Author Topic: S/N 1423  (Read 682 times)


S/N 1423
« on: December 29, 2020, 11:02:09 AM »
Hello, Helio community!
I read this site since 2013 and got a lot of useful information.
I purchased H-295 S/N 1423 in 2013. Previously the plane was registered as C-FXQY and based around Ontario. Currently the plane is based in Russia. I haven’t got big experience with this plane, because soon after purchasing it was necessary for me to go to another country to work (to fly). I flew about twenty hours in 2014 and since that time the plane on storage in hangar. The engine was fulfilled with oil to prevent corrosion. I still have a plan to make some modifications and fly that plane. I will highly appreciate your informational support!
May I ask you my questions?
1. I have a 60 gallons wings fuel tanks. Is it possible to modify to 120 gallons without changing the wings?
2. I am a bit concerned about wings attachment and carrythrough. How are this parts reliable? I read that it were some issues with five planes. How is it possible to check this parts? Should upper attachment bolts been changed periodically?
3. I also have questions about vertical stabiliser attachment and stabilator attachment. As I understand, there’s only three not big bolts serves as vertical stabiliser attachment. And consequently that bolts carry forces from stabilator. How is this part of plane reliable? And how is reliability of stabilator hinges?
4. One more question about engine. My engine has about 700 hours since overhaul. But, probably, due to long time not running it should be overhauled. Is it real to make it now?

Thank you in advance!
Best regards,


Re: S/N 1423
« Reply #1 on: December 30, 2020, 10:20:44 AM »
I would surely give a try with the engine without overall it.  Check the compression, check for metal in the screen.  If there is not, you are good.  The metal will tell you if the transmission ( reducer) is sound.  They are supposed to be fragile engine.  Depends how you treat them.  CHANGE THE OIL !!!.  Look at the oil you put in a car transmission.  Very very thicker than the engine.  The pressure between the teeth of the gears are tremendous.  A lot more than pressure in cams or bearing of the crankshaft.  So in a transmission, the oil have to be very thick.  Not fluid.  So there is always some oil between the teeth of the gears.  In our Helio engine, the engine and the transmission share the same oil that is formulated for an engine.  If we wait 50 hours to change the oil, that will be the second 25 hours running the transmission with an oil that is more like water that the syrup it should be for a transmission.  So these engine will be grateful if we change your oil past 22 hours.  With the right oil.  As thick as our weather permit.  With the little "plus" sign on the label that was developed for high torque engine.

After that, we can try not to induced vibration by cutting the power too fast and have the power reverse to the prop driving the engine instead of the contrary. 

Check your oil pressure.  If it is good, you have a good chance to skip the overall.  You can also crank the oil pressure to it's maximum permitted. 

To do an overall is not a quick affair.  You have to take six months to find all the parts.  If you don't do it, they will open the engine, check everything, and rebuild it with your old parts. We prefer to take our time and have all new parts before going to the overall.



Re: S/N 1423
« Reply #2 on: December 30, 2020, 10:24:39 AM »
For the stabilisator, i think it is very reliable.  With a lot of pre-sign before being dangerous.  What i saw, but i am no mechanic, is the small ball bearing becoming loose in their bracket.  But it is still be safe and easily replaced.  I would not be afraid of this end of the Helio.  But there is here on this website people that knows a magnitude more than me on the stab.



Re: S/N 1423
« Reply #3 on: December 30, 2020, 11:24:12 AM »
Thank you! Advisory about the oil is useful!
The engine was in good condition with compression 78-80, but I am worried about corrosion, especially camshaft corrosion.



Re: S/N 1423
« Reply #4 on: December 30, 2020, 11:56:03 AM »
Wings attachment and carrythrough.  That is a subject....   If you do fear about those, you can have them checked with some X-rays machine.  They called that Eddy Current inspection.  It can detect small crack in the metal before it becomes a danger.

It is not really the bolt the danger.  It does work on the shear side.  Strong.  The carry trough inside the cabin is bomb proof since we had to put the extra straps for the 3800 pounds increase. 

Talking about changing from 60 gallons to 120 gallons, i think i saw longer spar pickup part on the 120.  Not sure if it was for 60 to 120 gallos or if it was for a higher gross weight.  The less long pickup was on a 60 gallons -250 planes.  And the wing was changed for 120 gallons. They did change for a longer pickup part.  Did they change other thing like the skin or the spar ?  I don't know.  They did some metal work to install the second outside fuel tank.
So if you go from 60 to 120, i am quite sure you need the longer pickup.  May be you already have them on the 60 gallons, may be not.  Others here will know better than me what is involved in the modification. 

Fuel setup should straight forward on the fuselage side since the outside tank is pumped to the inside in the civil version.  Probably that only the fuel gage have to be change on the fuselage side.  Plus the wiring for the two pumps.

Quite a project !!



Re: S/N 1423
« Reply #5 on: December 31, 2020, 01:15:39 AM »
Thank you, Louis!
What is a spar pickup part? How does it look?


Re: S/N 1423
« Reply #6 on: December 31, 2020, 09:04:33 AM »
Good morning, Evgenii. I've been working on and refurbishing Helios since about 1973. I don't fly them, but I'm quite familiar with the skins and rivets, parts and pieces!

It isn't practical to convert wings to 120 gallon wings.
1. The rear spar is different as the 120 gallon wings use a 3 piece spar that is much longer going out to the aileron rib.
2. The outboard tank bay requires a formed doubler on top with tank hangars replacing wing ribs.
3. There is also a required liner on the bottom that is not present on the 60 gallon wings.
4. Of course plumbing, pumps etc. would be needed but these items are the least difficult to handle.

The carry-thru isn't a huge concern assuming the aircraft has the long straps required by the AD issued in 1982. The long straps have nothing to do with the 3800 lb. gross weight STC. They are required by the AD. Corrosion would be the major concern for the bolts, fittings and carrythru structure. You didn't indicate whether the aircraft has been inside or outside as that will make a difference. If water has gotten into the top cross tube, corrosion is probable. Remove the small covers at the upper attach points and check for water/corrosion in that area. The lower wing fittings are also steel and should not have a lot of corrosion.

The tail is surprisingly stout even though there doesn't seem to be much holding it together. I've never known of the vertical, rudder or stabilator to come off and the attachments generally survive an accident with little damage. The main issue I've seen is cracking on the main spar of the stabilator. By gently lifting up and down at the tips of the stabilator you can hear creaking of the spar if it is cracked. This is especially the case if the aircraft has been operated a lot on rough strips.

Your concern for corrosion on the engine camshaft and lifters is legitimate. You won't see immediate problems but if there is corrosion, they will eat themselves up. Corrosion on the cylinder barrels is also likely as oil in the engine, even full will not generally reach the top of the cylinders. A borescope will determine cylinder condition. If you want to check the camshaft and lifters, the front portion can be looked at by removing the nosecase assembly and looking through holes in the front of the case with a borescope. Otherwise, cylinders will have to be removed to determine any corrosion issues. It is also likely that the carburetor will give you grief since the diaphragms will have been sitting dry or at least unused for so long. Check you air intake filter. You don't want to suck in pieces of a stiff hard filter. Magnetos would also be of some concern. The bearings don't like to sit for long periods and they would be worth removing for overhaul.

If the aircraft has been sitting outside, the propeller would also be a major concern for corrosion.

Check all your hoses as they shouldn't be hard and stiff. You don't want your hoses leaking, especially fuel and oil.

You might find your bladder fuel tanks leak after sitting so long. A fill up will tell you the answer to that.

Jim Metzler

Doug Johnson

Re: S/N 1423
« Reply #7 on: December 31, 2020, 12:16:20 PM »
Its kind of interesting that 337s show that John Roberts (SC Helio dealer) converted coverted about 10 of the last 25 helios from 60 gallon to 120 gallon wings before he sold them.

The factory must have some kind of kit to make it possible. I had always thought it relatively easy to make that conversion since John Roberts had done so many, I guess not so.
« Last Edit: December 31, 2020, 12:18:33 PM by Doug Johnson »


Re: S/N 1423
« Reply #8 on: December 31, 2020, 12:45:09 PM »
Thank you so much!
I heard about your huge experience with Helio! And for me is very important to get your opinion!
My plane is been in hangar. I hope it protected him from corrosion. And before put him in storage, I used conservation oil for cylinders. At least, it will be necessary to make a carburettor and change the hoses.
The AD from 1982 should be done. I need to check the logbook. And plane on floats was flipped over in some 80’s during hurricane. After that carry-thru and wings have been changed.
It’s very desirable for me to make a 120 gallons fuel tanks. I understand that it’s not a practicable, but I hope that it isn’t impossible. Because, more difficult to find and bring new wings. But, 5 hours endurance is not enough for our area.

I really count on your informational support!

Happy New Year!


Re: S/N 1423
« Reply #9 on: December 31, 2020, 12:54:27 PM »
I remember that you told me about possibility to convert to 120 gallons.
According Jim information, I understand that it’s very problematic to make it.
But, even if it is not easy, I hope it is not impossible...
Is a chance to get a schematic for conversion?

Happy New Year!


Re: S/N 1423
« Reply #10 on: December 31, 2020, 03:17:19 PM »
Evgenil-  It is possible that I have a pair of wings from 391B/U10 which has four tanks.  Might be serviceable.  They are in CT.  Where are you?  Cheers and Happy New Year to all you guys/  Bob  Wallace  (H22)