I could not find anything on Android to calculate search patterns, so I have filled that gap with KearSARge:https://play.google.com/store/apps/details?id=appropel.com.kearsarge
This app supports parallel track, creeping line, expanding square, sector search, route search, and CAP grids. It is very easy to use: you just fill in the form, and at the press of a button a list of coordinates is calculated that can be copied and pasted into the flight plan field of another app such as Garmin Pilot.
The app is under active development and I will be putting out a new release shortly. I am very curious to hear feedback on what would make this app more useful. Thanks!