Helix maintenance

[jharkin]

There has been a lot of discussion lately about the Helix G700 conversion.. with HelixHeli not cutting kits anymore and talking about a restructuring. My Helix is coming up on 100 flights now so I did a partial tear down for some maintenance. I'll share my observations in th attempt to help folks keep these birds flying in the face of possible part shortages....


First off.. Align parts wear out. Fast.

The clutch:

• A few of us had issues with vibration from the HPI bell, and the solution was to use the Vertigo CNC bell. One problem I found - since the vertigo is a vented bell it coats EVERYTHING inside the frame in carbon dust. See below for some issues this causes with the bearings.

The head:

• All the cyclic ball links are sloppy, so I replaced them all. A couple of them I had already replaced. Figure every hundred flights or so these will need to be swapped.
• The anti-rotation pin had worn down flat spots where it slides in the guide. Replaced.
• The two upper screws that pin the head to the shaft above the jesus bolt where loose. Loctite the #*(&#$ out of these and check/re tighten often.
• I took the grips off to check and re grease the thrust bearings. The bearings are really stuck in there good and I could only get once side apart without heat. I recommend not tearing the grips down unless you have a spare set of bearings on hand. Good news is all the bearings seem fine.
• All the grease on the head axle seems to have dried up so it was a bit tough getting it out of the dampers. Worth checking periodically.

Mainshaft

• The 2 main bearing design is a known Align weakness. There are 3 bearing kits but they wont fix the helix. Instead I used the KDE thrusted bearing blocks. The bearings are holding up better but one problem I ran into is that all that clutch dust gets into the bearings and gunks them up with grit. Definitely plan to take them out, clean and re grease often. I'm thinking every 50 flights or so would be good.
• I took apart the OWB case and re-oiled the sprag with the MA special oil. Sprag looked in good condition.

Tail

• The TT ends area loose fit in the black gears. They are wearing out the x socket into an iron cross shape. I am replacing mine and following a tip to put scotch tape on the TT end until the fit is snug. Definitely check these - they will probably fail eventually.

• I took the tail grips apart. Thrust bearings where completely dry and dirty so I cleaned everything and re-greased. Otherwise it looks in good shape.
• I'm also trying a set of the $6 blade clips to see if it makes a difference in the vibes and tail hums. Other helifreakers have claimed a significant improvement. I noted that you have to sand them down quite a bit or the blades are VERY stiff in lead/lag.

Fuel tank.

• Still swollen but does not seem to have gotten any worse ince I opened up the frames last year. I was considering a swap but left it alone. These are getting hard to find so think carefully before you swap.

Landing Gear

• Another problem I have is that doing a lot of autos often snaps the screws off that hold on the skids. Then you have to pull the mounting blocks and use a dremel to slot out and remove the stubs.
• Problem is that it looks like those blocks are now out of production! After a lot of searching I found a vendor that still had a set of the KDE upgrade blocks (also out of production). These use a captive nylock to hold the screw on so no slotting if you break one. If you can find a set, grab it.

Gyro

• A while back I tossed the rubber isolaters and hard mounted the rear gyro plate. The BD3sx is much happier this way - cyclic response is faster and stops are more precise. Defiantly hard mount it if you run a BD.
• I also updated my BD firmware from 2.01 to 2.03. Haven't flown it yet to see any differences.

Align parts.
Here is the big problem. Its not just HelixHeli parts that may go away, I think Align is finally starting to phase out 700N Pro parts for real. I cant find any landing gear mount blocks and fuel tanks show low stock at most vendors - nothing at all at Aligntrexstore.com. The main gear is another one. I cant find any 115T gears unless you buy it in the HN7021D set. The other thing to be on the lookout for if you have a bad crash is availability of the tail case, frame spacers and E bearing blocks used on the pinion. Everything else - mainshafts, head, tail assembly, etc is all interchangeable to the DFC stuff.


Closing thoughts:

I still love this design in spite of its faults. Its amazingly light (I'm in the high 12s with the genny, lights and a big battery - mid 11s is totally doable). And I love how easy it is to drop and work on the engine. If Helix comes back with designs based on better donors I would still give them consideration.




For reference, my build thread with part #s:
https://www.helifreak.com/showthread.php?t=673185

[rbort]

Some maintenance is normal with machines, hopefully you can keep it going for a while as its a good 2nd gasser for you.

-=>Raja.

[neverhappy]

Nice write up...

After my crash I started the tear down. I noticed that the main shaft bearings were getting bad spots. Ie: jumping and catching. .

This was a used heli that was ready to fly with little air time (as the previous owner say).