Airworthiness Directives; Pratt & Whitney 4000 Series Turbofan Engines

[Federal Register Volume 67, Number 85 (Thursday, May 2, 2002)]
[Rules and Regulations]
[Pages 21988-21990]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-10274]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NE-25-AD; Amendment 39-12734; AD 2002-09-01]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney 4000 Series Turbofan 
Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), that 
is applicable to Pratt & Whitney (PW) PW4090, PW4090-3, PW4074D, 
PW4077D, PW4090D, and PW4098 turbofan engines with 15th stage high 
pressure compressor (HPC) disks having certain part numbers (P/N's). 
This amendment requires initial and repetitive borescope inspections of 
15th stage HPC disks for cracks in the knife edges, eddy current 
inspections (ECI's) of blade loading slots if required, and removal of 
cracked disks. In addition, this amendment requires the removal from 
service of these P/N disks, at a new lower cyclic life limit. This 
amendment is prompted by two reports of 15th stage HPC disks with 
cracks in the outer rim front rail of the blade loading slots, and in 
the front forward and middle knife edges. The actions specified by this 
AD are intended to prevent 15th stage HPC disk failures from cracks, 
which could result in an uncontained engine failure.

DATES: Effective date June 6, 2002. The incorporation by reference of 
certain publications listed in the regulations is approved by the 
Director of the Federal Register as of June 6, 2002.

ADDRESSES: The service information referenced in this AD may be 
obtained from Pratt & Whitney, 400 Main St., East Hartford, CT 06108; 
telephone (860) 565-6600, fax (860) 565-4503. This information may be 
examined, by appointment, at the Federal Aviation Administration (FAA), 
New England Region, Office of the Regional Counsel, 12 New England 
Executive Park, Burlington, MA; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Jason Yang, Aerospace Engineer, Engine 
Certification Office, FAA, Engine and Propeller Directorate, 12 New 
England Executive Park; telephone (781) 238-7747, fax (781) 238-7199.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to

[[Page 21989]]

include an AD that is applicable to PW4090, PW4090-3, PW4074D, PW4077D, 
PW4090D, and PW4098 turbofan engines with 15th stage high pressure 
compressor (HPC) disks having certain P/N's, was published in the 
Federal Register on November 23, 2001 (66 FR 58689). That action 
proposed to require initial and repetitive borescope inspections of 
15th stage HPC disks for cracks in the knife edges, eddy current 
inspections (ECI's) of blade loading slots if required, and removal of 
cracked disks. In addition, that action proposed to require the removal 
from service of these P/N disks, at a new lower cyclic life limit. The 
proposed actions were to be done in accordance with the Accomplishment 
Instructions of PW Service Bulletin PW4G-112-A72-242, dated May 1, 
2001.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    One commenter requests that in the paragraph entitled ``Differences 
Between this AD and Manufacturer's Service Information'' the sentence 
stating that PW has informed the FAA that to help reduce the operators' 
cost of replacing disks, PW may supply replacement disks at no cost, to 
be installed at the time disks with more than 2,000 cycles-since-new 
(CSN) are removed for maintenance, be deleted.
    The FAA agrees. Although this cost reduction information was 
supplied by the manufacturer for the proposed rule, the purposes of 
this AD are to mandate initial and repetitive inspections for cracks, 
and to establish a lower life limit for the disk. The replacement of 
disks with more than 2,000 CSN when in the shop was determined based on 
economic consideration, and is not a hard time limit for the disk. 
Therefore, to avoid confusion, the cost reduction information is 
removed from this final rule.
    One commenter requests that a typographical error be corrected in 
the paragraph entitled ``Manufacturer's Service Information'' from 
8,000 hours CSN, to 8,000 CSN.
    The FAA agrees that the sentence does contain a typographical 
error, however, the final rule does not contain the paragraph referred 
to and is not affected.
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule as proposed.

Economic Analysis

    There are approximately 160 PW4090, PW4090-3, PW4074D, PW4077D, 
PW4090D, and PW4098 turbofan engines of the affected design in the 
worldwide fleet. The FAA estimates that 70 engines installed on 
airplanes of U.S. registry would be affected by this AD. The FAA also 
estimates that it would take approximately 2.5 work hours per engine to 
accomplish an initial borescope inspection, and that the average labor 
rate is $60 per work hour. Required parts for a borescope inspection 
would cost approximately $9 per engine. Based on these figures, the 
total cost for the initial borescope inspection for U.S. operators is 
estimated to be $11,130. Assuming that all 70 engines would require 
15th stage HPC disk replacement, and that a replacement disk costs 
approximately $65,000, the total disk cost of the AD on U.S. operators 
is estimated to be $4,550,000.

Regulatory Analysis

    This final rule does not have federalism implications, as defined 
in Executive Order 13132, because it 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. Accordingly, 
the FAA has not consulted with state authorities prior to publication 
of this final rule.
    For the reasons discussed above, I certify that this action (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) if promulgated, 
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. A final evaluation has been prepared for 
this action and it is contained in the Rules Docket. A copy of it may 
be obtained by contacting the Rules Docket at the location provided 
under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

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

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (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. Section 39.13 is amended by adding a new airworthiness directive 
to read as follows:

2002-09-01  Pratt & Whitney: Amendment 39-12734. Docket No. 2001-NE-
25-AD.

    Applicability: This airworthiness directive (AD) is applicable 
to Pratt & Whitney (PW) PW4090, PW4090-3, PW4074D, PW4077D, PW4090D, 
and PW4098 turbofan engines with 15th stage high pressure compressor 
(HPC) disks part numbers (P/N's) 56H015 or 57H715. These engines are 
installed on, but not limited to Boeing 777 airplanes.

    Note 1: This AD applies to each engine identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For engines that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (c) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Compliance with this AD is required as indicated, 
unless already done.
    To prevent 15th stage HPC disk failures from cracks, which could 
result in an uncontained engine failure, do the following:

Initial Inspection

    (a) Perform an initial inspection for cracks in the front rail 
of the blade loading slots and front forward and middle knife edges 
of the 15th stage HPC disk, and replace disk in accordance with 
paragraphs 1.A. through 1.E.(4) of, ``For Engines Installed on 
Aircraft''; or paragraphs 2.A. through 2.E.(4) of, ``For Engines 
Removed From the Aircraft'', of the Accomplishment Instructions of 
PW Service Bulletin PW4G-112-A72-242, dated May 1, 2001, and the 
following Table 1:

[[Page 21990]]



            Table 1.--15th Stage HPC Disk Initial Inspection
------------------------------------------------------------------------
           Action                      If:                  Then:
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(1) Borescope-inspect disk,   (i) Borescope         Replace the disk
 within 4,600 cycles-since-    inspection shows a    with a serviceable
 new (CSN) or before 90 days   crack in any knife    disk before further
 after the effective date of   edge area.            flight.
 this AD, whichever occurs
 later.
                              (ii) Borescope        Perform an eddy
                               inspection shows a    current inspection
                               suspect crack in      (ECI) to confirm
                               any loading slot.     crack within the
                                                     next 25 cycles-in-
                                                     service (CIS), and
                                                     if cracked replace
                                                     with a serviceable
                                                     disk before further
                                                     flight.
------------------------------------------------------------------------

Repetitive Inspections

    (b) Perform repetitive inspections in accordance with the 
inspection procedures in paragraph (a) of this AD at intervals of no 
more than 1,000 CIS since the last inspection.

New Cyclic Life Limit

    (c) This AD establishes a new cyclic life limit for 15th stage 
HPC disks P/N's 56H015 and 57H715 of 8,000 cycles-since-new (CSN). 
Thereafter, except as provided in paragraph (d) of this AD, no 
alternative cyclic life limit may be approved for 15th stage HPC 
disks P/N's 56H015 and 57H715.

Alternative Methods of Compliance

    (d) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Engine Certification Office (ECO). 
Operators must submit their request through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, ECO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the ECO.

Special Flight Permits

    (e) Special flight permits may be issued in accordance with 
Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 
21.197 and 21.199) to operate the aircraft to a location where the 
requirements of this AD can be done.

Documents That Have Been Incorporated by Reference

    (f) The inspections must be done in accordance with PW Service 
Bulletin PW4G-112-A72-242, dated May 1, 2001.
    This incorporation by reference was approved by the Director of 
the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR 
part 51. Copies may be obtained from Pratt & Whitney, 400 Main St., 
East Hartford, CT 06108; telephone (860) 565-6600, fax (860) 565-
4503. This information may be examined, by appointment, at the FAA, 
New England Region, Office of the Regional Counsel, 12 New England 
Executive Park, Burlington, MA.; or at the Office of the Federal 
Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

Effective Date

    (g) This amendment becomes effective on June 6, 2002.

    Issued in Burlington, Massachusetts, on April 18, 2002.
Francis A. Favara,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 02-10274 Filed 5-1-02; 8:45 am]
BILLING CODE 4910-13-P

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