This is a Bristow helicopter, so you can use Database Explorer to add a new entry: Bristow Helicopters in column CN, BHL in column C3, and CG in column C2, then after you restart RadarBox,any aircraft with an ID of CGnnnn will show the BHL logo.
If you would rather CG showed a different logo, for example a Coastguard one, find any unused three-letter code and use that instead. I've just whipped up a general-purpose Coastguard logo called CGU that you could use for that (I'll repeat it in the logos thread.