I suspect the OAT (TAT & SAT indications, ADIRS info for the Airbus, ADC for the MD80?) would be an MEL item depending upon the availability of a second probe, (usually the case). Not sure if both probes are u/s. Anyone?
Found a MMEL
here.
I found no mention of OAT or TAT-indications, but RAT and SAT are mentioned:
RAT/Thrust Rating System (Series 30,40,50,80).
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(M) (O) The RAT portion may be inoperative provided:
a) A SAT or Standby RAT indicating System or PMS SAT readout is available,
b) Other Systems affected by the RAT Probe (DFGS, CADC, Thrust Rating, FMS, OMEG, PMS) are considered,
c) Thrust Rating System portion is considered inoperative for the Series 30, 40, and 50 and
Procedures are established to verify engine power setting.
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(O) The EPR Limit/Thrust Rating portion may be inoperative provided:
a) A RAT or SAT Indication System or PMS SAT readout is available,
b) EPR Limit Chevron Automatic Mode is considered inoperative for the Series 80,
c) EPR Limit Mode of the auto throttle is placarded inoperative, and is not used on the Series 80, and
Procedures are established to verify engine power settings
...and...
Static Air Temperature Indicator
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(O) May be inoperative provided Ram Air Temperature (RAT) System is operative.