Airworthiness Directives; Pratt & Whitney PW2000 Series Turbofan Engines

[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]
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