Help me this A321 MEL! Why 1,2,3 must be operative?

[lahoanghai]

76-11-01A
Repair interval Nbr installed Nbr required Placard
A 4 3 No
One may be inoperative on one engine for three days provided that:
1) The A/THR is operative, and
2) Both LGCIUs are operative, and
3) The L/G shock absorbers proximity detectors are operative

[akindofmagic]

I don't really understand your question. "Because Airbus says so" is a good enough reason for me. Do you understand what happens if the system loses valid thrust lever position input?

[lahoanghai]

Thank you inadvance for taking care abt my question . I'm taking an exam and get it from my Assessor. I'm trying to find out . Could you tell me in more detail? I'm a new technican.

[Cyclone733]

lahoanghai,

If you read the MEL in conjunction with PRO-ABN for ENG 1(2) THR LEVER FAULT and ENG 1(2) THR LEVER DISAGREE you'll see the aircraft uses A/THR to control engine thrust in a fault condition and requires inputs from LGCIU and L/G shock absorbers for air/ground mode, A/THR activation etc
DSC section also gives information on how the systems interact.
It's basically to mitigate against the added risk of a further failure