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###### Department of Transportation

###### Federal Aviation Administration

# AGENCY:

Federal Aviation Administration, DOT.

# ACTION:

Notice of available of proposed Advisory Circular (AC) 25.981-2A, and request for comments. 

# SUMMARY:

This notice announces the availability of and requests comments on a proposed advisory circular (AC) which sets forth an acceptable means, but not the only means, of demonstration compliance with the provisions of the airworthiness standards for transport category airplanes related to Fuel Tank Flammability Reduction. This proposed AC complements revisions to the airworthiness standards that are being proposed by a separate notice. This notice is necessary to give all interested persons an opportunity to present their views on the proposed AC.

# DATES:

Comments must be received on or before March 20, 2006.

# ADDRESSES:

Send all comments on proposed AC to: Federal Aviation Administration, Attention: Mike Dostert, Propulsion/Mechanical Systems Branch, ANM-112, FAA, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, WA 98055-4056. Comments may be inspected at the above address between 7:30 a.m. and 4 p.m. weekdays, except Federal holidays.

# FOR FURTHER INFORMATION CONTACT:

Jan Thor, Transport Standards Staff, at the address above, telephone (425) 227-2127.

# SUPPLEMENTARY INFORMATION:

## Comments Invited

                    Interested persons are invited to comment on the proposed AC by submitting such written data, views, or arguments, as they may desire. Commenters should identify AC 25.981-2A and submit comments, in duplicate, to the address specified above. All communications received on or before the closing date for comments will be considered by the Transport Standards Staff before issuing the final AC. The proposed AC can be found and downloaded from the Internet at                     *http://www.airweb.faa.gov/​rgl*                     under “Draft Advisory Circulars.” A paper copy of the proposed AC may be obtained by contacting the person named above under the caption                     **FOR FURTHER INFORMATION CONTACT**                    .                

## Discussion

This proposed AC provides information and guidance on compliance with the airworthiness standards for transport category airplanes about limiting the time a fuel tank may be flammable or mitigation of hazards from flammable fuel air mixtures within fuel tanks. This guidance is applicable to transport category airplanes for which a new, amended, or supplemental type certificate is requested and affected existing design approval holders as stated in proposed §§ 25.1815, 25.1817, 25.1819, and 25.1821 contained in a proposed new subpart I to Title 14, Code of Federal Regulations (14 CFR) part 25, “Continued Airworthiness and Safety Improvement.” The AC also provides guidance on compliance with the associated proposed requirements for operators of affected airplanes that must comply with the requirements of 14 CFR parts 91, 121, 125, and 129 (for a foreign person or foreign air carrier operating a U.S.-registered airplane) to incorporate flammability mitigation means by specified dates.

The Notice of Proposed Rulemaking would not apply the proposed new requirements to transport category airplanes designed solely for cargo carriage. However, AC 25.981-2 remains applicable to these airplanes, which must comply with the current flammability standards contained in § 25.981(c) that would be moved to the proposed section § 25.981(e). We will consider combining this guidance for all transport category airplanes into one AC when the final rule and AC are issued.

                    It is one means, but not the only means, of complying with the part 25 revisions proposed in Notice No. 05-14 entitled “Fuel Tank Flammability Reduction,” published in this same edition of the                     **Federal Register**                    . Issuance of AC 25.981-2A is contingent on final adoption of the proposed revisions to part 25.                

Issued in Renton, Washington, on November 16, 2005.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 05-23100  Filed 11-21-05; 8:45 am]

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