AK Rotors

[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...

[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]

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...

[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 ????

[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]

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]

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

[Brian]

Don't get me wrong. Robs Rotors Are great, give a great ride & give lots of lift & are very forgiving & got me out of some tough spots but i disliked the shake. Especially when you do thousands of hours getting shaken!
Have to say in i have a ak hub bar Jeff did for me that had 2* pitch built into it that vibrated &that wasn't pleasant either. Good whinger me !

[tonydenton]

whoops. that was just me in parrot fashion. repeating only what I had heard from 1 side of the story. [ opposite to spreading rumors ].

[Brian]

That's okay tony, I'm only one of hundreds of robs customers but making a point that there's a lot in the way rotors /hub bars ^ heads are built & everyone will have a story or two to tell.
An interesting fact I have found is that hub bars with .8 of a degree pitch will have less shake than a bar with 2 degrees pitch & that's simply cause it's not grabbing as much air & the more weight up the top of the mast the more shake you get &the heavier the gyro the more shake.
Hope I have confused everyone enough.

[tonydenton]

well anyway for the first time [ many years but low hours ] mine was getting worse and after the tune up , which wasn't much [besides the new bearings, and a smidgeon off cotton reels, I HATE SHIMS ] all was sweet again. so basically things can happen that is out of the control of one supplier or the other I think.

[Brian]

Doesn't take much to upset things & i dislike using shims .

[GraemeMonro]

Doesn't take much to upset things & i dislike using shims .

Each to their own Brian, I saw some shims in Singapore once , no way....

[RossM]

I saw some shims in Singapore once , no way....

That is your story anyway Graeme

[TROOPER]

Each to their own Brian, I saw some shims in Singapore once , no way....

Hmmmmmm, good 'horror day' was it? Not long got back from Bangkok. One regular comment from the 'broom pilot' while we were there was 'I wish my boobs were as big as his!!!'.

Sorry to hijack the thread Gents.