Airworthiness Directives; Pratt & Whitney Canada PT6A-25C and -114A Series Turboprop Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Pratt & Whitney Canada (P&WC) PT6A-25C and -114A turboprop engines. This proposal would require initial and repetitive visual inspections, and eventual replacement of the compressor bleed valve assembly, with a redesigned valve assembly for the -114A engines, and initial and repetitive visual inspections only for -25C engines. This proposal is prompted by reports of two occurrences of uncommanded engine power loss. The actions specified by the proposed AD are intended to detect wear in the compressor bleed valve assembly which may cause valve orifice blockage, resulting in a loss of power, inability of engine acceleration, and in-flight shut down.

DATES:

Comments must be received by November 20, 2000.

ADDRESSES:

Submit comments to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2000-NE-26-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: “9-ane-adcomment@faa.gov”. Comments sent via the Internet must contain the docket number in the subject line. Comments may be inspected at this location between 8:00 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 Canada, 1000 Marie-Victorin, Longueuil, Quebec, Canada J4G1A1. This information may be examined at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT:

James Rosa, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone: (781) 238-7152, fax: (781) 238-7199.

SUPPLEMENTARY INFORMATION:

This proposal would require initial and repetitive visual inspections, and replacement if necessary, of certain compressor bleed valve assembly components on PT6A-25C and -114A turboprop engines, in accordance with P&WC Service Bulletin (SB) No. 1574 Revision 2, dated October 14, 1999. This proposal would also require eventual replacement of compressor bleed valve assemblies with redesigned valve assemblies, on PT6A-114A turboprop engines, in accordance with P&WC SB No. 1588, dated February 18, 2000.

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 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 notice 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 notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NE-26-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. 2000-NE-26-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

Transport Canada (TC), which is the airworthiness authority for Canada, recently notified the FAA that an unsafe condition may exist on P&WC PT6A-25C and -114A series turboprop engines, which are installed on but not limited to Pilatus PC-7 and Cessna 208 Caravan airplanes. TC advises that engines, which have incorporated P&WC SB No. 1510, may experience cotter pin and diaphragm wear and fatigue inside the compressor bleed valve assembly. Separation of sections of the cotter pin and particles from diaphragm wear may cause blockage of one or both valve orifices, resulting in a power loss, inability of the engine to accelerate and/or in-flight shut down. P&WC has issued SB No. 1574, Revision 2, dated October 14, 1999, which specifies initial visual inspection of compressor bleed valve assembly cover, guide pin shaft, cotter pin, and diaphragm for wear, and, replacement of these parts if necessary. TC classified this SB as mandatory by issuing AD No. CF-99-23, dated September 14, 1999 in order to assure the continued airworthiness of these airplanes in Canada. P&WC has also issued SB No. 1588, dated February 18, 2000, for PT6A-114A turboprop engines that specify compressor bleed valve assembly replacement with a redesigned valve assembly.

Bilateral Airworthiness Agreement

These engine models are manufactured in Canada and are type certificated for operation in the United States under the provisions of § 21.29 of Title 14 of the Code of Federal Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, Transport Canada has kept the FAA informed of the situation described above. The FAA has examined the findings of Transport Canada, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Proposed Actions

Since an unsafe condition has been identified that is likely to exist or develop on other engines of the same type design registered in the United States, the proposed AD would require initial visual inspection of certain compressor bleed valve assembly components within 150 flight hours after the effective date of this AD, repetitive visual inspections within 600 flight hours after the last inspection, and if necessary, the replacement of certain components. The proposed AD would also require replacement of compressor bleed valve assemblies on PT6A-114A engines which have had Pratt & Whitney Canada SB No. 1510 incorporated, with a redesigned valve assembly at the next shop visit but no later than five years after the effective date of this AD. The actions would be required to be accomplished in accordance with the SB's described previously.

Economic Impact

There are about 504 engines of the affected design in the worldwide fleet. The FAA estimates that 353 engines installed on aircraft of U.S. registry would be affected by this proposed AD, that it would take about 2 work hours per engine to accomplish the initial inspections, and 1 hour to accomplish the replacement of the valve, and that the average labor rate is $60 per work hour. Required parts would cost about $7,458.00 per engine. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $2,696,214.00.

Regulatory Impact

This proposal 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 proposal.

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.