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 JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR turbofan engines. This proposal would require removal from service of certain part number (P/N) 3rd-4th and 4th-5th stage compressor rotor spacer assemblies and incorporation of a new tierod retention configuration. This proposal is prompted by two reports of uncontained failure of JT8D turbofan engines, caused by turbine rotor overspeed resulting from first and second stage fan section separation from the low pressure compressor (LPC). The actions specified by the proposed AD are intended to prevent first and second stage fan section separation from the LPC, resulting in turbine rotor overspeed, uncontained engine failure, and damage to the airplane.
Comments must be received by January 14, 2003.
Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2002-NE-27-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may be inspected at this location, by appointment, between 8 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:
Christopher Spinney, Aerospace Start Printed Page 69153Engineer, 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 2002-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. 2002-NE-27-AD, 12 New England Executive Park, Burlington, MA 01803-5299.
The FAA has received two reports of turbine rotor overspeed resulting in uncontained engine failure on JT8D turbofan engines. The overspeeds resulted from separation of the first and second stage fan section from the rear stages of the LPC. The separations resulted from LPC tierod fractures, which were caused by fretting due to spacer-to-disk snap diameter looseness. The manufacturer has determined that incorporating a tighter snap diameter fit by installing new design or modified parts and incorporating increased sleeve-to-tierod clearances will reduce the number of tierod fractures due to fatigue initiated by fretting. Installation of the new tierod retention configuration will reduce the likelihood of a single tierod fracture damaging the remaining tierods. This condition, if not corrected, could result in a first and second stage fan section separation from the LPC, uncontained engine failure, and damage to the airplane.
Manufacturer's Service Information
The FAA has reviewed and approved the technical contents of Pratt & Whitney Service Bulletin (SB) No. JT8D 6429, dated August 23, 2002, that describes procedures for incorporating a new tierod retention configuration. Pratt & Whitney SB's No. 5409, No. SB 5716, and No. SB No. 5734 are referenced in this proposal because they provide information on modification of the parts requiring removal to make them serviceable.
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 JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR turbofan engines of the same type design that are used on airplanes registered in the United States, the proposed AD would require at the next accessibility:
- Removing from service of 3rd-4th stage compressor rotor spacer assemblies part numbers (P/N's) 479927, 522194, 583385, 656814, 656815, 660649, 660655, 716851, 716853, 716854, 762140, 762145, 762271, 762468, 789554, and 789752 and replacement with a serviceable part.
- Removing from service of 4th-5th stage compressor rotor spacer assemblies P/N's 479929, 522196, 656816, 656817, 660650, 660656, 716855, 762138, and 762142 and replacement with a serviceable part.
- Removing from service 4th-5th stage compressor rotor spacer assemblies P/N 628778 that do not incorporate SB 5409 and replacement with a serviceable part.
- Incorporating a new tierod retention configuration in accordance with the service bulletin described previously.
There are approximately 4,180 engines of the affected design in the worldwide fleet. The FAA estimates that 1,800 engines installed on aircraft of U.S. registry would be affected by this proposed AD. The FAA also estimates that it would take approximately 41 work hours per engine to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Required parts would cost approximately $3,600 per engine. Based on these figures, the total cost of the proposed AD to U.S. operators is estimated to be $10,908,000.
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. 2002-NE-27-AD.
Applicability: This airworthiness directive (AD) is applicable to Pratt & Whitney JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR turbofan engines. These engines are installed on, but Start Printed Page 69154not limited to Boeing 727 and 737 series, 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 (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: Compliance with this AD is required as indicated, unless already done.
To prevent first and second stage fan section separation from the low pressure compressor (LPC), resulting in turbine rotor overspeed, uncontained engine failure, and damage to the airplane, do the following:
(a) At the next accessibility, do the following:
(1) Remove from service 3rd-4th stage compressor rotor spacer assemblies part numbers (P/N's) 479927, 522194, 583385, 656814, 656815, 660649, 660655, 716851, 716853, 716854, 762140, 762145, 762271, 762468, 789554, and 789752 and replace with a serviceable part.
(2) Remove from service 4th-5th stage compressor rotor spacer assemblies P/N's 479929, 522196, 656816, 656817, 660650, 660656, 716855, 762138, and 762142 and replace with a serviceable part.
(3) Remove from service 4th-5th stage compressor rotor spacer assemblies P/N's 628778 that do not incorporate SB 5409, and replace with a serviceable part.
Information on modifying parts listed in paragraphs (a)(1), (a)(2), and (a)(3) of this AD into servicable parts is contained in Pratt & Whitney (PW) SB's No. 5409, No. SB 5716, and No. SB No. 5734.
(4) Incorporate new tierods, retaining rings, 2nd stage compressor air seal or spacer assembly, flat washers and tierod nuts in the LPC in accordance with the Accomplishment Instructions of PW SB JT8D 6429, dated August 23, 2002.
(b) After the effective date of this AD, do not install 3rd-4th or 4th-5th stage compressor rotor spacer assemblies listed in paragraphs (a)(1), (a)(2), and (a)(3) of this AD into any engine.
(c) For the purpose of this AD, accessibility means removal of the LPC from the engine and disassembly that provides piece-part exposure to the parts listed in paragraph (a) of this AD.
Alternative Methods of Compliance
(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 (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
(e) 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 airplane to a location where the requirements of this AD can be done.
Issued in Burlington, Massachusetts, on November 8, 2002.
Francis A. Favara,
Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.
[FR Doc. 02-29002 Filed 11-14-02; 8:45 am]
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