(a) Each engine, including the combustor, turbine, and tailpipe
sections of turbine engine installations, must be isolated by a firewall,
shroud, or equivalent means, from personnel compartments, structures,
controls, rotor mechanisms, and other parts that are --
(1) Essential to controlled flight and landing; and
(2) Not protected under §29.861.
(b) Each auxiliary power unit, combustion heater, and other combustion
equipment to be used in flight, must be isolated from the rest of the
rotorcraft by firewalls, shrouds, or equivalent means.
(c) Each firewall or shroud must be constructed so that no hazardous
quantity of air, fluid, or flame can pass from any engine compartment to
other parts of the rotorcraft.
(d) Each opening in the firewall or shroud must be sealed with
close-fitting fireproof grommets, bushings, or firewall fittings.
(e) Each firewall and shroud must be fireproof and protected against
(f) In meeting this section, account must be taken of the probable path
of a fire as affected by the airflow in normal flight and in autorotation.