I have been following this thread and other's for some time now. and I, like other's here are interested to see the final ATSB report into what happened in flight.
Let me 1st introduce myself as an A.M.E
Several members here have already mentioned drive shaft damper bearing failure, flex plates cracked RB's etc etc. I am not an accident investigator by any means, however after several R22 and R44 rebuilds and 100 hourly inspections on R22 and R44's being operated in desert country (red dirt, mustering environments) I have come across many times over the years that there has been excessive wear associated with the C121-17 push pull tube connecting to the A120-3 Bellcrank Assembly on the TRGB, has excessive wear from dirt build up between the C121-17 Push pull tube and nylon guides within the tail cone.
The aircraft in question was only operated out of the industrial estate where the incident occurred. Never from bitumen or asphalt helipad as per the ATSB investigation. The aircraft would have spent it's life cycle ingesting dust and dirt each time it left or returned to it's home base. No doubt dust and debris was ingested into the tail cone and associated empennage for some time and probably since aircraft in question was sold in this country. I have seen wear on the C121-17 on many R22 and R44's which are based on the many cattle properties through out this country where the dirt build up between the nylon bushes has worn deep into the push pull rod and required replacement or renewed paint to be applied to effected areas.
To me, it looks as though the push pull tube has worn through which would not have been detected with a ground run and TR balance. The push pull tube has given way causing the TR to swing at an angle which resulted in complete loss of control and the TR blade to cut through the tail cone assembly resulting in the fatal incident currently under investigation.
Anyone who works on R22's or R44's which spend their lives mustering or in dirt\dust would have encounted the wear produced on the C121-17 tube from dirt build up between the nylon bushing.
IN MOST CASES I HAVE EXPERIENCED, THE PUSH PULL TUBE HAS NEEDED TO BE REMOVED TO FULLY INSPECT FOR WEAR BETWEEN THE NYLON BUSHINGS.
My reference book is the R44 IPC found here: R44 IPC - Robinson site *unable to post links until I have reached 10 posts"
65.0 - Item 8
C041-1 Damper Assembly
65.6 - Number 19
C121-17
67.90
C121-17 Push pull tube.
Anyone else able to shed some light on their experiences when removing the C121-17 on mustering choppers?
Cheers
Winfield.
Last edited by Winfield83; 13th Nov 2020 at 19:18.