Hopefully, final report will detail a more credible path of CO into cabin.
A few points apparent in Interim report:
- Coroner did not test for CO
- Post crash engine inspection did not flag CO leak issue.
- 2 years after crash, having drawn a blank on cause, ATSB tested for CO and found elevated levels in 3 of the 6 cabin occupants, zero in other 3.
- Subsequent engine examination identified cracked exhaust flange at cylinder as CO source. (Leak is into free air, that is propwash, slipstream and would be very much diluted.)
- CO path through fwd firewall into engine bay is not mentioned.
- Path from engine bay into cabin is said to be via missing bolts of magneto access panel. I am not familiar with Beaver, but typically we’re talking 3 x 3/16 bolt holes.
Question then is, is it possible for something nothing CO via broken path to cause elevated levels of CO in such a short, about 7 or 8 minutes, period of engine operation?