AET Data Bus Systems and Protocols 3

Question 1

Which avionics data bus standard supports data rates up to 100 Mbps and is used in modern commercial aircraft such as the A380 and Boeing 787?

Accepted Answer

ARINC 664 (AFDX)

Answer

ARINC 664 Part 7 (AFDX) supports data rates up to 100 Mbps and is the high-speed backbone network used in the A380 and Boeing 787.

Question 2

What is the specified characteristic impedance of a MIL-STD-1553 bus cable?

Accepted Answer

70 ohms

Answer

MIL-STD-1553 specifies a bus characteristic impedance of 70 ohms (±0.5 ohm) for the shielded twisted pair cable.

Question 3

When troubleshooting an ARINC 429 bus with no output signal, what should a technician check first?

Accepted Answer

Power supply voltage to the transmitter LRU

Answer

No signal on an ARINC 429 bus most commonly indicates a loss of power to the transmitter, so verifying power supply voltage is the logical first step.

Question 4

In MIL-STD-1553, what is a 'stub'?

Accepted Answer

A short cable connecting a terminal to the main bus

Answer

A stub is the short branch cable that connects a Remote Terminal or other device to the main MIL-STD-1553 bus cable, with maximum lengths defined by coupling type.

Question 5

What is the primary purpose of coupling transformers used in a MIL-STD-1553 bus installation?

Accepted Answer

Provide electrical isolation and impedance matching between terminal and bus

Answer

Coupling transformers provide galvanic isolation between the bus and each terminal while simultaneously matching impedance for proper signal integrity.

AET - Avionics Electronic Technicians Practice Test

AET - Avionics Electronic Technicians Practice Test

AET Data Bus Systems and Protocols 3