United Airlines Boeing 747-400 dff only mod. Original authors are CPTChris and Riba. Ported to Android by Los Santos guy.
I've included two methods for installing this mod:

The simple method. (dff only) The only thing you have to do is replace at400.dff with Img Tool Android
and move the file called 'txd' to Android/data/com.rockstargames.gtasa/files/texdb. This is a primitive
method. Because it's possible that you already have a file called 'txd' installed for another mod.

The Txd Tool (Android) method. (This method is the best) You have to import 'at400.txd' to 'txd.txt' with Txd Tool.
(And of course replace at400.dff with Img Tool Android)
I've made a tutorial on how to use Txd Tool: https://youtu.be/JNneVjkbxJM
When you imported at400.txd look for a file called 'boeingENG'. Rename it to 'boeingeng'. If you don't replace the capital letters with lower case letters the airplane will show up without textures.
Good luck and enjoy!