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carl(at)flyers.freeserve.
Guest

Posted: Wed Mar 18, 2009 6:32 am Post subject: Woodcomp Propellers

Help !



Does anyone amongst the UK Europa fraternity have experience in dealing 

directly with the Woodcomp factory.



I have one of the older Woodcomp propellers that I was hoping to fit to our 

Europa but the PFA have decreed that it requires a factory modification (or 

a dispensation from them to do the mod myself). The reason are these blades 

are capable of going into reverse and the PFA require stops fitting that 

would prevent this.



Conrad Beale was the UK agent but has recently ceased in this role. The new 

UK agent RotoSport have told me they cant help because they havent got their 

agency set up yet.



Also does anyone have a factory maintenance manual (or experience of 

assembling and disassembling the hub unit) - as I need to dismantle the hub 

and am reluctant to do so without proper instructions.



My other option is to scrap the existing blades (which are brand new) and 

order a new set directly from the factory.



Carl Pattinson

G-LABS 

_______________________________________

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josok-e(at)ukolo.fi
Guest

Posted: Wed Mar 18, 2009 7:47 am Post subject: Woodcomp Propellers

Hi Carl,



While i am not in the UK part of the Europa fraternity  i still feel i should respond. First of all, i am happy to hear that the PFA does not accept the Woodcomp in flight adjustable without modification. It could have to do with the accident that happened to me, where exactly such a thing happened.  My best advice is to scrap the hub and find another supplier. It could save your life and possibly others. Sorry for the outburst, please be assured that it is well ment. 



Regards,



Jos Okhuijsen

Visit -  www.EuropaOwners.org

christoph.both(at)acadiau
Guest

Posted: Wed Mar 18, 2009 8:38 am Post subject: Woodcomp Propellers

Carl,

How old are you blades and hub? I understand the newer versions have a

mechanical stop built in so the hub cannot move the blades beyond the

"fine" setting. This all makes perfect sense to me - thrust reverse

option would scare the living hell out of me. Do I really need thrust

reverse is such a simple aircraft as the Europa?



I bought a 2 blade SR3000-2 with scimitar blades I hope to put into

service this year. I bought it disassembled and the factory provided me

with a detailed assembly manual as we in Canada live far away from

Europe and the very high associated shipment fees. I opted for the

variable pitch only because I do have an additional set of glider wings

and feathering seems to make sense. Also, the performance

characteristics of both type of aircraft require a different power/prop

pitch curve for each set of wings, that is, a fixed prop might want

adjustment every time I switch the wings - not ideal. 



I have chosen 2 blade because of less resistance in gliding mode, but

also because I could save about 8 pounds weight right at the front tip

of the aircraft, not making it too nose heavy. Prop and hub come in at

8kg compared to 12 kg - a significant difference. Not much more than the

Warp fixed 3 blade! The scimitar blades look beautiful and are very well

made. I like their progressive twist towards centre compared to the Warp

as the Classic requires cooling close to the hub which will also be

positively provided by much broader blade chord in this area. I think it

is a nice combination - the top cowling also comes easily off which with

3 blades seems to be more difficult.



Why don't you ask the factory for a modification - or upgrade? I have

had good experiences with them (not with the Canadian Retailer in B.C.,

though - but this is another story!).



I am attaching the detailed manual.



Best,

Christoph Both

#223 TRI 912S Classic+Glider (Pre-paint stage)

Nova Scotia, Canada 

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christoph.both(at)acadiau
Guest

Posted: Wed Mar 18, 2009 8:42 am Post subject: Woodcomp Propellers

Thanks for putting the matter back into a proper and appropriate

perspective.

Christoph

--

kheindl(at)msn.com
Guest

Posted: Wed Mar 18, 2009 9:41 am Post subject: Woodcomp Propellers

  

Carl C

  

 The blades won't move a millimeter unless current is fed to the motor C either via a manual switch or by a software switch. Reverse is a crazy option C unless the aircraft is an amphibian. And then C as far as I know C all certified variable pitch props are hydraulic. 

 I had various problems with my Woodcomp C and I don't really trust automatic pitch control in an electric hub any more C with two motor failures.

 Nowadays I set the pitch to fine before I get into the aircraft for a flight. I leave the controller in manual C until I have reached a safe altitude C and then switch to automatic. Same for landing : I switch to manual when I start my descent.

 You should have no problem getting the hub modified by the factory C but shipping is always the problem.

  

 Karl

 



 

 



  

 	  Quote: 	
		   Subject: Re: Woodcomp Propellers

 From: josok-e(at)ukolo.fi

 Date: Wed C 18 Mar 2009 17:44:26 +0200

 To: europa-list(at)matronics.com

 

 --> Europa-List message posted by: "josok" <josok-e(at)ukolo.fi>

 

 Hi Carl C

 

 While i am not in the UK part of the Europa fraternity  i still feel i should respond. First of all C i am happy to hear that the PFA does not accept the Woodcomp in flight adjustable without modification. It could have to do with the accident that happened to me C where exactly such a thing happened. My best advice is to scrap the hub and find another supplier. It could save your life and possibly others. Sorry for the outburst C please be assured that it is well ment. 

 

 Regards C

 

 Jos Okhuijsen

 

 

 

 

 

 

 Visit - www.EuropaOwners.org

 

 

 

 

 

&gt=======================
	


&g=======

[quote] 

 

 

   	  Quote: 	
		  [b]

josok-e(at)ukolo.fi
Guest

Posted: Wed Mar 18, 2009 12:40 pm Post subject: Woodcomp Propellers

Just for the record: 1: The blades did not go in reverse but in superfine pitch. 2: This is the first time that a mechanical stop is ever mentioned. Woodcomp certainly never even pointed at the possibility. IMHO, if you power the motor directly, you can spin the blades all around on ANY Woodcomp. Until the motor burns out, which will be very quickly. As far as i know only MT manufactures electrical variable speed propellers with  mechanical endstops. 3: The problems i encountered were because of non suitable microswitches, diode and motor. The same hardware can be found in any Woodcomp in flight adjustables, wether those are straight, reverseble or sail. 



It's everybodies (and in the UK the LAA's) choice of how much risk you want to take. I can imagine it's difficult to scrap something you layed out your money for. I realize it's bad news for many happy pilots. I also would not forgive myself if i would not take this stand. Now everybody may continue to throw stones at the bad news prophet 



Regards,



Jos Okhuijsen

Visit -  www.EuropaOwners.org

loboloda(at)execulink.com
Guest

Posted: Wed Mar 18, 2009 1:05 pm Post subject: Woodcomp Propellers

Allow me to add my 2 cents.

After electrical and mechanical failures on my woodcomp, and a  

botched repair job by their Canadian rep, I took my prop out of service.

A big write off of dollars, made more painful as I sold my absolutely  

as new 1967 Triumph Tiger Cub, in order to pay for the prop,



Dave A061

On 18-Mar-09, at 3:36 PM, josok wrote:



 	  Quote: 	
		   



 Just for the record: 1: The blades did not go in reverse but in  

 superfine pitch. 2: This is the first time that a mechanical stop  

 is ever mentioned. Woodcomp certainly never even pointed at the  

 possibility. IMHO, if you power the motor directly, you can spin  

 the blades all around on ANY Woodcomp. Until the motor burns out,  

 which will be very quickly. As far as i know only MT manufactures  

 electrical variable speed propellers with  mechanical endstops. 3:  

 The problems i encountered were because of non suitable  

 microswitches, diode and motor. The same hardware can be found in  

 any Woodcomp in flight adjustables, wether those are straight,  

 reverseble or sail.



 It's everybodies (and in the UK the LAA's) choice of how much risk  

 you want to take. I can imagine it's difficult to scrap something  

 you layed out your money for. I realize it's bad news for many  

 happy pilots. I also would not forgive myself if i would not take  

 this stand. Now everybody may continue to throw stones at the bad  

 news prophet 



 Regards,



 Jos Okhuijsen

 Visit -  www.EuropaOwners.org

frans(at)paardnatuurlijk.
Guest

Posted: Wed Mar 18, 2009 1:17 pm Post subject: Woodcomp Propellers

josok wrote:



 	  Quote: 	
		   Just for the record: 1: The blades did not go in reverse but in

 superfine pitch.


	


It would be extremely helpful if you describe what exactly happened.



 	  Quote: 	
		   2: This is the first time that a mechanical stop is

 ever mentioned.


	


I red already on the Woodcomp site about the mechanical endstops before

your accident. Maybe they changed something after you purchased your prop?



 	  Quote: 	
		   The problems i encountered were because of non suitable

 microswitches, diode and motor.


	


Were they from the Woodcomp supplied parts? Or your own, but "similar"

to the hardware Woodcomp supplies?



 	  Quote: 	
		   It's everybodies (and in the UK the LAA's) choice of how much risk

 you want to take.


	


Flying is a risk. Any addition of functionality (like variable pitch

prop) introduces an additional risk factor. Add "reverse", and the risk

grows even further. What you don't have can not fail. To assess the

risk, I would like to know how many Woodcomp users experienced the same

problem. You know, Rotax engines also have failed sometimes, but that

doesn't mean that one has to scrap all Rotax engines. An importing thing

is to understand what exactly happened so one can avoid it, and that's

why I asked my first question: What exactly has happened, and what

introduced it? As long as I don't know this, I can only look at the

statistics, and see that Woodcomp has not an exceptional high failure rate.



-- 

Best regards,

Frans Veldman

kheindl(at)msn.com
Guest

Posted: Wed Mar 18, 2009 1:17 pm Post subject: Woodcomp Propellers

  

Hi Josok C

  

 I am not so sure about what you are saying. When I had early problems C I applied a 9V voltage to it directly C and the blades stopped at minimum and maximum pitch automatically. I would have been very concerned C if they hadn't.

 When you say superfine pitch C what does that mean ? I assume that the blades have gone past minimum pitch C on their way to reverse C because of overrun C and the lack of mechanical stops.

 I have the feathering option C which is handled quite differently C and on a separate circuit.

  

 Regards C  Karl

 



 

 



  

 	  Quote: 	
		   Subject: Re: Woodcomp Propellers

 From: josok-e(at)ukolo.fi

 Date: Wed C 18 Mar 2009 22:36:53 +0200

 To: europa-list(at)matronics.com

 

 --> Europa-List message posted by: "josok" <josok-e(at)ukolo.fi>

 

 Just for the record: 1: The blades did not go in reverse but in superfine pitch. 2: This is the first time that a mechanical stop is ever mentioned. Woodcomp certainly never even pointed at the possibility. IMHO C if you power the motor directly C you can spin the blades all around on ANY Woodcomp. Until the motor burns out C which will be very quickly. As far as i know only MT manufactures electrical variable speed propellers with mechanical endstops. 3: The problems i encountered were because of non suitable microswitches C diode and motor. The same hardware can be found in any Woodcomp in flight adjustables C wether those are straight C reverseble or sail. 

 

 It's everybodies (and in the UK the LAA's) choice of how much risk you want to take. I can imagine it's difficult to scrap something you layed out your money for. I realize it's bad news for many happy pilots. I also would not forgive myself if i would not take this stand. Now everybody may continue to throw stones at the bad news prophet 

 

 Regards C

 

 Jos Okhuijsen

 

 

 

 

 

 

 Visit - www.EuropaOwners.org

 

 

 

 

 

&gt=======================
	


&g=======

[quote] 

 

 

   	  Quote: 	
		  [b]

davidjoyce(at)doctors.org
Guest

Posted: Wed Mar 18, 2009 3:59 pm Post subject: Woodcomp Propellers

Jos, Are you stating your theory here or quoting the Austrian AAIB report, 

and if so where is it published?

        Incidentally although the SR3000 has double electrical cutout 

microswitches at each end of its pitch range, the SR200 does have a  single 

electrical system with a mechanical back up system.

        Regards, David Joyce ( with no problem SR3000!) G-XSDJ

---

m.grass(at)comcast.net
Guest

Posted: Wed Mar 18, 2009 6:43 pm Post subject: Woodcomp Propellers

Jos,



I am still very sad and sorry about your loss of your plane. You have been a 

great contributor to the Europa builder community and  I do appreciate this 

a lot.



I still try to figure out what exactly could have contributed to your 

accident. So far the only creditable information what happened came from you 

and it is consistent. What I believe you stated is:



1. You took of with a high power setting

2. A little later on climb out the engine started to rev up more but you 

lost forward trust. This, you explained later,  was caused by the prop going 

to super fine mode.



This is defiantly something I can not  understand what went wrong on the 

prop side. You pointed towards the limit switches and the diodes. However, I 

can't understand here the failure mode. I still assume that, at the initial 

climb out,  everything was ok and the blades where somewhere in the middle 

( means permissible)operating travel range. This means that all the limit 

switches had been depressed  ( at least the ones from the outer and the 

middle ring). Now I can go through all combinations of failure modes on the 

diodes and switches and I can not understand how the DC motor got a command 

to travel to fine. The worst thing what could have happened is that the 

switch on the outer ring would have failed to open, which means the prop 

would have not been able anymore to travel to coarse position but the prop 

went into fine.



Why??



The constant speed controller should have seen a control deviation with the 

increased motor speed and therefore command to go to course but not to fine.



I could see 3 single failure points causing this.



1st failure mode = "loss of feedback" (motor RPM). That could have set the 

controller to command less pitch (means travel to fine).

The loss of feedback could in a somehow failsafe control scheme could have 

been detected by a dual mean of feedback signal  (I doubt that you had this)

or (but less reliable) with an control algorithm to detect an impossible 

amount of change in RPM over a short interval of time. I don't know if any 

countermeasures are implemented.Do you know?



2nd A short in the driving  output transistor or FET. Typically, if a 

transistor or FET fails, it will short circuit. This means the motor will 

continuously commanded to go in a specific direction. If that would have 

happened then only the fine stop switch would have stopped the motor. You 

also could detect this in your controller and counteract (disable output) 

with a couple of differently methods.



3rd controller failure. Frozen microprocessor (controller) program. Here 

would only help redundancy again.



All those failure modes are not part of the actual prop but the controlling 

circuit which did not came from Woodcomp.



All those problems could have still potential been taken care of (if you 

would have had enough time) by a kill switch and transfer to an emergency 

manual command switch. It is my understanding that you had a 3rd party 

controller. Did your installation still provided this emergency mode?



I could see, only if you had two failures accumulated simultaneously by one 

of the 3 above failure modes AND the micro switch on the outer ring failed 

or the motor failed  you would not have been able to recover.



Another(4th)  remote possibility could have been that the DC motor might 

came completely detached from the 3 worm gears so the prop had no counter 

force and drifted (freewheeled) towards fine pitch setting.



So with all this I would like to ask the question:



Do you have a report by an independent person or agency stating what exactly 

failed or do you know exactly what failed?



Best regards



Michael Grass

(Yes I bought also a Woodcomp and would just like to get a better 

understanding what went wrong so I can plan accordingly)

---

josok-e(at)ukolo.fi
Guest

Posted: Thu Mar 19, 2009 2:50 am Post subject: Woodcomp Propellers

Ok, i'll try to answer the questions asked. Some of them have been asked and anwered before, and i hope these answers will be consistent with what was mentioned before  Latest news from the accident investigator was 3 weeks ago, where he told me that he wanted to finish the report within a week. Maybe there are new delays. 



Why did the prop run into super fine pitch? 

I took off normally, full throttle, prop controller in the take-off position. Everythinjg fine. At 500 ft above ground i switched the controller to cruise and throttled back. The controller adjusted the blades to 4350, my last descent cruise. I had forgotten to adjust the controller to 5000 rpm, my normal slow climb cruise. As a result the map went beyond an acceptable value. So i throttled down more, and at the same time toggled the controller to 5000 rpm. This caused the blades to turn more fine. Probably against the fine endstop position, if that endstop had been functional.  At that very moment the tower instructed the formation to switch frequencies, although i was still on crosswind, and number 3 probaly still on upwind. While changing frequencies i noticed that my number one was disappearing fast, added more power and noticed 6200 rpm and no thrust, 50 knots airspeed The blades were obviously in super fine. Also the prop CB had popped. Resetting the CB resulted in the 

 controller showing boot messages as normal, and the CB popped again. Because the controller booted normally, it is clear that there was no sc in there, and the controller only did what is was supposed to do: Turn fine to increase the demanded rpm, (fine endstop being the end of travel) turn coarse to reduce to demanded rpm.  Most probably the pitch motor had burnt. It could not cope with turning the blades at this high rpm. That the propellor was of a reversible version had nothing to do with the events. All components that played a role are present in any SR 3000. To resume: !st Endstops did not work, Woodcomp supplied component failure. 2nd: Motor burnt



The electrical components in the propeller are not suitable for the task. The end-stop microswitches are for indoor use, and not suitable to withstand weather influences. Most probably their DC amp rating is much lower then the current drawn by the motor. The diode across the switches is of a 5 A type, where the pitch motor can draw + 15A. The motor, for which i could not find any specifications, looks to be a 6 V type. Suitable for either very short tem useage or pcm control lower then 50 %. Woodcomp had repaired the prop. After the repair i had to increase the pcm ratio from 40% to 80% to make the pitch motor run. Either the mechanism was turning far more difficult, or the motor specifications had been changed. With the repared propellor came some parts, gears, and also a used motor. As usual with Woodcomp, there was no explanation or specification. 



As stated before: There is no mechanical endstop in the SR 3000 (Thanks David for the addition) Not in any Woodcomp 3000, being "normal", reverse or feathering. Proper working of the fine endstop relies only on proper working of the electrical circuit. This circuit, contradictory what David states, is NOT double. it relies on a single, underrated diode!. There are 2 fine endstops microswitches, probably because their rating is insufficient. As any electrical engineer can tell you, doubling contacts does not double the switching capacity. Reason being that one will always be earlier. There will be NO indication that either the microswitches or the diode has failed, until also the motor burns and you are in superfine pitch at 500 feet and at 50 knots  



Yes, also Rotax engines have failed, the difference is, ,that there are no underrated or misplaced components to point a finger at. There is proper documentation, and proper follow-up for anything that may cause a problem. The best Woodcomp came up with was to "No support for 3rd party controllers" That they are also the only supplier not contacting me after the accident does not make me happy either. 



Its only fair to admit my own mistakes. As an electrical engineer i should not have accepted the electrical setup of the prop. I should have known better. I should not have acepted their offer to repair the propellor. I should not have acceped the needed change in pcm without further explanation. I should have adjusted the cruise rpm before take-off. Maybe i should not have flown in rain. I should not have accepted the frequency change while still taking off. 

There were fields within range, if i would not have been distracted.



If you keep flying with a SR 3000: Please add a fine endstop check to you checklist for every take-off. 



Kind Regards,



Jos Okhuijsen

Visit -  www.EuropaOwners.org

frans(at)paardnatuurlijk.
Guest

Posted: Thu Mar 19, 2009 3:37 am Post subject: Woodcomp Propellers

Jos,



Since I intent to order a Woodcomp propellor soon, I'm very interested

in the cause of the accident.

I'm however still puzzled by your claim that a mechanical failure of the

Woodcomp propellor was the cause of your crash.

I was prepared to wait for the final AAIB report, but now you are

pointing to the quality of the Woodcomp propellor as being the cause of

the accident, I would love to hear the complete story.



You first state that the lack of an end-stop in the Woodcomp propellor

was the cause.

Later on, you blame diodes and relays of inferior quality.



These are two different things. Anyway, as someone else pointed out

already, the accident implies more or less that the propellor control

motor got somehow engaged. A missing end stop was nothing more than a

contributing factor, not the real cause. Since you had the reverse pitch

option, there could not be a mechanical end stop anyway. But even

without the end stop, the prop would have functioned correctly, IF the

prop pitch motor got not erroneously engaged during the flight.

The big question therefor remains: what caused the prop motor to start

cranking the prop to superfine?



Some of us are intrigued by a message from you, written the 19th of may

2007, in which you wrote:



"For reason of simplicity, exactly in a high stress situation (most of

my landings will be  ) managed to do away with the change-mode

switch. The 3-pole reverse-unreverse switch now operates a relay, that

changes the mode. This latched and warning labeled switch is IMHO

security enough against accidental operation.

Do you have to wait for full reverse before opening the throttle? Should

i think about an indicator light that indicates the reverse end stop

reached?"



See http://www.europaowners.org/viewtopic.php?t=4276



In a normal setup, you can not engage reverse, without changing the mode

first, and putting power back to idle first. In a standard Woodcomp

setup there are no relays involved at all. You are describing a

modification that bypasses the mode switch by the addition of a relay,

and could potentially switch the prop to full reverse without closing

the throttle first.

Could it be that your safety bypass, consisting of the addition of a

relay, played a role in this accident? Was this the malfunctioning relay

you are referring to? If this single additional relay would fail, could

it all by itself unintentionally power up the pitch control motor?



I hope you understand that I'm confused by your claim that it was just a

missing mechanical end stop that was the main cause of the accident. If

your modification made it easier for the prop pitch motor to

unintentionally start cranking the prop to fine/reverse, it doesn't make

sense to point so strongly to the Woodcomp company as being the cause of

the accident. So far, I have no reasons to believe that a Woodcomp prop,

without reverse option, and without safety bypass, would have a higher

risk than any other prop. There are no statistics that point into that

direction.



I'm not involved in the Woodcomp company, I even don't have a Woodcomp

propellor (yet). Hope you understand that I'm purely technically

interested in the chain of events that led to this tragedy. There might

be something that can be a lesson for us, so we avoid this from

happening again in the future. For the safety of us all, we'd better

stay away from emotions and look purely at the factual data we have. At

this moment, without substantial data, just pointing to Woodcomp as the

cause, is not really convincing, and not sufficient ground to start

talking people into selling their Woodcomp propellors. Just my 2 cents.



-- 

Frans Veldman

frans(at)paardnatuurlijk.
Guest

Posted: Thu Mar 19, 2009 4:13 am Post subject: Woodcomp Propellers

josok wrote:



 	  Quote: 	
		   Why did the prop run into super fine pitch?


	


Thanks for the information, but it still doesn't explain why the prop

went into super fine pitch in the first place. Was it commanded by the

prop controller?

I don't have a Woodcomp propellor yet, but it appears to me that control

of the prop pitch motor is some sort of feedback loop. In normal

operation, I assume the prop controller won't fling the pitch back and

forth between the end limits, but make small changes, evaluate the

result, and not go to super fine if the RPM is already very high.



Apart from this, I may assume that this system has been working

correctly in the past, and that going to super fine pitch and high RPM

was not part of your normal flying procedure. A burnt out motor can not

be the cause of going to super fine pitch, as a burnt out motor does not

do anything anymore, so I think something first powered the motor to

super fine pitch before the motor burned out. Maybe the motor burned out

because of this untintended move to super fine pitch. If this is the

case, the burning out of the motor was not the cause, but a result of

something else going wrong.



 	  Quote: 	
		   To resume: !st Endstops did not work, Woodcomp supplied component

 failure. 2nd: Motor burnt


	


The end stops, if they were there, would have been an *additional*

safety, but not for throwing the pitch against its limits over and over

again.



 	  Quote: 	
		   The diode across the

 switches is of a 5 A type, where the pitch motor can draw + 15A.


	


Diodes over switches are not there to let the main current through, but

to extinguish the opposite voltage that appears when you suddenly take

the power away from a coil. Since the motor is a coil, it will create a

spark everytime when you disconnect it, and the diode is there to

extinguish it. There is no reason why the diode should have the same amp

rating as the current demand of the pitch motor. 5 Amps sound generously

to me for this task, I bet 1 amp would have been fine as well.



 	  Quote: 	
		   The

 motor, for which i could not find any specifications, looks to be a 6

 V type.


	


The rating is something that the manufacturer comes up with, for

continuous use. There is no physical difference between a 12 Volt or 6

Volts motor. It is just a rating that describes the maximum voltage for

contineous usage. The same motor, with better cooling, or for shorter

durations, can handle a higher voltage.

It is fully acceptable that Woodcomp used a 6 Volt motor for the purpose

of being used in short bursts, in a very efficiently cooled area.



 	  Quote: 	
		   As stated before: There is no mechanical endstop in the SR 3000

 (Thanks David for the addition) Not in any Woodcomp 3000, being

 "normal", reverse or feathering. Proper working of the fine endstop

 relies only on proper working of the electrical circuit. This

 circuit, contradictory what David states, is NOT double. it relies on

 a single, underrated diode!. There are 2 fine endstops microswitches,

 probably because their rating is insufficient. As any electrical

 engineer can tell you, doubling contacts does not double the

 switching capacity.


	


Are they wired in series or in parallel? You are suggesting that they

are connected in parallel, and if so, I agree that this is a very dumb

thing. However, I hate not to have a Woodcomp propellor here, but I'm

betting that these switches are wired in series. In this case, if one

fails, you still have the other one.



 	  Quote: 	
		   There will be NO indication that either the microswitches or the

 diode has failed, until also the motor burns and you are in superfine

 pitch at 500 feet and at 50 knots 


	


Still, I wonder whether it is normal operation to rely on the

microswitches to stop the pitch motor, or that the propellor controller

is supposed to never try to command the propellor against its safety limits.



Even without mechanical end stops, diodes, and microswitches, the system

would have had to function normally. Until the moment that somewhere,

something catastrophically started to power up the pitch motor.



In the reverse circuit, there are no safety microswitches for superfine,

because the prop is intentionally moved through its super fine setting.

It is therefore likely that a failure occured in the reverse circuit.

Something tried to reverse the prop, the controller was fighting this,

with the result that the CB popped and the prop was stuck in super fine.

Since you made some modifications in the reverse circuit, it is not

really fair to blame Woodcomp for the catastrophic result.



 	  Quote: 	
		   If you keep flying with a SR 3000: Please add a fine endstop check to

 you checklist for every take-off.


	


This sounds to me as a wise thing to do. I will for sure add it to my

check list.

Thanks!



-- 

Frans Veldman

josok-e(at)ukolo.fi
Guest

Posted: Thu Mar 19, 2009 5:18 am Post subject: Woodcomp Propellers

Dear Frans



[quote:f042f8651c]You first state that the lack of an end-stop in the Woodcomp propellor was the cause. Later on, you blame diodes and relays of inferior quality. [/quote:f042f8651c]



Sorry, no. The fine pitch endstop is formed by two microswitches, parelled by one diode. Never mentioned a relay. 



[quote:f042f8651c]These are two different things. Anyway, as someone else pointed out already, the accident implies more or less that the propellor control

motor got somehow engaged. A missing end stop was nothing more than a contributing factor, not the real cause.[/quote:f042f8651c] 



Of course the pitch motor got engaged, not by mistake, but because the pilot, me reduced throttle. The not-working endstop was the first failing part. A burned out motor the second part. What real cause do you want? 



[quote:f042f8651c]Since you had the reverse pitch

option, there could not be a mechanical end stop anyway. [/quote:f042f8651c]



Irrelevant: Not any Woodcomp SR 3000 has a mechanical stop. 

Read my lips: Normal, reverse, feathering: No mechanical endstops.



[quote:f042f8651c]But even without the end stop, the prop would have functioned correctly, IF the prop pitch motor got not erroneously engaged during the flight. The big question therefor remains: what caused the prop motor to start cranking the prop to superfine?[/quote:f042f8651c]



Iv've tried to explain that, let's try again, real slow now, for the technically handicapped amongst us.  



Say you fly at 100 knots, and the controller has adjusted the rpm, as you have demanded, to 5000 rpm. 

Now, if you reduce throttle slightly the controller reduces the pitch to maintain the 5000 rpm that you asked for. Right? 

It will keep reducing the pitch at any further reducing of throttle, to keep up the RPM. The controller has no idea how fine it turns the blades. 

Only the endswitch will prevent the blades from turning into superfine or even further.  

Nothing strange about that, and nothing to worry about, 

IF THE ENDSTOPS ARE WORKING!



[quote:f042f8651c]Some of us are intrigued by a message from you, written the 19th of may 2007, in which you wrote:

"For reason of simplicity, exactly in a high stress situation (most of

my landings will be  ) managed to do away with the change-mode

switch. The 3-pole reverse-unreverse switch now operates a relay, that

changes the mode. This latched and warning labeled switch is IMHO

security enough against accidental operation. [/quote:f042f8651c]



Some of us? Intrigued? 

I fail to see where this connects to this thread other then do distract from the facts.

 



[quote:f042f8651c]Could it be that your safety bypass, consisting of the addition of a

relay, played a role in this accident? Was this the malfunctioning relay

you are referring to? If this single additional relay would fail, could

it all by itself unintentionally power up the pitch control motor?[/quote:f042f8651c]



Safety bypass? Please! 

If "my" relay would fail, it would either blow the CB immediatly, leaving the pitch unchanged, or simply leave the pitch motor without power, again leaving the pitch unchanged. The actual switching was done by a 4 pole 3 way switch. That switch could only do what it was supposed to do. I've shown the circuit to experts, and i have had the actual wiring checked by my inspector. His comment was "Better standard of wiring then seen sofar on experimentals"



You are classifying a pretty fail-safe setup as a safety bypass, without even knowing the details.  



[quote:f042f8651c]I hope you understand that I'm confused by your claim that it was just a missing mechanical end stop that was the main cause of the accident. [/quote:f042f8651c] 



You really can't read. Never said that. I doubt very much if this is caused by confusion or else. You seem to be constructing things. It's a pity. 



And believe me, wish you all the luck you will need. 



Regards,



Jos Okhuijsen

Visit -  www.EuropaOwners.org

frans(at)paardnatuurlijk.
Guest

Posted: Thu Mar 19, 2009 6:41 am Post subject: Woodcomp Propellers

josok wrote:

 	  Quote: 	
		   [quote:f042f8651c]You first state that the lack of an end-stop in the

 Woodcomp propellor was the cause. Later on, you blame diodes and

 relays of inferior quality. [/quote:f042f8651c]

 

 Sorry, no. The fine pitch endstop is formed by two microswitches,

 parelled by one diode. Never mentioned a relay.


	


You are right. My slip up.



 	  Quote: 	
		   Iv've tried to explain that, let's try again, real slow now, for the

 technically handicapped amongst us.

 

 Say you fly at 100 knots, and the controller has adjusted the rpm, as

 you have demanded, to 5000 rpm. Now, if you reduce throttle slightly

 the controller reduces the pitch to maintain the 5000 rpm that you

 asked for. Right?


	


So, let's assume for the moment I'm technically handicapped, and let me

ask just to be sure I don't misunderstand you:

If you throttle back from take-off power to cruise climb, the controller

tries to move the blades to the finest pitch possible, and it is the

task of the endswitches to prevent the blades from moving even further?

With other words, with every throttle move, the blades will always

travel to one of the endstops?



If this is the case, I can understand how a failed endstop immediately

caused the blades to travel to a non flyable position.



As I'm technically handicapped, I picture the working of the prop and

controller as follows:

Say you fly at 100 knots, and the controller has adjusted the rpm, as

you have demanded, to 5000 rpm. Now, if you reduce throttle slightly,

the controller reduces the pitch somewhat *without fully traveling to

the end stop*, measure the rpm again, evaluate if still below the target

rpm, reducing the pitch a little bit more, evaluate again, and stop when

the engine again is at 5000 rpm. The end switch has not been used in

this scenario, because the prop went never to its finest position in the

first place.



Even with the end switches shorted, you won't notice anything.



Until something else goes wrong...

For a failure, you need an additional factor, something that tries to

move the blades to an even finer pitch *while the rpm is already above

its target*.



I'm still looking for a scenario where the rpm can rise to 6200 rpm, the

blades are in super fine, and something is feeding power to the pitch

motor to move the blades even further. What is this "something". Once

again: even with all micro-switches shorted, the pitch motor won't run,

because power is fed only to these switches if something (the

controller, the reverse pitch relay) is sending power to the pitch motor

with the purpose of reducing the pitch. The end switches won't see any

power, shorted or not, unless something tries to move the pitch motor

even further.



 	  Quote: 	
		   It will keep reducing the pitch at any further

 reducing of throttle, to keep up the RPM.


	


Past the desired RPM?



 	  Quote: 	
		   [quote:f042f8651c]Some of us are intrigued by a message from you,

 written the 19th of may 2007, in which you wrote: "For reason of

 simplicity, exactly in a high stress situation (most of my landings

 will be  ) managed to do away with the change-mode switch. The

 3-pole reverse-unreverse switch now operates a relay, that changes

 the mode. This latched and warning labeled switch is IMHO security

 enough against accidental operation. [/quote:f042f8651c]

 

 Some of us? Intrigued? I fail to see where this connects to this

 thread other then do distract from the facts.


	


Let me spell it out: In a normal situation, when powering back from

take-off power to cruise power, the end/stops/limit switches never come

into play, because the controller cuts the power to the pitch motor long

before the fully finest position is reached.

In order for the limit switches to show their failure, something has to

keep sending power to the prop circuit, now putting all bets on the

limit switches to prevent the prop from going past fully fine. Once

again: I think it is not common practice to cruise along with the prop

in fully fine, so the end switches should never have been exercised. But

something tried to move the blades to fully fine, and apparently even

past fully fine.

Now, as I studied the schematics, there are only two power sources for

the prop pitch motor: the controller, and the reverse circuitry. One of

these circuits had to be inadvertently sending power to the pitch motor,

while the rpm was already way up.

By definition, the reverse circuitry has to bypass the microswitches,

because its purpose is to intentionally move the blades past fully fine.

That makes the reverse circuitry suspect number one.

If I then read that you have modified the reverse circuit, it is not

difficult to start to wonder if this has had something to do with it.



 	  Quote: 	
		   Safety bypass? Please! If "my" relay would fail, it would either blow

 the CB immediatly, leaving the pitch unchanged, or simply leave the

 pitch motor without power, again leaving the pitch unchanged.


	


If I recall correctly: on the Woodcomp there is a third slip ring, for

adding power to move the prop beyond its normal flying operating range.

This is used for reverse, or feathering. You need to put power on this

ring to feather or go to reverse.

This third ring is not connected to the controller, so the controller is

no longer suspect here.

Normally you put power on this third ring with a safety latched switch.

It appears from your message that you replaced the function of this

switch by a relay.

In this case, an inadvertently close of the relay contacts would

catastrophically power the pitch motor, bypass the end limit switches by

its very nature, keep power on the pitch motor until it finally gives up

the ghost. The controller, who sees the rpm going up, tries frantically

to move the pitch motor the other way via the other slip rings. This

will for sure pop the circuit braker. And will keep popping the circuit

breaker as long as rpm is too high, and the third slip ring remains

powered up.



A failure of the reverse switch/relay would exactly give you the

catastrophic results that you described. And the limit switches do not

even have to fail for this scenario to happen exactly as described. This

is the only "one-failure" scenario that I can think off, all other

scenario's require multiple failure points are not impossible, but less

likely.



 	  Quote: 	
		   actual switching was done by a 4 pole 3 way switch. That switch could

 only do what it was supposed to do. I've shown the circuit to

 experts, and i have had the actual wiring checked by my inspector.

 His comment was "Better standard of wiring then seen sofar on

 experimentals"


	


I do not suspect the wiring failed, but that the relay failed. Relais do

fail sometimes.

I would love to see the schematic, to see what you have done. Then we

can see which components need to fail to cause exactly the same results

as you experienced.



I'm sure there will be multiple scenario's.

However, all these scenario's would have in common that something else

failed before the failed(?) end switches came into play.



 	  Quote: 	
		   You are classifying a pretty fail-safe setup as a safety bypass,

 without even knowing the details.


	


I would love to know the details.

The whole problem is that you blame the end switches, and lack of

physical end stops, completely ignoring the fact that something must

first inadvertently power up the pitch motor to its fully finest pitch

before these end limits would come into the picture.



 	  Quote: 	
		   I doubt very much if this is

 caused by confusion or else. You seem to be constructing things. It's

 a pity.


	


I'm just trying to solve the puzzle. My own safety depends on it.

If I would just walk away from any part that has been involved in an

accident somewhere, I could't build an airplane. It is necessary to

construct how things went wrong, before you can really assess whether

the part is safe or unsafe. Is a Rotax engine unsafe, because someone

crashed with it? Dunno, unless I get a clear description of what was the

cause. Same with the Woodcomp prop.

Just be assured that my intention is not to blame you in anyway. In

fact, I never got involved in the discussion about your accident. But

now you so openly blame Woodcomp and completely ignoring the fact that

some "non-woodcomp-part" had to be feeding power to the pitch motor for

the failure to occur, it is our (Europa community) mutual interest to

put things into perspective.



-- 

Frans Veldman

josok-e(at)ukolo.fi
Guest

Posted: Thu Mar 19, 2009 10:48 am Post subject: Woodcomp Propellers

Dear Frans.



For the moment i am still willing to believe you honestly still do not understand what happened and try to fill in the gaps.

[quote:e2d9de2b1b]

If you throttle back from take-off power to cruise climb, the controller

tries to move the blades to the finest pitch possible, and it is the

task of the endswitches to prevent the blades from moving even further?

[/quote:e2d9de2b1b]

Correct.

[quote:e2d9de2b1b]

With other words, with every throttle move, the blades will always

travel to one of the endstops?

[/quote:e2d9de2b1b]

Of course not, where you did invent that idea now? 



The controlers task is to keep the rpm as instructed.

It will move the blades until that selected rpm is reached.

If you would nearly close the throttle it will never reach that rpm, and the fine endstop comes into play to prevent the blades from moving into an unflyable position. Still, even with disabled endstops, due spotwelded contacs, short-circuited  diode ect, adding power would increase rpm and the blades would return to a normal pitch. You would never notice what happened. Unless, that underrated pitch motor, which had been struggling hard to turn to negative pitch, now has to struggle again to positive pitch under full load and decides that enough is enough. It burns, blowing the CB. 

[quote:e2d9de2b1b]

If this is the case, I can understand how a failed endstop immediately

caused the blades to travel to a non flyable position.

[/quote:e2d9de2b1b]

No you don't 

[quote:e2d9de2b1b]

As I'm technically handicapped, I picture the working of the prop and

controller as follows:

Say you fly at 100 knots, and the controller has adjusted the rpm, as

you have demanded, to 5000 rpm. Now, if you reduce throttle slightly,

the controller reduces the pitch somewhat *without fully traveling to

the end stop*, measure the rpm again, evaluate if still below the target

rpm, reducing the pitch a little bit more, evaluate again, and stop when

the engine again is at 5000 rpm. The end switch has not been used in

this scenario, because the prop went never to its finest position in the

first place.[/quote:e2d9de2b1b]



Correct.

[quote:e2d9de2b1b]

Even with the end switches shorted, you won't notice anything.



Until something else goes wrong...

[/quote:e2d9de2b1b]

Like closing the throttle a little bit more.

[quote:e2d9de2b1b]

For a failure, you need an additional factor, something that tries to

move the blades to an even finer pitch *while the rpm is already above

its target*.

[/quote:e2d9de2b1b]

No you don't Just closing the throttle is enough to hang you life on the proper functioning of the fine end stop. 

[quote:e2d9de2b1b]

I'm still looking for a scenario where the rpm can rise to 6200 rpm, the

blades are in super fine, and something is feeding power to the pitch

motor to move the blades even further. What is this "something". Once

[/quote:e2d9de2b1b]

What about opening the thottle to full power because you are low and slow?

[quote:e2d9de2b1b]

again: even with all micro-switches shorted, the pitch motor won't run,

because power is fed only to these switches if something (the

controller, the reverse pitch relay) is sending power to the pitch motor

with the purpose of reducing the pitch. The end switches won't see any

power, shorted or not, unless something tries to move the pitch motor

even further.

[/quote:e2d9de2b1b]

There is no such thing as a reverse pitch relay. 

[quote:e2d9de2b1b]It will keep reducing the pitch at any further

reducing of throttle, to keep up the RPM.

[/quote:e2d9de2b1b]

[quote:e2d9de2b1b]Past the desired RPM?

[/quote:e2d9de2b1b]

Again, stage one: I did explain now how the pitch can turn into fine or negative on any Woodcomp SR 3000 with broken fine endswitches. 

Stage two: If the pitch moter burns at that critical point, it can't do anything to prevent to go past the desired rpm. 



[quote:e2d9de2b1b]

Let me spell it out: In a normal situation, when powering back from

take-off power to cruise power, the end/stops/limit switches never come

into play, because the controller cuts the power to the pitch motor long

before the fully finest position is reached.

[/quote:e2d9de2b1b]

Correct, partly. 

[quote:e2d9de2b1b]

In order for the limit switches to show their failure, something has to

keep sending power to the prop circuit, now putting all bets on the

limit switches to prevent the prop from going past fully fine. Once

again: I think it is not common practice to cruise along with the prop

in fully fine, so the end switches should never have been exercised. But

something tried to move the blades to fully fine, and apparently even

past fully fine.

[/quote:e2d9de2b1b]

You get the picture.

Just reducing the power under the power needed for the engine to keep the desired rpm will make the conmtroller send more "fine" power into the pitch motor.

[quote:e2d9de2b1b]

Now, as I studied the schematics, there are only two power sources for

the prop pitch motor: the controller, and the reverse circuitry. One of

these circuits had to be inadvertently sending power to the pitch motor,

while the rpm was already way up.

[/quote:e2d9de2b1b]

Wrong, you mixing up stage one, how to get the blades over fine pitch, with stage two, having burnt the pitch motor. The rpm will not go up, will never reach desired rpm unless there is enough power added. Adding power, burning the motor then will overrun the engine. 

[quote:e2d9de2b1b]

By definition, the reverse circuitry has to bypass the microswitches,

because its purpose is to intentionally move the blades past fully fine.

That makes the reverse circuitry suspect number one.

If I then read that you have modified the reverse circuit, it is not

difficult to start to wonder if this has had something to do with it.

[/quote:e2d9de2b1b]

Wrong again. The reverse circuitry uses it's own slipring, and has nothing to do with the fine pitch microswitches. By the way, the diode is there to return power to the pitch motor with opened micro switches. Not intended nor rated for spark killing. 



[quote:e2d9de2b1b]

If I recall correctly: on the Woodcomp there is a third slip ring, for

adding power to move the prop beyond its normal flying operating range.

This is used for reverse, or feathering. You need to put power on this

ring to feather or go to reverse.

This third ring is not connected to the controller, so the controller is

no longer suspect here.

Normally you put power on this third ring with a safety latched switch.

It appears from your message that you replaced the function of this

switch by a relay.

[/quote:e2d9de2b1b] 

I told you that the reverse circuit was switched off, no power, no relay power, powerless, cold not doing anything, dead, not working, not operating. Safety latched. It's just not possible for circuits to operate without power. Not in this world anyhow. I also explained how the pitch ended up super fine. I also explained why the pitch could not return to normal. Most probably you don't want to understand the facts, it is much easier to cap your ears. 



Last advice:

Find an SR 3000 and have a good look at the components. Google the specifications of those life critical parts. Poor water over these microswitches. Run then pitch motor up and down for an hour or so while restricting the blade movement. But on the ground please!



Regards,



Jos Okhuijsen

Visit -  www.EuropaOwners.org

kheindl(at)msn.com
Guest

Posted: Thu Mar 19, 2009 1:55 pm Post subject: Woodcomp Propellers

  

Josok C

  

 This is a most fascinating thread and I wish it had never happened. What I would lke to ask you is : How much of this is theory and how much is fact ? Was the hub recovered intact or did it burn as well ? In particular I would like to know if there really was a motor failure; as you know I had two motor failures. And I believe you when you say that the motor cannot turn the blades at high rpm. These are mickey mouse motors designed for the automotive industry. Jiri claims they are Bosch manufacture C but mine (they sent me 3 different types) all have the name Johnson stamped on it. I believe this is a Hongkong company producing millions of these things for the car manufacturers.

 For that reason I will avoid all pitch changes at high rpm and below 2000 feet.

  

 Karl

 



  

 	  Quote: 	
		   Subject: Re: Woodcomp Propellers

 From: josok-e(at)ukolo.fi

 Date: Thu C 19 Mar 2009 20:48:05 +0200

 To: europa-list(at)matronics.com

 

 --> Europa-List message posted by: "josok" <josok-e(at)ukolo.fi>

 

 Dear Frans.

 

 For the moment i am still willing to believe you honestly still do not understand what happened and try to fill in the gaps.

 [quote:e2d9de2b1b]

 If you throttle back from take-off power to cruise climb C the controller

 tries to move the blades to the finest pitch possible C and it is the

 task of the endswitches to prevent the blades from moving even further?

 [/quote:e2d9de2b1b]

 Correct.

 [quote:e2d9de2b1b]

 With other words C with every throttle move C the blades will always

 travel to one of the endstops?

 [/quote:e2d9de2b1b]

 Of course not C where you did invent that idea now? 

 

 The controlers task is to keep the rpm as instructed.

 It will move the blades until that selected rpm is reached.

 If you would nearly close the throttle it will never reach that rpm C and the fine endstop comes into play to prevent the blades from moving into an unflyable position. Still C even with disabled endstops C due spotwelded contacs C short-circuited diode ect C adding power would increase rpm and the blades would return to a normal pitch. You would never notice what happened. Unless C that underrated pitch motor C which had been struggling hard to turn to negative pitch C now has to struggle again to positive pitch under full load and decides that enough is enough. It burns C blowing the CB. 

 [quote:e2d9de2b1b]

 If this is the case C I can understand how a failed endstop immediately

 caused the blades to travel to a non flyable position.

 [/quote:e2d9de2b1b]

 No you don't 

 [quote:e2d9de2b1b]

 As I'm technically handicapped C I picture the working of the prop and

 controller as follows:

 Say you fly at 100 knots C and the controller has adjusted the rpm C as

 you have demanded C to 5000 rpm. Now C if you reduce throttle slightly C

 the controller reduces the pitch somewhat *without fully traveling to

 the end stop* C measure the rpm again C evaluate if still below the target

 rpm C reducing the pitch a little bit more C evaluate again C and stop when

 the engine again is at 5000 rpm. The end switch has not been used in

 this scenario C because the prop went never to its finest position in the

 first place.[/quote:e2d9de2b1b]

 

 Correct.

 [quote:e2d9de2b1b]

 Even with the end switches shorted C you won't notice anything.

 

 Until something else goes wrong...

 [/quote:e2d9de2b1b]

 Like closing the throttle a little bit more.

 [quote:e2d9de2b1b]

 For a failure C you need an additional factor C something that tries to

 move the blades to an even finer pitch *while the rpm is already above

 its target*.

 [/quote:e2d9de2b1b]

 No you don't Just closing the throttle is enough to hang you life on the proper functioning of the fine end stop. 

 [quote:e2d9de2b1b]

 I'm still looking for a scenario where the rpm can rise to 6200 rpm C the

 blades are in super fine C and something is feeding power to the pitch

 motor to move the blades even further. What is this "something". Once

 [/quote:e2d9de2b1b]

 What about opening the thottle to full power because you are low and slow?

 [quote:e2d9de2b1b]

 again: even with all micro-switches shorted C the pitch motor won't run C

 because power is fed only to these switches if something (the

 controller C the reverse pitch relay) is sending power to the pitch motor

 with the purpose of reducing the pitch. The end switches won't see any

 power C shorted or not C unless something tries to move the pitch motor

 even further.

 [/quote:e2d9de2b1b]

 There is no such thing as a reverse pitch relay. 

 [quote:e2d9de2b1b]It will keep reducing the pitch at any further

 reducing of throttle C to keep up the RPM.

 [/quote:e2d9de2b1b]

 [quote:e2d9de2b1b]Past the desired RPM?

 [/quote:e2d9de2b1b]

 Again C stage one: I did explain now how the pitch can turn into fine or negative on any Woodcomp SR 3000 with broken fine endswitches. 

 Stage two: If the pitch moter burns at that critical point C it can't do anything to prevent to go past the desired rpm. 

 

 [quote:e2d9de2b1b]

 Let me spell it out: In a normal situation C when powering back from

 take-off power to cruise power C the end/stops/limit switches never come

 into play C because the controller cuts the power to the pitch motor long

 before the fully finest position is reached.

 [/quote:e2d9de2b1b]

 Correct C partly. 

 [quote:e2d9de2b1b]

 In order for the limit switches to show their failure C something has to

 keep sending power to the prop circuit C now putting all bets on the

 limit switches to prevent the prop from going past fully fine. Once

 again: I think it is not common practice to cruise along with the prop

 in fully fine C so the end switches should never have been exercised. But

 something tried to move the blades to fully fine C and apparently even

 past fully fine.

 [/quote:e2d9de2b1b]

 You get the picture.

 Just reducing the power under the power needed for the engine to keep the desired rpm will make the conmtroller send more "fine" power into the pitch motor.

 [quote:e2d9de2b1b]

 Now C as I studied the schematics C there are only two power sources for

 the prop pitch motor: the controller C and the reverse circuitry. One of

 these circuits had to be inadvertently sending power to the pitch motor C

 while the rpm was already way up.

 [/quote:e2d9de2b1b]

 Wrong C you mixing up stage one C how to get the blades over fine pitch C with stage two C having burnt the pitch motor. The rpm will not go up C will never reach desired rpm unless there is enough power added. Adding power C burning the motor then will overrun the engine. 

 [quote:e2d9de2b1b]

 By definition C the reverse circuitry has to bypass the microswitches C

 because its purpose is to intentionally move the blades past fully fine.

 That makes the reverse circuitry suspect number one.

 If I then read that you have modified the reverse circuit C it is not

 difficult to start to wonder if this has had something to do with it.

 [/quote:e2d9de2b1b]

 Wrong again. The reverse circuitry uses it's own slipring C and has nothing to do with the fine pitch microswitches. By the way C the diode is there to return power to the pitch motor with opened micro switches. Not intended nor rated for spark killing. 

 

 [quote:e2d9de2b1b]

 If I recall correctly: on the Woodcomp there is a third slip ring C for

 adding power to move the prop beyond its normal flying operating range.

 This is used for reverse C or feathering. You need to put power on this

 ring to feather or go to reverse.

 This third ring is not connected to the controller C so the controller is

 no longer suspect here.

 Normally you put power on this third ring with a safety latched switch.

 It appears from your message that you replaced the function of this

 switch by a relay.

 [/quote:e2d9de2b1b] 

 I told you that the reverse circuit was switched off C no power C no relay power C powerless C cold not doing anything C dead C not working C not operating. Safety latched. It's just not possible for circuits to operate without power. Not in this world anyhow. I also explained how the pitch ended up super fine. I also explained why the pitch could not return to normal. Most probably you don't want to understand the facts C it is much easier to cap your ears. 

 

 Last advice:

 Find an SR 3000 and have a good look at the components. Google the specifications of those life critical parts. Poor water over these microswitches. Run then pitch motor up and down for an hour or so while restricting the blade movement. But on the ground please!

 

 Regards C

 

 Jos Okhuijsen

 

 

 

 

 

 

 Visit - www.EuropaOwners.org

 

 

 

 

 

&gt=======================
	


&g=======

[quote] 

 

 

   	  Quote: 	
		  [b]

stephan(at)scassel.se
Guest

Posted: Fri Mar 20, 2009 3:00 am Post subject: Woodcomp Propellers

Hi



I have read the thread with great interest and I think I need to add some

“facts”. Some already stated by Jos and

Frans.



I have used WoodComp SR2000 for three years with 100% success so far. Also

vent to WoodComp

for a two days course in order to conduct service and get a better

understanding.

It was very interesting indeed.



The quality of the different propeller parts is very good. I was allowed

to put one SR2000 and one SR3000

together. Supervised of course 



Here goes my list of remarks



1.

WoodComp makes good propellers. Propellers installed on many

ultralights/experimentals with success



2.

SR2000 end stop is better then SR3000. More ruggedized. The micro switch

used on SR3000 is not the very best.

I was a bit surprised when I first saw them



3.

SR2000 has push-rods instead of gear in order to change pitch. That means

that the SR2000 can not move to superfine.



4.

When you throttle back in order to enter the landing pattern for example,

the RPM will drop as soon as the end stop has been reached as explained by

Jos



5.

Normally you do not throttle back as much as Jos did in cruise but that

was due the fact the controllers settings was wrong.



6.

The end-stop should not normally be reached turning from climb- to

cruise-regime as Frans explained

My conclusion:



End stop that works is mandatory. SR3000’s micro switch is not the very best,



Jos reaction was human. He throttle back due the MAP reading.



Frans is correct the end stop was not the start of the event chain. The

incorrect setting seems to start the situation.

With a working end stop this sad accident would probably not happend



If the propeller goes “wild” or wrong setting: TURN OVER TO MANUAL. Use

manual now and then in order get used.

Drill this as much you simulate engine failure: Turn electric pump on

switch to reserve tank



One other thing worth mentioning here:

Set the HYSTERESIS regime to 100 (WoodComp recommendation)

That means that the regulator does not trigger the servo for minor changes

in prop-speed (rpm)

If the prop speed (rpm)  drops let say 70 rpm, the servo will stay

passive. This saves the servo and the mechanics evidently

Best regards



Stephan Cassel

LN-STE Mono – 140 hours

davidjoyce(at)doctors.org
Guest

Posted: Wed Mar 25, 2009 7:47 am Post subject: Woodcomp Propellers

I am slightly reluctant to restart this thread, but Woodcomp have just sent 

me a list of comments and corrections to some of the statements produced in 

the last two weeks:

1) All Woodcomp VP props have mechanical stops as well as electrical stops. 

For normal props these mechanical stops are at the fine & course limits, but 

for reversible props a fine limit mechanical stop is not possible. Instead 

there is a mechanical stop at the end of the reverse range, and similar 

arrangements apply to the feathering prop.

2) The electric motor of the SR3000 is supplied by Bosch and rated at 12 

volts

3) The microswitches are manufactured by Matsuschita and are rated at 16 

amps and the diodes are rated at 5 amps. The usual working current through 

the motor is 4-5amps, but this current only flows through the diodes for 

0.2-=0.3 secs

4) The microswitches at the fine pitch stop are connected in series and 

activating either one cuts the current through the normal range circuit 

operating through the outer and middle rings. They state that the only way 

to overwhelm the fine stop system and to proceed to superfine pitch is to 

apply a voltage to the reverse system, operating through the outer and inner 

pick up rings, and they do not know of any mechanical or electrical failure 

in their systems which could cause this.

           I have no financial interest in Woodcomp, but as the first person 

to get a Woodcomp prop accepted by the PFA, have become someone they talk to 

in the UK!

          Regards, David Joyce, G-XSDJ

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