Unsolved issues

[Hotscam]

I have been on holidays with the PH-SEP and visited 5 countries and did close to 60 hours.*
She is great and very few problems. Skyview 4 is in now and its quite an improvement.

Its a great plane.

I have however two issues I would like your opinion about

1. The rear window is starting to crack all over the place for some reason. All short 1/2 to one inch cracks random spread over the window. Not on edges or from drilled holes but all over and also on flat hardly bent pieces..
I know Lexan is sensitive to AVGAS but we fly Mogas which is less agressive and never spilt on the window. Moreover the cracks are also on the complete other side of the window away from the fuel cap. I saw on the forum more people experience this problem. What to do?

2. The nose gear still has a bad shimmy. I had the tyre balanced, adjusted the side force in steps from 10 up to 30 lbs. 22 lbs seems the best compromise between shimmy an good steering.*
At real low landing speed (50-55) and stick full up after touch down its not so bad, but when braking on short paved runways is required the nose goes down and its feels pretty bad.*
I am afraid it will break some time.*
Is there no way to dampen this by a gas damper

 

[Dave12]

I know Lexan is sensitive to AVGAS but we fly Mogas which is less agressive and never spilt on the window. Moreover the cracks are also on the complete other side of the window away from the fuel cap. I saw on the forum more people experience this problem. What to do?

Sounds like the attachment screws might be too tight. They should not be tight and should turn with little or no pressure using a screwdriver.

 

[RFSchaller]

Is your plane hangared? Ultraviolet rays can cause the lexan to degrade.

I have never had a shimmy problem, but read many accounts about it. Try checking the force it takes to turn the nose wheel. The plans seemed excessive (26 lbs if I remember correctly) but I set my tension to plan and have near had a shimmy.

 

[rvbuilder2002]

I have been on holidays with the PH-SEP and visited 5 countries and did close to 60 hours.*
She is great and very few problems. Skyview 4 is in now and its quite an improvement.

Its a great plane.

I have however two issues I would like your opinion about

1. The rear window is starting to crack all over the place for some reason. All short 1/2 to one inch cracks random spread over the window. Not on edges or from drilled holes but all over and also on flat hardly bent pieces..
I know Lexan is sensitive to AVGAS but we fly Mogas which is less agressive and never spilt on the window. Moreover the cracks are also on the complete other side of the window away from the fuel cap. I saw on the forum more people experience this problem. What to do?

2. The nose gear still has a bad shimmy. I had the tyre balanced, adjusted the side force in steps from 10 up to 30 lbs. 22 lbs seems the best compromise between shimmy an good steering.*
At real low landing speed (50-55) and stick full up after touch down its not so bad, but when braking on short paved runways is required the nose goes down and its feels pretty bad.*
I am afraid it will break some time.*
Is there no way to dampen this by a gas damper

Here in the U.S., mogas is the main problem with the lexan rear window. Particularly mogas with ethanol.

Has someone actually seen your nose wheel shimmy while you land? Are you certain that you are measuring the breakout force properly? The measurement is intended to be done with the pull location adjacent to the wheel axle. If you have adjusted the breakout properly, through that wide of a range (after also balancing the nose wheel), I would suggest you look at the mains.
Make sure both of your gear legs are still tight. Have someone watch your landing and take note of what they see.


BTW, I wouldn't classify a 50-55 kt landing in an RV-12 as being really slow.
An RV-12 flying at gross weight, stalls at 45 kts with no flaps. Landing with full flaps and typically at much less than gross weight, with the influence of ground effect, touch downs at about 40 kts are common. This is more of what would be classified as slow... 50-55 is more in line with many of the other 2 seat RV's.

 

[crashley]

nose wheel shimmy

Hi I had nose wheel shimmy which I found to be caused by a faulty front wheel bearing you couldnt feel it until you took the wheel off and turned each bearing independantly replaced wheel bearing now now shimmy

 

[Hotscam]

Thanks for the tips

I have never landed at 40 knots. The stall warning triggers at about 50 making me nervous. Hihi. Will try that, but on the other hand i think its too critical. I think it needs a damper some way. In sime condition you are forced to land at higher speed and break things.
I am sure i did the measument of force correct. At 35 lbs the shimmy is gone but steering at low speed is very difficult or impossible.
Also experimented with different tyre pressures Lower pressure improves but not as much as i like. Will also check the bearings as suggested.

As for the window. The plane is hangered and i am sure it is not caused by fuel.
The cracks do not appear near the filling point but the complete other side. It looks like bending stresses to me.
Any tips on better material as replacement ?