[Federal Register Volume 66, Number 56 (Thursday, March 22, 2001)]
[Proposed Rules]
[Pages 16017-16019]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-7081]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NE-49-AD]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan 
Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The Federal Aviation Administration (FAA) proposes to adopt a 
new airworthiness directive (AD) that is applicable to certain models 
of Pratt & Whitney (PW) PW4000 series turbofan engines. This proposal 
would require operators to perform initial and repetitive inspections 
for cracking of high pressure compressor (HPC) front drum rotors based 
on cycle usage. This proposal would also require the removal from 
service of any cracked HPC front drum rotors. This proposal is prompted 
by reports that seven HPC drum rotors have been found cracked on the 
spacer surface between the 6th and 7th stage disks. The actions 
specified by the proposed AD are intended to detect premature cracking 
of the HPC drum rotor that could result in an uncontained engine 
failure and damage to the airplane.

DATES: Comments must be received by May 21, 2001.

ADDRESSES: Submit comments to the Federal Aviation Administration 
(FAA), New England Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 2000-NE-49-AD, 12 New England Executive Park, 
Burlington, MA 01803-5299. Comments may also be sent via the Internet 
using the following address: ``[email protected]''. Comments sent 
via the Internet must contain the docket number in the subject line. 
Comments may be inspected at this location between 8:00 a.m. and 4:30 
p.m., Monday through Friday, except Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from Pratt & Whitney, 400 Main Street, East Hartford, CT 
06108. This information may be examined at the FAA, New England Region, 
Office of the Regional Counsel, 12 New England Executive Park, 
Burlington, MA.

FOR FURTHER INFORMATION CONTACT: Tara Goodman, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington MA 01803-5299; telephone: 781-
238-7130, fax: 781-238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications should identify the Rules Docket number 
and be submitted to the address specified above. All communications 
received on or before the closing date for comments, specified above, 
will be considered before taking action on the proposed rule. The 
proposals contained in this action may be changed in light of the 
comments received.

[[Page 16018]]

    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NE-49-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRM's

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, New England Region, Office of the Regional Counsel, 
Attention: Rules Docket No. 2000-NE-49-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    This proposal is prompted by reports that seven HPC front drum 
rotors have been found cracked in the axial direction on the spacer 
surface between the 6th and 7th stage disks. These axial cracks may 
propagate into the disk and lead to compressor disk fracture, which 
could result in an uncontained engine failure. The manufacturer is 
investigating the cause of the cracking. There is currently no 
terminating action to the repetitive inspection requirements of the 
proposed AD. This proposed rule may be revised based on the results of 
the manufacturer's investigation.

Manufacturer's Service Information

    The FAA has reviewed and approved the technical contents of PW 
Alert Service Bulletin (ASB) No. PW4ENG A72-722, dated September 29, 
2000. That ASB provides procedures for operators to perform on-wing and 
off-wing initial and repetitive HPC drum rotor borescope inspections.

Differences Between Manufacturer's Service Information and this AD

    Although ASB No. PW4ENG A72-722, dated September 29, 2000, exempts 
PW4158 engine serial numbers P728534 through P728546, from the 
inspection requirements, this AD includes those engines in the initial 
and repetitive inspections and requires replacing any drum rotor that 
is cracked. The FAA has determined that there is insufficient data to 
permit the exception of these particular engines from the proposed 
inspection requirements.
    Also, although ASB No. PW4ENG A72-722, dated September 29, 2000, 
provides procedures for operators to perform off-wing initial and 
repetitive HPC drum rotor inspections, the off-wing requirements are 
not mandated by the proposed rule. The FAA has evaluated a 20-year 
cumulative risk assessment and has determined that an acceptable level 
of safety will be met by requiring the on-wing inspections at the 
cyclic intervals detailed in the ASB.
    ASB No. PW4ENG A72-722, dated September 29, 2000, states in item 12 
of the Accomplishment Instructions for the on-wing inspection that an 
eddy current nondestructive inspection must be done within five engine 
cycles of finding a crack indication. The FAA has determined that if 
confirmation of cracking is necessary, an eddy current inspection must 
be conducted prior to further flight.

Proposed Actions

    Since an unsafe condition has been identified that is likely to 
exist or develop on other PW4000 series turbofan engines of this same 
type design, the proposed AD would require operators to perform initial 
borescope inspections on HPC drum rotors before accumulating 1,500 
cycles-since-new (CSN) on the effective date of this AD. This proposed 
AD would also require thereafter, inspections within 2,200 cycles-
since-last-inspection, and the removal from service of any cracked HPC 
front drum rotor. The compliance intervals were established by analysis 
of service data and evaluation of a risk analysis. The actions would be 
required to be accomplished in accordance with the ASB described 
previously.

Economic Analysis

    The FAA estimates that there are 1,970 engines of the affected 
design in the worldwide fleet, and that 538 engines installed on 
aircraft of U.S. registry would be affected by this proposed AD. The 
FAA also estimates that it would take approximately 2.5 work hours per 
engine to accomplish the proposed on-wing inspection, and that the 
average labor rate is $60 per work hour. It is estimated that three 
engines would be found with cracked HPC front drum rotors in the time 
frame of one year. Approximately 269 engines will be inspected on 
average per year. The cost of removal and reinstallation of an engine 
is approximately $10,000, and the cost of replacing the HPC front drum 
rotor is approximately $750,000. Required replacement parts would cost 
$356,130 per engine. Based on these figures, the total cost impact per 
year of the proposed AD for accomplishing initial inspections and 
replacing HPC front drum rotors, on U.S. operators is estimated to be 
$3,388,730.

Regulatory Impact

    This proposal 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 proposal.
    For the reasons discussed above, I certify that this 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) 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 copy of the draft 
regulatory evaluation prepared for this action 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, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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 the following new 
airworthiness directive:


Pratt & Whitney:  Docket No. 2000-NE-49-AD.

Applicability: This airworthiness directive (AD) applies to Pratt & 
Whitney (PW) models

[[Page 16019]]

PW4052, PW4056, PW4060, PW4062, PW4152, PW4156A, PW4158, PW4460, and 
PW4462 turbofan engines. These engines are installed on but not 
limited to Boeing 747, 767, McDonnell Douglas MD-11, Airbus 
Industrie A300, and A310 series 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

    Required as indicated, unless accomplished previously.
    To detect premature cracking of the high pressure compressor 
(HPC) front drum rotor, that could result in an uncontained engine 
failure and damage to the airplane, accomplish the following:

Initial Inspection

    (a) Perform an initial inspection in accordance with the 
Accomplishment Instructions, On-Wing paragraphs 1 through 13, of PW 
Alert Service Bulletin (ASB) No. PW4ENG A72-722, dated September 29, 
2000, as follows:
    (1) Perform an initial inspection of HPC front drum rotors 
before accumulating 1,500 cycles-since-new.
    (2) If the presence of a crack needs to be confirmed, perform an 
eddy current inspection (ECI) before further flight.
    (3) If the presence of a crack is confirmed, remove and replace 
with a serviceable HPC front drum rotor before further flight.

Repetitive Inspections

    (b) Thereafter, perform inspections within 2,200 cycles-since-
last-inspection, in accordance with the Accomplishment Instructions, 
On-Wing paragraphs 1 through 13, of PW ASB No. PW4ENG A72-722, dated 
September 29, 2000.
    (1) If the presence of a crack needs to be confirmed, perform an 
ECI before further flight.
    (2) If the presence of a crack is confirmed, remove and replace 
with a serviceable HPC front drum rotor before further flight.

Alternative Methods of Compliance

    (c) 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 shall submit their request through an appropriate Federal 
Aviation Administration (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

    (d) 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 airplane to a location where the 
requirements of this AD can be accomplished.

    Issued in Burlington, Massachusetts, on March 14, 2001.
Mark Liptak,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 01-7081 Filed 3-21-01; 8:45 am]
BILLING CODE 4910-13-P