EFIS & A/C data buses

[ben123]

Hello, I am a student currently studying avionic engineering at college, we are currently do some work on EFIS and aircraft data buses , I am finding it difficult to find out information to answer the questions below as the way the questions are set means that they are brief and vague, any help/information you could give me would be greatly appreciated;


1) If a single item of information is missing from all the electronic flight deck display screens on which it is normally displayed, then the most likely cause would be loss of signal from the :-

a) Display controller or symbol generator
b) Display controller or the input sensor
c) Symbol generator or input sensor

2) The Electronic flight instrument system consists of :-

a) Air data computer, airspeed indicator, altimeter and vertical speed indicators
b) Mode select panel, stroke and raster generators displays, display controllers and main processor
c) Heading situation indicator, attitude director indicators and symbol generators

3) In an ARINC 629 data transmission system, line replaceable units :-

a) May be connected to more than one data bus and can transmit and receive data on each individual data bus
b) Must transmit on one data bus and receive on a separate data bus
c) Can only transmit and receive on one data bus

4) The BITE test used for checking the correct alignment of sensors and actuators is the :-

a) System performance test
b) Line replaceable unit power-up self test
c) Line replaceable verification test


Thankyou for your help

Ben

[Golden Rivet]

Ok, I'll have a go first - like a lamb to the slaughter

1-C
2-C
3-C, have not come across it before, but A may be possible ?
4-C

Regards

GR

[it will do the trip]

I will go along with goldern rivet except for the 3rd question as he said. I'd prefer A as Arinc 629 is bi directional dual bus whilst Arinc 429 is uni directional and single bus.

[spannersatcx]

Re Q1 if the input is lost or no valid data do you not get an XXX?

Rather than no symbol?

I would of said 1a.

[mono]

In reverse order, like Eric Morely (who?)

4. C, the verify test. However it does not check correct alignment, etc it merely checks to confirm that input/actuator parameters are within a certain range of values which would correspond to normal operational maxima and minima. To truely check correct alignment the engineer would have to carry out more detailed checks.

3. A, yes 629 is bi-directional whereas 429 is not. The idea was to further reduce wiring and therefore weight. So 629 has integral tx/rx's feeding each data bus but 429 has individual tx's and rx's and, if bi-directional exchange of information was necessary would therefore require 2 separate databusses.

2. What a terrible question! None of the answers provided are truely correct. However, in an animal farm kind of way some are more correct than others. Therefore the correct answer is C, although I would have preferred it if they had listed EHSI, EADI, symbol generators, mode controllers and various input sensors. A refers to the airdata system and B more towards any generic CRT display (radar, EICAS, etc).

1. Another terrible question! However I agree with the majority here that the answer is C. Loss of for example the left ILS would cause the info to be lost on the left EFIS system.

Hope this helps.

[spannersatcx]

If ILS is working correctly then you would get LOC and G/S pointers as normal.

If you then had NCD (non computed data) the LOC and G/S pointers would be removed and freq/ident would be removed but still have the deviation scale.

If you had invalid data the pointers and scale would be removed and you would have a flag, freq/ident would be removed.

And status msg's.

If the input had failed you would get something like the above.

If you lost the Display controller then I would guess that you wouldn't get the flags displayed?

Does that sound about right or not??

As said a bit of an ambiguous question!