Transport Canada, which is the airworthiness authority for Canada, recently notified the FAA that an unsafe condition may exist on PWC PW206A and PW206E turboshaft engines. Transport Canada advises that there have been several reports of PW206- powered helicopters where axial shifting of compressor turbine blades and power turbine blades resulted in heavy blade rubs, causing an increase in internal engine temperature, triggering in-flight engine fire warnings and subsequent emergency landings.
Relevant Service Information
We have reviewed and approved the technical contents of the following Pratt & Whitney Canada service documents:
Alert Service Bulletin (ASB) No. PW200-72-A28242, Revision 1, dated October 2, 2002, that describes procedures for borescope inspecting of compressor turbine blades and power turbine blades for axial shift within the disks.
Service Bulletin (SB) No. PW200-72-28069, Revision 5, dated February 10, 2003, that describes procedures for replacing compressor turbine blade retaining rivets, the No. 3 bearing rotor air seal, and the No. 4 bearing front rotor air seal.
SB No. PW200-72-28239, Revision 2, dated February 10, 2003, that describes procedures for replacing power turbine blade retaining rivets.
Transport Canada classified these service bulletins as mandatory and issued AD CF-2003-06, dated February 4, 2003, in order to assure the airworthiness of these PWC PW206A and PW206E turboshaft engines in Canada.
Bilateral Airworthiness Agreement
This engine model is manufactured in Canada and is type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Under this bilateral airworthiness agreement, Transport Canada has kept the FAA informed of the situation described above. We have 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.
FAA's Determination and Requirements of This AD
The unsafe condition described previously is likely to exist or develop on other PWC PW206A and PW206E turboshaft engines of the same type design. We are issuing this AD to prevent turbine blade axial shift, leading to high levels of vibration, loss of engine torque, in- flight engine shutdown, and possible uncontained engine failure. This AD requires:
Initial and repetitive borescope inspections of compressor turbine blades and power turbine blades for blade axial shift within the turbine disks, and
Replacement of blade retaining rivets, the No. 3 bearing rotor air seal, and the No. 4 bearing front rotor air seal as mandatory terminating action for the repetitive borescope inspections.
You must use the service information described previously to perform the actions required by this AD.
FAA's Determination of the Effective Date
Since an unsafe condition exists that requires the immediate adoption of this AD, we have found that notice and opportunity for public comment before issuing this AD are impracticable, and that good cause exists for making this amendment effective in less than 30 days.
Changes to 14 CFR Part 39--Effect on the AD
On July 10, 2002, we issued a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs our AD system. This regulation now includes material that relates to special flight permits, alternative methods of compliance, and altered products. This material previously was included in each individual AD. Since this material is included in 14 CFR part 39, we will not include it in future AD actions.
Comments Invited
This AD is a final rule that involves requirements affecting flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit anywritten relevant data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include "AD Docket No. 2003-NE-25-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 rule that might suggest a need to modify it. If a person contacts us verbally, and that contact relates to a substantive part of this 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 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 with you. You may get more information about plain language at http://www.faa.gov/language and http://www.plainlanguage.gov
Regulatory Findings
We have determined that this AD will not have federalism implications under Executive Order 13132. This AD will 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 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. 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.
We prepared a summary ofthe costs to comply with this AD 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. 2003-NE-25-AD" in your request.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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. The FAA amends 39.13 by adding the following new airworthiness directive: