There 3 series of blades A016-1, A016-2 and now A016-4. (I don't know where the A016-3's went)
As far as I understand all the blade separation accidents in Oz have been in 016-2.
All 106-1 blades should now be past their usable life so none should be flying. There are plenty of 016-2's still around.
The difference between the -2 and -4s is basically:
The 016-2s
Have aluminium skin with a stainless leading edge. I am told they have 4 bearings in the spindle and the 016-4s have 5. (can't vouch for that) The root has several bolts that hold the leading edge spar onto the blade root. The problem area in the Australian accidents was found to be the bolt hole closest to the hub. The cracks began in spots of corrosion deep in the bolt hole and propagated sideways then backwards in an arc until they got so far through the blade separated.
The bolt and hole is covered by an aluminum plate held on by some sort of glue. The ATSB suggestion is that there were defects in the glue which allowed water to get in and track into the bolt hole where it set up pin points of corrosion.
The British machine that got the big crack in the root had it in a different place. The one mentioned in this thread seems like it was in an further different place since it started at the back from what I can work out and propagated forward.
Other blades have had problems with corrosion and and/or separation of the aluminium skin from the steel spar. Partly this is due to two dissimilar metals which set up a galvanic current and rapid corrosion if water gets in between the two.
Robinson now say if you park you machine outside, live in a tropical, coastal or humid area then you should replace the blades (016-2) every 5 years! The 016 -4s aren't subject to this recommendation.
The 016-4s:
Have stainless steel skin and stainless leading spar. The leading edge of the root is different to look at. It has a sharp leading edge running right to the rounded root with no flat plate over the bolt hole. I don't know what the inner design is like. I would assume they have still got bolts holding the leading edge spar on but they must have covered them up better to keep the water out.
I can tell you what the difference is to fly with them as I have just got new 016-4s on my machine after having new 016-2s for some months.
They are not as nice as the 016-2s were. They have needed quite a bit of work and they are still not quite right. The main problem has been the collective rides up rapidly while on the ground if the friction is off. The first time I fired it up the machine took off on its own when I took my hand off to change radio frequency. Even after lots of adjustments it still rides up slowly.
The other thing is that it sometimes gets a vibration on climb or when increasing throttle which stops when back in level flight or when the throttle settles to a new level. It's not much but is noticible.
Attempts to isolate the problem have been unsuccessful so far.
The auto characteristics may be a little better but I'm not sure. I do know that when I did the Auto RPM testing on these blades I was getting very low rates of descent (like 900 ft a minute) at 53 knots indicated compared with about 1300 to 1500 on the 016-2s at 65 knots. But it was a bit hard to compare cos it was at different speeds and density altitudes. I never did autos with the old blades at 53 knots at the same altitudes.
I liked the 016-2s more. They were smooth as silk and the collective stayed where I put it. But I guess the new design may help get rid some of the really disasterous problems.
I haven't heard of any cracks in the new 016-4s but that may just be because there are less around and they are all new. I hope its that they aren't ever going to get them again
