As Hallgatebank and Cold Fell are so close to each other I think you may have two versions of one crash.

The crash on Cold Fell was Dakota KG502 which flew into the top of the ridge on the North Western end of Cold Fell and was destroyed by fire killing all of the crew.

For this area I would suggest you contact Jim Corbett, http://www.acia.co.uk, as he has covered this area in a lot of detail in recent years.