QGIS exports corrupted .bil

Hi,

I am having a lot of trouble trying to get going with a new scenery. I have DL'ed the srtm data from earth explorer and managed to merge, warp and clip the data successfully. Aside from some missing data (how do we patch this???) everything looks fine in QGIS. When I open the .bil in RAW to TRN it is corrupted with just a set of jagged lines running across the image. I have gone through the process three times to try and eliminate any errors but always get the same result?

Please help.

I didn't find the right solution from the Internet.

References:-
http://www.condorsoaring.com/forums/viewtopic.php?t=18030
Motion graphics animation agency

Thanks!