Hartford, CT 06108; telephone 
(860) 565-8770; fax (860) 565-4503.
    You may examine the comments on this proposed AD in the AD docket 
on the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT: Kevin Donovan, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803; telephone (781) 238-
7743, fax (781) 238-7199.

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-2006-23742; 
Directorate Identifier 2005-NE-53-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://dms.dot.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 
DOT 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://dms.dot.gov.

Examining the AD Docket

    You may examine the docket that contains the proposal, any comments 
received and, any final disposition in person at the DOT Docket Office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Office (telephone (800) 647-5227) is located on 
the plaza level of the Department of Transportation Nassif Building at 
the street address stated in ADDRESSES. Comments will be available in 
the AD docket shortly after the Docket Management Facility receives 
them.

Discussion

    We have received two reports of failure of the 2nd stage HPT air 
seal assembly, part number (P/N) 815097, installed in JT9D-7R4G2 
turbofan engines. One of those failures was uncontained. We have also 
received reports of damage found during HPT module disassembly, such as 
cracked knife-edge seals, cracked antirotation slots, and brace gaps 
over limits, on 2nd stage HPT air seal assemblies.
    The old configuration 2nd stage HPT air seal assembly has a brace 
that can disengage and move radially, causing excessive rubbing of the 
air seal's knife edge against the static honeycomb seal. This rubbing 
leads to local excessive temperatures, cracks, thinning of the barrel 
of the 2nd stage HPT air seal assembly, and separation of material. The 
brace disengages from the air seal due to excessive buckling stress in 
the brace. The buckling stress is caused by the thermal interaction of 
the 2nd stage HPT air seal assembly and its constraining rotors. This 
thermal interaction causes higher-than-predicted temperatures leading 
to the brace disengaging. This condition, if not corrected, could 
result in uncontained failure of the 2nd stage HPT air seal assembly, 
leading to engine in-flight shutdown and damage to the airplane.

Relevant Service Information

    We have reviewed and approved the technical contents of PW Alert 
Service Bulletin JT9D-7R4-A72-596, dated September 15, 2005. That Alert 
Service Bulletin describes procedures for replacing 2nd stage HPT air 
seal assembly, P/N 815097, with a new configuration 2nd stage HPT air 
seal assembly that increases cooling air flow, either by installing a 
new 2nd stage air seal assembly or modifying the old configuration 2nd 
stage HPT seal assembly.

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 
at the next HPT module overhaul, replacing the 2nd stage HPT air seal 
assembly, P/N 815097, with a new configuration 2nd stage HPT air seal 
assembly that increases cooling air flow, either by installing a new 
2nd stage air seal assembly or modifying the old configuration 2nd 
stage seal assembly. The proposed AD would require you to use the 
service information described previously to perform these actions.

Costs of Compliance

    We estimate that this proposed AD would affect 176 PW JT9D-7R4G2 
turbofan engines installed on airplanes of U.S. registry. We also 
estimate that it would take about 64 workhours per engine to perform 
the proposed actions, and that the average labor rate is $80 per 
workhour. Required parts would cost about $5,400 per engine. Based on 
these figures, we estimate the total cost of the proposed AD to U.S. 
operators to be $1,851,520.

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 regulatory evaluation of the estimated costs to 
comply with this proposed AD. See the ADDRESSES

[[Page 24615]]

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 adding the following new 
airworthiness directive:

Pratt & Whitney: Docket No. FAA-2006-23742; Directorate Identifier 
2005-NE-53-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this airworthiness directive (AD) action by June 26, 
2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Pratt & Whitney (PW) JT9D-7R4G2 turbofan 
engines. These engines are installed on, but not limited to, Boeing 
747-200B, -200C, -200F, and -300 airplanes.

Unsafe Condition

    (d) This AD results from a report of an uncontained failure of 
the 2nd stage air seal assembly, caused by the air seal assembly 
brace disengaging from the air seal, due to insufficient cooling air 
flow. We are issuing this AD to prevent uncontained failure of the 
2nd stage high pressure turbine (HPT) air seal assembly, leading to 
engine in-flight shutdown and damage to the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed at the next HPT module exposure after the effective 
date of this AD, unless the actions have already been done.
    (f) Replace the 2nd stage HPT air seal assembly, part number 
815097, with a new configuration 2nd stage HPT air seal assembly 
that increases cooling air flow, either by installing a new 2nd 
stage air seal assembly, or modifying the old configuration 2nd 
stage HPT seal assembly.
    (g) Use the Accomplishment Instructions of PW Alert Service 
Bulletin JT9D-7R4-A72-596, dated September 15, 2005, to do the 
replacement.

Definition

    (h) For the purposes of this AD, an HPT module exposure is when 
the 1st stage HPT rotor and 2nd stage HPT rotor are removed from the 
HPT case, making the 2nd stage HPT vanes and 2nd stage HPT air seal 
assembly accessible in the HPT case.

Alternative Methods of Compliance

    (i) 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

    (j) None.

    Issued in Burlington, Massachusetts, on April 19, 2006.
Thomas A. Boudreau,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 06-3922 Filed 4-25-06; 8:45 am]
BILLING CODE 4910-13-P