AD 2010-17-11R1

We are revising an existing airworthiness directive (AD) that applies to all Dowty Propellers R408/6-123-F/17 model propellers. That AD currently requires initial applications of sealant between the bus bar assembly and the backplate assembly of certain line-replaceable units, and repetitive applications of sealant on all R408/6-123-F/17 model propellers. This new AD requires the same actions and allows the use of an equivalent sealant as prescribed in revised service information. This AD was prompted by the need to add an optional terminating action to the applications of sealant. We are issuing this AD to prevent an in-flight double generator failure, which could result in reduced control of the airplane.

Final rule.

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

0 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]

0 2. The FAA amends Sec. 39.13 by removing airworthiness directive (AD) 2010-17-11, Amendment 39-16403 (75 FR 51656, August 23, 2010), and adding the following new AD:

2010-17-11R1 Dowty Propellers: Amendment 39-17481; Docket No. FAA- 2009-0776; Directorate Identifier 2009-NE-32-AD.

(a) Effective Date

This AD is effective August 14, 2013.

(b) Affected ADs

This AD revises AD 2010-17-11, Amendment 39-16403 (75 FR 51656, August 23, 2010).

(c) Applicability

This AD applies to Dowty Propellers R408/6-123-F/17 model propellers.

(d) Unsafe Condition

This AD was prompted by the need to add an optional terminating action to the applications of sealant. We are issuing this AD to prevent an in-flight double generator failure, which could result in reduced control of the airplane.

(e) Compliance

Comply with this AD within the compliance times specified, unless already done.
(1) For R408/6-123-F/17 model propellers with a hub, actuator, and backplate assembly line-replaceable unit serial number below DAP0347, do the following initial sealant application within 5,000 flight hours (FHs) after September 27, 2010, or within 100 FHs from the effective date of this AD, whichever occurs later:
(i) Apply 3M 5300 or 3M 4200 sealant between the bus bar assemblies and the backplate assembly.
(ii) Use paragraph 3 of the Accomplishment Instructions of Dowty Propellers Alert Service Bulletin (ASB) No. D8400-61-A66, Revision 7, dated December 1, 2011, to apply the sealant.
(2) Thereafter, for all R408/6-123-F/17 model propellers, re- apply sealant as specified in paragraphs (e)(1)(i) through (e)(1)(ii) of this AD within every additional 10,000 FHs.

(f) Installation Prohibition

After the effective date of this AD, do not install any Dowty Propellers R408/6-123-F/17 model propeller unless 3M 5300 or 3M 4200 sealant has been applied between the bus bar assembly and the backplate assembly as specified by this AD, or unless the optional terminating action as specified in paragraph (h) of this AD has been performed.

(g) Credit for Previous Actions

Sealant applications performed before the effective date of this AD that followed Dowty Propellers Service Bulletin (SB) No. D8400- 61-66, dated February 9, 2007, Revision 1, dated May 4, 2007; ASB No. D8400-61-A66, Revision 2, dated August 19, 2009; Revision 3, dated November 10, 2009; Revision 4, dated January 19, 2010; Revision 5, dated June 16, 2010, or Revision 6, dated August 17, 2011 satisfy the initial sealant application requirement of this AD.

(h) Optional Terminating Action

As optionalterminating action to the sealant application requirements of this AD, replace the bus bar assembly with a slip ring de-icer harness. Use paragraph 3.A. of the Accomplishment Instructions of Dowty Propellers SB No. D8400-61-94, Revision 2, dated August 29, 2012, or Revision 3, dated October 23, 2012, to do the replacement.

(i) Alternative Methods of Compliance (AMOCs)

The Manager, Boston Aircraft Certification Office, FAA, may approve AMOCs for this AD. Use the procedures found in 14 CFR 39.19 to make your request.

(j) Related Information

(1) Refer to European Aviation Safety Agency AD 2009-0114R1 (correction: dated December 12, 2012) for related information.
(2) For more information about this AD, contact Michael Schwetz, Aerospace Engineer, Boston Aircraft Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; phone: 781-238-7761; fax 781-238-7170; email: michael.schwetz@faa.gov.

(k) Material Incorporated by Reference

(1) The Director of the Federal Register approved the incorporation by reference (IBR) of the service information listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this service information as applicable to do the actions required by this AD, unless the AD specifies otherwise.
(3) The following service information was approved for IBR on August 14, 2013.
(i) Dowty Propellers Alert Service Bulletin No. D8400-61-A66, Revision 7, dated December 1, 2011.
(ii) Dowty Propellers Service Bulletin No. D8400-61-94, Revision 2, dated August 29, 2012.
(iii) Dowty Propellers Service Bulletin No. D8400-61-94, Revision 3, dated October 23, 2012.
(4) For service information identified in this AD, contact Dowty Propellers, Anson Business Park, Cheltenham Road East, Gloucester GL 29QN, UK; phone: 44 (0) 1452 716000; fax: 44 (0) 1452 716001.
(5) You may view this service information at the FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA. For information on the availability of this material at the FAA, call 781-238-7125.
(6) You may view this service information 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.

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to revise AD 2010-17-11, Amendment 39-16403 (75 FR 51656, August 23, 2010). That AD applies to the specified products. The NPRM published in the Federal Register on February 7, 2013 (78 FR 9005). That NPRM proposed to add an optional terminating action to the applications of sealant.

Comments

We gave the public the opportunity to participate in developing this AD. The following presents the comments received on the proposal and the FAA's response to each comment.

Request To Add Revised Service Information

Horizon Air requested that we reference the latest revision of Dowty Alert Service Bulletin (ASB) No. D8400-61-A66, which is Revision 7, dated December 1, 2011 in the Compliance and the Credit for Previous Actions sections of the final rule.
We partially agree. We changed paragraph (e)(1)(ii) of the Compliance section to read, ``Use paragraph 3 of the Accomplishment Instructions of Dowty Propellers Alert Service Bulletin (ASB) No. D8400-61-A66, Revision 7, dated December 1, 2011 to apply the sealant.'' We do not agree with the change to the Credit for Previous Actions paragraph because referencing the ASB in the Compliance paragraph satisfies this request by directing the use of the latest revision as stated.

Request To Add Equivalent Sealant

Horizon Air requested that we allow the use of 3M 4200 sealant as an equivalent replacement for the 3M 5300 sealant listed in the Accomplishment Instructions of Dowty Propellers Service Bulletin (SB) No. D8400-61-94, Revision 3, dated October 23, 2012.
We agree. We changed the AD by modifying references to ``sealant'' to ``3M 5300 or 3M 4200 sealant'' in the Compliance and Installation Prohibition paragraphs.

Conclusion

We reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting theAD with the changes described previously and minor editorial changes. We have determined that these minor changes:
Are consistent with the intent that was proposed in the NPRM (78 FR 9005, February 7, 2013) for correcting the unsafe condition; and
Do not add any additional burden upon the public than was already proposed in the NPRM (78 FR 9005, February 7, 2013).

Differences Between This AD and the Service Information

Dowty Propellers SB No. D8400-61-94, Revision 3, dated October 23, 2012 requires the application of 3M 5300 sealant between the bus bar assembly and the backplate assembly of Dowty Propeller R408/6-123-F/17. This AD also permits use of 3M 4200 sealant as an acceptable equivalent to the 3M 5300 sealant.

Costs of Compliance

We estimate that this AD will affect about 104 propellers installed on airplanes of U.S. registry. We also estimate that it will take about 3 hours per propeller to apply the sealant and that required sealant will cost about$20 per propeller. We also estimate that it will take about 3 hours to replace the bus bar with a de-icer slip ring harness and that required parts will cost about $1,200 per propeller. The average labor rate is $85 per hour. Based on these figures, we estimate the cost of the AD on U.S. operators to be $171,080.

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

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because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

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 this AD:
(1) Is not a ``significant regulatory action'' under Executive Order 12866,
(2) Is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979),
(3) Will not affect intrastate aviation in Alaska to the extent that it justifies making a regulatory distinction, and
(4) Will not have a significant economic impact, positiveor negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.