(a) Each fuel tank must be supported so that tank loads are not
concentrated on unsupported tank surfaces. In addition --
(1) There must be pads, if necessary, to prevent chafing between each
tank and its supports;
(2) The padding must be nonabsorbent or treated to prevent the
absorption of fuel;
(3) If flexible tank liners are used, they must be supported so that
they are not required to withstand fluid loads; and
(4) Each interior surface of tank compartments must be smooth and free
of projections that could cause wear of the liner, unless --
(i) There are means for protection of the liner at those points; or
(ii) The construction of the liner itself provides such protection.
(b) Any spaces adjacent to tank surfaces must be adequately ventilated
to avoid accumulation of fuel or fumes in those spaces due to minor
leakage. If the tank is in a sealed compartment, ventilation may be
limited to drain holes that prevent clogging and that prevent excessive
pressure resulting from altitude changes. If flexible tank liners are
installed, the venting arrangement for the spaces between the liner and
its container must maintain the proper relationship to tank vent pressures
for any expected flight condition.
(c) The location of each tank must meet the requirements of §29.1185(b)
and (c).
(d) No rotorcraft skin immediately adjacent to a major air outlet from
the engine compartment may act as the wall of an integral tank.