Stick shake

[500E]

Have a 500N with lateral stick shake, new spigot bearings, new uniball,

droop stop bearings, rolers, plates,ETC.

The shake is there without the blades fitted, the head is ballanced to about 0.03 ips.at 100% there is about 1\4 inch shake,

Have had discusion with MDHI & followed their recomendations to no avail.

Maddness is close any input ideas are welcome

[Jaybee]

Need the mass of the blades to absorb the vibration ?

[500F]

.03 is ok, likely not your main problem but we wont settle for more than .02. Usually we can get .00.

Check the bell cranks in the mixer assembly. Might have some slop in there.

[Spike]

If I remember correctly, when you run it up, insure your frictions are all the way off…. If that doesn’t work, forget about your .03 and go back and set everything to nominal and start over from the beginning……

[Guest pokey]

i'm sure you already checked the scissor link for no 360 degree binding?

[500E]

Thanks all, 500f & Pokey yes have checked these, Spike all set to datums frictions off, Jb you do not require blades to balance head.

500F yes we normally get lower ips as well have had head off twice to check for anomalies as Pokey said we gave close inspection to SL for any damage, bell cranks have No wear in them, the darn thing has only flown 1200 TT.

No straps broken.

Has had to have pitch bearings & pins, droop stop plates springs rollers bushes, uni-ball. ETC. (big parts bill)

Never had a 500 that has stick stir without blades on.

Checking lateral trim unit, spring appears to measure short 2mm & wire size not as manual, will keep you informed.

[Hobie]

Still waiting for IChris to weigh in. In the meantime, here is a totally wild guess.

 

Wondering if the shake was a 1 / rpm of the main shaft? Since it is l/r shake it may a small nick or gouge that the swashplate hits/tracks at the same position each turn. But then again, you said it only happens at 100% power. So, probably not....

 

I hope you find it and post answer. Good mystery.

[500E]

Hi Pokey

No it is there all the time to a greater or lesser extent, have been over the SP with a x10.

Checked gear box, bolts mast support fixings, Spring did not cure it.

It is driving us Nuts.

Wondering if we have not been told all the story even after asking a couple of times if there is anything we should know

[RagMan]

Find the cause of the problem yet?

[500E]

We had a feeling there was more to it than just routine problem, we have now been told there was/could have been an incident!! much easier if we had been told in the beginning.(we did ask)

At the start we were told It had had a new blade due frost damage ?, & a pitch housing due to wear, we found same color damper would not stay at datum fitted new set cured that, But could not cure the stick shake.

Head off & returning to MD for check of strap pack for internal damage, the whole thing is strange with so many things badly worn in so low TT.

Could turn into a real $$$$$$ pit, hate these sort of problems if head U/S then blades scrap shaft MGB & so on level 2 strike.

It has been like drawing teeth without anesthetic