Document Headings

                    Document headings vary by document type but may contain                    the following:                  
                -                       the agency or agencies that issued and signed a document                    
                -                       the number of the CFR title and the number of each part                      the document amends, proposes to amend, or is directly                      related to                    
                -                       the agency docket number / agency internal file number                    
                -                       the RIN which identifies each regulatory action listed in                      the Unified Agenda of Federal Regulatory and Deregulatory                      Actions                    

                    See the                                          Document Drafting Handbook                                        for more details.                  

###### Department of Transportation

###### Federal Aviation Administration

# AGENCY:

Federal Aviation Administration, DOT.

# ACTION:

Notice of availability and request for public comment.

# SUMMARY:

This notice announces the availably of and requests comments on a proposed Advisory Circular (AC) 20-DATABUS, Aviation Databus Assurance. This proposed AC provides guidance for manufacturers of aircraft, aircraft engine, and avionics incorporating databuses and databus technology in the design of their aircraft, aircraft engine, or avionics systems. In the proposed AC, we recommend how you as the manufacturer, may get design and airworthiness approval for your databus.

# DATES:

Comments must be received on or before September 16, 2005.

# ADDRESSES:

Send all comments on the proposed AC to: Federal Aviation Administration (FAA), Aircraft Certification Service, Aircraft Engineering Division, Technical Programs and Continued Airworthiness Branch, AIR-120, 800 Independence Avenue, SW., Washington, DC 20591. ATTN: Mr. John Lewis, or deliver comments to: Federal Aviation Administration, Room 825, 800 Independence Avenue, SW., Washington, DC 20591.

# FOR FURTHER INFORMATION CONTACT:

                        Mr. John Lewis, AIR-120, Room 835, Federal Aviation Administration, Aircraft Certification Service, Aircraft Engineering Division, 800 Independence Avenue, SW., Washington, DC 20591. Telephone (202) 493-4841, FAX: (202) 267-5340. Or, via e-mail at:                         *john.lewis@faa.gov.*

# SUPPLEMENTARY INFORMATION:

## Comments Invited

Interested persons are invited to comment on the proposed AC listed in this notice by submitting such written data, views, or arguments as they desire to the above specified address. Comments received on the proposed AC may be examined, before and after the comment closing date, in Room 825, FAA Headquarters Building, 800 Independence Avenue, SW., Washington, DC 20591, weekdays except Federal holidays, between 8:30 a.m. and 4:30 p.m. All communications received on or before the closing date will be considered by the Director, Aircraft Certification Service, before issuing the final Advisory Circular.

## Background

Aircraft, aircraft engine, and avionics manufacturers may choose from several databus configurations for use on aircraft. The function of a databus is to transfer information between avionics modules, components, or line replaceable units (LRU) installed in an aircraft. As such, these databuses are becoming more complex as aircraft, aircraft engine, and avionics manufacturers integrate more avionics components into the aircraft and aircraft engine data sources, resulting in large data transfers between data buses. System design engineers have considerable flexibility when designing a databus because of the many physical and logical configurations for airborne systems architecture, data units or packets, protocols, message traffic, and so on, thereby providing manufacturers, vendors, and integrators more latitude when configuring databuses. This proposed AC contains the criteria applicants must address when developing, selecting, or integrating databus technology they will use to show compliance with the appropriate certification requirements for their aircraft or aircraft engine.

## How To Obtain Copies

                    You may get a copy of the proposed AC from the Internet at:                     *www.airweb.faa.gov/​rgl.*                     Once on the RGL Web site, select “Draft Advisory Circular”, then select the document by number. See section entitled                     **FOR FURTHER INFORMATION CONTACT**                     for the complete address if requesting a copy by mail.                

Issued in Washington, DC, on August 25, 2005.

Susan J.M. Cabler,

Assistant Manager, Aircraft Engineering Division, Aircraft Certification Service.

[FR Doc. 05-17383 Filed 8-31-05; 8:45 am]

BILLING CODE 4910-13-M