Since a number of the crew members were members of the Royal Canadian Air Force you must contact the the Canadian Archives and request from them extracts from teh two mens service records. The extracts will be free, the full service record will will incur a charge. Ask for those four airmens records with emphasis on any reports of the crash and reasons for same:
The RCAF crew men are Adams, Stratton and Bartleman, if you don;t have their details you can get them from the CWGC website.
www.cwgc.org
The contact details for the Canadian Archives are here:
Personnel Records Unit,
Library and Archives Canada,
395 Wellington Street,
Ottawa,
ON K1A 0N3
Fax: (613) 947 8456
http://www.collectionscanada.gc.ca/genealogy/022-909.007-e.html
You must check out the link above as it contains their procedures. Will take a few weeks for the records but worth the wait useually.
Dennis