AET Technical Knowledge and Skills 4

Question 1

In a CMOS logic circuit used in avionics, what is the most critical handling precaution?

Accepted Answer

Use ESD wrist straps and grounded work surfaces to prevent electrostatic discharge

Answer

Avoid exposure to fluorescent lighting

Answer

Store in a magnetic-shielded container

Answer

Never power the device above 3.3V

Question 2

Per IPC-A-610 and aerospace soldering standards, a solder joint exhibiting a concave fillet, shiny surface, and full lead outline is classified as:

Accepted Answer

An acceptable solder joint

Answer

A cold solder joint requiring rework

Answer

An insufficient solder joint

Answer

An overheated joint with intermetallic damage

Question 3

An ARINC 664 (AFDX) network in a modern aircraft serves as a replacement for which older avionics data bus architecture?

Accepted Answer

ARINC 429 point-to-point buses

Answer

MIL-STD-1553 dual-redundant bus

Answer

RS-232 serial links

Answer

CSDB (Collins Serial Data Bus)

Question 4

A MIL-STD-1553B data bus uses which physical medium and topology?

Accepted Answer

Twisted shielded pair with transformer coupling in a bus topology at 1 Mbps

Answer

Fiber optic star topology at 1 Gbps

Answer

Coaxial cable ring topology at 10 Mbps

Answer

CAT5 Ethernet at 100 Mbps

Question 5

Fiber optic cables used in avionics data systems are preferred over copper conductors primarily because they:

Accepted Answer

Are immune to electromagnetic interference and have much greater bandwidth potential

Answer

Carry higher electrical current for actuators

Answer

Require no connectors or termination

Answer

Can be repaired in the field with standard tools

Question 6

When installing a D-sub connector backshell on an avionics cable, the primary purpose of the backshell's strain relief is to:

Accepted Answer

Prevent mechanical stress on individual conductor solder joints or crimps at the connector pins

Answer

Provide additional EMI shielding only

Answer

Increase the connector's voltage rating

Answer

Allow quick-disconnect capability in flight

Question 7

A logic analyzer shows that a data bus has valid framing and clock, but all data bits read as logic '1'. The most likely cause is:

Accepted Answer

An open circuit on the data line causing it to float to the pull-up rail

Answer

The clock frequency is too high

Answer

The analyzer probe impedance is loading the bus

Answer

The power supply is 10% over nominal