[Federal Register Volume 64, Number 185 (Friday, September 24, 1999)]
[Rules and Regulations]
[Pages 51681-51683]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-24699]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NE-02-AD; Amendment 39-11333; AD 99-20-03]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney PW2000 Series Turbofan
Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment adopts a new airworthiness directive (AD),
applicable to Pratt & Whitney (PW) PW2000 series turbofan engines, that
requires initial and repetitive inspections of certain High Pressure
Turbine (HPT) stage 1 and stage 2 disks utilizing an improved
ultrasonic inspection method performed at an approved facility when the
disk is exposed during a shop visit, and if a crack indicating a
subsurface anomaly is found, removal from service and replacement with
a serviceable part. This amendment is prompted by the results of a
stage 1 HPT disk fracture investigation, which has identified a
population of HPT stage 1 and 2 disks that may have subsurface
anomalies formed during a forging process. The actions specified by
this AD are intended to prevent HPT disk fracture, which could result
in an uncontained engine failure, and damage to the aircraft.
DATES: Effective November 23, 1999.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of November 23, 1999.
ADDRESSES: The service information referenced in this AD may be
obtained from Pratt & Whitney, 400 Main St., East Hartford, CT 06108;
telephone (860) 565-8770, fax (860) 565-4503. This information may be
examined 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: Peter White, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (781)
238-7128, fax (781) 238-7199.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) to include an airworthiness
directive (AD) that is applicable to Pratt & Whitney (PW) PW2037,
PW2040, PW2037M, PW2240, and PW2337 series turbofan engines was
published in the Federal Register on March 23, 1999 (64 FR 13932). That
action proposed to require initial and repetitive inspections of
certain stage 1 and stage 2 high pressure turbine (HPT) disks using an
improved ultrasonic method whenever the disk is exposed during a shop
visit. The inspection must be performed at an approved facility listed
in PW Service Bulletin (SB) PW2000 72-628, dated January 4, 1999. If a
crack indicating a subsurface anomaly is found, the disk must be
removed from service and replaced with a serviceable part.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
Two commenters note that the proposed rule is more restrictive than
the PW SB, which addresses the same issue. The PW SB is a Category 6 SB
( perform upon piece-part exposure). The proposed rule requires
inspection upon disk separation from the module. One of the commenters
estimates that 25% of the HPT modules entering its shop that get
separated do not have the disks debladed. That commenter does not
perform a ``heavy'' maintenance on HPTs upon each exposure.
Approximately 25% of its HPT shop visits are for repair only. Due to
the additional labor cost to perform the increased requirements of the
proposed rule and the potential for increased scrap, that commenter
suggests that the rule be modified to the requirements of the PW SB.
The FAA does not concur. The change from the PW SB compliance
requirements to the requirements of the proposed rule were intentional,
and were predicated by the fact that the risk factor for this problem
was relatively high at 0.485 disk fractures predicted over the
remaining life of the program. The affected engines generally contain
two suspect disks each. The FAA therefore determined to increase the
compliance requirements over the PW SB. Furthermore, the FAA has
determined that only four additional engines would likely require
inspection upon disk separation from the module as opposed to the SB's
compliance time of piece-part exposure. The impact of this change is
predicted to be a small burden economically on operators, and increases
operational safety.
One commenter expresses concern that only one inspection source is
available for the requirements of the proposed rule, and that this one
source would limit shop timing and capacity. The commenter recommends
that the issuance of the AD be no sooner than 90 days after the end of
the comment period or July 20, 1999. The FAA does not concur.
Discussions with PW indicate that shop capacity and timing will not be
a factor with the vendors and the timing in the proposed rule. The
manufacturer believes that adequate shop capacity to handle the
inspection requirements exists now. A second inspection source is being
developed at this time, however, which should ease shop capacity
concerns.
[[Page 51682]]
One commenter states that the impact to their operation will be
minor. They have 20 disks affected by the proposed rule, and most are
approaching their life limits and will be scrapped at the next shop
visit. The commenter has no objections to the rule as proposed.
One commenter concurs with the rule as proposed.
The AD was edited to clarify the shipping requirements discussed in
the financial assessment in the compliance section. Due to the
complexity of the ultrasonic inspection, the compliance plan requires
that the disks be inspected at an approved facility to ensure that the
inspections meet the intent. As the inspection requires using a complex
process and unique equipment, the AD requires that only approved
facilities perform the inspection. This is not a change from the
original proposed rule, but paragraph (a) of the compliance section has
been edited to make this requirement more clear.
In addition, to simplify the AD, the definition of HPT disk piece
part accessibility of paragraph (c) was deleted and incorporated into
paragraph (a).
After careful review of the available data, including the comment
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule with the changes described
previously. The FAA has determined that these changes will neither
increase the economic burden on any operator nor increase the scope of
the AD.
There are approximately 332 affected disks installed in engines in
the worldwide fleet. The FAA estimates that 166 engines installed on
aircraft of US registry would be affected by this proposed AD, that the
shipping cost per disk to the facility which will inspect the disk and
its return will be approximately $210 per disk, that no engines will
require an unplanned HPT module disassembly/assembly, that the
inspection will take approximately 12 work hours per disk to accomplish
the proposed actions, and that the average labor rate is $60 per work
hour. Some disks will require multiple inspections during their service
life. Based on these figures, the total cost impact of the AD on US
operators is estimated to be $450,000. The manufacturer has advised the
FAA that the all costs relative to the inspection will be reimbursed to
the operator.
The regulations adopted herein will not have substantial direct
effects 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. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
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 DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979); and (3) 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
from 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 the following new
airworthiness directive:
99-20-03 Pratt & Whitney: Amendment 39-11333. Docket 99-NE-02-AD.
Applicability: Pratt & Whitney PW2037, PW2040, PW2037M, PW2240,
and PW2337 series turbofan engines, installed on but not limited to
Boeing 757 and Ilyushin IL-96T series airplanes.
Note 1: This airworthiness directive (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 (d) 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 prevent high pressure turbine (HPT) disk fracture, which
could result in an uncontained engine failure and damage to the
aircraft, accomplish the following:
(a) For engines with a HPT stage 1 or stage 2 disk installed
that has a serial number listed in the Accomplishment Instructions
section of PW Service Bulletin (SB) PW2000 72-628, dated January 4,
1999, perform initial and repetitive ultrasonic inspections in
accordance with PW SB PW2000 72-628, dated January 4, 1999 at each
separation of the HPT disk from the HPT module after the effective
date of this AD. The disk must be sent to an approved facility
listed in the Vendor Services or Special Components/Materials
section of PW SB PW2000 72-628, dated January 4, 1999, for
ultrasonic inspection.
(b) Remove from service those HPT disks found with a crack
indicating a subsurface anomaly and replace with a serviceable part.
(c) For engines that do not have a HPT stage 1 or stage 2 disk
installed that has a serial number listed in the Accomplishment
Instructions section of PW SB PW2000 72-628, dated January 4, 1999,
no inspections are required.
(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.
Operators shall submit their request through an appropriate FAA
Principal Maintenance Inspector, who may add comments and then send
it to the Manager, Engine Certification Office.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this airworthiness directive,
if any, may be obtained from the Engine Certification Office.
(e) Special flight permits may be issued in accordance with
sections 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 accomplished.
(f) The actions required by this AD shall be done in accordance
with the following PW SB:
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Document No. Pages Date
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PW2000 72-628...................... 1-13 January 4, 1999.
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Total Pages: 13.
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) 565-8770, fax (860) 565-
4503. Copies may be inspected 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
[[Page 51683]]
North Capitol Street, NW, suite 700, Washington, DC.
(g) This amendment becomes effective on November 23, 1999.
Issued in Burlington, Massachusetts, on September 16, 1999.
Donald E. Plouffe,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 99-24699 Filed 9-23-99; 8:45 am]
BILLING CODE 4910-13-U
