Condition Inspection Questions from an A&P

[Champ837]

I'm doing a condition inspection on a 9-A and see a note in the log from a previous inspection that the break-away of the nose wheel was checked. I'm familiar but don't know this particular procedure or how much force is needed and where it's measured from. Photos if possible. Can someone share and enlighten me.

[DanBaier]

Construction manual from a 7 (I think it's the same for 9) - Section 10 -

SETTING THE BREAKOUT FORCE OF THE NOSEWHEEL

When installing the nose wheel/fork assembly for use, tighten the nut down so it requires 14 ft/lbs of torque to swivel the fork on the axle. Measure this by rigging a small tension scale (like a fish scale) to pull in-line with the axis of the axle. DWG C1 shows this arrangement. Progressively tighten the axle nut while swiveling the fork and taking readings with the scale as the ‘‘break out’’ force increases. When the scales measure 22 pounds, temporarily safety the axle nut. Swivel the fork several times from stop to stop. Measure the pull both to the right and to the left. Be sure the scale is perpendicular to the wheel when pulling. If the sale reading varies significantly from one direction to the other, re-adjust the axle nut as required.

After the breakout force is correct, drill the gear leg for the cotter pin with the nut in place. You can drill from each side. Start with a drill that just fits the slot in the nut and drill just deep enough to get a drill point started. Then switch to the correct drill size for the cotter pin.

Dan

[WA85]

The RV-9/9A plans list a break out force, the owner may have these plans or you can get a plans CD from Vans. As an A&P maintaining several RVs, I went ahead an bought CDs for the 6, 8, 9. I would have to check the plans documents, but I believe the break out force should be in the 22-24 lbs range. The plans show how to measure it. The break out force is crucial in preventing nose wheel shimmy. There are several key inspections that need to be done on the A models pertaining to nose wheel. Make sure the tire pressure and wheel bearing drag forces are correct. If in doubt, search the VAF forum for info. Another inspection is to jack up the nose wheel and check the gear leg attachment bolt on the engine mount for looseness.

[Champ837]

Originally Posted by DanBaier

Construction manual from a 7 (I think it's the same for 9) - Section 10 -

SETTING THE BREAKOUT FORCE OF THE NOSEWHEEL

When installing the nose wheel/fork assembly for use, tighten the nut down so it requires 14 ft/lbs of torque to swivel the fork on the axle. Measure this by rigging a small tension scale (like a fish scale) to pull in-line with the axis of the axle. DWG C1 shows this arrangement. Progressively tighten the axle nut while swiveling the fork and taking readings with the scale as the ??break out?? force increases. When the scales measure 22 pounds, temporarily safety the axle nut. Swivel the fork several times from stop to stop. Measure the pull both to the right and to the left. Be sure the scale is perpendicular to the wheel when pulling. If the sale reading varies significantly from one direction to the other, re-adjust the axle nut as required.

After the breakout force is correct, drill the gear leg for the cotter pin with the nut in place. You can drill from each side. Start with a drill that just fits the slot in the nut and drill just deep enough to get a drill point started. Then switch to the correct drill size for the cotter pin.

Dan

The owner isn't the builder. He has the plans but hasn't studied nor have I. Is the point you pull from, the wheel axle?

[Champ837]

Originally Posted by DanBaier

Construction manual from a 7 (I think it's the same for 9) - Section 10 -

SETTING THE BREAKOUT FORCE OF THE NOSEWHEEL

When installing the nose wheel/fork assembly for use, tighten the nut down so it requires 14 ft/lbs of torque to swivel the fork on the axle. Measure this by rigging a small tension scale (like a fish scale) to pull in-line with the axis of the axle. DWG C1 shows this arrangement. Progressively tighten the axle nut while swiveling the fork and taking readings with the scale as the ??break out?? force increases. When the scales measure 22 pounds, temporarily safety the axle nut. Swivel the fork several times from stop to stop. Measure the pull both to the right and to the left. Be sure the scale is perpendicular to the wheel when pulling. If the sale reading varies significantly from one direction to the other, re-adjust the axle nut as required.

After the breakout force is correct, drill the gear leg for the cotter pin with the nut in place. You can drill from each side. Start with a drill that just fits the slot in the nut and drill just deep enough to get a drill point started. Then switch to the correct drill size for the cotter pin.

Dan

Once set and drilled. does it vary much over time? If it's drilled and pinned, is it changed easily?

[Champ837]

Originally Posted by WA85

The RV-9/9A plans list a break out force, the owner may have these plans or you can get a plans CD from Vans. As an A&P maintaining several RVs, I went ahead an bought CDs for the 6, 8, 9. I would have to check the plans documents, but I believe the break out force should be in the 22-24 lbs range. The plans show how to measure it. The break out force is crucial in preventing nose wheel shimmy. There are several key inspections that need to be done on the A models pertaining to nose wheel. Make sure the tire pressure and wheel bearing drag forces are correct. If in doubt, search the VAF forum for info. Another inspection is to jack up the nose wheel and check the gear leg attachment bolt on the engine mount for looseness.

Is there a jack point under the fuselage?

[DanBaier]

I really think the thing you should do is to get a PDF set of the plans / manual - $10 from Vans.

http://www.vansaircraft.com/cgi-bin/...oduct=cd_plans

I'd also suggest checking the Van's website for service information and revisions - http://www.vansaircraft.com/public/service.htm.

Dan

[Taildrgr]

Once set and drilled. does it vary much over time? If it's drilled and pinned, is it changed easily?

The nosewheel uses a castellated nut to adjust the breakout tension. It should be checked yearly as the belville washers can wear. Also the nose fork has a zerk fitting for grease.

Is there a jack point under the fuselage?

I use weights on the rear tiedown to pull the nosewheel up.

[RVDan]

First, good for you in coming to a great resource like VAF. But, would you do a 100 hrs inspection on a certified airplane without a maintenance or parts manual? Hopefully not.

For amatuer builts, the maintenance manual and parts manual are replaced by the kit instructions and print package. You need them to have some idea how to maintin the aircraft. Even then homebuilders will deviate from the plans. At that point it is up to you to have enough understanding of the airplane construction and systems to properly and safely maintain the airplane, including performing the condition inspection.

No harm in asking here though, but know the free advice is sometimes very good and sometimes not so good.

[Champ837]

Originally Posted by Taildrgr

The nosewheel uses a castellated nut to adjust the breakout tension. It should be checked yearly as the belville washers can wear. Also the nose fork has a zerk fitting for grease.



I use weights on the rear tiedown to pull the nosewheel up.

I did and it worked quite well. I'm seeing your note now after I finished doing it this morning. I checked the friction and it was good too. While looking things over and remembering what someone else mentioned about checking the nose strut bolt at the top of the strut, I noticed that the bolt must have been installed before the engine mount was attached to the firewall as one could not remove the bolt as it would hit the firewall. It was installed from the bottom with the nut on top. I guess if it ever needs replacing it must have the head cut off first. Thanks!