AK Rotors

[Brian]

Quite likely but definitely not always! first set i got were horrible, rough as guts! Second set perfect until 2nd hub bar then it turned to. .......3rd hub bar was improvement but not pleasant. Rob told me it was the rosco head causing the problems. Told that to rosco &he said ####**/$##@¥¥¥ rob .Rosco 3 D the head at least 3 times checking it but head was perfect of course. If head was problem why was second set perfect. The sad part was that i sent that hub back when rob did the 2nd bar & lost the 1st bar & nothing was the same ever again. Should have flown that 1st bar until it cracked. Quite possibly would have still been flying on that bar. Heard one bloke had done 3000 hours without changing the bar &there are some other makes with big hours out there too.Makes me wonder about what blokes do to their rotors to crack hub bars although after seeing how some fly i wonder how the gyro foesnt break in half.
Just my opion

[tonydenton]

I've had rob P tell me stories about complaints of his rotars causing stick shake and eventually had been able to prove that the gyro or parts of the gyro were to blame !

[Brian]

Its well worth getting the head checked as years ago I sold a set of 28's AK & the bloke when he took off the stick hit the dash it was shaking so much. Anyway, I bought the rotors back & tested them at Wangeratta & they were perfect .Nick Spehr also test flew them in his 2 seater & came back smiling & said he wouldn't sell them as they were so good.
Nick checked the gyro out that had the big shake & found that the head was way out of wack so that was the problem. Thought the story it was worth sharing !

[tonydenton]

Although the plate isn't ideal, it's better than in some cases having to shim under the teeter block of the Hub bar to get the blades to fly in the same plane leaving an uneven surface under the block.
wow, I've just done my first copy and paste.
so anyway , this isn't actually a shim to make the blades track .
not a bold statement to say fitting this plate wouldn't be ideal, but is it actually illegal ????? or just stupid ???
as Allan has said [ well the things he has said anyway ] it could of just been a test to check clearances of a new height that might of been required.
was it even flown ????

[Tsemler]

I wouldn't of thought so Ross, there's a lot of pilots out there that aren't ASRA Members and live in their own little world.... You can lead a horse to water but can't make it drink...

[RossM]

Just to clarify this isn't my fix, I only heard about the problem.

Hi Trent,
Who had the Gyrotech rotor head? (I have one, and there a a few about).
Is it going to be reported on the incident reporting system?

Regards....Ross

[Tsemler]

Ahhh Trent,

Seems the consensus here is that a plate between the hub bar and teeter block is not a good idea and I agree. So your suggested fix for excess teeter is not what pleases. My suggestion would to build up the teeter stops with a suitable nylon type material or a machined aluminium plate matched to the teeter angle at the stop point. The recommended teeter is +/- 9*, total 18* and the minimum recommended is total 16*. As an aside, the manufacturer in question uses a CNC machine for all his components so it is highly unlikely that it was accidently machined too short, assuming of course that the faulty rotor system was from the manufacturer in question.

Another sixpence worth from me.

Waddles.

P.S. It is interesting that none of the problems that are often discussed in this place are never reported to ASRA. It is possible to use the Incident reporting system to report a defect. If it's done that way, there is a positive paper trail and that helps.

Hi Allan,

Just to clarify this isn't my fix, I only heard about the problem. I agree that limiting the teeter on the rotorhead is a better idea, so long as you aren't swapping blades often and you don't sell it to some not knowing that the rotorhead has been altered.

I believe, not confirmed, this was a batch CNC issue, discovered after arriving in Oz.

Although the plate isn't ideal, it's better than in some cases having to shim under the teeter block of the Hub bar to get the blades to fly in the same plane leaving an uneven surface under the block.

So long as the plate isn't smoking (movement) and it's correctly tensioned I can't see the problem. But that's my opinion. As always it's upto the manufacturer to make that call as to if it's okay or if they exchange it for a new one...

[Waddles]

if this is the issue I've heard about, the teeter block on the hub bar was machine off too much when built, creating too much teeter and therefor the Hubbar contacted the ring gear or electric prerotator. By fitting the spacer between the teeter block and Hub bar it got it back to the required clearance.
Hope I've explained that clearly enough to understand

Ahhh Trent,

Seems the consensus here is that a plate between the hub bar and teeter block is not a good idea and I agree. So your suggested fix for excess teeter is not what pleases. My suggestion would to build up the teeter stops with a suitable nylon type material or a machined aluminium plate matched to the teeter angle at the stop point. The recommended teeter is +/- 9*, total 18* and the minimum recommended is total 16*. As an aside, the manufacturer in question uses a CNC machine for all his components so it is highly unlikely that it was accidently machined too short, assuming of course that the faulty rotor system was from the manufacturer in question.

Another sixpence worth from me.

Waddles.

P.S. It is interesting that none of the problems that are often discussed in this place are never reported to ASRA. It is possible to use the Incident reporting system to report a defect. If it's done that way, there is a positive paper trail and that helps.

[Brian]

I was told they came out of the of the shed that houses only AK rotors. It is possible someone had previously taken that hub bar & had put that spacer plate in & then returned it without it being checked by the person handling the ak rotors.

Thanks Jeff . It does warrant getting to the bottom of for everyone's sake.

Having said that, I think its good practice no matter where you buy from to have a very careful look & check out the hub bar & rotors for scratches / dings etc, during assembly make sure hub bar is firm in the straps, string line them. Put them on the gyro checking clearance in the towers & check clearances between blade & prop & tail . Make sure you have plenty of teeter & nothing is binding.

Always good practice when you have taken the rotors off to give the head a good spin to check the head bearing. It seems some people believe they never wear out ! That awful grinding noise is NOT good & if not replaced will end in tragedy !!

[jeff b]

I have made contact with the AK manufacturer in NZ. The manufacturer advised they have never sent out a head block with a spacer plate. Are the teeter towers from another manufacturer, and consequently not suitable for this AK head block? I'm checking. Regards, Jeff B. Ops.

[Tsemler]

if this is the issue I've heard about, the teeter block on the hub bar was machine off too much when built, creating too much teeter and therefor the Hubbar contacted the ring gear or electric prerotator. By fitting the spacer between the teeter block and Hub bar it got it back to the required clearance.
Hope I've explained that clearly enough to understand

[Brian]

Eric can't log in here but he's going to post on gyrocopters Australia face book so hope that helps. He did say that hub bar was purchased from a well known bloke who has a sizeable stick of aks .

[Brian]

It's not my gyro or hub bar. Allan is spot on in regard to rotors matching the head & i have to say i haven't that information in regard to these examples.
I will see if Eric can post that information so we can check on what make rotor heads were involved. Speculation is not helpful but I think its serious enough to be careful.
I have bought 2 new hub bars from Jeff Price & both have been spot on.

[tonydenton]

how do they get on with the 2 bolts [ IN LINE ALONG THE CENTRE OF THE HUB BAR ] compared to some others that offset the holes , compared to the Goodwin rotars with only a centre bolt and 2 small short dowels.
in the original forum 1.0 there was some stuff happening about some hub bars cracking did that get sorted ??? thinking now it was probably when a total hours flown rule came in. nearly half way there for me to the total hours on hub bars. cause that's nearly 12 years too. .

[Waddles]

Might pay to find out who put the plate there before blaming the manufacturer outright. I know one distributor has $60,000 worth of blades in stock and none have a plate like this one!!

Not enough teeter in standard AK rotors??Sounds like the rotors didn't match the head. So, was a custom order made for a teeter or pillow block of specific dimensions or did the customer just order stock standard hub bar?? If a standard hub bar was ordered, I don't think the manufacturer can be blamed which seems to be the insinuation. Hope I'm wrong.

Regards,

Waddles.