Originally Posted by CONF iture
But are not NAV ADR FAULT and faulty ADR two different species ?
- NAV ADR FAULT is the result of an ADR internal failure or a manual switch OFF.
- faulty ADR provides erroneous information but is not an ADR failure.
You are semantically right concerning internal/external faults but what matter is that those erroneous informations won't be used by the flight systems but still be displayed to the crew for information and troubleshooting. All relevant systems based on erroneous outputs would be declared inop during the fault isolation sequence (AP/FD, A/THR, PROT, RTLU, WINDSHEAR, SPD LIM, TCAS)
Concerning FMGCs and FCPCs monitoring, the effect is a rejection of the faulty sources (channel); in our case, all 3 ADRs are declared faulty by them and rejected. There is no cockpit circuit breaker at probe-pitot level and what could be displayed is a fault on ADR pannel; one may want to turn it off.
Until all ADRs are turned off, the stall warning based on Alpha is still working (if at least one AOA channel is not declared faulty), but it's computed differently as this function use a Mach correction and Mach is replaced by a default value. On the other hand, the computed stall warning based on Low Speed (VSw) is lost. Concerning Overspeed warning, it is lost as this function is based on faulty ADR channels, as well as VMax which is not displayed.