The venerable Bell 47

[twinstar_ca]

Originally Posted by Teefor Gage

At a training school in the 80's, one B47 G2 cut the T/R drive shaft with the blades due to a heavy EOL. The instructor thought they had got away with it and was winding up the rotors again when he had an R/T call from a colleague to say "The T/R's not going round - is this normal??"

would there not have been a feeling of imbalance felt in the airframe and pedals if the t/r wasn't spooling up with the m/r??

[Teefor Gage]

Originally posted by twinstar ca
would there not have been a feeling of imbalance felt in the airframe and pedals if the t/r wasn't spooling up with the m/r??

I'm sure that all sorts of hints were there to tell him that there was a problem. Maybe he was just checking to see if anybody else had noticed!!

[bullshitproof]

bell 47 part required

Does anyone no where i can get a break away coupleing for a 47 fitted with the large 48 gall crashproof tanks.
kind regards bull****proof

[Flingwing207]

Try Scott's Helicopters in Minnesota, USA:
Scott's Helicopters Website

[outofwhack]

To B47 operators out there

Is it normal to have cracks in the paint on the underside of B47 metal blades? The cracks I saw were in direction from leading edge to trailing edge and evenly spaced say quarter of an inch apart and repeated from root to approx 1/3 or 1/2 span. I've been assured its just the paint!
Just wondering if all blades go like this or whether its a sign of too many 'to the ground autos' with its extreme coning. ie a training machine. The blades are half life. Can I expect the blades to go to full life without blade retirement/death???

Do most or all blades get to full life?

[Darren999]

Outofwhack- With the metals blades there should be no reason they should not go to time life, 5000hrs I beleive, However, you may want to look round for another set soon if you intend to keep the machine, they are pretty scarce to come by. The cracks you mention,once you have them check are usually OK from leading edge to trailing edge. The ones you don't want run along the blade. You sometimes find the cracks around the root end near the metal brace, close to the grip. Normally the paint on the surface cracks, that's my expirence with woodn blades too, as you say probably due to coing, not all down to Auto's either. I know a couple of places that may help you. Rotorcraft Blades in Texas, and East Coast Helicopters in PA.
All the best
Darren

[outofwhack]

Mixture control

Can anyone tell me why most, if not all, the Bell 47 in Australia have their mixture control lever sawn off in the cockpit.

ie. so that you cannot adjust mixture

Surely a Lyc435 tuned at sea-level is going to splutter quite a bit trying to operate out of a strip at 5000'. Leaning a bit would surely help regain the lost performance wouldnt it? So why are they disabled?

[brett s]

Because they have an altitude compensating carb - all the 47's I flew did anyways.

[imabell]

the mixture control in a 47 is only an idle cut off and only works when the throttle is fully shut.

there is an automatic mixture control, (amc), inside the carburettor that does it all for you. it is an aneroid that changes the jet setting as you climb.

please do not lean out any helicopter. you might get a big fright.

[outofwhack]

Thanks guys, I knew there was an answer.

So they are not really that useful !
They cant save fuel!

I will also assume that they're cut off to remove all chances of confusing it with carby-heat lever as they are rather close arent they!

OOW

[XT244]

...there is an automatic mixture control, (amc), inside the carburettor that does it all for you. it is an aneroid that changes the jet setting as you climb...

That's correct!
Do never lean!
I was flown with my B47G3B1 from 1'400ft up to 15'700ft to the Montblanc without any problems.
All temperatures in green arc ... and NO lean
http://www.adpro-ltd.ch/bilder/20060316megeve/index.htm

[topendtorque]

I was flown with my B47G3B1 from 1'400ft up to 15'700ft

bet you didn't shut it down

If you want to see spluttering around a '47, then the best thing to do is stick around when the engineer has fitted a replacement amc, that was sent AOG (ah yes, remember that old term of long gone respect), but the gadget was dispatched in a non pressurized cargo hold. heh hehe

[ericferret]

I believe there was a fatal accident in the UK with an inflight tailboom strike.
It was a long time ago and would require a search in the AAIB reports to come up with the details.

[outofwhack]

Why not a parachute?

Wow, those photos nearly give me a nose bleed.

I took some skydivers up to 5000' a few weeks back in a 47 and the feeling of loneliness and being too high after they had bailed out was quite unexpected.

Given the risks of parachutes around I wore a safety chute myself - felt good when the ground was so far away.

Being a newbie - dare I ask the question why helicopter pilots dont have parachutes. The old reason of not being high enough to use them does not apply anymore. Base jumpers prove that.

You'd think that Robbie flyers would buy em!

[outofwhack]

B47 engine management

Another thing dawned on me while flying around, wondering whats about to go wrong [like a good pilot should?] with my 'new to me' Bell47.

The [sea-level] school I started my initial training with never really mentioned much about the manifold pressure limits as placarded except to say climb with 25inches and cruise with 22/23 inches. I dare say the second school I continued at may have assumed my knowledge of MP limits was complete. Well I am still learning for sure - hence this question....

Is the Bell 47 with Lyc435 (unboosted) bulletproof in this regard or very sensitive to MP abuse?

How would I know if these limits havent been observed in the past?
What does abuse of the figures cause?
OOW

[topendtorque]

Fairly simple answer, not much.
The same engine in other F/W installs runs continuously at around 275 hp.

Your MP limitation applies to the max continuous power ( from memory 220 hp???) that you are allowed to put through the xmon. Therefore the engine cooling system is designed to keep the engine cool at that power rating. - continuously-

Make sure that someone hasn't put a bigger engine cooling fan on it, I.E. from a turbocharged model. we often did in the hot climes to keep them cooler.

One tip is that the main power jet cranks open at about 22.5". keep it a shade under that and you'll cruise at 3 to 4 litres per hour less and only 1 or 2 knots slower.

Another tip, if you have a wet sump engine always keep an eye on the magneto idler gear shaft where it bolts into the accessory housing. if there is one drop of oil seeping from it, do not fly - it will fail inside the next 25 hours.

apart from that they are bulletproof, and magic to oprerate.

[outofwhack]

Thanks for the tips TopEndTorque,

It is absolute magic and I am totally happy with my recent purcase. Its funny how so many people assume I bought a Robinson. I have 1 hour in a Robbo and its not increasing. I just love the 47 always have! I love the noise too but I must admit to having heard nearly enough on day 7 at Oshkosh with two 47s flying overhead dawn to dusk doing joyflights.

Can Robbie owners claim similar enjoyment with a R22/44? I suppose they take a lot less greasing but I dont think they have the timeless looks of a classic like the 47 or 206.


Now to find the magneto idle gear shaft.

I will look for a drip of oil there when I find it - but how clean can one of these engines be anyway?

It does have a wet sump but there always seems to be some oil sprayed around near the dipstick and around the intake manifold. It could be just drops from the bottle when filling. Wish it had the seperate sump! But cleaning does make me inspect quite well.

Next question ... how to polish the bubble and keep it clean?

[phoenix4]

get the right one

I have a 47g4a with the 540 16 gph 90kns vne no problem ! cruze 80kns 21ins lots of power not to be mixed up with a g3 (no chance of vne small chance of a 60knt cruze) slow at the side of a 44 and not has cheap to keep in avgas as a 300 but a very safe and well loved helicopter .But you need to want a 47 and not becouse you think it would be cheap flyin.

[outofwhack]

I get 75 knots in my G5A some have said because it is quite light at 804kg and thats why it is so fast.

My engineer recommends, for best efficiency, fly high enough to the point where the throttle is wide open. Max throttle height?????

I think the argument is that "that is where the engine is developing its full rated power" and this is supposed to translate to best efficiency. I dont quite understand the logic though.....

.... if you put your foot to the floor on a car you will go fast but I am sure its miles per gallon goes down.

Can anyone explain?
OOW

[John Eacott]

Originally Posted by outofwhack

Next question ... how to polish the bubble and keep it clean?

I suspect that this has been asked before! I've always found 210 to be the best cleaner for perspex: always wash dust and dirt off first with plenty of water and a quality cleaner, and dry with a good, clean chamois. Apply 210 with a soft, clean rag in straight, sweeping lines. Never clean in a circular motion, nor rub hard in one spot to remove a mark: you'll leave a scar in the perspex if you do. Straight lines will give the least chance of sunlight reflecting on the minute score marks that sometimes get left: if the score marks are circular, there will always be a relection Buff the screen with another clean, soft cloth after you've cleaned with 210. Don't forget to clean inside the screen, too: it's remarkable how dirty it can get.

Also, wash with clean water and a clean cloth/chamois after each flight, it's easier to get the bugs off when they're new and soft! It's worked for me for many a year now