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Old 01-10-2017, 09:41 AM
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Cammie Patch Cammie Patch is offline
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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.
Cammie Patch
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Old 01-10-2017, 10:43 AM
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Vance Vance is offline
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Default 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.
Regards, Vance Breese Gyroplane CFI
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Old 01-10-2017, 05:30 PM
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bryancobb bryancobb is offline
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Default As You Know

Originally Posted by Mike G View Post
One thing that is missing from all of the manuals I've seen are vibration limits.

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.
Bryan Cobb, Helicopter Enthusiast
Mfg.Engineer., Composites, Meggitt Aerospace, Rockmart, GA

Last edited by bryancobb; 01-10-2017 at 05:58 PM.
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Old 01-10-2017, 10:46 PM
JAL JAL is offline
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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.
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Old 01-11-2017, 11:19 PM
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scandtours scandtours is offline
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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.
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Last edited by scandtours; 01-13-2017 at 06:29 AM.
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Old 01-12-2017, 10:30 AM
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Mike G Mike G is offline
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I'm 100% behind you if you want to start a new thread "with discussions, ideas, experiences and how curing the problem so that everybody can learn something." and yes please post the rest of the Bensen article, there's always something to learn from old timers.

However, I think you'll find that it has been tried before and the real problem is that unless people like Nicholas is prepared to tell us how he achieves such low levels of vibration (I wouldn't give my secrets to the competition if I was him) we will descend into the subjective "my rotors are as smoother than yours" type comments that get us nowhere.

I have absolutely zero faith in any subjective assessment of gyro vibration by "feel" and ignore anything I see written because I regularly MEASURE gyro vibration and often find that what I felt was an improvement or degradation in vibration was the actually reverse or no change at all when I look at the measurements.

I have balanced over 50 different eurogyros of all types and despite reading on different forums that "my rotors are butter smooth" I have never come across a gyro that didn't vibrate. Maybe I'm just unlucky or it's because people only come to me when they're in trouble but I always measure vibration outside accepted limits.

I recently had two extreme examples.
1) In Senegal I "tracked" the rotor of a popular Eurogyro and reduced the synchronous (1/rev) vibration from over 1.0 IPS to below 0.1 IPS and the owner, who had tracked it using the "flag" method, felt it was better before. I showed him the vibration data but he insisted so we "detracked" it back to his setting and I flew the gyro again. I must confess that even though I could feel the 1/rev vibration due to the tracking there was a sort of comfort in that 1/rev "galloping horse" feel that wasn't there when the 1/rev was eliminated.

2) I was recently asked to do a vibration analysis and balance of a new prototype eurogyro from eastern Europe. The rotor was badly unbalanced in chord and we quickly realised it was due to the misalignment of the blades. I realigned them and by further balancing reduced the 1/rev from 0.7 IPS to below 0.15. The test pilot insisted that it "felt better" before. He then asked his second pilot fly it and he came to the same conclusion. I was in the back seat, so near the CofG, and don't get the same sensations as the pilot in the front seat but I could understand their feeling, there was something more comfortable about having that 1/rev vibration on top of the 2/rev.

Over time as I balance different rotors I've often felt that as I reduced the 1/rev (balance and tracking) vibration the 2/rev increased. Looking at the data this isn't true, usually the 2/rev remains pretty constant. I don't even trust my own feeling when it comes to vibration.

If people are prepared to post real data then it can be useful, otherwise it's just "opinion engineering" filling cyberspace.

As an old time engineer once said to me "give me the data and I'll give you my analysis, without data I'm just another poor sod with an opinion".

Mike G

Last edited by Mike G; 01-12-2017 at 10:55 AM. Reason: sent before finishing
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Old 01-13-2017, 05:50 AM
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scandtours scandtours is offline
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Sorry, this is the video I wanted to share, with no stick vibrations.
Flying AVIOMANIA GENESIS G1sa with hands off unlimited it is possible, as the video shows here below. You can use stick on the ground (during rolling for take off) and as soon you reach an airspeed of 40-45 you can leave your hand off it. Fraction of a second later the nose wheel of the gyro will lift off, the machine will climb and level by itself by using throttle only. You can enter a turn or make a 360 turns by applying a light pressure on resp petal. Note stick reactions when using rudder.
No doubt ,this is not for everybody flying a Genesis. It's when you become one with your gyro.
The slight stick movements its from the wind that strikes it from the open frame..
Best watch it in full screen.

Last edited by scandtours; 01-15-2017 at 05:25 AM.
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