fire bottle extinguishing rules

April 25, 2007

FEDERAL AVIATION ADMINISTRATION (FAA)

Air carrier certification and operations, extinguishing agent container requirements: Change in Extinguishing Agent Container Requirements, Federal Register, April 20, 2007, Volume 72, Number 76, Rules and Regulations, Page 19793, 14 CFR Parts 121, 135, Docket No. FAA-2007-26969, Amendment Nos. 121-331 and 135-109, RIN 2120-AI99, Direct final rule, request for comments.
[TEXT] [PDF]
(This direct final rule is effective June 4, 2007. Any public comments for inclusion in the Rules Docket must be received on or before May 21, 2007.)

SUMMARY: This action aligns the operational and certification safety requirements regarding over-pressurization of airplane extinguishing agent containers or fire bottles to prevent bursting; and it removes an obsolete section reference from part 135. This action eliminates the requirement for an over-pressurized fire bottle to discharge extinguishing agent outside an airplane to prevent bursting, because newer non-corrosive extinguishing agents can now be discharged inside an airplane without degrading an airframe.

DETAIL: Since at least 1949, the FAA has required fire extinguishing containers (fire bottle) to have a pressure relief line to prevent a container from bursting in case of excessive internal pressure. This pressure relief line would discharge outside the airplane because fire extinguishing agents were corrosive.
Eventually, industry developed non-corrosive extinguishing agents, and in 1977, the FAA published in the Federal Register a final rule that amended the airplane certification rules in 14 CFR 25.1199 to adopt a performance standard. This rule changed the airplane certification standards, to require airplane manufacturers to place pressure relief discharge lines in such a way to not damage an airplane, which could be inside or outside the airplane.
However, the corresponding operational requirements in Section 121.267, and by reference in Section 135.169, were not changed in 1977 and therefore only allow for the termination of the fire bottle discharge line outside the airplane. This final rule changes the fire bottle requirements so the pressure relief valve can be inside or outside the plane.
This direct final rule also removes an obsolete section reference from part 135. In a December 20, 1995 rulemaking (60 FR 65832) the FAA removed and reserved Section 121.213, which contained special airworthiness requirements, which were included in Section 121.211 (Applicability). However, a reference to Section 121.213 was inadvertently left in Section 135.169(a). This direct final rule amends part 135 to remove the reference to Section 121.213.

AMENDMENTS: 14 CFR Part 121 and 135 is amended as follows:

PART 121--OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS

Section 121.267 is revised to read as follows:

Section 121.267 Extinguishing agent container pressure relief mechanism.

(a) Extinguishing agent containers must be provided with a pressure relief mechanism to prevent bursting of the container because of excessive internal pressures. The discharge line from the relief connection must be installed in a manner so it can be inspected from the ground. Depending upon whether the discharge line terminates outside or inside the airplane, the certificate holder must accomplish the following inspections pre-departure:

(1) The discharge line terminates outside the airplane. As part of the pre-departure check, visually inspect the pressure indicator at the end of the discharge line to confirm that the container has not discharged.
(2) The discharge line terminates inside the airplane. As part of a pre-departure check, visually inspect the pressure indicator for the container for loss of pressure within the container.

(b) The certificate holder also must ensure that only non-corrosive extinguishing agents are used in systems where the pressure discharge line terminates inside the airplane.


PART 135--OPERATING REQUIREMENTS: COMMUTER AND ON DEMAND OPERATIONS AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT

Section 135.169 is amended by revising paragraph (a) to read as follows:


Section 135.169 Additional airworthiness requirements.

(a) Except for commuter category airplanes, no person may operate a large airplane unless it meets the additional airworthiness requirements of Sections 121.215 through 121.283 and 121.307 of this chapter.
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