ATA 32-60, Air/Ground Fault

First called out for a flagged "SPD" on the captains EADI. The speed tape should be displayed on normal system power up and it does not need the IRS's up. The on-side airspeed indicator was not flagged.



Noticed TAT(Total Air Temp) indication on EICAS reading 70C or more. Captain's pitot heat system was also indicating on.



EICAS status showed a Nose Air/Ground disagree.



The nose position disagree could be cleared via the maintenance panel reset, but we still had something stuck in air mode. Checking the Proximity Box for both nose and main gear tilt showed S246 (Right Gear - System 1) with a target showing "near" when the other three showing "far". Far is normal for ground indication.

As far as the troubleshooting on the "SPD" flag, some items need to be noted.

1. The flag did not disappear when the ADC system was switched to "Both on Two".

2. It did not show up on the F/O's side when switched to "Both on One".

3. The flag showed on F/O's side when Air/Ground system 2 was placed in air mode.

It has to be assumed that the EADI's speed indication is "on-side" only. It must take actual ram airspeed applied to indicate in the air.
Questions remain if either of those two statements are correct?????