J

justinmg

Active Member
This is not specifically a nosegear issue, more of a general engineering problem.

We are trying to remove the old nose leg of the our 9a. The bolt holding it at the top is stuck. The nut at the bottom is now loose and free.

If you are familiar with the mount, you will know that work space is very limited in that area. There is what seems to be the cabin heat airbox just above the nut head making getting a ratchet on impossible. So the only way seems to be getting a 9/16 spanner at the side. The bolt turns about 1/4 turn max, so we know it has not totally seized.

We have tried tapping the whole bolt backward and upward (it is tapered so this should help a lot), but there is a tight frame and difficult angle underneath, so this has not got us far. Prying the head up is also not helping.

How to get this very tight, but partially freed bolt out of the mounting frame / noseleg is turning out to be suprisingly challenging.

I purchased the aircraft -built, so have not had the engineering challenges that you builders have. So any ideas? How about cooling the bolt to shrink it?
I cant believe that taking the hoses and / or engine off is required to do this!

Justin
 
There should be a hole in the firewall (covered with a metal snap-in plug) just aft of the bolt head. The position of the hole will vary from plane to plane. However, you may end up removing the engine and/or the mount from the fuselage to gain better access to the bolt.
Steve
 
Possibilities

You didn't say if you have the weight off of the gear. I'm guessing you do. If not this could be putting pressure on the bolt.

Hit the area with some light oil and keep trying. At a quarter turn at a time it will take some time.

Good luck and let us know your results.
 
Hole in the firewall?

If the hole in the firewall is not there you may have to take a hole cutter to the inside of the firewall (think Dumpster diving...Or if your in England.."Dustbin diving"..)

Typically the plans have you cut a hole for a 3/4" electrical conduit blanking plug to fit into ...I cut mine for a 1" to give me a bit more room.

Once you have the hole you should have access to tap it out.

Frank..American to English translations a speciality...:)
 
justinmg said:
The bolt turns about 1/4 turn max, so we know it has not totally seized.
Click to expand...
The bolt turns 1/4 turn and then freezes, or you only have room to get a 1/4 turn because of the wrench? I'm not familiar with the set up, but are you familiar with "crow's feet" wrenches and would that not help?
 
Thanks,
The nosewheel is off the ground. Perhaps light traction on the noseleg might help.

There is no hole in the firewall, just a lot of scuff marks where they clearly had problems, when the leg was replaced in the past.

Are there plans in the builders manual for such a hole?

We will try a jubilee clip wrapped around the bottom of the bolt and then tightened to force it upwards, tomorrow.
 
justinmg said:
Thanks,

Are there plans in the builders manual for such a hole?

We will try a jubilee clip wrapped around the bottom of the bolt and then tightened to force it upwards, tomorrow.
Click to expand...


Yes there is...Sounds like you need the hole...No wonder somebody had problems!

Frank
 
Justin:
First, you need to determine that there is no firewall penetration below the bolt. Not sure how the nose gear could have been attached without this, unless is was assembled upside down or before the engine mount was bolted to the firewall. In any event, you will first need to remove the heater covering inside the cabin. This will expose the center section of the firewall. If there is indeed no access hole, you will need to make one using a one inch hole saw. THE BOLT CANNOT BE REMOVED/INSTALLED WITHOUT THIS HOLE (unless you remove the engine mount from the firewall, or the bolt was installed with the head pointing toward the engine- in the latter case, you will need to remove the heater box).

The location of the center of this hole is shown on construction drawing 19 and is determined by position relative to the horizontal and vertical rivet lines in the lower center of the firewall. From either the right or left vertical lines, the hole center should be 4 13/32 in. inboard. This should be the horizontal center between the two innermost vertical angle stiffeners.

For vertical position, measure down from the horizontal line that fastens the bottom edge of the firewall recess box. The vertical distance from this line to the hole center should be 7 17/32 inches.

I agree with one of the earlier posts in that the drawing calls for a 3/4 in. diameter hole. Making it slightly larger will give you better access with a socket, should you need to twist it on removal. In any event, you will need a wrench on the bolt head when you re-install and torque.

Finally, I would also agree that you will need to take the load off of the nose when you attempt to remove the bolt. Once clamping force is released from the fastener, the bolt becomes a pin which is now in shear and difficult to remove.

When you re-install the gear leg, you will need to purchase a stainless one inch expansion plug which you can press fit into the hole, and then finish off with either high temperature RTV or proseal.

Hope this helps.

Terry
RV9A
N323TP
 
Justin:
One other point. The design (drawing #19) calls for the bolt to be mounted with the threaded end pointed upward, toward the engine. While fastener applications generally call for the male part to be mounted threads down (to lessen the chance of losing the bolt if the nut backs off), this application is inverted to allow access to the nut. This is important because when you torque the assembly, you never want to do it from the bolt head end as most of your torque is lost in overcoming friction between bolt shank and parts being joined. If your mounting is upside down, fix it. This will allow you to properly torque the joint and lessen chance of movement between gear leg and socket (which can cause "creaking" and may also result in joint failure).
Terry
 
I had this same problem on my 6A, when I wanted to remove the nose gear for inspection after about 200 hours. The problem with the design is two-fold. First, the bolt fits somewhat loosely in the hole, and second, the bolt does not compress the motor mount against the gear leg. So, the bolt simply functions as a pin. Well, the gear movement works against the bolt until it upsets the bolt enough such that it is very, very difficult to remove. I do not have the heater business that yours has, but it probably took me 3 or 4 hours to get that &^@$* bolt out. I devised various tools to pry up on the bolt while rotating it back and forth. It was the single most frustrating event since starting the project.

I would suspect that most will have a similar problem if they go to remove the nose gear leg, but perhaps not. I replaced the standard AN bolt with a close tolerance bolt, which in my case, made for a nice fit. I have removed the gear leg again after perhaps 400 more hours with no problems.

If I were building again, I'd come up with some way for the bolt to clamp the motor mount against the gear leg, perhaps splitting the socket or something similar. This would prevent all movement. Simply putting in a harder pin will only cause the upsetting to occur on the gear leg, making it difficult to remove.

BTW, in my case I could apply more than twice the normal torque to the bolt and it would not cause the socket to compress against the gear leg. I'm sure some are at the opposite ends of the tolerance and can tighten the bolt and create compression.
 
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Thanks all,
This is becoming a lot clearer. No wonder we are having problems!

There is no nosegear access hole in the fw, so when it was last replaced, it was facing thread down. Also being tapered, I think it has worked itself down, and jammed.

The options currently 1) We are making a tapered fork which can be tapped against the bolt head to pry it up ( like Alex did!!)
2)Cut a hole in the firewall and try to tap the bolt up and out. Seems easy on the face of it, but looks like a panel in the footwell in the cockpit also need removing, so may turn out to be a bigger job, thanks for the instructions Terry.
3)Leave the old leg on, extend the thread up the leg, cut off just over an inch, and put the new fork on that.
4) Leave it all to the Winter inspection, take off the engine and do it then.

Bearing in mind I am not an RV builder, these all seem like big jobs to me!!!
 
Justin:
That center panel really isn't too difficult to remove. There are really only two pieces. The first is a cover plate in the lower right center of the firewall that covers the aux fuel pump and thru which are mounted the control cables. I believe there are five machine screws holding this on. When these are removed, you should be able to slide the cover up the cables, out of the way. The second, larger piece is bent 90 degrees and covers both the floor tunnel (your fuel lines and brake lines reside here) as well as the heater inlet on the lower center of the firewall. You can remove this cover by pulling machine screws as follows:
1.two screws on the front of the fuel selector box (you may need to remove this box/more #8 screws).
2. three screw on each side of the tunnel cover.
3. two screws on the vertical part of the cover above the heat fins.

While it would be my recommendation to do this and make the firewall hole, you won't know how your fuel and brake lines are routed and whether these will interfer with the cutting of the hole and subsequent access for a socket wrench. On the other hand, you only need to pull about 15 screws to find out.

A couple of suggestions:
If you pull the machine screws, run a tap into the nut plates (#8-32) before replacing. The nut plates are prevailing torque type and can be made free running by tapping. This will make future service much easier.
If you cut the hole, make certain that the expansion cap you plug into the hole is steel (preferably stainless-you can purchase at ACO) and not aluminum or some other low temperature material. The purpose of the firewall is to prevent fire from entering the cabin in event of engine fire. Having a meltable bung directly in front of fuel lines would not be a good idea.

Don't stress over the work, have fun. Most problems can be readily fixed by looking at plans (you can order a set from Van's), hitting the forums, and a little patience. Might seem like a lot of work, but you're looking at a job which could be accomplished in a couple of hours. One of my friends just finished installing his fourth instrument panel in an aircraft less than 6 years old - enjoy the journey as well as the destination.
Terry
 
Thanks for the encouraging words Terry.
I will certainly look at the hole possibilty. I am more of a flyer than a builder, but I am looking forward to re-doing the panel later in the year!
Justin
 
Aerokroil seems ideal except to get a can shipped to the uk is $100 (hazardous material).
Can anyone suggest an equivalent?
 
ss firewall plug, source?

This is an interesting and informative thread. I reviewed my plans and it does not show a hole in the firewall to access the nosegear bolt/pin. I test fitted my engine mount last night and it became clear that I do indeed need a hole there. I like Franks suggestion to go with a 1in hole instead of the 3/4 inch hole.

1. What tood are you guys using to cut that hole?

2. Does anyone know a source for 1" stainless plugs?

3. Is it best to put the plug on the forward or rear side of the firewall?
 
Befriend an electrician...

I just did this a few weeks ago! The friend who helped me hang my engine is an electrician, and he lent me his Greeley punches - used to punch holes in electrical boxes. I used the 1" punch. Then you go to the aviation/electrical aisle of your local hardware store and get a 1" knockout plug. It's not stainless, but it is steel. It has tabs that go through the hole and hold it in place. I had to remove (just bent out of the way) a few of the tabs to clear the mount. I inserted it from the inside (the only way possible), and sealed it up with hi-temp RTV.
 
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