Federal Aviation Administration, DOT.
Notice of proposed rulemaking (NPRM).
The Federal Aviation Administration (FAA) proposes to adopt a new airworthiness directive (AD) that is applicable to Pratt & Whitney (PW) JT9D-59A, -70A, -7Q, and -7Q3 turbofan engines. This proposal would require fluorescent penetrant inspection of the high pressure turbine (HPT) second stage airseal knife edges for cracks, each time the airseal is accessible. This proposal is prompted by reports of cracks found in the knife edges of HPT second stage airseals during HPT disassembly. The actions specified by the proposed AD are intended to prevent failure of HPT second stage airseals due to cracks in the knife edges, which if not detected could result in uncontained engine failure and damage to the airplane.
Comments must be received by January 22, 2002.
Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2001-NE-27-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may be inspected at this location, by Start Printed Page 58692appointment, between 8:00 a.m. and 4:30 p.m., Monday through Friday, except Federal Holidays. 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. 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, by appointment, 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:
Tara Goodman, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7130, 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 2001-NE-27-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. 2001-NE-27-AD, 12 New England Executive Park, Burlington, MA 01803-5299.
The FAA has received 25 reports of cracks found in the knife edges of HPT second stage airseals, part numbers (P/N's) 5002537-01 and 807410, during HPT disassembly. To date, no failed airseal has caused an uncontained engine failure. Results from an evaluation conducted by PW reveal that engine operating temperatures and stresses in the stage 1-to-stage 2 airseal cavity are higher than anticipated. As a result, heavy rubbing and thermal mechanical fatigue in a hot compression environment are causing cracks to initiate in the rear knife edge. These cracks will propagate axially until the airseal fails. Eleven of the 25 cracked HPT second stage airseals found at overhaul were fractured through from snap to snap. This condition, if not corrected, could result in an uncontained engine failure and damage to the airplane.
Manufacturer's Service Information
The FAA has reviewed and approved the technical contents of PW service bulletin (SB) JT9D 6409, dated July 27, 2001, that describes procedures for fluorescent penetrant inspecting knife edges of HPT second stage airseals.
FAA's Determination of an Unsafe Condition and Proposed Actions
Since an unsafe condition has been identified that is likely to exist or develop on other PW JT9D-59A, -70A, -7Q, and -7Q3 turbofan engines of the same type design, the proposed AD would require fluorescent penetrant inspection of the knife edges of HPT second stage airseals for cracks each time the airseal is accessible. The actions would be required to be done in accordance with the SB described previously. The FAA has been informed by PW that a new design HPT second stage airseal is being developed. The FAA may revise this action to introduce the new design as terminating action.
There are approximately 564 engines of the affected design PW JT9D-59A, -70A, -7Q, and -7Q3 turbofan engines in the worldwide fleet. The FAA estimates that 176 engines installed on airplanes of U.S. registry would be affected by this proposed AD. The FAA also estimates that it would take approximately 1 work hour per engine to perform the fluorescent penetrant inspection, and that the average labor rate is $60 per work hour. Based on these figures, the total labor cost effect annually of the proposed AD on U.S. operators is estimated to be $10,560.
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
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. 2001-NE-27-AD.
Applicability: This airworthiness directive (AD) is applicable to Pratt & Whitney (PW) JT9D-59A, -70A, -7Q, and -7Q3 turbofan engines. These engines are installed on, but not limited to, Airbus Indusrie A300 series, Boeing 747 series, and McDonnell Douglas DC-10 series airplanes.Start Printed Page 58693
This 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: Compliance with this AD is required as indicated, unless already done.
To prevent failure of high pressure turbine (HPT) second stage airseals due to cracks in the knife edges, which if not detected could result in uncontained engine failure and damage to the airplane, do the following:
(a) Perform a fluorescent penetrant inspection of the HPT second stage airseal knife edges for cracks in accordance with Accomplishment Instructions, Paragraphs 1 through 3 of PW Service Bulletin (SB) JT9D 6409, dated July 27, 2001, each time the HPT stage 1 and stage 2 rotors are separated. Remove from service those airseals that are found cracked.
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 must submit their request 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 §§ 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 done.
Issued in Burlington, Massachusetts, on November 14, 2001.
Donald E. Plouffe,
Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.
[FR Doc. 01-29190 Filed 11-21-01; 8:45 am]
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