Thanks Ian, I think it would be great if you posted photos for everyone.
I might consider pulling the counterweight next time I do an inspection. M On Sat, Jun 3, 2023, 10:57 AM Ian Williams <i...@agcon.co.nz> wrote: > Hi Michael, > The cracking really is only visible when disassembled > The radial cracking only when the blade is removed and counterweights > removed > The vertical cracking tho could be seen if the counterweights were removed > I can send you some pictures if you want > tHe ferrells are made from aluminium which probably is not a good idea > > Best regards > Ian W > > Sent from my iPad > > On 4/06/2023, at 3:18 AM, Michael Stockhill <sto...@gmail.com> wrote: > > > Thanks Ian for your insights and concerns. > > Regarding ferrell cracks, are you able to identify them without > disassembly during your inspections? Or are they being found during > overhaul? > > Best, > > Michael Stockhill > Polson, MT > > On Sat, Jun 3, 2023 at 3:51 AM Ian Williams <i...@agcon.co.nz> wrote: > >> Hi All, >> Could you read below and comment. I would be very interested in any >> suggestions or comments about this issue. >> Basically trying to address a solution to some pretty significant issues >> I am having with Hoffmann. I really dont know exactly what is happening … >> have heard a few slightly different stories but fundamentally they appear >> to no longer be interested in supporting our HO-V62 props. >> So I have been looking at alternatives. >> Some background >> I am the maintaining engineer here in New Zealand for 2 H36’s and 2 Grob >> 109A’s. >> Hoffmann produced an SB regarding a 6 year Calendar life for these props >> (and were quite anal about that) >> So as I had 3 props that were basically overdue, I organised a calendar >> service. Of the 3 props only one was serviceable, the others had cracked >> ferrells .. one a hairline radial crack which was not easy to see and the >> others had very significant vertical cracks and significant damage to the >> ferrells between the 2 halves of the counterweight clamps. Basically the >> blades are unserviceable. >> THere is a lot of other background detail here, but to keep this >> discussion short that could be discussed later.. >> The problem is that Hoffmann seem unable (OR UNWILLING) to provide any >> technical support in terms of Acceptable Technical Data (ATD) to even >> their Hoffmann approved service dealer ( Australia and New Zealand). THat >> company has indicated to me that they have been so frustrated with lack of >> support they have terminated their relationship with Hoffmann. >> SO WHAT TO DO. >> Consider that the HO-V62 props and their mechanical pitch change have >> been around for a very long time in fact since the late 1970’s. Apart >> from the P mod (8mm rods) and various SB’s plus the BT blades, there has >> been no significant design change over those years (40 plus). I guess >> being type certified there is no real incentive to change owing to >> litigation vulnerability.maybe. >> I have no operational issue with these props .. have many hundreds of >> hours behind them over the years and while there has been some minor >> glitches , fundamentally they have been quite OK. And if supported by >> Hoffmann , OK into the future as well. >> However with an apparent communication and support brick wall from >> HOFFMANN I think a modern alternative is needed. >> Seems there are 2 >> One is the MT prop ( electric version). The other is the Airmaster prop >> from down here in New Zealand (electric constant speed with feather) >> Obviously I am following up the Airmaster being Local. The issue is of >> course that the Airmaster prop is not TSO’d so a little tricky to install >> on a type certified aircraft. >> There is a lot of detail about Airmaster props on YouTube if you want >> more information. Yesterday I had a meeting with their chief engineer (and >> owner) who gave me a very detailed tour of their facility. on a scale of 1 >> to 10, it would be 100. They make full use of CNC machining equipment and >> up to date design systems. All the hub engineering design and manufacture >> is carried out in house. Only the blades are externally sourced ( >> Sensnich). They are composite and are a slightly different shape than the >> Hoffmann blades. IMy suggestion would be 2 blades. So at first glance would >> look the same as the Hoffmann >> So to cut a long story short, I am following up. ( Note in New Zealand) >> * A change from a standard category C of A fo a Special Catagory C of A. >> * Ordering a set of blades for rh rotation designed specifically for the >> L2000 engine and speed range for the H36. >> * if all OK, installing prop on our H36 flight testing etc and flying >> happily ever after. >> >> THe constant speed facility would be a real plus especially on take off >> where the engine RPM increases significantly with speed. THe time from >> feather to full fine is around 20 seconds (which we can live with) >> >> So. That do you think. ,, am I going in the right direction >> >> Best regards >> >> Ian Williams >> ZK GCB >> New Zealand >> >> --------------------------------------------------------------------- >> You are subscribed to the Dimona Owners Group mailing list. >> This list is archived in public. http://waikeriegliding.com/dog/ >> To unsubscribe, send email to: dog-unsubscr...@lists.riverland.net.au >> >>
