Not sure how many R44 Raven II pilots are on this thread, but I own and fly one. This is a very interesting incident. As others have alluded to variously above, and with the standard "interweb accident investigator"
disclaimer:
- Robinsons do not fly well on one mag, it's pretty obvious when picking up with only one mag running. The audio and instrument readings imply normal operation of two mag's.
- The engine completely and dramatically stops at 1:25 in the video, engine RPM is zero. If it is a mag related problem then that's both mag's going offline.
- The video evidence shows the key in either the OFF or R position. The OFF position presents a much simpler set of mag related failure modes.
- Failure modes: this suggests an intermittent ground to the ignition switch, or an intermittent ignition switch. Either of those failures could account for two, simultaneous P-lead failures (open P-lead on both mag's). So it was intermittent open during the pre-takeoff mag checks, then it became intermittent closed with the switch in the OFF position in flight, killing both mags and thus the engine.
- When diagnosing an open or intermittent P-lead during pre-takeoff mag checks, the double-check test is to turn the key to OFF and if things keep running there's definitely at least one open P-lead circuit, thus confirming a lack of RPM drop when one or the other mag is selected.
- If the switch was in the R position, that would mean the left mag P-lead was open, if one agrees that all other indications (audio, instrumentation) demonstrate that both mag's are running. However that implies an even more complex and less likely failure mode in the wiring or ignition switch.
Silly, wild internet accident investigator guess: pilot does his mag checks and finds both P-leads are functionally failed open, i.e. observes no RPM drop in either the L or R position, checks it in the OFF position and it all keeps running. At this point becomes so non-plussed by this quite unusual circumstance, i.e. he thinks "Both P-leads? No way!", and/or distracted by passengers/whatever, that he leaves the key in the OFF position and ultimately departs.
Unfortunately, there is nothing in the
FAA system I can find on this event.