§ 35.23 Propeller control system.

The requirements of this section apply to any system or component that controls, limits or monitors propeller functions. (a) The propeller control system must be designed, constructed and validated to show that: (1) The propeller control system, operating in normal and alternative operating modes and in transition between operating modes, performs the functions defined by the applicant throughout the declared operating conditions and flight envelope. (2) The propeller control system functionality is not adversely affected by the declared environmental conditions, including temperature, electromagnetic interference (EMI), high intensity radiated fields (HIRF) and lightning. The environmental limits to which the system has been satisfactorily validated must be documented in the appropriate propeller manuals. (3) A method is provided to indicate that an operating mode change has occurred if flight crew action is required. In such an event, operating instructions must be provided in the appropriate manuals. (b) The propeller control system must be designed and constructed so that, in addition to compliance with § 35.15: (1) No single failure or malfunction of electrical or electronic components in the control system results in a hazardous propeller effect. (2) Failures or malfunctions directly affecting the propeller control system in a typical airplane, such as structural failures of attachments to the control, fire, or overheat, do not lead to a hazardous propeller effect. (3) The loss of normal propeller pitch control does not cause a hazardous propeller effect under the intended operating conditions. (4) The failure or corruption of data or signals shared across propellers does not cause a hazardous propeller effect. (c) Electronic propeller control system imbedded software must be designed and implemented by a method approved by the Administrator that is consistent with the criticality of the performed functions and that minimizes the existence of software errors. (d) The propeller control system must be designed and constructed so that the failure or corruption of airplane-supplied data does not result in hazardous propeller effects. (e) The propeller control system must be designed and constructed so that the loss, interruption or abnormal characteristic of airplane-supplied electrical power does not result in hazardous propeller effects. The power quality requirements must be described in the appropriate manuals.