When logging on using Xsquawkbox, there's no
BA-4B in the aircraft selection menu. 

My suggestion is that you add this line to the 
equipment.csv file, which will allow both you to log
on using what you fly and others to see your aircraft
as something similar, if you use
manufacturer: ANDREASSON
type: BA-4B

PTS1,ANDREASSON,BA-4B,P,P