I've done a quick scan of Johm Hamlin's: Flat Out the story of 30 Sqn.
I could find no reliable reference to the accident. However, there is reference to a parachute jump in January 1931 which is claimed to have been the first abandonment from a sqn Wapiti. Might, therefore, be worth looking later than October 1930.
The index of names does not mention Passmore - who later became quite famous - or the air gunner. The list of Wapitis on the sqn isn't any help with your query. Sorry!!