Airworthiness Directives; Dowty Propellers Type R212/4-30-4/22 and R251/4-30-4/49 Propeller Assemblies

Summary:

We are adopting a new airworthiness directive (AD) for the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) issued by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

Reports have been received from a small number of HS.748 operators of finding cracks in the propeller hub port buttress threads of R212 and R251 propellers. The affected hubs had accumulated in excess of 6,000 flight hours. This condition, if not detected and corrected, could lead to propeller blade separation, possibly resulting in damage to the aeroplane and/or injury to persons on the ground.

Table of Contents

We are issuing this AD to prevent propeller hub failure due to cracks in the hub, which could result in damage to the airplane.

Addresses:

The Docket Operations office is located at Docket Management Facility, U.S. Department of Transportation, 1200 New Jersey Avenue, SE., West Building Ground Floor, Room W12-140, Washington, DC 20590-0001.

For further information contact:

Michael Schwetz, Aerospace Engineer, Boston Aircraft Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803;phone:781-238-7761;fax:781-238-7170;e-mail: michael.schwetz@faa.gov.

Supplementary information:

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to the specified products. That NPRM was published in the Federal Register on May 11, 2011 (76 FR 27281). That NPRM proposed to correct an unsafe condition for the specified products. The MCAI states that:

Reports have been received from a small number of HS.748 operators of finding cracks in the propeller hub port buttress threads of R212 and R251 propellers. The affected hubs had accumulated in excess of 6,000 flight hours. This condition, if not detected and corrected, could lead to propeller blade separation, possibly resulting in damage to the aeroplane and/or injury to persons on the ground.

The cracks originating from the root of the buttress threads in the blade ports are caused by high-cycle fatigue.

Comments

We gave the public the opportunity to participate in developing this AD. We received no comments on the NPRM published in the Federal Register on May 11, 2011 (76 FR 27281) or on the determination of the cost to the public.

Since we published the NPRM in the Federal Register on May 11, 2011 (76 FR 27281), we changed the AD Docket No. from FAA-2011-0033, to FAA-2011-0735. The original number was inadvertently used both by the FAA Engine & Propeller Directorate, and the FAA Transport Airplane Directorate.

Also since we published the NPRM in the Federal Register on May 11, 2011 (76 FR 27281), we became aware that Dowty Propellers made minor changes to Alert Service Bulletin (ASB) No. 61-1043, Revision 6, and issued Revision 7, dated March 1, 2011. Revision 6 of the ASB had an incorrect Non-Destructive Testing (NDT) reference in Effectivity paragraph 1.D. We do not reference that paragraph in this AD, however, we changed the AD to reference the most current ASB, which is Revision 7.

Conclusion

We reviewed the available data and determined that air safety and the public interest require adopting the AD with the changes described previously. We determined that these changes will not increase the economic burden on any operator or increase the scope of the AD.

Costs of Compliance

Based on the service information, we estimate that this AD will affect about 2 propellers installed on one airplane of U.S. registry. We also estimate that it will take about 1 work-hour per propeller to comply with this AD. The average labor rate is $85 per work-hour. Required parts will cost about $20,000 per propeller. Based on these figures, we estimate the cost of the AD on U.S. operators to be $40,170.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. “Subtitle VII: Aviation Programs,” describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in “Subtitle VII, Part A, Subpart III, Section 44701: General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

We 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 this AD:

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 regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Operations office between 9 a.m.and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (phone: (800) 647-5527) is provided in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

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 FAA amends 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 2. The FAA amends § 39.13 by adding the following new AD:

2011-19-02Dowty Propellers (formerly Dowty Aerospace; Dowty Rotol Limited; and Dowty Rotol): Amendment 39-16807. Docket No. FAA-2011-0735; Directorate Identifier 2011-NE-01-AD.

Effective Date

(a) This airworthiness directive (AD) becomes effective November 9, 2011.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Dowty Propellers type R212/4-30-4/22 propeller assemblies with hub and driving center assembly part number (P/N) 601022105, 601022211, 601022294, 601021426, 601021858, or 601021859 installed, and type R251/4-30-4/49 propeller assemblies with hub and driving center assembly P/N 660207202 or P/N 660207203 installed.

Reason

(d) This AD results from mandatory continuing airworthiness information (MCAI) issued by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. We are issuing this AD to prevent propeller hub failure due to cracks in the hub, which could result in damage to the airplane.

Actions and Compliance

(e) Unless already done, do the following:

(1) Within 500 flight hours after the effective date of this AD, and thereafter at intervals not exceeding 500 flight hours, inspect the buttress threads in the propeller hub and driving center assembly for cracks.

(2) Use paragraphs 2.A.(1) through 2.A.(4)(a) of Accomplishment Instructions of Dowty Propellers Alert Service Bulletin No. 61-1043, Revision 7, dated March 1, 2011, and NDT Technique NDT 175U (Appendix A of Dowty Propellers Alert Service Bulletin No. 61-1043, Revision 7, dated March 1, 2011), to do the inspection.

(3) If a crack is found, remove the propeller assembly from service before further flight.

(4) After the effective date of this AD, do not install this propeller on any airplane unless the propeller hub and driving center has passed the inspections required by this AD.

FAA AD Differences

(f) This AD differs from the service information as follows:

(1) Although the service bulletin tells you to return the affected parts to the manufacturer, this AD does not require that action.

(2) Although the service bulletin tells you to submit information to the manufacturer, this AD does not require that action.

Alternative Methods of Compliance (AMOCs)

(g) The Manager, Boston Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19.

Related Information

(h) Refer to MCAI European Aviation Safety Agency AD 2011-0012, dated January 20, 2011, for related information.

(i) Contact Michael Schwetz, Aerospace Engineer, Boston Aircraft Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803;phone:781-238-7761;fax:781-238-7170, e-mail: michael.schwetz@faa.gov for more information about this AD.

Material Incorporated by Reference

(j) You must use Dowty Propellers Alert Service Bulletin No. 61-1043, Revision 7, dated March 1, 2011, to do the actions required by this AD, unless the AD specifies otherwise.

(k) The Director of the Federal Register approved the incorporation by reference of this service information under 5 U.S.C. 552(a) and 1 CFR part 51.

(l) For service information identified in this AD, contact Dowty Propellers, 114 Powers Court, Sterling, VA 20166, phone:703-421-4434;fax:703-450-0087.

(m) You may review copies at the FAA, New England Region, 12 New England Executive Park, Burlington, MA; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to:http://www.archives.gov/federal-register/cfr/ibr-locations.html.

Issued in Burlington, Massachusetts, on September 7, 2011. Peter A. White,

Manager, Engine & Propeller Directorate, Aircraft Certification Service.

References

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