Hughes OH6A

[Mav27]

Question for those who have experience with the Hughes OH6A or 500C.

I am looking at getting a Hughes and was wondering if in the OH6A or 500C models if the C18 works ok or is one best to look for a C20. Also was wondering if you can change the skids from short to high and if so, about how much would that cost. I will be using it for personal use only.

[HeliNZee]

An educated guess would say the C20 definitely come up trumps. here is a thread of interest if you haven't already seen it, there is quite a bit of talk on the engines near the middle somewhere:
http://www.pprune.org/rotorheads/407911-md500-series-specific-photo-thread.html

[blackhand]

I am looking at getting a Hughes and was wondering if in the OH6A or 500C models if the C18 works ok or is one best to look for a C20.
The C18 is basically a disposable engine these days.
Also becoming very difficult to procure spares.
I would suggest going for the C20.

Cheers
BH

[Mav27]

Well the guy that has the OH6A for sale was saying that the C18 works just as well as the C20 in the 4 blade model and that the C20 was used when they went to the 5 blade D,E models for the extra power and lift. He said if your not trying to use the OH6 or C model for line work there is no real benefit to having a C20. In fact you use less gallons per hr with the C18. This particular turbine is the military version a 250-C10D which he says has a continuous 317 hp.

[Hell Man]

Mav

You asked was wondering if in the OH6A or 500C models if the C18 works ok or is one best to look for a C20 and most people I know would recommend the C20.

Its not because the OH6 can't fly on an 18, it can but you asked or is one best to look for a C20 and to which I would say it is best to look for a C20.

The C20 will give you just that little extra power (the OH6A was under-powered to begin with) and which is an important safety factor.

A lot of private flyers dont have heaps of flight time and running around in a limited power helo always has the potential to court danger.

You might tell yourself you'll use it as a two-person ship (great) but the day will come one day one time when you've landed in your friend's back yard and a couple of people plead with you to ride in the back and you tell yourself 'just this once'. By the time you're four up and staring at the tree tops (above you) with limited power reserves and a downdraft comes and takes what you've got left - it will be too late to be thinking about C20s!

I've said this to countless friends over the years and I'll say it again. If you don't have enough money to fly rite, don't fly at all!

That may sound a bit harsh but here's the deal, in aviation when money is an issue - safety often gets compromised and that just doesn't 'fly' in the aviation game!

Having said this - you can operate an OH6 with a C18 (if you're real careful about what you do and real disciplined also) but, a C20 is better.

High skids are an easy mod for the OH6/C model.

HM

[Hughes500]

Problems with C18 engine
1. 1250 hours on turbine overhaul
2. Above about 25 degrees C the engine will TOT out before torquing out
3. More expensive to overhaul, parts havent been made for years

Advantages

1. No cycle count
2. about 15 to 18 gals an hour

The C20 engine in a c model is the hot and high version of the 369HS (C18). Basically all 4 bladed models have a max transmission limit of 275 shp of which both engines give at 15 degrees. Hence stick a c20 in and she will take off at higher temps as she doesnt tot out

High skids will slow you down a bit and you will have to pay about $ 20k as you have to change the dampers as well as legs and skid tubes !

The C20B engine was used in the D and E models as the transmission went to 350 cont and 375 for take off ( C20b about 420shp)
Hope this helps

[Mav27]

Hell man,

Thanks thats is the info i was looking for. This is a really nice OH6, However i was concerned about the C18 power limitations. The field elevation here is 4200 and much of my flying will be in mountain areas. He says that he has taken 4 people in the OH6 and did not seem to have any problems. However his field elevation is about 2100 and what kind of take off area would be required for 4 people on board with the C18 as to not get into a tot problem.

[spinwing]

Mmmm ...

I've been away from the 500 for awhile but to add to all the above ....


Definitely the C20/C20B engine is the (now) more reliable way to go .. I've experienced many warped C18 compressor backplates on 500's and they will cost you !!!

Also ensure you have all the latest T/R bearings and mods done ... DO not use the old Fibreglass T/R blades (if they still exist?) ... go for the metal blades.

Have fun ... they're a great machine .. :D

[Mav27]

Hughes 500,

This component times sheet on this OH6 shows Turbine Component time
425.8 and 1324.2 remaining. So this info is wrong then. The C18 can't go 1750 to overhaul. So if the trans can only handle 275 max then when you are using the C20 for take off does it exceed the trans limits. Do they ever use a C20B in a OH6 or a 500C model.

Thanks for all the input
Big investment and i want to get it wright the first time.

[mfriskel]

There are C20Bs installed in some. You never have to worry about TOT then. I had to take an OH-6A(OVL) to 13,000 feet to reach a point where the engine produced less power than the transmission limit.

[widgeon]

1974 HUGHES 500C Turbine Helicopters For Sale At Controller.com (http://www.controller.com/listingsdetail/aircraft-for-sale/HUGHES-500C/1974-HUGHES-500C/1182181.htm)

One here might be a wee bit of a ferry flight though.

[Mav27]

So if you put a C20B in a OH6 it will have to have a trans also. What else would it have to have to comply with the stc's.

[500e]

The 369C will make you watch the TOT like a hawk even with only 2 people & fuel & that's in the UK it ain't hot & high.
With the high skids you stand less chance of setting the lawn on fire, still makes brown patches though :E

[mfriskel]

MAV27- What are you saying/asking? trans also?

[Mav27]

So what is going to be better for higher elevation flying, Considering they all
had a C20B in them, a Jet Ranger, OH58, OH6A, or a 500C.

[chopjock]

I love my C18, very economical,reliable and powerfull. The best thing of all is you do not have the cycle count limitation associated with the C20. I heard of one guy had to have an overhaul at half life because he did a lot of short flights and ran out of starts. No problems finding spares either. Sure you have to watch the tot in the summer, but at least you won't overtorque the transmission. Go with the C18, I would recommend it. http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif

[Hughes500]

Mav27
The transmission is the limiting factor on a 369HS or OH6. On an ICAO std day of 15 degrees the engine will provide you a tad more power than the trx can handle. However as the temp goes up or you go higher you will run out of tot before torque hence the more powerful C20 ( yes you can put a C20B) in the C model. However the limiting factor is still the drivetrain. Thats why D model came along, bigger trx extra blade etc etc
The C20 series has the follwing times for turbine
N1 side 1750 hours or 3000 starts
N2 4500 hours or 6000 starts

C18 has 1250 hours N1 and no start limitation, sorry cant remember N2
The other way to go is to buy the machien and when engine needs overhauling slap in a C20 adds value to machine. Have to check have correct trx, tailboom and tr blades though

[mfriskel]

Transmissions in the 500 are fairly bulletproof. I would rather have to pay for an over-torque inspection than an over-temp inspection. Over-torques won't be a problem if you watch your guages, just as over-temps won't be. The big difference comes in in the way you fly. With an engine that delivers more power than the transmission limits, you can fly the same in the summer or winter. With an engine limited system, you have to change the way you fly with the seasons. Adjusted passenger loads, adjusted fuel loads, not being able to go up the mountain ect..... Since you are already starting off at 4200 feet, you are already limited somewhat with the C-18.

With the questions that you are asking, you should get in touch with someone who knows what they are talking about and sit down face to face. A non-partial party who won't profit fromwhat you purchase. Look at performance charts for the machines available, look at spares availability, look at operating costs, look at each machine's emtpy weight- and if you want to fly people in the rear- sit in the back of the 500 for a bit. I would not want to part with the amount of money you are talking about and still be asking the questions you are asking.

Mark

[Chris P Bacon]

The C20 Turbine will need two FAA air directives complied with before October, which will then make it into a C20B. Save the expense and get one with the C20B already installed.
If you do go for the C18, I can confirm that there is NO new part support of this model 250 by Rolls Royce. Yes, you can pick up low cost modules, but these will no doubt be ex military, old and probably have been stored up for a long time.
There is a big difference buying a C18 powered aircraft you don't know to having owned and cherished your own C18 powered aircraft.

[rjtjrt]

What is the cycle count limitation on the C18?
John

[Hughes500]

rjt

There is no turbine cycle count on a C18 but you loose 500 hours !

[Mav27]

Hughes,

So where did you find the information on the C18 only going to 1250 TBO. I have looked and can not find anything to suggest that, or the cycles. Could you provide me with the link for that information.

Thanks

[Bcopters500]

The directives are true , It turns our C-20 into a Anchor Weight.:ok:

[Hughes500]

Mav27

Used to run one with a c18 in.
Have owned abot 9 500's over the years, the best is the D model

[Chris P Bacon]

The C18 Turbine (if it is the Blue Ribbon standard) has a stage 1 and 2 wheel life limit of 1550 hour, with a TBO of 1250 hours. The life limits can be found in tables 4 - 7 of the 5W2 Operations and Maintenance manual (section II, page 16)
Can't post a link as the manuals are subscription only.

[500 Fan]

Hypothetically speaking, if you own a standard OH-6A with a C-18 engine, are the following options a runner?

1. If you replace your C-18 with a C-20B, does the aircraft remain in the standard category for certification purposes, provided it is N-registered?

2. Will the C-20B conversion require any modification to the tail rotor drive shaft and gearbox to handle the extra power, in the case where a standard OH-6A main rotor transmission is retained with its limitations taken into account?

3. Can you go the whole hog and fit the OH-6A with a C-20B engine, D-model main transmission, five-blade rotor head and D-model tail rotor drive train and have your helicopter certified as a standard machine, as opposed to an "Experimental"?

I reckon the modifications in No.3 would put it in the experimental category. In the 1970's and early 80's, Hughes flew three OH-6As and two early 500s with five-blade main and four-blade tail rotor systems and C-20s/C-20Bs and one D-Model with a V-Tail, so every combination seems possible. It's just a question of whether the authorities will let you get away with it or not.

500 Fan.

[Hughes500]

50 fan, no prizes for guessing the answer to 3 NO

[mfriskel]

Look in the 500 thread to see a picture of the "quiet one" or mostly quiet one still in operation in the Seattle area.

[turbo2]

Have had a personal OH 6 with a C18 for about 5 years. Typically fly alone or with someone in front. Rarely haul extra people- typically have about 100 of gear in back.
This is an excellent engine for my use. All the engine you need for virtually any situation if you use your head and manage power. Having flown hand throttled, underpowered helos in the past is excellent training for using all aspects of efficiencies in helicopters. Depending on only turbine power is an invitation to disaster. Don't get me wrong- a C20 0r C30 would be great- but using proper balance of power, speed, wind, ... the C18 will do a lot much cheaper than the larger powerplant and I think keep you a sharper pilot. Look at what these engines and ships were doing in Vietnam in their day under hot and heavy conditions.
If you are expecting to do heavy, hard or high missions think about a newer ship in general like a D or E model. The OH6 is pretty well suited for the C18.

[spinwing]

Mmmmm .....


....... Look at what these engines and ships were doing in Vietnam in their day under hot and heavy conditions. ....


Those Vietnam machines got a hiding and repair costs were NOT a consideration ... they also tended to get trashed pretty quickly ... engines were changed out very regularly ... I don't believe real comparisons can be made.

:eek:

[500 Fan]

I'm with Turbo2 on this one. The OH-6A/C-18 is a good machine for private flying when flown sensibly and within its limits. On a cool day, it will lift four people with plenty of fuel.

500 Fan.

[500e]

& on 18 Gal HR but it does teach you not to just twist & go

[170']

The 500C/Loach with a C18 is all the helicopter you need for private flying

It's still lots of fun to throw around, even if it lacks the excess power of the D. I call it excess power because it felt like it in comparison to everything else available at the time.(except the Lama) If you ever miscalculate :uhoh: it's also the best thing to be sitting in if you land less than upright.

Check around for èntire C18 engines, there were a lot of them available a few years ago at bargain basement prices due to 'restricted' but they may still be out there somewheres.If you can locate one of them it would be a great 'spares package' as they were being sold 'in the can' for less than a fuel nozzle for a C20B.

You won't get the performance of the D model, but it will be fun machine anyway

Post some pics if you make it happen.

Best regards ....170'