Airworthiness directives: Pratt & Whitney,

[Federal Register: December 8, 1999 (Volume 64, Number 235)]

[Proposed Rules]

[Page 68640-68642]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr08de99-18]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NE-44-AD]

RIN 2120-AA64

Airworthiness Directives; Pratt & Whitney Canada PT6A Series Turboshaft 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 PT6A series turboprop engines that have certain turbine exhaust ducts that were modified by Standard Aero Limited (SAL) of Winnipeg, Canada before September 1, 1997. This proposal would

[[Page 68641]]

require initial and repetitive inspections for cracks and, if necessary, replacing the duct if the cracks exceed allowable limits. This proposal is prompted by reports of cracks along the weld seams of certain turbine exhaust ducts. The actions specified by the proposed AD are intended to prevent failure of the turbine exhaust duct due to cracking that could result in possible separation of the reduction gearbox and propeller from the engine, and possible loss of control of the airplane.

DATES: Comments must be received by February 7, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-NE-44-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be submitted to the Rules Docket by using the following Internet address: ``9-ane-adcomment@faa.gov''. Comments may be inspected at this location between 8:00 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: James Lawrence, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7176, fax (781) 238-7199.

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 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 filedin 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 99-NE-44-AD.'' The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

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. 99-NE-44-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

Transport Canada (TC), which is the airworthiness authority for Canada, recently notified the Federal Aviation Administration (FAA) that an unsafe condition may exist on Pratt & Whitney Canada (P&WC) PT6A series turboprop engines. TC advises the FAA that certain exhaust ducts part number (P/N) 3012290, P/N 3031988, P/N 3032117, P/N 3035784, P/N 3035786, P/N 3105890-01, P/N 3112167-01, P/N 3112171-01, and P/N 3111780-01 were modified before September 1, 1997, by Standard Aero Limited (SAL) of Winnipeg, Canada, using the alternate gas tungsten arc welding (GTAW) process instead of the resistance (seam or stitch) weld process that were specified in P&WC service bulletin (SB) 1430. Some of those ducts have experienced cracking that may be attributed to the GTAW process. TC issued AD CF-98-41 on November 26, 1998, in order to assure the airworthiness of these P&WC PT6A series turboprop engines in Canada.

Bilateral Airworthiness Agreement

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

Requirements of this AD

Since an unsafe condition has been identified that is likely to exist or develop on other PT6A series turboprop engines of the same type design registered in the United States, the proposed AD would require initial and repetitive visual inspections of certain turbine exhaust ducts P/N 3012290, P/N 3031988, P/N 3032117, P/N 3035784, P/N 3035786, P/N 3105890-01, P/N 3112167-01, P/N 3112171-01, and P/N 3111780-01, that were modified using a GTAW procedure by SAL before September 1, 1997.

Cost Impact

There are approximately 22,000 engines of the affected design in the worldwide fleet. The FAA estimates that 7,000 engines installed on airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 2 work hours per engine to determine if an affected duct is installed, and that it would take approximately 20 hours to replace an affected duct. There are approximately 116 engines worldwide that may have an affected duct installed, however, it is not known how many of those engines are installed on airplanes of U.S. registry. The average labor rate is $60 per work hour. Required parts would cost approximately $32,000 per engine. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $840,000 to determine if an affected duct is installed on an engine, and $3,851,200 to replace the ducts if all ducts are installed in engines that are installed on airplanes of U.S. registry The estimated total economic impact may be $4,691,200.

Regulatory Impact

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.

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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.

    Sec. 39.13 [Amended]

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

    Pratt & Whitney Canada: Docket No. 99-NE-44-AD.

    Applicability: Pratt & Whitney Canada (P&WC) PT6A series turboprop engines with certain exhaust ducts part number (P/N) 3012290, P/N 3031988, P/N 3032117, P/N 3035784, P/N 3035786, P/N 3105890-01, P/N 3112167-01, P/N 3112171-01, and P/N 3111780-01, that were modified before September 1, 1997, by Standard Aero Limited (SAL) of Winnipeg, Canada. These engines are installed on, but not limited to, Beechcraft King Air-90 and -100 series, Bombadier DHC-6 series, Empresa Brasielira de Aeronautica, S.A. (Embraer) EMB-110 series, Pilatus PC-6 series, and Piper PA-42 series airplanes.

    Note 1: 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 (g) 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: Required as indicated, unless accomplished previously.

    To prevent failure of the turbine exhaust duct due to cracking that could result in possible separation of the reduction gearbox and propeller from the engine, and possible loss of control of the airplane, accomplish the following:

    Inspection of Exhaust Duct

    (a) If the exhaust duct was not modified before September 1, 1997, by SAL of Winnipeg, Canada, using the gas tungsten arc weld (GTAW) process of P&WC service bulletin (SB) 1430, no further action is required

    Note 2: Engine log books, engine maintenance records, etc., can be used to determine if the duct was modified before September 1, 1997, by SAL of Winnipeg, Canada, using the GTAW process of P&WC SB 1430.

    (b) If the exhaust duct P/N 3012290, P/N 3031988, P/N 3032117, P/N 3035784, P/N 3035786, P/N 3105890-01, P/N 3112167-01, P/N 3112171-01, and P/N 3111780-01 was modified before September 1, 1997 by SAL using the GTAW process of P&WC SB 1430, or if it cannot be determined if the GTAW process was used in complying with P&WC SB 1430, do the following within 100 hours time-in-service (TIS) after the effective date of this AD:

    Initial Visual Inspection of Affected Exhaust Ducts for Cracks

    (1) Use 5X magnification to visually inspect the circumference of the forward area of the exhaust duct from the propeller reduction gearbox mounting flange to 2 inches aft of the flange for any crack indications. Return the duct to service or replace with a serviceable part as follows:

    (i) If no cracks are found, the duct may be returned to service. Or,

    (ii) If three or less cracks are found, and the total cumulative length of the cracks exceeds 2.0 inches, replace the duct with a serviceable part. Or,

    (iii) If any one crack exceeds 1.0 inches in length, replace the duct with a serviceable part. Or,

    (iv) If any two cracks are separated by less than six times the length of the longest crack (6L) or by less than 3.0 inches, whichever is less, replace the duct with a serviceable part. Or,

    (v) If more than three cracks are found, replace the duct with a serviceable part.

    (2) Mark all allowable cracks, on the duct, with a suitable metal marking pencil.

    Note 3: Marking materials that are suitable for use on the the exhaust duct may be found in the P&WC Engine Manual.

    (3) Record the length of the crack, location, number of duct hours, and time since overhaul (TSO).

    Repetitive Visual Inspection of Affected Exhaust Ducts for Cracks

    (c) Repeat the inspection specified in paragraph (b)(1) as follows:

    (1) For ducts that did not exhibit any cracking at the last inspection, repeat the inspection within 150 hours TIS since the last inspection. Return the duct to service or replace with a serviceable part as specified in paragraph (b)(1)(i) through paragraph (b)(2).

    (2) For ducts that exhibited cracking at the last inspection, repeat the inspection within 25 hours TIS since the last inspection. Return the duct to service or replace with a serviceable part as follows:

    (i) For new cracks that have developed since the last inspection, return the duct to service or replace with a serviceable part as specified in paragraph (b)(1)(ii) through paragraph (b)(3).

    (ii) Inspect cracks that were recorded as specified in paragraph (b)(2). Return the duct to service or replace with a serviceable part as specified in paragraph (b)(1)(ii) through paragraph (b)(2). In addition, if the growth rate of an existing crack exceeds 0.015 inch per hour TIS since the last inspection, replace the duct with a serviceable part.

    Optional Terminating Action

    (d) Replacing an affected exhaust duct with a serviceable part constitutes terminating action for the repetitive inspection requirements of this AD.

    Definition of a Serviceable Exhaust Duct

    (e) For the purposes of this AD, a serviceable duct is defined as a duct that has been modified per P&WC SB 1430, but did not use the GTAW process.

    Alternative Method of Compliance

    (f) 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 shall submit their request through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, ECO.

    Note 4: 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

    (g) Special flight permits may be issued in accordance with Sec. Sec. 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 accomplished.

    Issued in Burlington, Massachusetts, on December 1, 1999. Thomas A. Boudreau, Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.

    [FR Doc. 99-31816Filed12-7-99; 8:45 am]

    BILLING CODE 4910-13-U

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