Federal Aviation Administration, DOT.
Notice of proposed rulemaking (NPRM).
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Pratt Start Printed Page 77531& Whitney (PW) JT8D series turbofan engines. This proposal would require removing certain 2nd stage compressor disks, specified by serial number, from service. This proposal is prompted by a report from PW of a number of JT8D engine 2nd stage compressor disks that were delivered to the field with potential machining damage to the tie rod, counterweight, and pin holes. The actions specified by the proposed AD are intended to prevent rupture of the 2nd stage compressor disk caused by machining damage, which could result in an uncontained engine failure and damage to the airplane.
Comments must be received by February 12, 2001.
Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 98-ANE-71-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: “email@example.com.” Comments sent via the Internet must contain the docket number in the subject line. Comments may be inspected at this location between 8 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) 565-6600, 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.Start Further Info
FOR FURTHER INFORMATION CONTACT:
Christopher Spinney, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7175; fax (781) 238-7199.End Further Info End Preamble Start Supplemental Information
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 action 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 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 98-ANE-71-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. 98-ANE-71-AD, 12 New England Executive Park, Burlington, MA 01803-5299.
Pratt & Whitney (PW) notified the Federal Aviation Administration (FAA) of the possibility of machining damage in the holes of five hundred twenty-three 2nd stage compressor disks, part number (P/N) 745902, P/N 790832, and P/N 807502. Machining damage may have resulted in distorted microstructure in the tie rod, counterweight, and pin holes. Increased stress due to the distorted microstructure could cause cracks that propagate through the disk. This condition, if not corrected, could result in rupture of the 2nd stage compressor disk caused by machining damage, which could result in an uncontained engine failure and damage to the airplane.
Explanation of Relevant Service Information
The FAA has reviewed and approved the technical content of JT8D Alert Service Bulletin (ASB) JT8D A6336, Revision 1, dated June 29, 1999, that lists the serial numbers (SN's) of certain 2nd stage compressor disks, P/N 745902, P/N 790832, and P/N 807502, and describes procedures replacing the disk if it is listed by SN in the ASB.
Explanation of Requirements of the Rule
Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, this AD is being proposed to prevent rupture of the 2nd stage compressor disk caused by machining damage, which could result in an uncontained engine failure and damage to the airplane. This proposed AD would require removal of 2nd stage compressor disks, P/N 745902, P/N 790832, and P/N 807502, before accumulating 2,000 cycles-since-new if the SN is listed in the ASB. The compliance time was established based on the safety concerns and the life management analysis. The actions would be required to be accomplished in accordance with the ASB described previously.
There are approximately 110 engines of the affected design in the worldwide fleet. The FAA estimates that 60 engines, installed on airplanes of U.S. registry, would be affected by this proposed AD, that it would take approximately 48 work hours per airplane to accomplish the proposed actions, and that the average labor rate is $60 per work hour. The prorated cost of the unusable life of a 2nd stage disk is $30,000. The manufacturer has informed the FAA that it may pay the cost of the disk, which may lower the cost to operators. Based on these figures, the FAA estimates the total cost impact of the proposed AD on U.S. operators to be $1,972,800.
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.Start List of Subjects Start Printed Page 77532
List of Subjects in 14 CFR Part 39
- Air transportation
- Aviation 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:Start Part
PART 39—AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
2. Section 39.13 is amended by adding the following new airworthiness directive:
Pratt & Whitney: Docket No. 98-ANE-71-AD.
Applicability: JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A,-11, -15, -15A, -17, -17A, -17R, and -17AR series turbofan engines with 2nd stage compressor disks, part number (P/N) 745902, P/N 790832, and P/N 807502, installed. These engines are installed on, but not limited to Boeing 727 series airplanes, Boeing 737-100 and -200 series airplanes and McDonnell Douglas DC-9 series airplanes.
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 (b) 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 a rupture of the 2nd stage compressor disk, caused by machining damage, which could result in an uncontained engine failure and damage to the airplane, accomplish the following:
Removal of Disk
(a) Remove from service 2nd stage compressor disks, P/N 745902, P/N 790832, and P/N 807502, identified by serial number in the Accomplishment Instructions of JT8D Alert Service Bulletin (ASB) JT8D A6336, Revision 1, dated June 29, 1999, prior to accumulating 2,000 cycles since new.
Alternative Methods of Compliance
(b) 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 requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, ECO.
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
(c) Special flight permits may be issued in accordance with 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 December 5, 2000.
Diane S. Romanosky,
Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.
[FR Doc. 00-31614 Filed 12-11-00; 8:45 am]
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