Airworthiness directives: Pratt & Whitney,
[Federal Register: October 27, 1999 (Volume 64, Number 207)]
[Proposed Rules]
[Page 57810-57811]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr27oc99-21]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NE-04-AD]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Pratt & Whitney (PW) JT8D series turbofan engines. This proposal would require recalculation of cyclic life limits for certain compressor and turbine disks installed on engines with hush kits (Stage III noise reduction systems) installed in accordance with PW Service Bulletin No. 5947, removal from service of disks that exceed the new, lower cyclic life limits, and replacement with serviceable parts. This proposal is prompted by reports that compressor and turbine disks have higher rotor speeds on engines with hush kits that result in lower cyclic lives. The actions specified by the proposed AD are intended to prevent compressor and turbine disk failure due to reduced cyclic lives, which could result in an uncontained engine failure and damage to the airplane.
DATES: Comments must be received by December 27, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-NE-04-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: ``9-ane- adcomment@faa.gov''. 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 St., East Hartford, CT 06108; telephone (860) 565-8770, fax (860) 565-4503. 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: James Rosa, Aerospace Engineer, 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:
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 in triplicate 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 notice may be changed in light of the comments received.
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 filedin the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 99-NE-04-AD.'' The postcard will be date stamped and returned to the commenter.
Availability of NPRMs
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. 99-NE-04-AD, 12 New
[[Page 57811]]
England Executive Park, Burlington, MA 01803-5299.
Discussion
The Federal Aviation Administration (FAA) has received reports of higher than normal rotor speeds on certain compressor and turbine disks installed on Pratt & Whitney (PW) JT8D-1, -1A, -1B, -7, -7A, -7B, -9, - 9A, -11, -15, -15A, -17, and -7A series turbofan engines with hush kits (Stage III noise reduction systems) installed in accordance with PW Service Bulletin (SB) No. 5947. Analysis indicates that higher rotor speeds result in reduced cyclic lives for affected disks. This condition, if not corrected, could result in compressor and turbine disk failure due to reduced cyclic lives, which could result in an uncontained engine failure and damage to the airplane.
The FAA has reviewed and approved the technical contents of PW Alert Service Bulletin (ASB) No. A6340, dated June 25, 1998, that identifies affected compressor and rotor disks by part number (P/N), and describes formulae for recalculating cyclic disk lives.
Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require recalculation of cyclic life limits for certain compressor and turbine disks installed on engines with hush kits installed in accordance with PW SB No. 5947, removal from service of disks that exceed the new, lower cyclic life limits, and replacement with serviceable parts. The actions would be required to be accomplished in accordance with the ASB described previously.
There are approximately 2,872 engines of the affected design in the worldwide fleet. The FAA estimates that 2,585 engines installed on aircraft of U.S. registry would be affected by this proposed AD, and that the prorated life reduction would cost approximately $5,700 per engine over the life of the engine. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $14,734,500.
The regulations proposed herein would 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 proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.
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
-
The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
-
Section 39.13 is amended by adding the following new airworthiness directive:
Pratt & Whitney: Docket No. 99-NE-04-AD.
Applicability: Pratt & Whitney (PW) JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17, and -17A series turbofan engines with hush kits (Stage III noise reduction systems) installed in accordance with PW Service Bulletin (SB) No. 5947. These engines are installed on but not limited to Boeing 727 and 737 series aircraft, and McDonnell Douglas DC-9 series aircraft.
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 compressor and turbine disk failure due to reduced cyclic lives, which could result in an uncontained engine failure and damage to the airplane, accomplish the following:
(a) Within twenty five (25) cycles-in-service after the effective date of this AD, recalculate the cyclic life limits of affected compressor and turbine disks listed by part number (P/N) in PW Alert Service Bulletin (ASB) No. A6340 dated June 25, 1998, in accordance with the formulae described in the Accomplishment Instructions of the ASB.
(b) After recalculating the new cyclic life limits in accordance with paragraph (a) of this AD, but prior to further flight, remove from service affected compressor and turbine disks that exceed the new, lower cyclic life limits calculated in accordance with paragraph (a) of this AD, and replace with serviceable parts.
(c) Except as provided in paragraph (d) of this AD, this AD established new, lower cyclic life limits for affected compressor and turbine disks installed on engines with hush kits.
(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 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 accomplished.
Issued in Burlington, Massachusetts, on October 21, 1999. David A. Downey, Assistant Manager, Engine and Propeller Directorate, Aircraft Certification Service.
[FR Doc. 99-28087Filed10-26-99; 8:45 am]
BILLING CODE 4910-13-U
