For reciprocating engine powered rotorcraft the following apply:
(a) Each exhaust heat exchanger must be constructed and installed to
withstand the vibration, inertia, and other loads to which it would be
subjected in operation. In addition --
(1) Each exchanger must be suitable for continued operation at high
temperatures and resistant to corrosion from exhaust gases;
(2) There must be means for inspecting the critical parts of each
exchanger;
(3) Each exchanger must have cooling provisions wherever it is subject
to contact with exhaust gases; and
(4) No exhaust heat exchanger or muff may have stagnant areas or liquid
traps that would increase the probability of ignition of flammable fluids
or vapors that might be present in case of the failure or malfunction of
components carrying flammable fluids.
(b) If an exhaust heat exchanger is used for heating ventilating air
used by personnel --
(1) There must be a secondary heat exchanger between the primary
exhaust gas heat exchanger and the ventilating air system; or
(2) Other means must be used to prevent harmful contamination of the
ventilating air.