Thread: Reports of a large air tanker crash in NSW

Originally Posted by 4bee

Good image Ron.

No wonder it crashed if they killed all the engines like that.

Looks like the prop synchrophase was on

Originally Posted by Hugh Jars

Looks like the prop synchrophase was on

Just as a point of interest, all engines on a C 130 run at constant speed all of the time. Just the propeller pitch is changed as required as thrust is needed.

Originally Posted by Old Farang

Just as a point of interest, all engines on a C 130 run at constant speed all of the time. Just the propeller pitch is changed as required as thrust is needed.

Correct, but they do have propeller synchrophasing

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.

Originally Posted by JDNSW

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!