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You're right cg, not good enough. However, I don't think most machines are much better.

A few years back we stopped for fuel (212) in Yorkton, Sask. for fuel on one of our cross Canada fire flaps. There was a Bell 205 sitting on the ramp with an oil covered tailboom. It seems that on short final the MBG oil pressure dropped to zero. Very shortly after landing the blades ground to a shuddering halt and pivoted the machine on the skids about 20 degrees. Total time from initial pressure drop to MRG seizure....less than 3 minutes!!!

Ever since I saw that I have always kept one eye permanently glued to the MRG gauge.

Was that 205 ETK?

 

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so this may be the wrong place to be asking this question, but given the incident involved it might be appropriate... i have very limited engineering/design/mechanical smarts (so i expect a quick "duh" response from smart engineers :lol: ) but i find myself wondering if it would be possible to put some kind of freewheeling unit on the rotor mas itself, effectively keeping it seperate from the MGB? i guess it would need another swashplate, which would be added complexity/weight, and it would probably be less durable, and im sure it would need some interesting bearing system to be able to spin freely while supporting the aircrafts weight. but is this plausible? or is there a complete duh factor that im not thinking about here?

 

 

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So here is your quick "duh" responce ;) : Astars, the models with the roller bearing mast, actually have a shear point just below the bearings and above the epiclyclic drive (planetary gears) for this reason. The lower drive portion of the transmission could fail (say from lack of oil) and the inertia of the rotor system would shear at this area allowing autorotation to the ground. The newer roller bearing masts that are in Astars now do not have this feature, (guess Eurocopter does not think it necessary). Eurocopter put both upper and lower mast support bearings above the drive gearing making this possible.

Most other helicopters manufacturers have the mast support bearings above and below the rotor drive gearing.

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Have also seen this "sheer point" in Astar training manuals, but have seen a few horrendous crashes involving the rotor system smashing into the earth and have never seen the mast sheer,,,not saying it won't but just don't understand the forces required to make it sheer. For example a 350B hit a steel vent pipe which caused the machine to fall down and flop all over the place, mark on ground from chineese hat but yet main rotor drive still intact...four other unsurvivable crashes and still the main drive intact?

 

Also in some types of helicopters(204,205,212 for expample) the main trainsmission drives the t/r thus if transmission fails you also lose t/r drive.

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Yes it was ETK when Venture leased it from Eagle, a picker truck had to move it away from the fuel pump. Were you crewing OKW?

 

No 18, I was crewing a "Yellow 212". Joined Canadian a few months later. Were you involved with ETK at the time and is she still around?

 

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