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First Flight Lessons - Nose Wheel pre load

Aussieflyer

Active Member
Dear RV14 colleagues,

VH-XIV our RV14A has had its first flight. Apologies when I learn how to upload photo's I will post same. However we have found an important lesson that those following should take note. We followed the plans regarding preloading the nose wheel. On first flight it flew beautifully and again the Van's grin quickly filled out test pilots face (sorry we didn't have enough hours on type to first fly it ourselves - that's safety - we began flying it for its second flight).

On the first landing the nose wheel shimmed (oscillated left to right violently). We immediately removed the split pin and tightened the nut on the castering wheel. All was good for the next two or three landings and then again the nose wheel started shimming on landing. Spectators on the ground said it looked scary. Pilot in the plane (self) thought it was a little scary too. The nose wheel steering nut again took up another flat of tightening. All is good again. However I suspect while the bearing settles in another tightening may be expected.

We have removed the damaged wheel spat and intersection fairing for repairs. They will not be replaced until we are confident that the nose wheel pre-tension is finally set and no adjustment is necessary.

Recommend all builders leave nose wheel pants and intersection fairings off for initial flights. Recommend all builders carefully inspect the pre-load tensions on the nosewheel at construction, then after pushing the aircraft around the hangar and other maneuverers such as down to the fuel bowser and back. Make sure the nose wheel always stays within pre load tolerances otherwise you can expect an uncomfortable landing and possibly some damage. Hope advice is helpful for those to follow. What a wonderful aircraft!!!
 
Congratulations on first flight. 25 hrs. on mine and zero shimmy noticed so far. I will check friction before next flight to see if it has changed since original. I had been moving the RV around the hangar for quite a while before adjusting the friction days before first flight. This might have made a difference. Also all the aircraft weight (as in aircraft was finished) when friction was set, this might make a difference from when the plans have install the nose fork with out the engine.
 
Congratulations Alan and Susanne

Looking good guys !

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First Engine Start

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Ready for First Flight

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Blue Skies ahead !
 
When I was building there were two camps regarding whether to have pants and fairings on for the first part of the test regime. I went with no pants or fairings to ensure that the plane flew straight without them and to keep the speeds lower at engine break-in power settings. I also had to solve shimmy issues on both nose and main gear and was glad I didn't have the pants and fairings on.
 
Alan,
Congrats on first flight.

In regards to shimmy, make sure you are measuring the pull by pulling at the axle.
An over inflated nose tire will also increase the chance of shimmy.

It is normal for the friction to settle in as the airplane acquires hours, and require readjustment, but I would bet that the friction was not correct when the airplane left the ground the first time. It would also be very unusual for the adjustment to change a lot on each of the first few flights.
Readjustment at 5-10 hrs and then again at 30-40 usually takes care of it.


Dear RV14 colleagues,

VH-XIV our RV14A has had its first flight. Apologies when I learn how to upload photo's I will post same. However we have found an important lesson that those following should take note. We followed the plans regarding preloading the nose wheel. On first flight it flew beautifully and again the Van's grin quickly filled out test pilots face (sorry we didn't have enough hours on type to first fly it ourselves - that's safety - we began flying it for its second flight).

On the first landing the nose wheel shimmed (oscillated left to right violently). We immediately removed the split pin and tightened the nut on the castering wheel. All was good for the next two or three landings and then again the nose wheel started shimming on landing. Spectators on the ground said it looked scary. Pilot in the plane (self) thought it was a little scary too. The nose wheel steering nut again took up another flat of tightening. All is good again. However I suspect while the bearing settles in another tightening may be expected.

We have removed the damaged wheel spat and intersection fairing for repairs. They will not be replaced until we are confident that the nose wheel pre-tension is finally set and no adjustment is necessary.

Recommend all builders leave nose wheel pants and intersection fairings off for initial flights. Recommend all builders carefully inspect the pre-load tensions on the nosewheel at construction, then after pushing the aircraft around the hangar and other maneuverers such as down to the fuel bowser and back. Make sure the nose wheel always stays within pre load tolerances otherwise you can expect an uncomfortable landing and possibly some damage. Hope advice is helpful for those to follow. What a wonderful aircraft!!!
 
...

It is normal for the friction to settle in as the airplane acquires hours, and require readjustment, but I would bet that the friction was not correct when the airplane left the ground the first time. It would also be very unusual for the adjustment to change a lot on each of the first few flights.
Readjustment at 5-10 hrs and then again at 30-40 usually takes care of it.

Scott,

Do the factory RV's start off with dry or greased Bellville washers?
 
You probably really won't be adjusting them within the first couple flights, like Scott said. Maybe after 5-10 hours and then before 50 sometime. The RV-14 and RV-10 are the same basic nosewheel assembly and it's the same deal with those. They will loosen a lot in the first few hours, then after a short bit they will loosen again. After that they don't change very much anymore and you can check it at annual time. This is very common on the -10. I made sure to crank that nut over tight the first time, then backed it off to the required breakout force. It may help to give it a good firm crank when you first assemble it. Mine didn't loosen up too badly.

The one change that I myself did though was to use a higher initial force for the first go-around. I put mine around 30-35lbs, which definitely is stiffer, but by using that setting it didn't loosen up nearly so badly. I used the same setting on the RV-10 for the 2nd torquing and it ended up loosening up fairly quickly into the mid-20's. So while I don't think deviating from the plans is necessary, it may give you a little longer run before it gets real loose. The change is pretty dramatic in how loose it does get as they wear in. Thankfully it only happens a couple times.
 
Many Congratulations

On a great first flight. Steve has been keeping me up to date and sent pics by email yesterday. I am glad to read you got her off. More Experimentals for Redcliffe!!!!!
 
Greased bellville washer ..

If you grease them by installation and set the preload like this, it will stay greased and nothing will change. If you have them dry, and they get some grease, the situation change.

Also you can grind at the contact point between the two bellville washer a radius instead the sharp production egde, then there will be much less change.

Dominik
 
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