Yes, I believe you are right. According to the story in the original post in this thread, that was the one that crashed.
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Multiengine prop planes tend to make a nasty beat frequency vibration if the prop speeds are close but not exactly the same. Older and smaller aircraft rely on pilot/flight engineer expertise to adjust speeds to exactly the same, but newer and larger aircraft have been fitted with increasingly sophisticated automatic adjustment - I take it from Hugh's comment that the C130 has equipment that even sychronises the relative prop blade positions.
That's right, John.
Even jets can get a vibration/harmonic. I notice it sometimes when taxiing around. Not as bad as props, but if the N1 (fan speed) differs by about 1% you can hear it. Once the autothrottle is engaged at takeoff, the N1s are matched electronically.
The reason for the crash still remains a mystery.
Air tanker crash that killed three US firefighters remains a mystery as cockpit audio was never recorded
At the other end of the scale, why not record / video it yourself ?
While learning, I had a small Helmet-Cam attached inside the cabin the wired mic dangling into my headset. Looked out the front and recorded audio of anything that came through. Cheap, simple and invaluable for revision between lessons.
GoPro make a dedicated intercom interface which would still be cheaper than a FDR and possibly just as useful in this type of sad event.
There's a video-cam in all my cars, and I wear a Body-Camera during Bus driving... shows my speedo, steering wheel and the outside world. Lasts for +5 hours per charge
- Best $120 camera I've owned !
If it survived the event!
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