The AP9121 Fuel Flow Interface Module, is a +28V powered signal conditioning module developed to provide fuel flow conversions between the fuel flow sensors (TNAS 1024-118) and the FMS (GNS-XLS) on the Eurocopter Dauphin (CDSR VIP).
The AP9121 module provides two analog inputs, two frequency (tacho) inputs, and two discrete inputs. The AP9121 also has two analogue outputs, two ARINC-429 outputs, two PWM outputs and a +28V discrete status output.
The AP9121 uses our propriatory signal shaping circuitry to convert the variable amplitude AC sinusoidal fuel flow waveform into a fixed amplitude square wave for digital sampling.
The AP9121 provides 2 input channels for flow and 2 input channels for temperature and can output corrected flow rate as either an analog output, PWM discrete, or ARINC-429 data word.
The AP9121 also provides optional analog filters (3Hz cutoff) for the temperature input channels, for use in very noisy environments.
The AP9121 uses the following transfer function to convert the measured resistance to temperature.
The AP9121 electrical interface is fully specified in Nginuity Interface Control Document AP9121-ICD which is available from our downloads page (login required).
The AP9121 is supported by Nginuity's "Product Configurator" software application, available from our downloads page (login required).