02-23776. Airworthiness Directives; Pratt & Whitney JT8D-200 Series Turbofan Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The Federal Aviation Administration (FAA) proposes to adopt a new airworthiness directive (AD) that is applicable to Pratt & Whitney (PW) JT8D-200 series turbofan engines. This proposal would require initial and repetitive visual inspections, fluorescent magnetic particle inspections (FMPI), and fretting wear inspections of high pressure compressor (HPC) front hubs that have operated with PWA-110 coating in the interface between the hub and the stage 8-9 spacer. This proposal is prompted by the discovery of cracked tierod holes found during routine engine overhauls. The actions specified by the proposed AD are intended to prevent a rupture of the HPC front hub that could result in an uncontained engine failure and damage to the airplane.

DATES:

Comments must be received by October 21, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2001-NE-30-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may be inspected at this location, by appointment, 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: “[e-mail]”. 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 [phone]; fax [phone]. 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.

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 [phone], fax [phone].

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 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-30-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-30-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

The FAA has received reports of eighteen cracked PW JT8D-200 series HPC front hubs with PWA-110 coating in the interface between the hub and the stage 8-9 spacer. The cracks were discovered at engine overhauls after the engines had accumulated as few as 9,900 cycles-in-service. The cracks initiated at the site of fretting wear between the interface of the stage 8-9 spacer and the HPC front hub. The results of metallurgical examination indicate that the cracks had begun to propagate due to low-cycle fatigue (LCF). Eventually these cracks could propagate to a critical crack length, causing a rupture of the HPC front hub, which could result in an uncontained engine failure and damage to the airplane. The FAA has reviewed the statistical evaluation of the crack data and has determined that HPC front hubs should be inspected using the intervals and procedures outlined in PW Alert Service Bulletin (ASB) JT8D A6430, dated September 5, 2002. 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 Alert Service Bulletin (ASB) JT8D A6430, dated September 5, 2002, that describes procedures for visual, FMPI, and fretting inspections of HPC front hubs and replacement of the hubs, if necessary.

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 JT8D-200 series turbofan engines, this proposal would require initial and repetitive visual inspections, FMPI's, and fretting wear inspections of HPC front hubs that have operated with PWA-110 coating in the interface between the hub and the stage 8-9 spacer. The actions would be required to be done in accordance with the service bulletin described previously.

Economic Analysis

There are approximately 2,648 PW JT8D-200 series turbofan engines of the affected design in the worldwide fleet. The FAA estimates that 2,352 engines installed on airplanes of U.S. registry would be affected by this proposed AD. The FAA also estimates that it would take approximately 6 work hours per engine to perform the proposed inspection, and that the average labor rate is $60 per work hour. Based on these figures, the total cost of the initial inspection to U.S. operators is estimated to be $846,720.

Regulatory Analysis

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

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

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13

[Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

Pratt and Whitney: Docket No. 2001-NE-30-AD.

Applicability

This airworthiness directive (AD) is applicable to Pratt & Whitney (PW) JT8D-209, -217, -217A, 217C, and -219 series turbofan engines that have high pressure compressor (HPC) front hubs installed that have operated with PWA-110 coating in the interface between the HPC front hub and the stage 8-9 spacer (PWA-110 coating applied to either the spacer or the hub) and were manufactured after June 1, 1988. These engines are installed on, but not limited to McDonnell Douglas MD-80 series airplanes.

Note 1:

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 (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 a rupture of the HPC front hub, that could result in an uncontained engine failure and damage to the airplane, do the following:

Inspect Hubs

(a) Strip the protective coating, visually inspect for fretting wear, fluorescent magnetic particle inspect (FMPI), reidentify and replate HPC front hubs and the stage 8-9 spacers and replace if necessary in accordance with the accomplishment instructions of Pratt & Whitney Alert Service Bulletin (ASB) JT8D A6430, dated September 5, 2002, as follows:

(1) For HPC front hubs with fewer than 17,000 total cycles-in-service (CIS) on the effective date of this AD, inspect at the first shop visit after accumulating 9,000 total CIS or before accumulating 18,000 total CIS, whichever occurs first.

(2) For HPC front hubs with greater than or equal to 17,000 total CIS but less than 19,000 total CIS on the effective date of this AD, inspect at the next shop visit, not to exceed 1,000 CIS from the effective date of this AD or 19,500 total CIS, whichever occurs first.

(3) For HPC front hubs with greater than or equal to 19,000 total CIS on the effective date of this AD, inspect within 500 CIS from the effective date of this AD.

Repetitive-Inspections

(b) Thereafter, strip the protective coating, visually inspect for fretting wear, FMPI and replate HPC front hubs and replace if necessary in accordance with the accomplishment instructions of Pratt & Whitney Alert Service Bulletin (ASB) JT8D A6430, dated September 5, 2002, at intervals not to exceed 6,500 CIS since the last inspection

Optional Terminating Action

(c) Installation of a Nickel-Cadmium plated HPC front hub that has never operated with PWA-110 coating in the interface between the HPC front hub and the stage 8-9 spacer and a Nickel-Cadmium or Electroless Nickel plated spacer is an optional terminating action for the inspections of paragraphs (a) and (b) of this AD.

Definitions

(d) For the purposes of this AD, a shop visit is defined as an engine removal, where engine maintenance entails separation of pairs of major engine flanges or the removal of a disk, hub, or spool at a maintenance facility, regardless of other planned maintenance, except as follows:

(1) Engine removal for the purpose of performing field maintenance type activities at a maintenance facility in lieu of performing them on-wing is not a “shop visit”.

(2) Separation of flanges of the Combustion Chamber and Turbine Fan Duct Assembly (split flanges) for the purpose of accessing non-rotating accessory hardware is not a “shop visit”.

(3) Separation of flanges for the purpose of shipment without subsequent internal maintenance is not a “shop visit”.

Alternative Methods of Compliance

(e) 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 requests 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

(f) 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 September 10, 2002.

Jay J. Pardee,

Manager, Engine and Propeller Directorate, Aircraft Certification Service.