Rotor Balance "Qualifications"

[Mike G]

In another thread I bought up the question of who is “qualified” to balance an autogyro rotor.

I was reading the Aviomania manual that states that :
“The complete rotor system may be balanced further to reduce stick shake. This task must be performed by a qualified person."

I unwittingly put Nicholas of Aviomania on the spot by asking what qualifications would be necessary to be considered “qualified”.

That was unfair of me because I suspect that all manufacturers’ manuals would require that any rotor balancing be done by a “qualified” person. If it isn’t clearly written (as in the Aviomania manual) I’m sure it’s implied.

So my question to the manufacturers’ representatives on this forum is
“What qualifications do you consider necessary to balance one of your rotors?”

I regularly balance rotors and have no formal “qualifications” but in France the rules for ultralights are sufficiently vague to allow this. How does this work in other countries?
Mike G

 

[phantom]

I think in most places you would be qualified to balance the rotor of a home built craft, the only exception mey be Britain they seem to have an incredible amount of stupidity that they gave to deal with due to way to many years of their citizens blindly following the rules and not enough government officials being killed by citizens, governments should always have at least some fear of the people that they lead.
I think it is more important that anyone has a working knowledge of how and why a rotor works and what needs to be done to correct a problem than any papers on the subject, I have built and flown many rotors but I have no papers that says that I can do anything to a rotor, I just had to learn what works and what didn't.
Norm

 

[All_In]

Hi Mike

First I do not have the experience to even knowing who is qualified here in San Diego to balance blades so you can evaluate my inexperienced anwser.

Second, in the states there is no qualification certificates to balance the blades.
If you need a log book entry then you would need at least an A&P to observe the person balancing them so he could write up the log book entry. Else anyone here could buy the equipment and open a shop.


What I will do is either find a PRA or gyro brother with the equipment and experience in balancing blades and learn how by watching. Then I'll buy the equipment and try and teach myself.

The main qualification I'm looking for is someone with experience balancing a few and know how to read the data produced by the equipment and be able to know where to place the weight that the only qualification that matters.

Or I will ask around locally who had done a good job balancing helio's?

 

[JEFF TIPTON]

Typically the qualification comes from either performing the balancing under the supervision of someone who is qualified, or attend a training course for the manufacturer of the balancing equipment being used.

 

[WaspAir]

in the states ...
If you need a log book entry...

You do need an entry.

 

[All_In]

You do need an entry.

Thank you Jon I really wasn't sure.

And PS:
Mike buddy from reading your posts on balancing and use of equipment, and teaching how to use the equipment, you are qualified!!!

 

[Uncle Willie]

Mike,

As you stated, in France and many other places the rules are vague enough that the authorities can declare you as being Un-Qualified AFTER anything goes wrong.

This may sound like a humorous reply, but there is a lot of truth in it.

If you are confident and you think you are qualified, you probably are.
If you don't feel you are qualified, you definitely aren't.
If you balanced the rotors and they ended up better than they were when you started, You're Qualified!
If you attempt to balance the rotors and made them worse, you were not qualified.

Most Importantly; If you were the last person to touch the rotors before an accident caused by a rotor problem,
you can be sure the legal authorities and the manufacturer are going to declare that you were unqualified to perform any maintenance on the blades.

Qualified or Un-Qualified is the Cover-All to assign blame AFTER the Fact!

 

[Jincamty]

That is going on my wall. So true!

 

[PW_Plack]

So my question to the manufacturers’ representatives on this forum is “What qualifications do you consider necessary to balance one of your rotors?”

Mike, that's a little vague. Balancing, tracking, pitch adjustment, lead/lag, centering in the teeter towers are all operations done routinely by owners of experimental gyros in the US. Since anyone can legally do this on an experimental here, anyone is qualified under FAA regulations.

Every time a Dragon Wings owner arrives at a fly-in, assembles his blades and "strings" them, he's adjusting lead/lag and balance, and then centering when he mounts the rotor. Is anyone suggesting this requires an entry in the maintenance log every time it's done?

As time goes on, the two-place machines seem to be moving toward less and less hands-on involvement by owners and pilots, are more likely to be factory-built, and are more likely to be hangared than trailered. Perhaps, in that environment, the services of a specialist are required, and formal log entries more appropriate.

 

[All_In]

mike,

as you stated, in france and many other places the rules are vague enough that the authorities can declare you as being un-qualified after anything goes wrong.

This may sound like a humorous reply, but there is a lot of truth in it.

If you are confident and you think you are qualified, you probably are.
If you don't feel you are qualified, you definitely aren't.
If you balanced the rotors and they ended up better than they were when you started, you're qualified!
If you attempt to balance the rotors and made them worse, you were not qualified.

Most importantly; if you were the last person to touch the rotors before an accident caused by a rotor problem,
you can be sure the legal authorities and the manufacturer are going to declare that you were unqualified to perform any maintenance on the blades.

Qualified or un-qualified is the cover-all to assign blame after the fact!

brilliant!!

 

[Aviomania]

Hello Mike and sorry for not clarifying this earlier for you.

Some countries require that the person touching the gyroplane ( for maintenance, balancing etc. ) must be approved by the competent authority. So..... for us to avoid any legal issues we state in the manuals that an authorized person must perform any maintenance.

In countries that the owner / operator is the person responsible for the maintenance then he is authorised to do it..... he might not be qualified... but he is allowed.

We as Aviomania Aircraft can authorize someone to perform maintenance ( or rotor balancing) and issue a certificate. this will require training and an interview / exam for the complete maintenance Aviomania Certificate.

For rotor balancing (and with your experience) a skype training and explanation of the accepted adjustments of the rotor system is enough to issue a certificate.

This certificate can then be presented to the competent authority (if required by it) and it MIGHT be accepted in order to be authorized by that authority.

 

[Mike G]

Thanks guys for the interest in this.
Paul (Plack)
You’re right I should have said “balancing, tracking, pitch adjustment etc” but that would have made the title of the thread too long.

Norm
It seems that in the US most gyros are officially homebuilt/experimental so the owner/builder can do pretty much what he wants. I understand that even the eurogyros (except perhaps the latest AutoGyro certified machine) are 51% owner built so my question probably doesn’t apply unless there is a factory manual that says or implies a qualification requirement.
I agree with your thoughts but I’m stuck with this word “qualified” and the legal ramifications in the event of an accident.

I think Uncle Willlie summed up the problem well in that the authorities will take the manual text and demand to see some sort of “qualification” (after the accident of course).

Here in Europe we have different requirements per country and I can see that globally Nicolas and the other manufacturers have a tough time writing something in the manual that suits everybody.

The problem for me is that once you write “qualified” you open the door to misuse by the authorities and create the requirement to define how one becomes qualified.

Nicolas
Thanks for your informative and positive reply, I will contact you about skype training, I might even come out to Cyprus for a little holiday.

Jeff (Tipton)
In my opinion the problem with asking the balancer manufacturer for training is that most of the balancer manufacturers have a wealth of experience balancing helis and assume that an autogyro will be a piece of cake. I’ve found that autogyros require a slightly different approach and that the gyro manufacturers are probably better placed to do the gyro specific training.

John
I’ve said this before, when I started promoting the Smart Avionics PB3/4 balancer I encouraged everybody to buy one. I now regret that because I realise with time that using a balancer efficiently requires a certain degree of technical competence and, like any computer program, needs to be practiced regularly to avoid going up the learning curve every time you take it out of the box. My recommendation is that you should buy a balancer as a group (or PRA chapter) and choose the most enthusiastic technically minded member to do all the balancing of the groups gyros. This way the group rapidly acquires a “memory” and a data base making each operation faster and more efficient.

Mike G

 

[ckurz7000]

I agree with Mike: simply having the equipment does not make you a person qualified to balance rotors. You need experience und some theoretical understanding.

I would estimate that balancing 2-3 gyros together with an experienced person (about 2 days' worth of balancing time, maybe) would give a technically minded person enough experience to continue learning and gather experience by himself from then on.

-- Chris.

 

[Mike G]

One thing that is missing from all of the manuals I've seen are vibration limits.

example
1/rev < X IPS OK
1/rev < Y IPS recommend balance
1/rev < Z IPS mandatory balance
1/rev > Z rotor removal inspection & balance

2/rev < ? IPS acceptable
2/rev > ? IPS unacceptable return to factory

Obviously you'd need to specify where to measure these vibrations.

Does anybody have any data like this?

Mike G

 

[WaspAir]

Every time a Dragon Wings owner arrives at a fly-in, assembles his blades and "strings" them, he's adjusting lead/lag and balance, and then centering when he mounts the rotor. Is anyone suggesting this requires an entry in the maintenance log every time it's done?

Yes.

Maybe your FSDO will think otherwise, but I've had an FAA Inspector tell me that every time I pull my sailplane out of the trailer, put on the wings and slide in the locking pin, I must make a log notation. There is no rigging or adjustment to be done in that operation. Compare that to stringing the blades, which changes the behavior of the system.

If nobody ever looks at your logs, there may be nothing to worry about, but the FAA can show a real instinct for the capillaries from time to time.

 

[Cammie Patch]

Actually, for aircraft in the experimental category, there are no requirements for a logbook entry for anything other than condition inspections, transponder checks, or 100 hour inspections if they are required.

In the USA, anyone can do maintenance on an experimental aircraft.

Despite all that, I recommend treating an experimental just like a standard category aircraft; complete all AD/SDs, and log all maintenance.

I don't recommend replacing parts on a time in service basis however, except for rubber parts. I find that replacing on condition is the safest route, and the military agrees with me. Google the "Waddington Effect" for the background on this protocol.

Rotax previously had a 5 year "mandatory" rubber parts replacement schedule. The FAA told them that they could not make regs, so now it is not required. For fuel and oil lines I recommend "on condition", but for the coolant lines, it has been found that electrolysis occurs in the hoses where there is turbulence caused by the fittings, and they tend to degrade there. Because of this, you would be wise to replace the coolant lines every five years.

 

[Vance]

I find value in logging maintenance.

I find value in logging maintenance.

I log the maintenance on The Predator and sign her off as airworthy.

I have found it useful on several occasions.

As part of my LODA I am required to have hundred hour inspections in addition to my annual inspections. I use an Airframe & Power plant mechanic with inspection authority.

I was told by a representative of the Van Nuys FSDO that I needed to log replacing my gas caps.

I typically just replace them when the gasket begins to show signs of cracking. They seem to last about two years.

I felt this was apposite advice as a gas cap gasket swelling and covering the vent had led to an inflight engine stoppage.

I had not previously logged replacing the gas caps and none of those who had done my annuals and 100 hour inspections had logged the cap replacement.

It turns out it is important on some fixed wing aircraft because it the cap leaks it can allow water get into the fuel when left out overnight.

I mention this because I feel there is value in logging all maintenance.

 

[bryancobb]

As You Know

As You Know

One thing that is missing from all of the manuals I've seen are vibration limits.

example
1/rev < X IPS OK
1/rev < Y IPS recommend balance
1/rev < Z IPS mandatory balance
1/rev > Z rotor removal inspection & balance

2/rev < ? IPS acceptable
2/rev > ? IPS unacceptable return to factory

Obviously you'd need to specify where to measure these vibrations.

Does anybody have any data like this?

Mike G

On U.S. Type-Certificated aircraft, the manufacturer usually determines and publishes these specific numbers. Less specific but accepted FAA limits are published in _?? I cannot put my finger on it but the FAA standard is 0.3 IPS or below. Robinson Helicopters` max on the R-44 is 0.2 IPS.

 

[JAL]

Mike,

A good idea it to "assist' the owner. That is that you help them balance the rotor, or do it for them under their supervision, and they sign the logbook if required.

If they do not want to take the responsibility then you shouldn't touch their gyro anyway as you are exposing yourself unnecessarily to possible legal action later.

If they won't sign the logbook then they have to take it to a proper shop and pay the price, that is if the shop will touch a gyro.

 

[scandtours]

I read this post with great interest.
Why not opening a thread with discussions, ideas, experiences and how curing the problem so that everybody can learn something.
I can start with Dr. Igor Bensen ‘s advices on how to identify and then cure the problem. Below is what he wrote in his “Bensen Flying News “ and if it’s of help I can send the whole reading.
I send also a video that it is possible to fly the rotors without vibrations. It shows that I could fly hands off continually and without touching the stick flying from point A to B to C and so on. I shouldn’t be able doing this if had stick shakes. I have plenty of videos on YouTube demos trading this with Granny Genesis.