DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2009-0776; Directorate Identifier 2009-NE-32-AD]
RIN 2120-AA64

Airworthiness Directives; Dowty Propellers Constant Speed
Propellers

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to revise airworthiness directive (AD) 2010-17-
11R1, which applies to all Dowty Propellers R408/6-123-F/17 model
propellers. AD 2010-17-11R1 requires initial and repetitive application
of sealant between the bus bar assembly and the backplate assembly of
certain line-replaceable units (LRUs). That AD also provides an
optional terminating action to the repetitive re-application of
sealant. This proposed AD would increase the interval allowed between
the required re-application of sealant, and would specify an additional
acceptable sealant. We are proposing this AD to prevent an in-flight
double generator failure, which could result in reduced control of the
airplane.

DATES: We must receive comments on this proposed AD by May 19, 2014.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:

Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the
instructions for submitting comments.

Fax: 202-493-2251.

Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE., Washington, DC 20590.

Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this AD, contact Dowty
Propellers, Anson Business Park, Cheltenham Road East, Gloucester GL2
9QN, UK; phone: 44 (0) 1452 716000; fax: 44 (0) 1452 716001. 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.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.
gov by searching for and locating Docket No. FAA-2009-
0776; or in person at the Docket Management Facility between 9 a.m. and
5 p.m., Monday through Friday, except Federal holidays. The AD docket
contains this proposed AD, the mandatory continuing airworthiness
information, the regulatory evaluation, any comments received, and
other information. The street address for the Docket Office (phone:
800-647-5527) is in the ADDRESSES section. Comments will be available
in the AD docket shortly after receipt.

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; email: michael.schwetz@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or
arguments about this proposed AD. Send your comments to an address
listed under the ADDRESSES section. Include "Docket No. FAA-2009-0776;
Directorate Identifier 2009-NE-32-AD" at the beginning of your
comments. We specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of this proposed AD. We
will consider all comments received by the closing date and may amend
this proposed AD because of those comments.

We will post all comments we receive, without change, to http://
www.regulations.gov, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact we
receive about this proposed AD.

Discussion

On August 5, 2010, we issued AD 2010-17-11, Amendment 39-16403 (75
FR 51656, August 23, 2010), ("AD 2010-17-11"), for Dowty Propellers
model R408/6-123-F/17 propellers. AD 2010-17-11 required initial
application and repetitive re-application of sealant between the bus
bar assembly and the backplate assembly of LRU serial numbers below
DAP0347. AD 2010-17-11 resulted from failure of the propeller de-ice
bus bar due to friction or contact between the bus bar and the
backplate assembly, consequent intermittent short circuit, and possible
dual alternating current generator failure.

On June 18, 2013, we issued AD 2010-17-11R1, Amendment 39-17481 (78
FR 41283, July 10, 2013), for Dowty Propellers R408/6-123-F/17 model
propellers. AD 2010-17-11R1 added an optional terminating action to the
requirement for the repetitive re-application of sealant. AD 2010-17-
11R1 resulted from Dowty Propellers development of a new slip ring de-
icer harness to replace the bus bar assembly. We issued AD 2010-17-11R1
to prevent an in-flight double generator failure, which could result in
reduced control of the airplane.

Actions Since AD 2010-17-11R1 Was Issued

Since we issued AD 2010-17-11R1, Dowty Propellers issued Alert
Service Bulletin (ASB) No. D8400-61-A66, Revision 8, dated October 31,
2013. That ASB increased the interval between required re-application
of sealant from 10,000 flight hours (FHs) to 10,500 FHs. That ASB
identified an additional acceptable sealant. The European Aviation
Safety Agency has issued AD 2009-0114R2, dated December 16, 2013, which
incorporates the revised schedule for re-application of sealant.

Relevant Service Information

We reviewed Dowty Propellers ASB No. D8400-61-A66, Revision 8,
dated October 31, 2013. The ASB describes procedures for performing
initial and repetitive re-application of sealant between the bus bar
assembly and the backplate assembly of certain LRUs.

FAA's Determination

We are proposing this AD because we evaluated all the relevant
information and determined the unsafe condition described previously is
likely to exist or develop in other products of the same type design.

Proposed AD Requirements

This proposed AD would increase the interval from 10,000 FHs to
10,500 FHs between re-application of sealant, and would allow use of an
additional acceptable sealant.

Costs of Compliance

We estimate that this proposed AD would affect 104 propellers
installed on airplanes of U.S. registry. We also estimate that it would
take about 2 hours per propeller to comply with this proposed AD. The
average labor rate is $85 per hour. Required parts cost about $20 per
propeller. Based on these figures, we estimate the total cost of this
proposed AD to U.S. operators is $19,760.

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 have determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD 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.

For the reasons discussed above, I certify that the 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),

(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, positive or
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.

The Proposed Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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. Amend Sec. 39.13 by removing airworthiness directive (AD) 2010-17-
11R1, Amendment 39-17481 (78 FR 41283, July 10, 2013), and adding the
following new AD: