Airworthiness Directives; Pratt & Whitney Canada (PWC) Model PW305 and PW305A Turbofan Engines

[Federal Register Volume 66, Number 42 (Friday, March 2, 2001)]
[Rules and Regulations]
[Pages 13010-13011]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-4889]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NE-24-AD; Amendment 39-12129; AD 2001-04-10]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney Canada (PWC) Model 
PW305 and PW305A 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 Canada (PWC) Models PW305 and PW305A 
turbofan engines, that requires removing stage 4 low pressure turbine 
(LPT) disks from service before exceeding new, lower cyclic life 
limits. This amendment is prompted by the results of a spin pit test 
analysis which indicate that the stage 4 LPT disk does not have full 
published life. The actions specified by this AD are intended to 
prevent LPT disk failure resulting from premature cracking of the LPT 
disks, which could result in an uncontained engine failure and damage 
to the airplane.

DATES: Effective date April 6, 2001.

FOR FURTHER INFORMATION CONTACT: James Rosa, Aerospace Engineer, Engine 
Certification Office, FAA, Engine and Propeller Directorate, 12 New 
England Executive Park, Burlington, MA 01803-5299; telephone: (781) 
238-7152; 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 PWC Models PW305 and PW305A 
turbofan engines, was published in the Federal Register on November 16, 
2000 (65 FR 69258). That action proposed to require removing stage 4 
LPT disks from service before exceeding new, lower cyclic life limits.

No Comments Received

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. No comments were received on the 
proposal or the FAA's determination of the cost to the public. The FAA 
has determined that air safety and the public interest require the 
adoption of the rule as proposed.

Economic Impact

    There are currently 358 engines in the domestic fleet containing 
the affected stage 4 LPT disks, part numbers (P/N's) 30A1457 and 
30A1499, and a total of 484 engines in the worldwide fleet. The total 
cost to the domestic fleet to remove and replace these disks at the new 
life limit of 4000 cycles-in-service (CIS), rather than the former life 
limit of 5000 CIS, is estimated to be $6,331,015.

Regulatory Impact

    This proposed 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 proposed rule.
    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.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the

[[Page 13011]]

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:

2001-04-10  Pratt & Whitney Canada: Amendment 39-12129. Docket 2000-
NE-24-AD.

Applicability

    Pratt & Whitney Canada (PWC) Models PW305 and PW305A turbofan 
engines with stage 4 low pressure turbine (LPT) disks, part numbers 
(P/N's) 30A1457 and 30A1499. These engines are installed on but not 
limited to British Aerospace BAe. 125 1000A, BAe. 125 1000B, Hawker 
1000, and Learjet 60 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 (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 prevent premature LPT disk failure due to cracking of the LPT 
disks, which could result in an uncontained engine failure and 
damage to the airplane, accomplish the following:

New Stage 4 LPT Disk Life Limit

    (a) Remove stage 4 LPT disks, P/N's 30A1457 and 30A1499, prior 
to exceeding the new life limit of 4000 cycles-in-service (CIS).
    (b) Except for the provisions of paragraph (c) of this AD, no 
parts, identified by P/N in paragraph (a) of this AD, that exceed 
the new life limit of 4000 CIS, may be installed.

Alternative Method 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 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.

Effective Date

    (e) This amendment becomes effective on April 6, 2001.

    Issued in Burlington, Massachusetts, on February 21, 2001.
David A. Downey,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 01-4889 Filed 3-1-01; 8:45 am]
BILLING CODE 4910-13-P

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