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Proposed Advisory Circulars 25.856-1X, Thermal/Acoustic Insulation Flame Propagation Test Method Details; and 25.856-2X, Installation of Thermal/Acoustic Insulation for Burnthrough Protection

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Federal Aviation Administration (FAA), DOT.


Notice of proposed advisory circulars and request for comments.


The Federal Aviation Administration invites public comment on two draft advisory circulars concerning thermal.acoustic insulation installed on transport category airplanes. The draft advisory material provides for demonstrating compliance with amendment 25-111, which was adopted on July 31, 2003.


Comments must be received on or before January 28, 2005.


You should send your comments to the Federal Aviation Administration, Transport Airplane Directorate, Attention: Jeff Gardlin, Airframe/Cabin Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, Washington 98055-4056. You may also fax your comments to (425) 227-1149, or you may send them electronically to: You may review all comments received at the above address between 7:30 a.m. and 4 p.m. weekdays, except Federal holidays.

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Jeff Gardlin at the above address, telephone (425) 227-2136.

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How Do I Obtain a Copy of the Proposed Advisory Circular?

An electronic copy of the draft advisory circulars is available at the following Internet address:​rgl. If you do not have access to the Internet, you may request a copy by contacting Jeff Gardlin at the address or phone number listed above.

How Do I Submit Comments on the Proposed Advisory Circular

You are invited to comment on the draft ACs by submitting written comments, data, or views. Please identify the ACs by title and number. You should submit your comments to the address specified above. We will consider all comments that we receive on or before the closing date for comments before issuing the final AC.


On July 31, 2003, we published amendment 25-111 to 14 CFR part 25 (68 FR 45046). That amendment added new fire protection requirements applicable to thermal/acoustic insulation materials. It introduced a new test method and requirement that improves the fire penetration resistance of those materials, and added new test requirements related to flame propagation and burnthrough penetration resistance.

We have developed two draft advisory circulars to assist in demonstrating compliance with amendment 25-111. These ACs are:

  • AC 25.756-1X, “Thermal/Acoustic Insulation Flame Propagation Test Method Details.” This AC describes the test method to determine the flammability and flame propagation characteristics of thermal/acoustic insulation materials. It addresses issues such as test sample construction, test conduct considerations, and the applicability of amendment 25-111 to certain materials and installations.
  • AC 25.856-2X, “Installation of Thermal/Acoustic Insulation for Burnthrough Protection.” This AC provides guidance concerning the test method to determine the burnthrough resistance of thermal/acoustic insulation materials installed in transport category airplanes. Also included is guidance on the installation details and techniques, as well as test condition details.
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Issued in Renton, Washington, on December 3, 2004.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

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[FR Doc. 04-27359 Filed 12-13-04; 8:45 am]