14 CFR 23.1309 - Equipment, systems, and installations.
The requirements of this section, except as identified in paragraphs (a) through (d), are applicable, in addition to specific design requirements of part 23, to any equipment or system as installed in the airplane. This section is a regulation of general requirements and does not supersede any requirements contained in another section of part 23.
(a) The airplane equipment and systems must be designed and installed so that:
(1) Those required for type certification or by operating rules perform as intended under the airplane operating and environmental conditions, including the indirect effects of lightning strikes.
(b) Minor, major, hazardous, or catastrophic failure condition(s), which occur during Type Inspection Authorization or FAA flight-certification testing, must have root cause analysis and corrective action.
(c) The airplane systems and associated components considered separately and in relation to other systems, must be designed and installed so that:
(1) Each catastrophic failure condition is extremely improbable and does not result from a single failure;
(2) Each hazardous failure condition is extremely remote; and
(3) Each major failure condition is remote.
(d) Information concerning an unsafe system operating condition must be provided in a timely manner to the crew to enable them to take appropriate corrective action. An appropriate alert must be provided if immediate pilot awareness and immediate or subsequent corrective action is required. Systems and controls, including indications and annunciations, must be designed to minimize crew errors which could create additional hazards.