AK Rotors

[Brian]

A warning for those buying new AK rotors or new hub bars. Seems one hub bar has turned up with a plate between the pillar block & the hub bar. Totally unacceptable.
Also check once fitted rotors fitted to gyro that you have the full amount of teeter clearance because one set of AK's did NOT have the required clearance, fortunately the pilot had enough experience to recover from the hammering that came through the stick when he tried his first turn.

[tonydenton]

I have just fitted new bearings into my Patroney Rotar head last week . and tweeked a couple of cotton reels. it was actually satisfying to familerise myself with it all pulled apart , been that long a good check up was overdue.
I don't turn in mine , I just fly straight and level..

[Brian]

Its good to get to learn as much as you can about those extremely important bits of your gyro so that if something is not right, you can identify it & get it fixed.

I once flew for 3 hours in a straight line, will never forget it ! into a howling headwind ( 40 Kilometers per hour) ground speed ) and rough as guts to boot, however I was flying the Rosco ! Had I been in the Green machine, it would at least been a nice smooth ride

[Tsemler]

Is that your rotorhead Brian? It was brought to my attention that a bloke over this way has found a crack in a rotorhead similar in design (one piece) to the head in your picture. Hopefully the photo is below... (crack is in the corner)

[RossM]

Your photo Trent is of a Gyrotech rotor head, made at Inverell (I think) in Northern NSW.
retired years ago.
also made rotors, which there is a AD on.
http://asra.org.au/application/files...tor_Blades.pdf

Brians photo, is this a Revolution by Rob Patroney?

[Tsemler]

Thanks Ross, I knew it wasn't a Patroney Head, I couldn't remember the name of the manufacture when I posted it, but I do recall Gyrotech being mentioned, Thanks

[Tim]

Totally unacceptable.

Like the nyloc nut on the teeter bolt.

[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.

[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. .

[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.

[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 .

[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

[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.

[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 !!

[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.