Author Topic: Oleo shock strut legs for Helio 800/700  (Read 558 times)

tailhook

Oleo shock strut legs for Helio 800/700
« on: January 03, 2019, 08:44:56 AM »
Hello Helio Community,

Back before Christmas I had a talk with J.Metzler about installation of the 250/395/295 gear legs to 800/700 airframe. He was under the impression that they were not applicable to these airframes, due to weight, and differences to the firewall during production in 1983/84. I know Pima County Sheriff's H-22 N400HE that was acquired from David Maytag with the Russian M-14P radial was the airframe used for RR/Allison 250 B-17C. The reason is that now B.Wallace is undergoing transition to wheels and he wanted to know if H-395 gears legs support a 4000 pound airplane. I'm quite sure they do but cannot find an STC if there is available.

The attached photo clearly shows the oleo strut legs.

Stephen
« Last Edit: January 03, 2019, 10:18:47 AM by tailhook »

tailhook

Re: Oleo shock strut legs for Helio 800/700
« Reply #1 on: January 03, 2019, 10:21:00 AM »
H-22 N400HE


tailhook

Re: Oleo shock strut legs for Helio 800/700
« Reply #2 on: January 03, 2019, 10:23:49 AM »
And another H-22

Doug Johnson 1

Re: Oleo shock strut legs for Helio 800/700
« Reply #3 on: January 03, 2019, 11:28:13 AM »
Here's my two cent worth

I believe I remember when talking with Mr. Maytag the reason the H-7/800s didn't have the same gear as the H-295, is because the H-295 gear legs were no longer in production and to put them back into production was going to take longer than the Helio Factory was willing to wait plus the manufacture wanted a commitment to a minimal order the same problem for using a Lycoming GO-540 engine. I think I remember a minimum order of 100 was required.

Maytag said they intended to bring back the original Oleo shock strut when they went back into production. I don't remember much about the conversation on GO-540 engines but if I remember correctly the GO-480 was no longer supported by the factory but he was enthusiastic about his radial engine and he talked about a turbine engine they were testing.

Also the H-295 oleo strut is rated at 3800 lbs on landing. I suspect just like the H-7/800 which is rated 4000 lbs on takeoff and 3800 lbs for landing with Fiberglas gear legs the oleo strut would probably be rated the same way.

Again there are so much that is the same between the H-295 and the H-7/800 that it shouldn't be that much of a problem to put H-295 gear on an H-800 particularly one in the experimental category.

I believe there is a minor modification needed to use H-391 oleo struts on H-395 a brace or bracket and a recommended minor mod to go from H-395 to H-295. Hopefully someone can add to that.

I just remembered Bob Wallace saying that the H-295 Oleo struts have some shortcomings with the much lighter turbine 212 lb engine on H-22, vs GO-480s (492 lbs).

Another reason to believe that with the much lighter engine the H-395 gear legs would probably work fine.
« Last Edit: January 03, 2019, 12:34:25 PM by Doug Johnson 1 »

tailhook

Re: Oleo shock strut legs for Helio 800/700
« Reply #4 on: January 03, 2019, 12:05:36 PM »
Jim Metzler told me that the gear legs for 1400 series 295's are from the H-250 and 4 pounds lighter than 395/295 series. The vendor for those gear legs was Cleveland Pneumatic in Ohio, that facility burned down in 2000.

When we were pursuing the TC's for Helio in 1987, Lycoming was willing to build the IGO-540 for $63,000 per copy. The IGO-540 is a dry sump powerplant used for the Aero Commander 560F in 1961. Hartzell still had a number of blades for 295's per 10151C.

https://www.lycoming.com/sites/default/files/IGO-IGSO-540%20Operator%20Manual%2060297-15.pdf

Stephen
« Last Edit: January 03, 2019, 12:16:18 PM by tailhook »

Doug Johnson 1

Re: Oleo shock strut legs for Helio 800/700
« Reply #5 on: January 03, 2019, 12:38:06 PM »
Does 4 lbs lighter on the H-250/1400 series mean the 4 lbs heavier H-395/1200 series gear legs are stronger?

tailhook

Re: Oleo shock strut legs for Helio 800/700
« Reply #6 on: January 03, 2019, 12:49:45 PM »
Doug,

According to Metzler not so much, as in the 1400 series they added sound-proofing, interior upgrades, and the new center stack panel, there are minor differences in the way they are fabricated, but for strength, they handle a 3400 pound Helio as well as earlier versions of the 395/295 production. The #3800 pound upgrades handle as well with either legs. A drawing would help refine that equation.

Louis

Re: Oleo shock strut legs for Helio 800/700
« Reply #7 on: January 04, 2019, 11:11:38 AM »
I wouldn't replace a 800 gear with a 295 gear on a 800 with a lycoming 720.  The gear on the 800 had a much bigger job to do with this huge io720 engine that was installed even further in front than the geared 480 on a 295.  There were a lot stronger than a 295 legs, weighing also a lot more, in both version ( original fibreglass and stc'd aluminium ).  A 295 gear on a 800 would not last long.  The 800 is a challenge to land without bumping compare to a 295.  The fibreglass gear, or aluminium gear, show signs of hard work after 500 cycles of taking the punishment to absorb the weight of the IO 720 and it's CG. 

But now, we are not talking about replacing a 800 gear on a real 800.  We are talking about putting a 295 gear on a modified Helio that have a lightweight turbine engine.  This is no more a 800 helio if we remove the Lycoming io720 to replace it with a turbine AND put the CG at the same place, or behind, the CG of a 295.  It is probably now the most lightweight Helio-like aircraft.  Probably even lighter  than a 250.  No need to install the gear of the heaviest version Helio on the most lightest version.

The frame would allow it, and the firewall would have to be modify so it could accept the shock absorber. 

I have a 295 that was made-repaired with a 800 frame.  With a 295 gear.  And a 480 engine.  I don't call it a 800.  It is a 295.  With the limit of 3800 pounds of a 295.

The turbine modified Helio is no more a 800, or a 295.  It is probably classified as experimental.  As so, whatever Gross weight you want, but i would say 3800 pounds would be the easiest number to prove  since we don't have anything to able to prove that the 295 gear leg are good for more than that.

With the safety margin of the certification, the gear would probably handle loads a magnitude over that.  But to choose a number easy to document, i would stick to 3800 and fly whatever fit's in this experimental turbine powered plane.

The kind gentleman that STC'd the aluminum gear on the 800 showed to me what he had to do to prove his design from fibreglass to aluminium.  Letting the 800 drop on the cement from a quite high height.  Nobody wants to do that with his own airplane just to be able to write a higher number than the easy 3800. 

And yes, i would prefer to live with a paperwork of 3800 with a shock absorbent 295 gear than to fly the terrible springy gear of a 800 with paperwork at 4000 and it's poor angle of attack.  Part of the so difficult handling of the 800 is because to his gear.  When we approach a loaded 295, the legs are hanging down far away from the fuselage.  We are able to do a three point.  Do it with a similar loaded 800, and we touch the tailwheel on the ground when the tires are still two feet high.  Then the bumps when the 800 falls.  The gear of the 800 is simply not designed to allow the high angle of attack of the Helio approach.  Or take-off.

Louis
« Last Edit: January 04, 2019, 11:36:27 AM by Louis »

tailhook

Re: Oleo shock strut legs for Helio 800/700
« Reply #8 on: January 05, 2019, 11:31:41 AM »
The Lycoming IO-720-B1A hardly develops 400 HP and weighs in @ 600 pounds. The boys at Mid-States MFG. were in a hurry to get the airplane certified as the H-800, and I think N4002M was the first unit out the door having been rushed into production under James Cox. So here we have a 2700 pound airplane that originally had a MTOW of 3888 on land, and with floats at 4000 pounds. Helio Aircraft LTD did not want to wait for Hartzell to come up with a suitable prop for the IO-720.

Helio 800's that are converted to GO-480 and weight reduction measures may have something all together different in application, such as 295.

Stephen

Doug Johnson 1

Re: Oleo shock strut legs for Helio 800/700
« Reply #9 on: January 05, 2019, 11:59:15 AM »
I believe from some conversation with Bob Casebeer that it wasn't so much that James cox was unwilling to wait, as a money problem and guaranteed minimal orders, Hartzell had a four bladed prop in development for both the H-800 and Ag-Rat'lr that would have able to put the 400hp to use but the factory closed before it could happen, again lack of demand and money.

tailhook

Re: Oleo shock strut legs for Helio 800/700
« Reply #10 on: January 05, 2019, 12:16:21 PM »
Entirely possible, and yes, that is probably the final scenario for Helio Aircraft LTD. by 1984 Loren Abbot had ran Aerospace Technologies right into the ground and Helio closed it's doors and the bills did not get paid and they padlocked the doors.

tailhook

Re: Oleo shock strut legs for Helio 800/700
« Reply #11 on: January 05, 2019, 12:25:30 PM »
I recently got a call from John Fuller about H-700 N50DV that is for sale in Minden, NV. Any direct-drive Helio that burns 20GPH may be a hard sell, the 700 is not the best of the lot.

Stephen