Perhaps there is more to this, then again, perhaps not. All that I want to do here is present to you my experience with NHP blades and the following communication. What I want to make clear to anyone reading this is that my NHP 680's (Curtis FAI) had never been knocked around. The roughest treatment they ever received from me was being wiped down with Glass Plus and a Viva paper towel before leaving the field. Apart from that, they had been used in mild 3D at a fairly modest 1650 RPM.
Here is how it happened: I was traversing the field in level, inverted flight at about 20 feet above the ground. Just as my Tsurugi approached abeam of my position, the rotor disk appeared to fatten. Instead of the crisp looking disk that you expect when the blades are in track, the whole disk looked blurred. As soon as I observed this, I attempted to roll upright in order to hit throttle hold. Unfortunately, it never got that far. By the time my Tsurugi had rolled 90 degrees it was totally out of control. I engaged throttle hold as a matter of course, and the whole lot landed inverted.
As I knelt over the wreckage examining the remains, a cyclist who had been watching me said that he saw something fly off. This surprised me as I had not noticed anything flying off, but then my attention was devoted to trying to land. The cyclist left me and returned a minute later. Imagine my real surprise when he handed me the whole bottom half of one of my NHP blades. The only thing not complete was the area around the bolt hole. That looked like it had been torn away like a piece of cloth. Unbelievably, the remainder of the blade was still attached to the blade holder and from my viewing angle, looked like a complete blade. Turning the blade over revealed the interior foam complete with lead weights; the blade had not even been broken in the crash.
The lower half of the blade had separated perfectly clean at the seam where the upper and lower halves are brought together. There is less than a millimeter (on my blades) of material running the length of the leading edge that provides the mating surface area. Is this enough? I am not qualified to say so, but it is significantly less than the area joining the two halves of a Miniature Aircraft blade (manufactured in Germany). I have had midair collisions with MA blades and landed safely (yes, and I have it on video!) so one would consider them to be structurally sound.
The next business day, I phoned Horizon and spoke with Jeff Keagle. He asked that I ship the blades to him, which I did. After a week or so I called to inquire whether they had received the blades and performed an inspection of them. There was some damage to the blades at the tips as a result of the crash, but he wanted to be sure that this damage was not done prior to the blade delaminating. I assured him that the blades were in perfect visual condition and that they had not been stressed in any other way. After discussing this with his manager, Horizon shipped me a replacement set of blades free of charge.
Of course this is the way business should be taken care of if a product fails during normal service, and I am certainly thankful for that. It did not help rebuild my Tsurugi, but at least it saved me something. The issue that Horizon needs to address is whether there is some manufacturing problem, or perhaps a substandard lot, or some other cause for this blade's failure. Obviously I am not alone in this occurrence as evidenced below.
On 26 Nov 1998 19:46:19 GMT, xsnxs@aol.com (XSNXS) wrote:
>I just suffered my greatest loss in a decade of flying.
Due to the in flight
>delamination of NHP Carbon Fiber blades, my 5 year old TSK
BlackStar
>has been totally destroyed! This was my favorite bird with
extensive carbon
>fiber, anodized parts and airbrushed paint.
>I will NEVER buy NHP blades again. I've used Sitars, GP-9's,
Hi-Products &
>Miniature Aircraft Carbon Pros on this bird over the years
and never had a
>problem, until I switched to NHP's. May my BlackStar rest in
peace. May Dave
>Whitney build a heli fast enough to escape me if I ever see
him.
>NHP Rotor Blades SUCK!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Dear xsnxs ?
We are more than a little distressed that you have chosen to
"bad
mouth" our product before contacting us directly and giving
us the
opportunity to inspect the allegedly faulty blades. As we make
1000's
of blades a year we do have on very rare occasions blades
returned to
us, and in every case I can remember the blades have received
damage
to them and have then been continued to be used with total
disregard
to the damage until failure occurred.
We have received blades back which "just" split open in
flight, but
the models were on each occasion apparently landed without
crashing,
so the customers are hard pushed to explain why the blades have
evidence of being repaired with cyano or epoxy or why there
should be
mud or even in one case bark and wood from a tree inside the
blade.
We are not saying this IS the case with your blades as we can not
comment further on these particular blades with out seeing them.
We
do receive blades back that have been damaged in transit and
obviously
we can not control their care and handling once they have left
us, but
it is certainly possible that transit damage could severely
weaken the
blade, any damage like this should be immediately evident, any
damaged
blade regardless of the make should not be used.
Just to clarify things we do not know of a single case of any of
our
blades delaminating in flight through a manufacturing fault. I
personally have put thousands of hours on our blades as has
Curtis
Youngblood and the integrity of the blade is about the only thing
we
can take for granted on a helicopter.
Dave Whitney would be very happy to discuss this with you, either
by
phone, fax or face to face, you can ring him on +44 (0) 161 928
5984,
or if you forward him a phone number and name he will contact
you.
Best regards,
Bob Johnston
Research & Development
NHP Ltd