Skip to Content

Proposed Rule

Airworthiness Directives; Agusta S.p.A. Helicopters

Document Details

Information about this document as published in the Federal Register.

Enhanced Content

Relevant information about this document from provides additional context. This information is not part of the official Federal Register document.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.


Notice of proposed rulemaking (NPRM).


We propose to adopt a new airworthiness directive (AD) for Agusta S.p.A. (Agusta) Model AB139 and AW139 helicopters with a certain generator control unit (GCU). This proposed AD was prompted by laboratory tests which revealed a potential fault in the overvoltage protection on a certain part-numbered GCU. This proposed AD would require replacing each affected GCU with an airworthy GCU. In addition, any affected GCU is not approved for installation on any helicopter. We are proposing this AD to prevent failure of the overvoltage protection of the GCU, degraded performance of the electrical power generation and distribution systems, a fire, and subsequent loss of control of the helicopter.


We must receive comments on this proposed AD by March 20, 2012.


You may send comments by any of the following methods:

  • Federal eRulemaking Docket: Go to Follow the online instructions for sending your comments electronically.
  • Fax: (202) 493-2251.
  • Mail: Send comments to the U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590-0001.
  • Hand Delivery: Deliver to the “Mail” address between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Examining The AD Docket: You may examine the AD docket on the Internet at 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 proposed AD, the economic evaluation, any comments received, and other information. The street address for the Docket Operations Office (telephone (800) 647-5527) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

For service information identified in this proposed AD, contact Agusta Westland, Customer Support & Services, Via Per Tornavento 15, 21019 Somma Lombardo (VA) Italy, ATTN: Giovanni Cecchelli; telephone 39-0331-711133; fax 39-0331-711180; or at You may review copies of the referenced service information at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137.


Mark Wiley, Aerospace Engineer, FAA, Regulations and Policy Group, Rotorcraft Directorate, 2601 Meacham Blvd., Fort Worth, Texas 76137; telephone: (817) 222-5134; fax: (817) 222-5961; email:


Comments Invited

We invite you to participate in this rulemaking by submitting written comments, data, or views. We also invite comments relating to the economic, environmental, energy, or federalism impacts that might result from adopting the proposals in this document. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. To ensure the docket does not contain duplicate comments, commenters should send only one copy of written comments, or if comments are filed electronically, commenters should submit only one time.

We will file in the docket all comments that we receive, as well as a report summarizing each substantive public contact with FAA personnel concerning this proposed rulemaking. Before acting on this proposal, we will consider all comments we receive on or before the closing date for comments. We will consider comments filed after the comment period has closed if it is possible to do so without incurring expense or delay. We may change this proposal in light of the comments we receive.


The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Union, has issued AD No. 2009-0042, dated February 25, 2009 (AD-2009-0042) to correct an unsafe condition for the Agusta Model AB139 and AW139 helicopters, all serial numbers (S/Ns) except S/Ns 31002, 31003, 31004, and 31007. EASA advises that laboratory tests performed on a new GCU model under development have shown a potential fault in the overvoltage protection of currently installed GCUs, part number (P/N) 1152550-3. EASA advises that this condition, if not corrected, could adversely affect the helicopter's electrical power generation and distribution system functionalities.

FAA's Determination

We are proposing this AD because we evaluated all known relevant information and determined that an unsafe condition exists and is likely to exist or develop on other helicopters of these same type designs.

Related Service Information

Agusta S.p.A. issued Mandatory Bollettino Tecnico No. 139-133, Revision A, dated March 17, 2009 (BT), for Model AB139 and AW139 helicopters, S/Ns 31005 up to S/N 31143, except for S/Ns 31007, 31037, 31038, 31094; S/N 31112; S/Ns 31146 up to S/N 31148; S/N 31155; S/Ns 31201 up to S/N 31218; and S/Ns 41001 up to S/N 41022, except S/N 41007; with a GCU, P/N 1152550-3. This BT specifies, within 6 months from receipt of the BT, removing GCU, P/N 1152550-3, modifying electrical connector A13P1 and A14P1, and replacing each GCU with an airworthy GCU, P/N 1152550-4 or 1152550-5, to improve electrical power generation and distribution system functionalities. EASA classified this BT as mandatory and issued AD 2009-0048 to ensure the continued airworthiness of these helicopters.

Proposed AD Requirements

This proposed AD would require, within 6 months, removing the No. 1 and No.2 GCU, P/N 1152550-3, modifying the electrical connectors A13P1 and A14P1 by installing wiring to the power distribution panel, and installing a No. 1 and No. 2 GCU with P/N 1152550-4 or 1152550-5. Both GCUs must have identical P/Ns on the same helicopter.

Differences Between This Proposed AD and the EASA AD

The EASA AD does not apply to certain serial-numbered Model AB139 and AW139 helicopters, and this proposed AD applies to all serial-numbered Model AB139 and AW139 helicopters.

Costs of Compliance

We estimate that this proposed AD would affect 72 helicopters of U.S. Registry. We estimate that operators may incur the following costs in order to comply with this AD. We estimate that it would take about 4 work hours per helicopter at an average labor rate of $85 per work hour. Required parts would cost about $42,384 per helicopter. Based on these figures, we estimate the total cost impact of the proposed AD for the U.S. operator fleet to be $3,076,128.

According to the Agusta service information some of the costs of this proposed AD may be covered under warranty, thereby reducing the cost impact on affected individuals. We do not control warranty coverage by Agusta. Accordingly, we have included all costs in our cost estimate.

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 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, I certify 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);

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.

We prepared an economic evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket.

List of Subjects in 14 CFR Part 39

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:


1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.


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

Agusta S.P.A. Helicopters (Agusta): Docket No. FAA-2012-0013; Directorate Identifier 2010-SW-043-AD.

(a) Applicability

This AD applies to Agusta Model AB139 and AW139 helicopters, with a generator control unit (GCU), part-number (P/N) 1152550-3 installed; certificated in any category.

(b) Unsafe Condition

This AD defines the unsafe condition as a potential fault in the overvoltage protection in GCUs currently installed on Model AB139 and AW139 helicopters. We are proposing this AD to prevent failure of the overvoltage protection of the GCU, degraded performance of the electrical power generation and distribution systems, or fire, and subsequent loss of control of the helicopter.

(c) Compliance

You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.

(d) Requirements

(1) Remove the No. 1 and No. 2 GCU, P/N 1152550-3. Do not install GCU, P/N 1152550-3, on any helicopter.

(2) Modify the electrical connector A13P1 (GCU #1) and A14P1 (GCU #2) by installing the wiring to the power distribution panel (PDP) for your serial-numbered helicopter as depicted in Figure 1 of Agusta Bollettino Tecnico No. 139-133, Revision A, dated March 17, 2009.

(3) Using either GCU P/N 1152550-4 or GCU P/N 1152550-5, install a No. 1 and No. 2 GCU that has the same part number. Having different part-numbered GCUs on the same helicopter is not approved.

(e) Alternative Methods of Compliance (AMOC)

(1) The Manager, Safety Management Group, Rotorcraft Directorate, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the ACO, send it to the attention of the person identified in the Related Information section of this AD.

(2) For operations conducted under a Part 119 operating certificate or under Part 91, Subpart K, we suggest that you notify your principal inspector, or lacking a principal inspector, the manager of the local flight standards district office or certificate holding district office, before operating any aircraft complying with this AD through an AMOC.

(f) Additional Information

The subject of this AD is addressed in European Aviation Safety Agency (Italy) AD 2009-0042, dated February 25, 2009.

(g) Subject

Joint Aircraft Service Component (JASC) Code: 2430 DC generating system.

Issued in Fort Worth, Texas, on January 5, 2012.

Lance T. Gant,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.

[FR Doc. 2012-1121 Filed 1-19-12; 8:45 am]