Airworthiness Directives; Pratt & Whitney JT8D-209, -217, -217A, -217C, and -219 Series Turbofan Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to supersede an existing airworthiness directive (AD) for Pratt & Whitney (PW) JT8D-209, -217, -217A, -217C, and -219 series turbofan engines. That AD currently requires torque inspection of the 3rd stage and 4th stage low pressure turbine (LPT) blades for shroud notch wear and replacement of the blade if wear limits are exceeded. This proposed AD would require torque inspections at shorter inspection intervals of the refurbished 3rd stage and 4th stage LPT blades, but the same or longer inspection intervals of the new 3rd stage and 4th stage LPT blades, for shroud notch wear and replacement of the blade if wear limits are exceeded. This proposed AD would also require replacing LPT-to-exhaust case bolts and nuts with bolts and nuts made of Tinidur material. This proposed AD results from reports of 194 blade fractures since 1991, with 37 of those blade fractures resulting in LPT case separation, and three reports of uncontained 3rd stage and 4th stage LPT blade failures with cowl penetration. We are proposing this AD to prevent an uncontained blade failure that could result in damage to the airplane.

DATES:

We must receive any comments on this proposed AD by October 15, 2004.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD:

• By mail: Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 98-ANE-80-AD, 12 New England Executive Park, Burlington, MA 01803-5299.
• By fax: (781) 238-7055.
• By e-mail: 9-ane-adcomment@faa.gov

You can get the service information identified in this proposed AD from Pratt & Whitney, 400 Main St., East Hartford, CT 06108; telephone (860) 565-8770, fax (860) 565-4503.

You may examine the AD docket at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT:

Keith Lardie, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7189, fax (781) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include “AD Docket No. 98-ANE-80-AD” in the subject line of your comments. If you want us to acknowledge receipt of your mailed comments, send us a self-addressed, stamped postcard with the docket number written on it; we will date-stamp your postcard and mail it back to you. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. If a person contacts us verbally, and that contact relates to a substantive part of this proposed AD, we will summarize the contact and place the summary in the docket. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications that affect you. You may get more information about plain language at http://www.faa.gov/language and http://www.plainlanguage.gov.

Examining the AD Docket

You may examine the AD Docket (including any comments and service information), by appointment, between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. See ADDRESSES for the location.

Discussion

On December 20, 1999, the FAA issued AD 99-27-01, Amendment 39-11482 (64 FR 72916, December 29, 1999). That AD requires torque inspection of the 3rd stage and 4th stage LPT blades for shroud notch wear and replacement of the blade if wear limits are exceeded. That AD was the result of a report of an uncontained blade failure. That condition, if not corrected, could result in uncontained blade failure, leading to damage to the airplane. Also, on October 21,1999, we issued AD 99-22-14, Amendment 39-11392(64 FR 58328, October 29, 1999). That AD requires replacing LPT-to-exhaust case bolts and nuts with improved containment hardware. That AD was the result of reports of LPT flange separation resulting from LPT blade failures. That condition, if not corrected, could result in LPT flange separations resulting from LPT blade failures.

Actions Since We Issued AD 99-27-01 and AD 99-22-14

Since we issued AD 99-27-01, there have been two additional uncontained engine failures. The fracture rate of 3rd stage and 4th stage LPT blades remains unchanged, with about 12 to 18 fractures occurring per year. PW has determined that torque inspections of the 3rd stage and 4th stage LPT blades for shroud notch wear must be performed at shorter inspection intervals for refurbished blades, to prevent LPT blade failures. Also, since we issued AD 99-22-14, PW determined that the LPT-to-exhaust case bolts and nuts introduced by that AD have a higher failure rate than the previous interim nut and bolt configuration. We issued a Notice of Proposed Rulemaking (NPRM), Docket No. 92-ANE-15-AD, on July 7, 2004, to supersede AD 99-22-14. That NPRM proposes to no longer require replacing the LPT-to-exhaust case bolts and nuts.

Relevant Service Information

We have reviewed and approved the technical contents of PW Alert Service Bulletin (ASB) No. JT8D A6224, Revision 5, dated June 11, 2004, that describes procedures for initial and repetitive torque inspections of 3rd stage and 4th stage LPT blades for shroud notch wear at revised inspection thresholds and intervals.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other JT8D-209, -217, -217A, -217C, and -219 series turbofan engines of this same type design. We are proposing this AD, which would require initial and repetitive torque inspections of the 3rd stage and 4th stage LPT blades for shroud notch wear at the thresholds and intervals specified in the compliance section, and replacement of LPT-to-exhaust case bolts part number (P/N) ST1315-15 and nuts P/N 4023466 with bolts and nuts made of Tinidur material. The proposed AD would require that you do the torque inspections using the service information described previously.

Interim Action

These actions are interim actions and we may take further rulemaking actions in the future.

Costs of Compliance

There are about 2,345 PW JT8D-200 series turbofan engines of the affected design in the worldwide fleet. We estimate that 1,143 engines installed on airplanes of U.S. registry would be affected by this proposed AD. We also estimate that it would take approximately 1 work hour per engine to perform a proposed torque inspection, and 1 work hour per engine to perform the proposed bolt and nut replacements. The average labor rate is $65 per work hour. Required parts would cost approximately $1,734 per engine. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to perform one torque inspection, and bolt and nut replacements to be $2,130,552.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD 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.

For the reasons discussed above, I certify that the 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. Would not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

We prepared a summary of the costs to comply with this proposal and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include “AD Docket No. 98-ANE-80-AD” in your request.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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.