Nose Strut Pressure

[Mark Hislop]

My nose strut looks low to me. I want to check the pressure to see if it is where it is supposed to be (35 psi extended), but I can't figure out how to get at the filler valve. The parts and service manuals show it at the top rear of the strut. I can't even see up there, much less reach in with a pressure guage or air hose. How does one access the filler valve?

Thanks

Mark

[FRED-E]

Go Here:

http://www.337skymaster.com/messages...=&threadid=433

I think you will find what you need.
Fred N358

[SkyKing]

Mark,

To begin this project you'll need to jack up the nose of the plane using a small hydraulic bottle jack. You should place it on top of a 6x6" block of wood under the front jack point, so that when you begin the jacking operation the jack is already snug against the jack point in its collapsed position, as most of these smaller 3 and 4-ton jacks only have a 7" to 15" maximum lift height.

As most of these automotive bottle jacks are flat on top, you'll need to fashion an adapter, either out of a small block of wood or go to a metal fabricator and have one made out of steel. A piece of hard wood, or even a small block of 2X4 will do the job. What you'll need to do is drill out a hole in one side to fit tightly over the top of the jack, and on the opposite side, drill out a recessed inverted 'tit' to fit the jack point.

Once you've got your 'adapter' completed and fitted, make sure to block the main wheels securely so that the plane will not roll, then jack up the nose so that the nose wheel is just barely off the floor and the strut is fully extended.

What you're going to do now is release the pressure on the nose gear downlock so you can manually push the strut/nose gear partially forward and up into the wheel well. This step is necessary to that you can get a screwdriver on all of the screws of the inspection panel that's directly behind the nose gear door on the belly, and once this is removed you can then reach up inside and service the strut and follow the procedure in the manual in Section 2-25, with respect to Figure 2-5.

With the master switch off, pull the landing gear breaker out so that NO POWER will be applied to the landing gear circuit. Then, standing outside the plane next to the pilot's side storm window, reach through and turn the master switch on, then move the landing gear lever to "UP"... THEN VERY CAREFULLY and JUST MOMENTARILY, tap the landing gear circuit breaker in so that the pump motor starts and the lock releases. As the nose gear strut begins to kicks forward, pull the landing gear breaker out and shut the master off. This happens pretty quickly so be on the ready.

Now, you'll be able to position the nose gear strut so as to reach the fitting through the inspection panel, and to also perform the complete strut service operation in Section 2-25 of the Service Manual, if desired.

BTW, with the nose gear inspection panel open, you can get a good look at the uplock mechanism and this provides an opportunity to clean this area, as well as lubricate the cam followers and the track.

SkyKing

[Mark Hislop]

Fred:

Thanks for the reply. I understand how to get the nose up so that the strut extends. I just don't know how to get at the filler valve. Can I reach it from underneath the aircraft?

PS Can you email me the drawings fro the PVC supports?

Thanks

Mark
mhislop@aol.com

[Mark Hislop]

JR:

Thanks! Now I get it. I appreciate the help.

Mark

[kevin]

Mark,

If all you want to do is add air to your nose strut, you can do that without jacking the aircraft, although it is a challenge. You can use a 90 degree bent adapter to get your air hose on the filler. Then have one or two friends push down on the tail. (Your choice, we do it with only one person, but some say that is not good for the airplane, and that one person should push down on each tail boom. Others say that the only correct procedure is to jack the airplane.) Anyway, after raising the nose gear in whatever way, add air to the strut, then let the nose down. Usually this will add too much air, and the strut will be overextended a bit. Release air from the filler until you have about 3 fingers of distance from bottom to top (i.e. the shiny part of the piston that is showing when weight is on the nose wheel). Raise the nose and lower it again o make sure the strut is not "sticking". Don't add too much air, if you do, the strut will lock the nosewheel straight ahead.

If you have to do this very often at all (my personal rule is more than once between annuals), you should jack the nosegear, fix the leak in the strut, and service it properly with fluid and air.

I learned this procedure from an ex Air Force O-2 mechanic, and do it only when supervised by an A&P. I don't know whether it is Cessna approved or not, so use it at your own risk. It works fine for us. Please see also the thread that Fred referred you to in his previous message in this thread for more comments from various folks on this subject.

Kevin

[Wayne Pearce]

The service manual suggests the appropriate pressure for your aircraft. I go by strut extension not by pressure. No jacking is required. Make a piece of guage capilliary tube 1/8 or 3/16 with female SAE fittings about 20" long and make about 3" U bend on one end. Have available 7/16" & 3/8" open end spanners and male female schraeder valve extension. Open gear doors, remove schraeder valve cap dont forget to replace o ring attach tube while doing final shaping in situ and "voila" you have extension ready to attach guage, on/off valve and compressed air or dry nitrogen. Also have available adj mirror and magnetic pick up for the cap that I bet you will drop first time.

This is not hard just a pain in the wrist for the first time, the second time it will take you about five minutes flat.

Oh and continually rock the front wheel back and forth and this will release any side friction on the strut piston and rod.

Its easy, accurate and quick.

Regards ........ Wayne Hey made a 4 hour flight the other day with side window open, 35 deg C on ground absolutely fantastic.

[James Bennon]

Need to reseal front strut--how do you get lower and upper struts separated?
Service manual speaks of a small hole that allows you to release snap ring on lower end of upper strut, where is hole located??

[stackj]

Mark,

I remove the access door directly behind the nose gear door and reach up to the top of the strut with an automotive valve extender in hand (about 1/2 to 3/4 inch long). I screw the valve extender on and that extends the valve allowing me to service it with a regular air hose fitting.

I would also recommend that you use only nitrogen to service the strut. It is dry, which results in reduced potential corrosion inside the strut and it lasts longer than plain old compressed air.

I usually find that I cannot get the strut to compress after being filled to 35 psi with the strut extended. I relieve pressure until the strut shows about 4 inches of extension after pulling down on the nose and releasing. Be careful! just tap the valve core lightly until you get the result you want. The nose strut is not a large volume cylinder and the position can change very quickly.

DONT FORGET TO REMOVE THE VALVE EXTENDER and replace the valve cap before closing up the access door.