14 CFR § 27.1183

Except as provided in paragraph (b) of this section, each line, fitting, and other component carrying flammable fluid in any area subject to engine fire conditions must be fire resistant, except that flammable fluid tanks and supports which are part of and attached to the engine must be fireproof or be enclosed by a fireproof shield unless damage by fire to any non-fireproof part will not cause leakage or spillage of flammable fluid. Components must be shielded or located so as to safeguard against the ignition of leaking flammable fluid. An integral oil sump of less than 25-quart capacity on a reciprocating engine need not be fireproof nor be enclosed by a fireproof shield.

Paragraph (a) does not apply to—

Lines, fittings, and components which are already approved as part of a type certificated engine; and

Vent and drain lines, and their fittings, whose failure will not result in, or add to, a fire hazard.

Each flammable fluid drain and vent must discharge clear of the induction system air inlet.