AH-1000 Block Diagram and Subassemblies

Question 1

AHRU Power Inputs

Answer 1

Two 28 VDC Inputs. Need to switch back and forth without interruption.

Some airplanes only have 1. Need to provide hold up for transient power drop-outs.

AC Power inputs can vary from 12 VDC to 32 VDC

No On/Off. when power is applied the AHRU is on

Question 2

AH-1000 AHRS Shipset

Answer 2

2 AHRUs
2 AHRU mounting trays
2 External Configuration Modules
2 Magnetometer units (also called MSU’s, magnetic sensing units)

Question 3

ARINC 429

Answer 3

network consists of a single transmitter (source) connected to a single receiver (sink). Up to 20 receivers can be connected to a single transmitter. ARINC 429 systems can include many of these connections to share data between the elements of the avionics system.

Question 4

AHRU ARINC 429 Inputs

Answer 4

3 different A429 Transmitters

Question 5

AHRU ARINC 429 Outputs

Answer 5

6 different A429 Receivers, 4 are used and 2 are currently spares

Question 6

Discrete I/O

Answer 6

discrete I/O modules in PLCs refer to data when it is in one of two states: on or off. The signals are also referred to as 1 and 0, or open and closed. Discrete I/Os are typically far more simple than analog I/Os when learning PLC programming.

Question 7

bus between AHRU and Test Equipment

Answer 7

RS-232 bus- This is the Maintenance Mode interface bus. This bus is not connected on the airplane.

Question 8

bus between AHRU and its External Config Module (APM) only

Answer 8

I2C bus

Question 9

bus between AHRU and its Magnetometer only

Answer 9

CAN bus

Question 10

How many are there AHRU Discrete Inputs and Outputs

Answer 10

10 inputs, some are spares
2 outputs

Question 11

AHRU Discrete Outputs

Answer 11

AHRS Warning Discrete Output: communicates that the AHRU is in a faulted state.

BASIC Mode Annunciator: communicates if the AHRU is in Basic mode or Normal mode.

Question 12

AH-1000 subassemblies

Answer 12

Front Panel Assembly with Connector CCA.
Processor CCA
Power Supply CCA
Accel CCA (Accelerometer)
Gyro CCA (Rate Sensor)
Other Mechanicals: Chassis, CCA Frame, Ring Isolator, Side cover, Flex Tapes

Question 13

Transient voltage

Answer 13

Voltage Transients are defined as short duration surges of electrical energy and are the result of the sudden release of energy previously stored or induced by other means, such as heavy inductive loads or lightning. In electrical or electronic circuits, this energy can be released in a predictable manner via controlled switching actions, or randomly induced into a circuit from external sources.

Question 14

Transient voltage protection

Answer 14

Transient protection devices attempt to re-direct the energy in these transients by taking advantage of the differences between the transient waveform and the intended signal or power waveform.

Question 15

Power Supply CCA VDC Input Voltage Requirement

Answer 15

10-34 VDC input voltage

Question 16

Power Supply CCA output voltages Requirement

Answer 16

+2.6V, 3.3V, 6.2V, 5.0V, +15V, +16.5V, -15V, -16.5V

Question 17

Other Power Supply Requirements

Answer 17

Maintain normal operation through a 200 msec power interruption every 30 seconds.
Provide a Power Fail indicator for the CPU.
Provide short protection on the outputs.
Provide over voltage protection from up to an 80V spike.
Provide power sequencing for proper MPC565 and FPGA operation.

Question 18

Processor CCA

Answer 18

CPU is a Motorola power PC version, MPC 565 popular in the automotive industry. MPC 565 has many internal features that are used. It is the ‘brain’ of the AH-1000. SW is divided into BOOT SW, OPS and Maintenance SW. FPGA is the ‘brain stem’ of the AH-1000. It does many ‘automated’ functions. FPGA is firmware and is programmable. Both FPGA and SW are loaded at Card Test.

Question 19

Accelerometer CCA

Answer 19

The Accelerometer CCA is a 3 axis, MEMS based accelerometer card. The MEMS sensors used in the Accel CCA sense linear acceleration along their “sense” axis.

Question 20

3 Accelerometer outputs

Answer 20

Square wave output
Duty cycle proportional to acceleration. (25% = 0g’s)
Processor CCA (TPU in MCP565) decodes duty cycle information.

Question 21

1 Temperature Output

Answer 21

Voltage (0 to 5 Vdc) proportional to temperature.
Decoded by MCP565)