Lear35A: Altimeter issues

[bpcw001 22]

Hi,

 

I was wondering about the altimeter synchronization and the altitude display in the Lear 35A:

 

When pushing the button that sets the altimeters to standard pressure, the main altimeters for CAPT and FO read 1013mb and 29.92 mmHg.

However, the standby backup altimeter synchronizes to 29.91 mmHg. Since all altimeters are tied, there is no way to rectify this by adjusting the backup altimeter only without negatively affecting the main altimeters.

Please kindly have a look into this.

 

Also, when having set the altitude selector to e. g. 41000 and then leveling out at FL410, altimeters at standard pressure (main at 29.92, standby altimeter at 29.91), the digital readout of the main altimeters will show 40980 most of the time, even in perfectly smooth winds and weather.

(I use ASN). Small altitude fluctuations will occur, but the system always appears to settle back at 40980, not at 41000, so apparently systematically just one notch below the full thousand.

 

I don't know if this is idiosyncratic real-world behavior or just a glitch.