HK550GT Fly-Bar & Belt Drive Build - RC Groups
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Oct 01, 2012, 12:41 AM
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Build Log

HK550GT Fly-Bar & Belt Drive Build

So... here it is. I know there is a few builds going around on the HK550gt, but I thought I would do a little more in depth with the packaging, quality of the parts, any assemble issues and fixes with recommended replacement parts I & others used. I tend to update this page with new information when I come across them and hopefully we will have some beneficial material for those wanting to build this kit.

This heli will be built for sports flying and I may attempt some basic 3D moves if my skills allow.

The base of my build will be with the aid of the Align Trex 550E Combo Manual & info from the web.

Please note that this build will take some time to complete, so donít expect this kit to be flying in a month.

The Proposed Parts that will be fitted to my kit;
- 3x TURNIGY 1258TG DIGITAL cyclic servos
- 1x Futaba BLS251 or Align DS620 Digital tail servo
- Align step down Regulator for tail servo (5.1v)
- Hobbyking YEP 100A (2~6S) SBEC Brushless Speed Controller
- T600-1100 - Turnigy T600 Brushless Outrunner for 600 Heli (1100kv)
- Futaba GY-520 Gyro
- 520mm TIG Carbon Fiber Main Blades
- Turnigy 9X8Cv2 Receiver
- Turnigy nano-tech 5000mah 6S 25~50C Lipo Pack

Shipping and Packaging
I bought the kit from HK NSW warehouse on 20/09/2012 and it arrived on my desk on the 24/09/2012. Not bad shipping timeframe for $13.99. Then again I have never had any shipping issues from the NSW warehouse.

The packaging was very good. It was double boxed with bubble wrap protecting the inner main box from moving around. Upon opening the main box I was relieved to see that it was not packed like the current HK500 kits. In fact they have now gone down the same path as the Align kits where Align has 4 parts boxes and here we have 3. Looks very promising so far.

Opening box 550B we had the tail assembly, main gear set, tail stabiliser fins and a bag of misalliance parts which contained a pinion gear with grub screw & motor mount bolts, servo screws & metal servo mounts, main blade holder, flybar paddles, ball-links with nuts & bolts for servos, small bag of kit screws and a few small tie-wraps.

Next box to be open was the no-marked box. This is the longest box of the 3 and would obviously hold all the long bits. Pulling the box out of the main box I was somehow hoping HK would have slipped in a set of main blades in there, but I was sadly disappointed to only have received an alloy tail-boom, CF boom holders & metal mount, a flybar rod, plastic tube for analogue radios, tail control rod & control rod guides and gyro double sided tape.

On first inspection of the bag I did notice that it was deliberately open and stapled closed again. I believe there was an issue with the first batch of kits where some receiving 2 tail control rods and no flybar rod. Good to see HK has fixed this.

Box label 550A was the next to be open. This would be the deciding factor if HK has sorted out their packing issues with damage canopies with the main frame. Unfortunately for me the canopy did not survive the trip to my desk. From looking at the way they pack Box 550A with very minimal packing material and a main head sitting on the canopy, the poor HK canopy didnít stand a chance. HK will really need to look at how they pack this box as there will be a lot of people complaining about damaged canopies. The parts contained in this box where the main frame, main head, canopy & landing gear assemble with a canopy clip and the auto rotation/gyro mount hidden inside the main frame.

So after taking all the bits out and doing a quick inspection I found a few items that were damage. These items were:

Canopy cracked and badly scratched by main head and poor packing.
1 landing gear strut missing feet to hold skid pipe.

With these issues I hope an email to HK can have these items resolved quickly. Ė Will let you know how I go.

Next report will be on the Main Head
Last edited by evltoy; Oct 01, 2012 at 02:19 AM.
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Oct 01, 2012, 12:51 AM
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Another damaged Item

After logging a support call with HK about the damaged items, I decided to still continue with the build. When I did a closer inspection of the other items in the kit I found that the 170T main gear had a crack in it. Ė Oh well, call me unlucky. Here is another damaged item on the list for HK.

So far I have
A canopy
A landing gear
A 170T main gear.

I will get to the build soon I hope.
Oct 01, 2012, 01:51 AM
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Ok. Time to start. With the setbacks behind me I needed to start this project.

First up. Main Head.

Just looking at the head the metal grade looks very good. There are a few marks on the polished areas of the main blade grips, but this will not affect its performance. One thing that might annoy others is how sharp the edges of the blade grips are. Starting to break down the head I found that the person putting these together was placing way too much thread lock on the screws. 90% of the screws needed to be heated up with a hot iron before cracking the HK thread lock. Not doing this can easily have damaged my Hex drivers. The other 10% were finger tight with no thread lock at all.

Pulling the main blade grips off the feathering shaft I found that all washers & thrust bearings were there. The only thing I notice was the thrust bearing cage was on the wrong way. This didnít matter as I needed to pull this apart and pack with grease. Putting back together was easy enough. There is no side play at all while the bearings are silky smooth. I also think these feathering shaft bolts are pretty good and will hold well. One thing is missing though is the dampener sleeve which I will end up installing with new dampeners as the HK once look pretty soft for my likings.

Moving on to the fly-bar area, there is not much to report other then the washers missing on the outside screw which is used to hold the SF mixing arms. I did notice that the HK screws used for the SF arms doesnít have a thread going all the way up to the head and maybe the reason why no washer is needed... who knows. Anyways it didnít affect the bearings as it is extremely smooth. Installing the flybar cage together went well. I did notice that the flybar control rods donít have an offset to keep the linkages nice and vertical to the washout arms.

Linkages Ė Having a look at these and the ones on my HK500, I found that HK are using the HK500 linkages on this kit. The diameter of the linkages in this kit are around 1.6mm. This is on the too little side for me so I will be getting Align SS 2.0mm sets instead.

Working down to the washout base and I found my first set of screws finger tight. Good for me as it was less time on the hot iron. The metal washout base is of good quality and the plastic radius arms and bearings look ok too. But we have hit another snag. There was a reason why the screws were finger tight. Upon assembly of the radius arms to the control arm I found that one radius arm was folding in while I had tighten up the screws. This had also caused the radius arm to lockup. I had switched the radius arms around and the same thing happen to the other radius arm on a particular washout arm. Further inspection and measuring found that one washout arm had a shorter bush insert. The bearings in the radius arms did not sit flush on the bush causing the radius arm to fold when you tighten it up.

Works on the head is now stopped and another part is on the HK support call defect list.

All good still as I can work on the main frame in the mean time.
Last edited by evltoy; Oct 01, 2012 at 02:11 AM.
Oct 01, 2012, 09:50 AM
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Last edited by Dejavu*Xion; Oct 05, 2012 at 01:00 AM.
Oct 07, 2012, 11:07 PM
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main frame section

Here is the low down on the main frame.

The main frame plates are 1.6mm CF. The stamping of these and all other CF parts is the standard HK quality. I had to sand all the edges of each CF part as they were all very sharp.

While stripping down the half assembled frame I notice a few things;

1 – As per expected, only some of the main fame 3Mx6mm screws had thread lock which I just dissolved & clean in rubbing alcohol & ready for fresh lock tight.

2- The bottom plate mounting blocks did not sit well on the main frame side plates. I had to fix this by attacking the side plates with my dermal for a snug fit. By not doing this I found the bottom plate was not sitting level & throwing out the side frames when base was flat on the ground. Also the pan head type screws used on the sides to affix the side plates to the mounting blocks were too big. I found that the head on the screws were hitting the mounts and preventing the screws from locking down the side plates. I had to use the dermal again and grind back the mounting bock tabs to allow the pan heads to screw all the way in. A minor fix, but a fix nevertheless. Another way to fix this is to either buy the metal HK base plate with new type screws or buy the Align main frame screw set.

3- The metal battery tray has a slight bend in it due to the stamping of the inside slots. I can see that down the track I may have an issue with the lipo not sitting 100% flat with the look and loop tape. Not sure why HK has put slots in the tray as there is now less contact area when you apply the hook & loop tape. Also the screws for the tray are smaller then the 3Mx6mm screws used throughout the main frame.

4- You only receive 1 RX/gyro CF mount. For some people this might be ok, but if you like to hide/protect all your components you will need to buy another one. I found that the mount is somewhat loose when fitted into the main frame and don’t recommend putting your gyro on it as the plate moves around and can attract vibration. Best way to solve this is to buy the metal RX/gyro tray and screw it into the main frame.

5 – I have had another faulty part come up on me. This time it was the bottom main bearing & bearing block for the main shaft. Looking at the bearing you can see that it has been pressed into a bearing block that is not 100% round. The bearing is slightly ovaled and causing the race to bind up in 90% of its rotation. So main block and bearing is now another item on the HK support faulty list  The other bearing is very smooth like butter.

6- The internal tail servo mount is pretty cool. The milling & finishing on the part is very clean. When installed the mount doesn’t sit centre inside the frame.. It sits hard up to one side which I don’t see being an issue. The screws used for the mount are the same size as the battery tray which I don’t like. It would have been nice to see the 3Mx6mm screws used instead.

7- There is no frame mounting blocks in the kit. HK should put these in as they will stiffen up the main frame a lot better. I will have to put this on the list of extra items to buy.

8- The 3Mx6mm screws used throughout the main frame is good as they are a pan head type and cover more surface area. I have not yet damage any heads so far which is also a good thing. Just remember to hot iron any screws with factory glue in them and soak in rubbing alcohol before reusing. The good old tooth brush after a soak seems to remove the old glue too.

So after 1 faulty bearing/bearing block, a quick tinker to the mounting blocks and side plate’s fitment & missing frame mount blocks (I’ll buy from Align) I was pretty happy with the end product of the main frame.

Next up.... tail section.
Last edited by evltoy; Oct 07, 2012 at 11:14 PM.
Oct 08, 2012, 09:08 PM
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So far so good other then the faulty Bearing/block..And damn~~ I think your the most meticulous guy i know when it comes to building a kit. ha ,,this is a good thing.
Oct 08, 2012, 09:29 PM
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I really do want to iron out all potential issues by taking my time... there is no rush here.

My 500 has over 130 flights and still going strong with minimal fuss/failures. I have been very impress with that kit & this one looks to be better besides the unlucky parts I had.

Fingers cross my tail section has no faulty parts
Dec 05, 2012, 02:29 PM
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ATVAlliance's Avatar
Have you finished your 550? Im in the process of building one myself and coincidentally purchased the same Turnigy 1258TG's that you are using for my own build.

With very little information/reviews out there on these servos I thought I would see if you have been flying your 550 and if so how the cyclic servos are holding up.

I had a crash last week with my 500 using Turnigy 930MG's on cyclic and one of them contracted a problem during the flight, causing me to lose elevator control...which resulted ina pretty nasty crash.

Im kind of hesitant to use Turnigy servos it would be nice to see your opinion on the 1258's before I go further with finishing the build since there is very little talk on the interwebs about this particular servo from Turnigy.

I have to say though that they do look really nice and come packaged better than much more expensive servos I have bought from HiTec, JR, Futaba in the past. Nice litte tins...but of course that doesnt mean that they wont have any issues.

Thanks for any input you can give me on them in advance.
Dec 05, 2012, 07:25 PM
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Hi ATVAlliance

This project is taking its time. The kit has been pretty much complete with all the faulty parts replaced with Align. I have yet to buy the electronics for this kit other then the T600 1100kv motor and swaping out my Futaba 520 gyro from the 500.

As far as I know the Turnigy 1258TG's are pretty good. They are still a new item so no long term info is availabe as yet.

With regards to the MG930's... I have 3 in my 500 with only 1 doing a full fail and the others are still going strong with over 150 flights.
Dec 06, 2012, 09:08 AM
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Originally Posted by evltoy
Hi ATVAlliance

This project is taking its time. The kit has been pretty much complete with all the faulty parts replaced with Align. I have yet to buy the electronics for this kit other then the T600 1100kv motor and swaping out my Futaba 520 gyro from the 500.

As far as I know the Turnigy 1258TG's are pretty good. They are still a new item so no long term info is availabe as yet.

With regards to the MG930's... I have 3 in my 500 with only 1 doing a full fail and the others are still going strong with over 150 flights.
I too had some faulty parts with my HK 550GT. My slider control linkage arm was broken and one of my landing skid pipes had a couple crush/ding marks on it. I didnt really notice too much "sharpness" on the edges of the frames but I did notice that most of the head pieces were grinded and had very sharp edges. I could see it slicing some skin if not careful. But I had an Align 550 head that I swapped out directly and am just going to keep the HK head as a spare. The HK swashplate is not as "beefy" as the Align one is...not sure if that will matter...but the Align head is much nicer...but comes with a much higher cost.

Also, the plastic canopy that came with mine is complete garbage. It was smashed and so flimsy I wouldnt ever think of using it. I actually tossed it in the garbage as soon as I unpacked it. I bought an Align blank canopy as I have my own airbrush and vinyl cutting machine to be able to create a custom canopy for it anyway. But still...I would think they could come up with a better canopy and still keep the price reasonable. I only paid 15 dollars for the actual Align blank white canopy and its fiberglass and really nice. The custom paint will finish it off.

All in all I am happy with the quality of my 550, but it is the first HK heli I have 500 and 450 are EXI and they seem to be much better "quality wise" in what you get out of the box. I never had to replace anything on the EXI kits...but EXI doesnt make a here I am. I also have a CopterX 250 and its quality is on par with EXI or maybe a tad better.

Im not bashing the 550 at all...just wish that I didnt have to fool with having a few issues right out of the box is all. The tail pitch slider linkage arm will be replaced with a metal Align one. And the skid pipes as well. I'll probably buy some Gorilla landing gear as well since they made me a believer of them after crashing my 500 with them on it last week. They didnt break! First crash Ive had that I didnt take out at least one of the landing gears. lol

I wish I had good luck with the 930's as you have. I only had maybe no more than two dozen flights on them when the elevator cyclic servo lost its control to keep centered. This resulted in the heli taking off forward and looping to inverted right as I was trying to land. Luckily for me and any bystanders it went forward instead of back...I got off very lucky.

I just bought 3 Align DS510's to replace the 930's with. And now that I had a horrifying experience with the 930's, Im second guessing my purchase of the 1258TG's. Its one thing to crash because of dumbthumbs or lack of skill...but crashing because of faulty hardware/electronics just plain and simply..."SUCKS"!! lol

I'll keep an eye on this thread and look forward to us comparing notes on our 550's. Ive really anticipated owning one since my Raptor 50 is the biggest heli I own and I really love the heli...just dont care for having to pay 32 bucks a gallon for fuel for it. So I dont fly it much because of that. Otherwise, Id not have bought the 550 and went straight to the 700 instead.

Goodluck with the rest of your build.
Dec 06, 2012, 07:05 PM
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I did very much the same with the servos on the 500. Elevator played up so I bought 2 MG930's and used one to replace the faulty servo. I still have a spare 930 sitting i the box. I few months later I decided to buy some DS510 to replace the 930's. Instead they sat around for 2+ months so then decided to use them in my new 500FBL build.
Dec 06, 2012, 07:22 PM
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An update on the 550 build

Ok. After a few emails to & from with HK, they did recognise the issues I had with my kit and came to the table with a solution that I was very satisfied with. Thank you HK.

Now the only problem I had was I had already bought Align replacements for all the faulty parts in the kit as I wasnít sure what my outcome would have been with HK.

So here are the parts I ended up replacing from the faulty ones in the kit.

Align 700F 3C Landing Skid
Align Main Drive Gear/170T
Align Metal Main shaft Bearing Block
Align Metal washout Control Arm

Here are the parts I replaced after personally thinking the kit ones were inadequate.

Align 500 Carbon Fiber Flybar Paddle
Align 550E Main shaft Set
Align 85 Carbon Fiber Tail Blade
Align Feathering Shaft Sleeve Set
Align Frame mounting bolt
Align Main Shaft Spacer
Align Metal Tail rotor control Arm set
Align Stainless steel Linkage Rod

Tail section next
Dec 10, 2012, 11:57 PM
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* Roll call * I'm still here and taking notes.
Dec 11, 2012, 05:08 PM
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ATVAlliance's Avatar
Mine is coming along. Still need to order a few things though and paint the canopy too. Here is a pic though as it is right now.

Also...did you get the canopy spacers with yours? I either threw them away by accident or this kit just doesnt come with them.

Also...seems like I have about 1mm "play" on my main shaft. Was there a "spacer" that goes between the drive gear and the bearing to take this play out? Maybe another part that got discarded by accident. Or maybe its the difference in an Align shaft and HK shaft (using a complete Align 550 head and shaft). Since these shafts have the collar made to them...there is no way to take up the "play"...why I thought there may be a spacer/washer that I am missing. The "play" is very small...< 1mm if I had to guess. Actually way less than 1mm now that I think about it, but too much to fly it IMO.

I should probably download the manual. Havent really needed it as this heli sets up just like all of my other Trex/Clone helis.
Dec 11, 2012, 05:16 PM
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evltoy's Avatar
Hey ATVAlliance

Build looks like its coming together well.

If you are using the Align 550 main shaft you will also need the Align Main Shaft Spacer to shim out that play you have.

Part number:
What you get:
Main shaft spacer(0.3) x 2(F10.1xF14x0.3mm)
Main shaft spacer(0.5) x 2(F10.1xF14x0.5mm)

I think I had to use 1 0.3 spacer.


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