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Century Hawk - Falcon - Raven - Predator > Hawk Sport - Dead Clutch
 
 
nheather
Veteran
Location: Horsham, West Sussex, UK

I took my Hawk Sport out for the third time for a bit of hovering practice.

Only a few minutes in and it didn't feel right so I stopped.

As I got close to the heli I notice there were plastic shavings everywhere and the rotor wasn't slowing down. I had to shut the engine down to stop the rotor and when I did the rotors snapped to an abrupt stop.

I susepcted the clutch. When I took it out it looks like this:







You can probably see that there are residue shavings and melted plastic between the cooloing fan and bell housing. The whole assembly seems fused together. I also noticed that the main gear lost a tooth - probably when the whole rotor came to a grinding halt.

I'd appreciate any advice on:

i) Why it happened - is this common
ii) How I get the assembly apart
iii) How to improve my morale

I reckon this is going to cost 50GBP (80USD). I wouldn't mind if I crashed - I'm prepared for that - but I did nothing. It's only the 4th tank and this happens. I must admit that my morale and faith in Century products have taken a big hit.

Any advice will be greatfully received.

Cheers,

Nigel
04-12-2003 Over year old.
 
 
nheather
Veteran
Location: Horsham, West Sussex, UK

I got the clutch apart. Here's the picture:



The bearings seem fine

The clutch shoe looks like its a goner. I assume it's supposed to be round. Mine is oval with arms splayed out.

Oh and before anyone makes the comment, I had difficulty getting the prop nut off. It was nice and secure and the red locktite did not give up easily.

What could have caused this. My theories are:

a) Faulty component
b) Lining not stuck in propoerly when assembled in Taiwan (or wherever)

Cheers,

Nigel
04-12-2003 Over year old.
 
 
Phil_Mart
Veteran
Location: Newcastle UK

The only way that the unit is going to have got hot enough for that to happen is with a load of clutch slip. However is there any sign of heat tempering (colour change) on the clutch shoes?

If there is that would indicate that the shoes were slipping on the lining and generating the heat. If not, it would seem more likely that the lining lost its bond with the bell and cooked the unit.

Whilst your replacing the parts I can recommend the ally fan unit. Since I've installed one on mine the cooling is a lot better. I also balanced and clocked mine onto the motor and this has reduced the level of vibration in the heli
04-12-2003 Over year old.
 
 
jimmyhua
Veteran
Location: Guam

Pretty cool pics.

As for root cause analysis, It's definitely B.

That lining must have slipped and slided while you were hovering. The plastic clutch bell and fan kept the heat in. They eventually melted and glued the whole mess together.

With some luck, none of that gunk got sucked in the carb, so you would only be out $20 (fan+ plastic clutch bell).


Jimmy
04-12-2003 Over year old.
 
 
nheather
Veteran
Location: Horsham, West Sussex, UK

jimmyhua

It would certainly be good if I didn't have to replace the clutch shoe.

How can I tell whether its okay.

A replacement shoe has the arms parallel, so that seen from above the whole shoe is circular and the slots are straight.

The arms of mine are splayed out, so that seen from above, the shoe is slightly oval and the slots are V-Shaped.

I guess this is done by centrifugal force and is how the clutch works, but how do I know if mine is okay and can be reused?

Cheers,

Nigel
04-12-2003 Over year old.
 
 
gwallace1
Veteran
Location: Susanville, CA

I would definitely get some new clutch shoes. It will be nearly impossible to get the proper clearance with tha. Spend the extra $$ and go new, or you'll probably end up smoking another one.

Greg
04-12-2003 Over year old.
HOMEPAGE  
 
 
nheather
Veteran
Location: Horsham, West Sussex, UK

gwallace1

Tend to agree and I will probably buy new.

What niggles me is that I have no guarantee that it won't happen with new.

Having studied the remains in detail now, it is clear that the clutch lining did come untuck and move upwards until it jammed against the cooling fan. And that was with new parts.

The lining was pre-assembled by Century. It failed on the 4th tank of fuel. I'm just beginning, trying to hover a foot of the ground so I can hardly be said to be stressing the machine.

It needles me, that having been in receipt of faulty goods from a company, I end up having to buy yet more from them. They are laughing all the way to the bank. My clutch shoes may be perfectly serviceable, but who knows and the community says give the company more money, its safer than being sorry.

Cheers,

Nigel
04-12-2003 Over year old.
 
 
gwallace1
Veteran
Location: Susanville, CA

Give them a call and tell them what happened. Especially if it was assembled by them. No guarantee on whether they will replace it, but you have pics and it is worth a shot.

Greg
04-12-2003 Over year old.
HOMEPAGE  
 
 
BountyHunter
Heliman
Location: Copperas Cove,TX

i agree,give them a call and see if they'll cover it. only on the 4th tank and that happened seems like a production or pre assembly era on their part.they should cover their product ?
04-13-2003 Over year old.
 
 
bellecrank
Veteran
Location: Canada

From the pictures

Looks to me like the clutch bell assembly came loose and rode up into the fan (worn circle in the fan). Or when the engine is idled at too high an RPM or has a "run-away".

This is usually caused by the clutch and nut not being secured adequately with locktite etc. and/or starting a semi-flooded engine.

If you use muffler pressure then be sure to remove the line when refueling or you can get raw fuel directly into the muffler when doing so. As soon as you turn the engine over this raw fuel will be sucked into the combustion chamber and cause an overly rich (semi-flooded) condition. Very common with newbie fliers.
04-13-2003 Over year old.
 
 
jimmyhua
Veteran
Location: Guam

Thanks Fidman,

I didn't catch that. Only the tail rotors should have snapped to a stop. The mainblades should have slowed down nice and smooth thanks to the auto bearing.

Jimmy
04-13-2003 Over year old.
 
 
Phil_Mart
Veteran
Location: Newcastle UK

Nigel,

The fault is clearly with the pre-assembled clutch liner. Where did you buy the heli from? Talk to them as the point of sale, re the Sale of Goods Act, not fit or suitable for the purpose for which it was sold!

Also I would say that there is no way you can use those clutch shoes again. If you try to push them back into shape you will DEFINITELY generate some stress cracks at the 'pivot' point of the shoes. This means that next time you try to use them the shoe tips will part from the body and wreck your new clutch and possibly much more
04-13-2003 Over year old.
 
 
nheather
Veteran
Location: Horsham, West Sussex, UK

jimmyhua, Fidman
==============

You could be right about the main rotors. It was the tail rotor that caught my attention when it snapped shut. I may have had to stop the mains with the head button, I can't recall 100% - I guess I had a lot of thoughts swimming through my mind at the time.


Anyway I've order a complete set of new parts and were persist with the Hawk until it is totalled or I get round to advancing.


All
==

I have contacted Century USA and Century UK. This is what they said.

Century UK
"Yeah, seen this before. It's because your pitch was too high. Engine got hot and melted the lining glue"
Comment - Funny that my heli was hovering on half throttle at 5% pitch at the time. The top end is set to 9% and as a begiiner doing bunny hops I've got nowhere near that.

Century USA
"This is what happens when you don't tighten and loctite the engine nut. What are you asking for?"
Comment - My email clearly stated that the engine nut was still tight and locked when I removed it. Clearly, Century USA don't want or are unable to comprehend plain English.


To be honest, I wasn't expecting anything from either of them. But this sought of buck passing really dents my opinion and confidence in the company.


Cheers,

Nigel
04-14-2003 Over year old.
 
 
Phil_Mart
Veteran
Location: Newcastle UK

F**K the proverbial Duck!! Just how hot has the engine got to be to cause that. I would have thought the engine would have gone into melt-down long before that!

Just goes to prove what I've thought for some time now. I like the Hawk Sport, but once they've sold you it Century couldn't give a flying f**k about the customer
04-14-2003 Over year old.
 
 
rdoupe
Heliman
Location: Long Beach, CA.

Does anyone know if the nylon clutch bell on a Hawk can be replaced with an aluminum one - such as one for a Raven?

I melted one down on my Raven, but only because I forgot to make sure the shoes / lining were oil-free. It burned up immediately - within 30 seconds.
04-15-2003 Over year old.
 
 
nheather
Veteran
Location: Horsham, West Sussex, UK

Fidman23

I'll send a copy email to you directly. I don't think it is correct to post it on a public forum.

I'm working away from home until Thursday night now, so won't be able to post it until then.


Cheers,

Nigel
04-15-2003 Over year old.
 
 
dennis_cica
Senior Heliman
Location: San Jose, CA

Dear Century Customer

my appologies for how long it took for me to get this information.
Please give us you address and we will send you replacements for the parts damaged. You can call me (I'm Dennis) 408-942-9521 We will be more than willing to send you our aluminum clutch bell to repay you for the damages.

We will continue to provide the best service possible here at Century.

Thank You

Dennis Cica
Century Helicopter Products
04-17-2003 Over year old.
HOMEPAGE  
 
 
Lift
Elite Veteran
Location: Houston, TX

Kabaaam!!! There ya go dude!

Hope you get it worked out. That seems like a pretty decent response to me!
04-17-2003 Over year old.
 
 
gwallace1
Veteran
Location: Susanville, CA

Good job Dennis! Hope to see you more on the forum.

Greg
04-17-2003 Over year old.
HOMEPAGE  
 
 
nheather
Veteran
Location: Horsham, West Sussex, UK

Dennis,

Thanks very much for your kind response. I've already purchased replacement parts from your UK distributor, but I'll still give you a call after the easter holidays (vacation).

Thanks again,

Nigel
04-18-2003 Over year old.
 
 
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Century Hawk - Falcon - Raven - Predator > Hawk Sport - Dead Clutch
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