David, good friend,
Thanks for your honest explanation of your bias towards Woodcomp. Your
position, as their unpaid salesman must be awkward, and it must be very
difficult to change your position.
I on my turn have to admit that it has taken a long time to recover
mentally and be able to reason clearly and stronly about the accident.
Your next quote takes us to the cultprit of our difference of
interpretation of the facts.
"and it was apparent that the blades were close to zero pitch, so that
regardless of how they got there it would be safe to say that a similar
accident could not happen with an SR3000 that does not have the reverse
option (which is not accepted by the LAA following your accident), as
the standard props have not only electronic stops at the fine limits but
also mechanical ones. "
According to woodcomp, invited by the inspector, the blades were at a
flyable pitch. Remembering the lack of thrust, and the overrevving, they
must have been at a positive angle, NOT REVERSE, but with a pitch not
enough to stay airborne.
Why stopped the motor at that blade position and not later or sooner?
Because, at the same moment the microswitch should cut in, it burned
with a short circuit to ground, defying it's purpose and allowing the
motor to run further. Next, adding throttle, the controller jumped in,
reversing the polarity of the motor. The voltage now came direct, not
anymore over the motor, on the microswitch and the breaker popped.
Blaming the accident on the reversbility of the prop, thus assuming that
a mechanical endstop makes it impossible for the prop to turn too fine
to fly is mute as long nobody ever has checked that mechanical endstop.
Sofar i have not heard of anybody who has checked this mechanical
endstop on the non-reversable prop. Unless somebody, preferrably you,
shorts or otherwise disables the end switches, and runs the motor till
it jams, relying on the mechanical stop is not very wise to say the
least. It would be also interesting to know if the gears would survive
such a try.
Has the LAA approved the feathering version? There is no mechanical
endstop on the course side. Even more people will be relying on non
reliable microswitches.
I think it was Mark of Smartavionics who told be about Woodcomp banning
its product. Mark, correct me if i am wrong.
Next one:
"The microswitches have changed over the years largely to improve their
mechanical security but whether they are waterproof or not seems a bit
irrelevant. I have flown through prolonged rain and found no problems,
and you would expect that any water finding its way into a structure
rotating at 2000+ rpm would very rapidly find its way out again. If you
had parked the plane under a waterfall and the spinner was full of water
before start up you might expect to notice problems when you switched on
and went though the recommended pitch change check. "
I read that as "there have been problems with the microswitches over the
years". I challenge you to find any application were microswitches are
used in open air. None are to be found in cars for example. As for
flying in rain, and the behavior of water and air on a spinning service,
have a look at any centrifugal pump. The backplate of the spinner, where
the switches are and the big end opening in the cowl form such a pump.
The rotating plate sheds water and air from it's side and sucks more
in..... As for the pitch range check: The only thing you do is check
that at that moment things are ok. It does not improve the quality of
these switches.
Apart from that everybody will hopefully understand the importance of
using weatherproof components in weather. There are classes for humidity
for electrical components and appliances. Those microswitches are
manufactured for dry room use. And, let's not forget, they are heavily
underrated in current as well. Proper switches for the application
would physically never fit on that backplate.
I hope the LAA will review its approval. I don't quite understand how
this item passed in the first place.
Regards,
Jos
27.6.2011 12:12, David Joyce kirjoitti:
> <davidjoyce@doctors.org.uk>
>
> Jos, I count you as a good friend but have to dispute many of your
> statements. I also will state that I am no expert, but nevertheless am
> a very interested amateur prepared to go to great lengths to get to
> the bottom of something that affects my safety, ( and having said that
> Tim did spend a lot of years as a radar/ electronics technician in
> the RAF). I have on the other hand been a sort of unofficial (but
> unpaid I hasten to add) Woodcomp agent in the UK having brought (and
> bought) the first Woodcomp prop into the UK and then pursued the very
> lengthy process of getting it fully accepted by the PFA.
> As you know I was there at the accident, with the same plane
> and the same controller and the same SR3000 (albeit without the
> reverse option). I flew back to try to help you and subsequently
> examined the wreckage and spent some time helping the Austrian AAIB
> man. As the accident happened flying out of the Rotax Factory Flyin
> it's not surprising that they were quickly able to help. Secondly
> since Mark Burton, owner of Smart Avionics,was flying with us he was
> quick to talk to the investigator. I may say that I gave the
> investigator my copies of the Smart Avionics controller and SR3000
> handbooks and allowed him to look at the complete workings of my set
> up which was the official factory set up of an SR3000 without the
> reverse option that you had and without the non Woodcomp/personal
> simplifications to the wiring system that you had incorporated into
> the circuitry. There wasn't too much left of the plane after the fire
> but the prop hub was there and it was apparent that the blades were
> close to zero pitch, so that regardless of how they got there it would
> be safe to say that a similar accident could not happen with an SR3000
> that does not have the reverse option (which is not accepted by the
> LAA following your accident), as the standard props have not only
> electronic stops at the fine limits but also mechanical ones.
> My understanding of the investigation was that no prime cause
> could be positively identified, and if I do not misquote him I believe
> this is also Mark Burton's view (who is also of course an electronics
> professional.)
> The microswitches have changed over the years largely to
> improve their mechanical security but whether they are waterproof or
> not seems a bit irrelevant. I have flown through prolonged rain and
> found no problems, and you would expect that any water finding its way
> into a structure rotating at 2000+ rpm would very rapidly find its way
> out again. If you had parked the plane under a waterfall and the
> spinner was full of water before start up you might expect to notice
> problems when you switched on and went though the recommended pitch
> change check.
> You refer to the problem experienced by someone having some
> teeth break on the gearing that determines the pitch angle of each
> blade and this was promptly dealt with by Woodcomp replacing it both
> on new models and retrospectively with a slightly heavier version of
> the gears. Woodcomp certainly have no problem about the Smartavionics
> controller which is the choice of the majority o f the substantial
> number of UK Woodcomp owners.
> Apart from your problem I have not come across problems that
> were not of the failsafe variety, and feel that describing the prop as
> a deathtrap is entirely unwarranted
> Regards and best wishes David, G-XSDJ
> You mention
>
> ----- Original Message ----- From: "josok-e" <josok-e@ukolo.fi>
> To: <europa-list@matronics.com>
> Sent: Sunday, June 26, 2011 11:46 PM
> Subject: Re: Europa-List: Woodcomp after Sales Service
>
>
>> Tim,
>>
>> I've sent the report to somebody who is German en fluently in English,
>> on his offer to translate. This translation takes an incredible amount
>> of time obviously.
>> But, as a matter of fact, the investigator thanks me for diverting from
>> my line of descent into an occupied office building to trees. The
>> wreckage was badly burnt. He also reports that he had Woodcomp check the
>> remains of the propellor, and that they stated that the blades "must
>> have been at a flyable angle" Also there was no obvious fault with the
>> engine. It has not been possible to determine what the cause of the
>> accident was. You may doubt of course that i have summarized properly as
>> well.
>> Significant might be also that after the accident Rotax was the first to
>> talk to me, smartavionics next, the factory was very interested also.
>> But no question, no word from Woodcomp.
>>
>> I find it strange that you start an argument by telling us that you are
>> not an expert. And reach a conclusion, which is false. I am an expert,
>> electricity, electronics have been my profession and hobby. I know
>> microswitches and diodes, and if i tell you they are grossly underrated
>> and not up wet conditions, you can take my word for it.
>>
>> My only interest is to save your lives. If you don't want it, please let
>> me know.
>>
>> So, let me explain how the prop ended in a non-flyable position, so
>> simple that a non-expert can understand. I commanded via the controller
>> to go finer. That makes the motor run the blades to fine. The motor runs
>> then as long as the controller command it to go finer or the fine limit
>> switch cuts the current. In this case, because the desired rpm was high,
>> and i was climbing, the fine limit switch should cut in. But it didn't
>> because it was burnt, and short circuited to earth. The controller
>> reversed it voltage to increase pitch and we had a short circuit on the
>> plus now. The circuitbreaker popped. The revs went to 6200, with no
>> pull. Attempting to reset it booted the controller. Which proved it was
>> still working, And after the boot it popped again, The accident
>> conditions were there, low on altitude, low on speed.
>>
>> I find it amazing that people defend such a product. Everybody i spoke
>> to privatly admids there have been problems with communication, with
>> quality of parts, with forgotten or loose parts, splitting blades,
>> whatever. Oh, of course, they will cut the blades in a banana form, or
>> apple, or anything else you fancy as fast. Very flexible indeed.
>>
>> There is a good working product available, has been for years, factory
>> choice, with only plusses but the price.
>> Everybody makes a mistake, and i can admit it was my mistake to go on
>> the cheap and settle for a Woodcomp.
>>
>> Regards,
>>
>> Jos
>>
>>
>>
>> 27.6.2011 0:25, houlihan kirjoitti:
>>> Hi
>>> Further to Jos's comments about his very serious accident I seem to
>>> recall that the Austrian authorities planned to issue a report
>>> regarding the possible cause. I may have missed it so can anyone let
>>> me know what it contained, preferably in English.
>>> Not being an expert in these things I find I have problems linking the
>>> limit switch failure Jos talks about to the fact that for the
>>> propeller to go to fully fine or even beyond fully fine to a beta
>>> state requires the motor to be powered to drive it there. I am sure
>>> there may be a mechanism that will make that happen but I cannot see
>>> how it can do that just because a limit switch fails.
>>> Also my understanding is that Woodcomp do not support the Smartavioncs
>>> controller not surprising really as it is not their product and it is
>>> in competition with them but " banning" it is beyond their remit.
>>> Tim H
>>>
>>> On 26 June 2011 20:10, Jos Okhuijsen <josok-e@ukolo.fi
>>> <mailto:josok-e@ukolo.fi>> wrote:
>>>
>>> <josok-e@ukolo.fi>Hi <mailto:josok-e@ukolo.fi%3EHi>
>>>
>>> Sorry to remember you all that my Woodcomp prop nearly took my
>>> life.
>>>
>>> I hate to repeat my words, but memories seem to be short.
>>> The propeller i had was equipped with microswitches, which were
>>> and ,after a change, still are not designed for outside use.
>>> Nethertheless these switches are mounted on the backplate, open
>>> for weather.
>>> These switches are designed for AC 240 V, not for DC 12 V, and the
>>> Amp rating is way below the current going through them.
>>> The cross-over diodes are specified for less then half the current
>>> drawn.
>>> Even when activated only occasionally, it's a design flaw.
>>>
>>> Know to me are 3 incidents with short circuiting micro-switches,
>>> both other pilots could land their plane without damage to their
>>> plane or themselves. An incident with a loose gear, causing one
>>> of the blades at a totally diffent angle then the others was
>>> reported to me, and never made it to this forum. This seems to be
>>> the happy family show, which i am now spoiling. :-(
>>> It may well be that there are others, or people never fly in rain.
>>> or are just very lucky.
>>>
>>> In my case, to the best of my knowledge, a microswitch short
>>> circuited, taking the prop to a feather situation, shortly after
>>> take-off. I had been flying in heavy rain for hours the other day.
>>>
>>> Unless thing have changed is Jyrki the only one who understands
>>> English, if he's not available you are on your own.
>>>
>>> After my incident Woodcomp banned the Smart Avionic controller.
>>> What that means is unclear to me. As far as i know, they never got
>>> there own controller working decently.
>>>
>>> As for the figures, i've had trouble to keep up with a 912 with a
>>> fixed prop and i was flying with a 914 and a Woodcomp 3000. The
>>> only good figure seems to be the price.
>>>
>>> So in short: Save a few, risk your plane and life.
>>> The choice is yours....
>>>
>>> Regards,
>>>
>>> Jos Okhuijsen
>>> (enjoying his second life :-)
>>>
>>> . 26.6.2011 19:16, Frans Veldman kirjoitti:
>>>
>>> --> Europa-List message posted by: Frans
>>> Veldman<frans@privatepilots.nl <mailto:frans@privatepilots.nl>>
>>>
>>> On 06/26/2011 04:02 PM, Paul McAllister wrote:
>>>
>>> I was very impressed with the results that David Joyce got
>>> with his SR
>>> 3000W propeller from Woodcomp. I would like to some
>>> feedback from the
>>> forum about there after sales experience from Woodcomp.
>>> Please give me
>>> the 'good, the bad and the ugly'
>>>
>>> I got excellent support and advice when I was ordering the
>>> propeller
>>> from Woodcomp directly and delivery was prompt. After that I
>>> had no
>>> reason to contact them again as the prop works flawlessly and
>>> performs
>>> better than expected. Had to service it at 50 hours and did
>>> that at a
>>> local Woodcomp dealer. Found that one spinner screw was
>>> missing and got
>>> a complete new spinner fastening set free of charge. Ordered
>>> spare
>>> brushes, but at the 100 hour check I discovered that the
>>> brushes were
>>> almost like new and it looks like it is going to take a long
>>> while
>>> before I have to replace them.
>>>
>>> Have now 100+ hours but have had no issues with the prop.
>>> A few notes though:
>>> 1) I'm using the controller from Smart Avionics which is very
>>> configurable and able to match the prop exactly to the
>>> engine/airframe
>>> characteristics.
>>> 2) I have a prop with feather capability (to anticipate a
>>> potential
>>> future use of the glider wings). The props with feather
>>> capability have
>>> a stronger and faster motor. Maybe this is the reason why the
>>> Woodcomp
>>> prop behaves like a hydraulic prop and reacts so fast that it
>>> never
>>> allows the RPM to surge off its target.
>>>
>>> Hope this helps,
>>>
>>> Frans
>>>
>>>
>>>
>>>
>>>
>>>
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>>>
>>>
>>> *
>>
>>
>
>
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