I won't be starting back on the plane for another few weeks though as the garage needs sorting out, a good clean and shelving put up.
Wednesday, 26 February 2014
The big move
The worst of my moving is over. One more big weekend to go and it will be done. The Twister looks small now in it's new home.
I won't be starting back on the plane for another few weeks though as the garage needs sorting out, a good clean and shelving put up.
I won't be starting back on the plane for another few weeks though as the garage needs sorting out, a good clean and shelving put up.
Tuesday, 4 February 2014
LAA Safety Spot reports on Twister tailplane failure.
Our LAA magazine has a 'Safety Spot' section - which highlights any issues.
This month the Twister takes centre stage.
The only part of the article I have omitted is Malcolm McBride's letter to us Twister owners - which I already published in an earlier post (so no need to repeat it here).
As you can see the cause has now been identified.
The plastic guide tube was touching the elevator tube (the manual clearly states that it must go underneath the plastic bearing - and not touch the elevator tube).
Over time the movement of the elevator tube has worn through the plastic guide tube (and indeed was wearing into the securing wire itself).
This is what allowed the securing wire to pass outside of the plastic guide tube and over the spigot. Thereby not securing the tailplane to the fuselage.
Glad to hear that the pilot was able to walk away from this one.
The black arrow in Malcom's article (2nd page - middle picture) is not pointing in the right place so I have added a red arrow to show where the plastic guide tube is touching the elevator tube.
Click on the images for a much bigger view.
This month the Twister takes centre stage.
The only part of the article I have omitted is Malcolm McBride's letter to us Twister owners - which I already published in an earlier post (so no need to repeat it here).
As you can see the cause has now been identified.
The plastic guide tube was touching the elevator tube (the manual clearly states that it must go underneath the plastic bearing - and not touch the elevator tube).
Over time the movement of the elevator tube has worn through the plastic guide tube (and indeed was wearing into the securing wire itself).
This is what allowed the securing wire to pass outside of the plastic guide tube and over the spigot. Thereby not securing the tailplane to the fuselage.
Glad to hear that the pilot was able to walk away from this one.
The black arrow in Malcom's article (2nd page - middle picture) is not pointing in the right place so I have added a red arrow to show where the plastic guide tube is touching the elevator tube.
Click on the images for a much bigger view.
Tuesday, 28 January 2014
Twisters over Bahrain
Formally the SWIP team and now sponsored by Huawei.
A great photo of Pete and Guy enjoying themselves in the sun.
A great photo of Pete and Guy enjoying themselves in the sun.
Saturday, 25 January 2014
In-Flight control failure
Hi all, I'm sharing this information with the permission of the LAA.
They sent me a letter regarding a recent disturbing incident of a UK based Twister.
The letter reads:
I am writing to let you know that there has been a serious in-flight control failure involving a Silence Twister and to explain, as far as I'm able, what happened and what you need to do during your pre-flight inspection to ensure that a similar event doesn’t happen again.
The investigation is at a very early stage and discussions haven’t taken place between the aircraft’s kit manufacturer or the UK agent so we’re not sure whether it would be possible for this event to be repeated on other machines; nonetheless, we feel that it is important to act early by letting you know about the incident... ‘just in case’.
The aircraft had been de-rigged to conduct minor maintenance and was subsequently re-rigged by the maintainer for the owner; both the LAA Inspector and the owner conducted a thorough pre-flight inspection, including normal post-rig control checks.
During the post-maintenance test flight, conducted by the owner, an experienced pilot but fairly new to the type, a loud bang was heard and the aircraft simultaneously yawed and rolled to the right.
The pilot was able, just, to keep the aircraft in a relatively level attitude using full opposite rudder and nearly full opposite aileron.
The pilot noted that the aircraft’s rate of decent was ‘quite high’ and application of power didn’t appear to change this very much.
The pilot was wearing a parachute and considered evacuating the aircraft but felt that he was too low for this to be done with any real confidence; he therefore selected a field and conducted a forced landing.
During the subsequent landing the aircraft’s undercarriage gave way and the underside of the aircraft, engine cowling and propellor suffered damage. The pilot was uninjured.
The pilot, having evacuated the aircraft, noted that the starboard tailplane and elevator assembly had rotated on its tubular main spar and was at 90 degrees to the normal airflow. (see pic below).
The aircraft was recovered back to its operating base by road and, on inspection, it was found that the wire securing pin (4800115) had left the side of the plastic guide tube before the end of the tube and hadn’t, therefore, been in a correct position to direct the pin into the securing spigot (480053) thus the tailplane was not mechanically secured to the fuselage before flight. (see pics below of the plastic guide tube and spigot).
It is highly recommended that before you next fly your aircraft that you ensure that the tailplanes are securely locked in place; this can be done by firmly trying to remove the tailplane, it would be appropriate, to be absolutely sure, to engage the services of an assistant to hold the fuselage in place during this process.
One owner has commented that he always checks the pin is actually passing through its plastic guide correctly before finally fitting the tailplane... sounds like good advice.
If, when you check your tailplane’s security, you do find anything amiss please let me know as soon as you are able.
Thank you for your attention to this matter.
Yours Faithfully
Malcolm McBride
Airworthiness Engineer.
LAA
malcolm.mcbride@laa.co.uk
After reading this I sent Malcolm a reply with some pics from this blog of the construction of the securing wire (pin).
See my Week 96 post - to refresh your memory.
I explained the use of a metal bush and how it makes the system flawless - as copied from Pete Wells.
He has since replied back with another letter and says:
"I think this failure was caused because there was a lack of familiarity with the rigging system although the build quality of this particular item wasn't very good".
I have to agree with Malcolm - if you look at the photos below you can see that the plastic guide tube is not completely encapsulated in flock (as per the instructions in the manual). This allowed the plastic guide to move around a bit and also wear out it seems as the wire was able to leave the tube before the end.
Of course the overall message is - don't let someone else rig your plane!
Fly safe everyone.
They sent me a letter regarding a recent disturbing incident of a UK based Twister.
The letter reads:
I am writing to let you know that there has been a serious in-flight control failure involving a Silence Twister and to explain, as far as I'm able, what happened and what you need to do during your pre-flight inspection to ensure that a similar event doesn’t happen again.
The investigation is at a very early stage and discussions haven’t taken place between the aircraft’s kit manufacturer or the UK agent so we’re not sure whether it would be possible for this event to be repeated on other machines; nonetheless, we feel that it is important to act early by letting you know about the incident... ‘just in case’.
The aircraft had been de-rigged to conduct minor maintenance and was subsequently re-rigged by the maintainer for the owner; both the LAA Inspector and the owner conducted a thorough pre-flight inspection, including normal post-rig control checks.
During the post-maintenance test flight, conducted by the owner, an experienced pilot but fairly new to the type, a loud bang was heard and the aircraft simultaneously yawed and rolled to the right.
The pilot was able, just, to keep the aircraft in a relatively level attitude using full opposite rudder and nearly full opposite aileron.
The pilot noted that the aircraft’s rate of decent was ‘quite high’ and application of power didn’t appear to change this very much.
The pilot was wearing a parachute and considered evacuating the aircraft but felt that he was too low for this to be done with any real confidence; he therefore selected a field and conducted a forced landing.
During the subsequent landing the aircraft’s undercarriage gave way and the underside of the aircraft, engine cowling and propellor suffered damage. The pilot was uninjured.
The pilot, having evacuated the aircraft, noted that the starboard tailplane and elevator assembly had rotated on its tubular main spar and was at 90 degrees to the normal airflow. (see pic below).
The aircraft was recovered back to its operating base by road and, on inspection, it was found that the wire securing pin (4800115) had left the side of the plastic guide tube before the end of the tube and hadn’t, therefore, been in a correct position to direct the pin into the securing spigot (480053) thus the tailplane was not mechanically secured to the fuselage before flight. (see pics below of the plastic guide tube and spigot).
It is highly recommended that before you next fly your aircraft that you ensure that the tailplanes are securely locked in place; this can be done by firmly trying to remove the tailplane, it would be appropriate, to be absolutely sure, to engage the services of an assistant to hold the fuselage in place during this process.
One owner has commented that he always checks the pin is actually passing through its plastic guide correctly before finally fitting the tailplane... sounds like good advice.
If, when you check your tailplane’s security, you do find anything amiss please let me know as soon as you are able.
Thank you for your attention to this matter.
Yours Faithfully
Malcolm McBride
Airworthiness Engineer.
LAA
malcolm.mcbride@laa.co.uk
After reading this I sent Malcolm a reply with some pics from this blog of the construction of the securing wire (pin).
See my Week 96 post - to refresh your memory.
I explained the use of a metal bush and how it makes the system flawless - as copied from Pete Wells.
He has since replied back with another letter and says:
"I think this failure was caused because there was a lack of familiarity with the rigging system although the build quality of this particular item wasn't very good".
I have to agree with Malcolm - if you look at the photos below you can see that the plastic guide tube is not completely encapsulated in flock (as per the instructions in the manual). This allowed the plastic guide to move around a bit and also wear out it seems as the wire was able to leave the tube before the end.
Of course the overall message is - don't let someone else rig your plane!
Fly safe everyone.
 |
| Tailplane rotated 90 degrees |
 |
Tuesday, 21 January 2014
New digs
Hello and Happy New Year to all.
Sorry for the big gap in posts but many things are afoot!
I am in the process of letting a new house - outside of London.
The garage is massive compared to my current setup. See pic below (my existing garage space is shown in grey).
As you can see I will now be able to complete the firewall forward work. Also there is a big space outside, so on a nice day I can even wheel out into the sunshine and fit the wings. So I'll be able to complete those jobs that have evaded me to date due to space restrictions.
I hope to be all moved in within a month or two, so there will most likely be another big gap between posts while this happens and I set up my new workshop.
Then it should be full steam ahead!
Sorry for the big gap in posts but many things are afoot!
I am in the process of letting a new house - outside of London.
The garage is massive compared to my current setup. See pic below (my existing garage space is shown in grey).
As you can see I will now be able to complete the firewall forward work. Also there is a big space outside, so on a nice day I can even wheel out into the sunshine and fit the wings. So I'll be able to complete those jobs that have evaded me to date due to space restrictions.
I hope to be all moved in within a month or two, so there will most likely be another big gap between posts while this happens and I set up my new workshop.
Then it should be full steam ahead!
Tuesday, 24 December 2013
Week 123 - Wiring
Hours to date: 1222.5
I've been getting on with the wiring, doing what I can before the painting of the cockpit.
I have painted the fuse box holder - the outside can be painted later to match the cockpit but I am happy for the inside just to be grey primer.
I've also fitted some brushes to the throttle/brake assembly hole so that no foreign objects can find their way down there. I just cut-down a door draft excluder that I bought from a local hardware shop. Seems to work pretty well.
As you will see below I've also decided to fit some switch guards to the outer ends of the bank of switches. They are made from stainless and will prevent any inadvertent switch throwing by a trouser leg catching on the outer switches.
The ammeter shunt and it's cover are all done. Just have to wire them up now.
An update with the wheels and brakes. After contacting the factory to clarify, the axles do indeed need an 8mm thread cutting into them. As I have the fixed gear I should have used a 6mm bolt through the gear leg, axle and brake (rather than the 8mm one I used). It's no great harm done to use the 8mm in my opinion.
As you can see the brake needs to be aligned with the gear leg - 120 degrees - then drilled through the 8mm hole (6 if you're doing it right!). Then I put a short 8mm bolt through the axle and brake and tightened that up to hold it in place while I drilled out the three 6mm holes into the brake.
I'm off on holiday for 2 weeks tomorrow (my first holiday since starting the kit) so there won't be another blog update for about 3 weeks.
I'm off to the Yucatan peninsula for some sun and snorkelling plus a trip to several Mayan ruins.
See you in the New Year.
I've been getting on with the wiring, doing what I can before the painting of the cockpit.
I have painted the fuse box holder - the outside can be painted later to match the cockpit but I am happy for the inside just to be grey primer.
I've also fitted some brushes to the throttle/brake assembly hole so that no foreign objects can find their way down there. I just cut-down a door draft excluder that I bought from a local hardware shop. Seems to work pretty well.
As you will see below I've also decided to fit some switch guards to the outer ends of the bank of switches. They are made from stainless and will prevent any inadvertent switch throwing by a trouser leg catching on the outer switches.
The ammeter shunt and it's cover are all done. Just have to wire them up now.
An update with the wheels and brakes. After contacting the factory to clarify, the axles do indeed need an 8mm thread cutting into them. As I have the fixed gear I should have used a 6mm bolt through the gear leg, axle and brake (rather than the 8mm one I used). It's no great harm done to use the 8mm in my opinion.
As you can see the brake needs to be aligned with the gear leg - 120 degrees - then drilled through the 8mm hole (6 if you're doing it right!). Then I put a short 8mm bolt through the axle and brake and tightened that up to hold it in place while I drilled out the three 6mm holes into the brake.
I'm off on holiday for 2 weeks tomorrow (my first holiday since starting the kit) so there won't be another blog update for about 3 weeks.
I'm off to the Yucatan peninsula for some sun and snorkelling plus a trip to several Mayan ruins.
See you in the New Year.
 |
| Ammeter shunt with it's cover in place |
 |
| Lining up the brake with the gear leg - 120 degrees |
 |
| Clamping the brake before drilling through the 8mm hole. |
 |
| Short 8mm bolt through the axle and brake before drilling out the x3 6mm holes |
 |
| Brushes for the throttle/brake assembly hole |
 |
| Fuse box holder all painted up with primer |
 |
| Brushes flocked in place |
 |
| Switch guards at either end. |
 |
| Getting some wiring done ahead of time |
Thursday, 19 December 2013
Load sheet and laziness
It's been a very lazy few weeks for me on the kit.
I've not been in the garage for 3 weekends now. A combination of being very busy at work and also feeling like I needed a break.
But I have been organizing the electrics - buying parts etc.
One of the things I've been meaning to do for a while but didnt get around to was putting together a Load sheet - for the electrics.
A guideline is to use no more than 80% of your alternators output.
As you will see below from my load sheet I am right on 80% with my total - although this is a theoretical maximum rather than a practical one.
I won't ever be using the starter while transmitting on the radio and lowering the flaps all at the same time.
Even the continuous figure I give is a theoretical Max rather than practical.
I'm also updating my main power wiring diagram and will upload that soon.
I've not been in the garage for 3 weekends now. A combination of being very busy at work and also feeling like I needed a break.
But I have been organizing the electrics - buying parts etc.
One of the things I've been meaning to do for a while but didnt get around to was putting together a Load sheet - for the electrics.
A guideline is to use no more than 80% of your alternators output.
As you will see below from my load sheet I am right on 80% with my total - although this is a theoretical maximum rather than a practical one.
I won't ever be using the starter while transmitting on the radio and lowering the flaps all at the same time.
Even the continuous figure I give is a theoretical Max rather than practical.
I'm also updating my main power wiring diagram and will upload that soon.
Tuesday, 26 November 2013
Week 119 - Wheels and brakes
Hours to date: 1211.5
Onto the wheels and brakes now.
There seems to be some discrepancies in the manual - which has confused me a bit.
Also because I am going for the fixed gear then the section 3 - fuselage - part of the manual talks about doing one thing and then section 8 - Fixed gear - talks about another.
Neither of them seem to make perfect sense.
I've followed what Pete does with the brakes - M6, 20mm screws with Nylocks on the outside. Section 3 of the manual talks about M6 10mm screws - but these would not go through the axle flange and brake (which combined are about 11mm) let alone give enough thread for a nut and washer on the outside.
Note that I've needed to very slightly grind away a 'wedge' on the gear leg to allow the brake to sit fully against the gear leg - we are only talking about 1-2mm here - see photo below.
I've also used an M8 bolt to secure the axle and brake to the gear leg. Section 8 talks about using an M6 bolt - but then says to put an M8 nut on the end of it! So that's clearly an error. Also the stated M6 bolt (55mm) was not included in my kit.
Here's where it gets complicated...
So after fitting the brake and wheel (which is partially held on by the brake disc rotor - which must be bolted to the wheel after putting inside the brake pads) I thought I would go ahead and see how the wheel spat is fitted.
After quite a bit of head scratching it seemed to be that the ali bracket which attaches to the gear leg has 1. An M6 hole where my M8 bolt is and 2. An M8 hole where the centre of the axle is. This would indicate that I need to put an M8 bolt through into the axle - but as you will see below the axle does not have thread on the inside.
I see on the French Twister they ended up flipping the bracket up the other way and then drilling another hole through the M6 hole in the bracket - right through the gear leg and securing it that way. Then after that they still went back and made a thread in the axle and fitted another large washer and M8 bolt through that to secure the axle.
I am hoping to be able to not have to do that.
I would like to use the existing bracket - but if it means making up a new one - then so be it.
I've also included a photo of what Pete does at the bottom - this is not in the manual - so is another of his mods. Seems to make sense though - the one M8 bolt does not seem enough to hold the axle onto the gear leg.
To be continued...
Onto the wheels and brakes now.
There seems to be some discrepancies in the manual - which has confused me a bit.
Also because I am going for the fixed gear then the section 3 - fuselage - part of the manual talks about doing one thing and then section 8 - Fixed gear - talks about another.
Neither of them seem to make perfect sense.
I've followed what Pete does with the brakes - M6, 20mm screws with Nylocks on the outside. Section 3 of the manual talks about M6 10mm screws - but these would not go through the axle flange and brake (which combined are about 11mm) let alone give enough thread for a nut and washer on the outside.
Note that I've needed to very slightly grind away a 'wedge' on the gear leg to allow the brake to sit fully against the gear leg - we are only talking about 1-2mm here - see photo below.
I've also used an M8 bolt to secure the axle and brake to the gear leg. Section 8 talks about using an M6 bolt - but then says to put an M8 nut on the end of it! So that's clearly an error. Also the stated M6 bolt (55mm) was not included in my kit.
Here's where it gets complicated...
So after fitting the brake and wheel (which is partially held on by the brake disc rotor - which must be bolted to the wheel after putting inside the brake pads) I thought I would go ahead and see how the wheel spat is fitted.
After quite a bit of head scratching it seemed to be that the ali bracket which attaches to the gear leg has 1. An M6 hole where my M8 bolt is and 2. An M8 hole where the centre of the axle is. This would indicate that I need to put an M8 bolt through into the axle - but as you will see below the axle does not have thread on the inside.
I see on the French Twister they ended up flipping the bracket up the other way and then drilling another hole through the M6 hole in the bracket - right through the gear leg and securing it that way. Then after that they still went back and made a thread in the axle and fitted another large washer and M8 bolt through that to secure the axle.
I am hoping to be able to not have to do that.
I would like to use the existing bracket - but if it means making up a new one - then so be it.
I've also included a photo of what Pete does at the bottom - this is not in the manual - so is another of his mods. Seems to make sense though - the one M8 bolt does not seem enough to hold the axle onto the gear leg.
To be continued...
 |
| Brake from the outside |
 |
| Brake from the inside - angled 120 degrees from black line. |
 |
| Small wedge that needs cutting into gear leg for brake to sit flush |
 |
| Wheel in place |
 |
| Brake disc rotor must be put on brake first then bolted to wheel. |
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| Wheel spat bracket |
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| No thread inside axle... |
 |
| Position of spat bracket from manual |
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| Confusing part of the manual M6 with a M8 nut |
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| Fuselage part of the manual |
 |
| What Pete does... |
Thursday, 21 November 2013
Monday, 18 November 2013
Week 118 - Various
Hours to date: 1200.5
Well Pete has still not made up the canopy parts I need so I've moved onto other jobs.
Kind of a blessing in disguise actually as I am now doing all the little jobs that I've not got around to previously.
The baggage tray is finished - I'm pleased with the way it turned out.
I discussed the throttle/brake assembly with Pete and he agreed it needed more than just flock to hold it in place so I'll put a couple of bolts through there. More worryingly the throttle cable in it's current position would have to go through the spar tunnel (indeed Pete says that what people end up doing - drilling a hole through the spar tunnel). Obviously I am not keen on this idea.
I see the French Twister had the assembly round the other way - so that the throttle is on the outside - this puts the cable in a better position so I will most likely follow suit here.
For such a critical component it seems to have not been thought out properly in the design stage. I'll be spending a bit of time on this as for me the throttle action (and security) must be perfect.
Another thing that Johan pointed out to me is that the throttle friction cannot be adjusted in flight - in fact the access to the friction is only through the bottom of the aircraft via an inspection panel.
For these reasons you can understand why Pete has switched to a vernier type throttle.
Another couple of jobs I did are: Reinforcing the rest of the main gear posts - I'd only done one side before as that was what the manual indicated but I noticed that the French Twister had the whole post reinforced. This doesn't add any weight really so I've done the same. The manual can also be interpreted this way to do this. The other job is making an access panel for the connection of my cowl flap - where access is very limited so it's a bit of a necessity.
I've also installed the radio and transponder antenna cables - these follow the route of the rudder cable guides. This job is great way to take all the skin off your knuckles!
I determined the position of the flap drive 'box' and have used the composite fasteners I got from Germany to put in some mounting posts for this. They are stuck on with flock and I put a single layer of glass over the top as Pete does (although the fastener manufacturer says that flock alone is enough).
Next up is the ammeter shunt - see photo below for location. I'm making a cover for this as well - the ammeter shunt carries the same charge as the terminals of the battery so it must never come into contact with anything else. Given this - it's a wonder that they don't supply a cover with them.
Finally I've installed 3 warning lights (red LEDs) into the panel. These are for 1. Starter operating (a UK CAA requirement), 2. ECU fault and 3. Low volts warning (both of which are required for the UL Power engine setup.)
Next up I will work on the main gear and wheels and brakes I think. I'm having a new spacer made up for the hub that is missing one (!) by my friend in New Zealand - Peter Boettcher - Thanks Peter!
Well Pete has still not made up the canopy parts I need so I've moved onto other jobs.
Kind of a blessing in disguise actually as I am now doing all the little jobs that I've not got around to previously.
The baggage tray is finished - I'm pleased with the way it turned out.
I discussed the throttle/brake assembly with Pete and he agreed it needed more than just flock to hold it in place so I'll put a couple of bolts through there. More worryingly the throttle cable in it's current position would have to go through the spar tunnel (indeed Pete says that what people end up doing - drilling a hole through the spar tunnel). Obviously I am not keen on this idea.
I see the French Twister had the assembly round the other way - so that the throttle is on the outside - this puts the cable in a better position so I will most likely follow suit here.
For such a critical component it seems to have not been thought out properly in the design stage. I'll be spending a bit of time on this as for me the throttle action (and security) must be perfect.
Another thing that Johan pointed out to me is that the throttle friction cannot be adjusted in flight - in fact the access to the friction is only through the bottom of the aircraft via an inspection panel.
For these reasons you can understand why Pete has switched to a vernier type throttle.
Another couple of jobs I did are: Reinforcing the rest of the main gear posts - I'd only done one side before as that was what the manual indicated but I noticed that the French Twister had the whole post reinforced. This doesn't add any weight really so I've done the same. The manual can also be interpreted this way to do this. The other job is making an access panel for the connection of my cowl flap - where access is very limited so it's a bit of a necessity.
I've also installed the radio and transponder antenna cables - these follow the route of the rudder cable guides. This job is great way to take all the skin off your knuckles!
I determined the position of the flap drive 'box' and have used the composite fasteners I got from Germany to put in some mounting posts for this. They are stuck on with flock and I put a single layer of glass over the top as Pete does (although the fastener manufacturer says that flock alone is enough).
Next up is the ammeter shunt - see photo below for location. I'm making a cover for this as well - the ammeter shunt carries the same charge as the terminals of the battery so it must never come into contact with anything else. Given this - it's a wonder that they don't supply a cover with them.
Finally I've installed 3 warning lights (red LEDs) into the panel. These are for 1. Starter operating (a UK CAA requirement), 2. ECU fault and 3. Low volts warning (both of which are required for the UL Power engine setup.)
Next up I will work on the main gear and wheels and brakes I think. I'm having a new spacer made up for the hub that is missing one (!) by my friend in New Zealand - Peter Boettcher - Thanks Peter!
 |
| Baggage tray all done |
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| Carbon tabs on the side fixes it nicely in place |
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| Throttle cable position - red line indicates current position |
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| Front of throttle assembly - not much room before spar tunnel |
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| Access panel for cowl flap connection |
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| Carbon reinforcement around main gear post |
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| Flap 'box' mounting posts |
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| Radio and Transponder antenna cables |
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| Ammeter shunt location |
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| 3 Red LED warning lights added to panel |
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