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Proposed Rule

Extension of Comment Period; Airplane and Engine Certification Requirements in Supercooled Large Drop, Mixed Phase, and Ice Crystal Icing Conditions

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Federal Aviation Administration (FAA), DOT.


Notice of proposed rulemaking (NPRM); extension of comment period.


This action extends the comment period for an NPRM that was published on June 29, 2010. In that document, the FAA proposed to amend the airworthiness standards applicable to certain transport category airplanes certified for flight in icing conditions and the icing airworthiness standards applicable to certain aircraft engines. The proposed regulations would improve safety by addressing supercooled large drop icing conditions for transport category airplanes most affected by these icing conditions, mixed phase and ice crystal conditions for all transport category airplanes, and supercooled large drop, mixed phase, and ice crystal icing conditions for all turbine engines. Bombardier Aerospace, an airframe manufacturer, and Turbomeca Groupe SAFRAN, an engine manufacturer, have requested an extension of the comment period from 60 days to 120 days to allow time to adequately analyze the NPRM and prepare comments.


The comment period for the NPRM published on June 29, 2010 (75 FR 37311) was scheduled to close on August 30, 2010, and is extended until September 29, 2010.


You may send comments identified by Docket Number FAA-2010-0636 using any of the following methods:

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

For more information on the rulemaking process, see the SUPPLEMENTARY INFORMATION section of this document.

Privacy: We will post all comments we receive, without change, to, including any personal information you provide. Using the search function of our docket Web site, anyone can find and read the comments received into any of our dockets, including the name of the individual sending the comment (or signing the comment for an association, business, labor union, etc.). You may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78) or you may visit

Docket: To read background documents or comments received, go to at any time or to Docket Operations in Room W12-140 of the West Building Ground Floor at 1200 New Jersey Avenue, SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

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Robert Hettman, FAA, Propulsion/Mechanical Systems Branch, ANM-112, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue, SW., Renton, WA 98057-3356; telephone (425) 227-2683; facsimile (425) 227-1320; e-mail

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Comments Invited

The FAA invites interested persons 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, please send only one copy of written comments, or if you are filing comments electronically, please submit your comments only one time.

We will file in the docket all comments 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.

Availability of Rulemaking Documents

You can get an electronic copy using the Internet by:

(1) Searching the Federal eRulemaking Portal at;​

(2) Visiting the Office of Rulemaking's Web page at​avr/​arm/​index.cfm;​ or

(3) Accessing the Government Printing Office's Web page at​fr/​index.html.

You can also get a copy by sending a request to the Federal Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence Avenue, SW., Washington, DC 20591, or by calling (202) 267-9680. Make sure to identify the docket number, notice number, or amendment number of this rulemaking.

Proprietary or Confidential Business Information

Do not file in the docket information that you consider to be proprietary or confidential business information. Send or deliver this information directly to the person identified in the FOR FURTHER Start Printed Page 49866INFORMATION CONTACT section of this document. You must mark the information that you consider proprietary or confidential. If you send the information on a disk or CD-ROM, mark the outside of the disk or CD-ROM and also identify electronically within the disk or CD-ROM the specific information that is proprietary or confidential.

Under 14 CFR 11.35(b), when we are aware of proprietary information filed with a comment, we do not place it in the docket. We hold it in a separate file to which the public does not have access, and place a note in the docket that we have received it. If we receive a request to examine or copy this information, we treat it as any other request under the Freedom of Information Act (5 U.S.C. 552). We process such a request under the DOT procedures found in 49 CFR part 7.


On June 29, 2010, the FAA issued Notice No. 10-10, entitled “Airplane and Engine Certification Requirements in Supercooled Large Drop, Mixed Phase, and Ice Crystal Icing Conditions” (75 FR 37311, Docket No. FAA-2010-0636). Comments to that document were to be received on or before August 30, 2010.

By letter dated July 9, 2010, Bombardier Aerospace (Bombardier) advised that the comment period for NPRMs has typically been 90 days for proposed rule changes of far lesser significance and complexity. Given the potential impact of the rule, and the magnitude of the effort required to review it, Bombardier stated that the comment period should be 120 days instead of 60 days. By letter dated July 26, 2010, Turbomeca Groupe SAFRAN (Turbomeca) also requested an extension to the comment period from 60 days to 120 days, citing the same reasons as Bombardier.

While the FAA concurs with Bombardier and Turbomeca's assessments of the NPRM's significance and complexity, we do not support extending the comment period for an additional 60 days. The NPRM went through the Aviation Rulemaking Advisory Committee (ARAC) process, which gave the aviation industry the opportunity to become familiar with the content of the NPRM. The ARAC working group that provided recommendations for the NPRM was comprised of members from the FAA, the European Aviation Safety Agency, and the aviation industry, including Bombardier. Because of the significant industry involvement in the rulemaking process for this NPRM, a 120-day comment period is not justified and would adversely impact the final rulemaking process. However, the FAA does support a 90-day comment period by adding an additional 30 days to the current comment period. A 90-day comment period is consistent with other recent rulemaking activities associated with aircraft icing.

Absent unusual circumstances, the FAA does not anticipate any further extension of the comment period for this rulemaking.

Extension of Comment Period

In accordance with § 11.47(c) of Title 14, Code of Federal Regulations, the FAA has reviewed Bombardier and Turbomeca's petitions for extension of the comment period to Notice No. 10-10. Bombardier and Turbomeca have shown a substantive interest in the proposed rule and good cause for the extension. The FAA has determined that an extension of the comment period is consistent with the public interest, and that good cause exists for taking this action.

Accordingly, the comment period for Notice No. 10-10 is extended until September 29, 2010.

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Issued in Washington, DC, on August 11, 2010.

Pamela Hamilton-Powell,

Director, Office of Rulemaking.

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[FR Doc. 2010-20155 Filed 8-13-10; 8:45 am]