warrenmiller11

hi my corsair has robart retract with airtank and valve but i cant put more then 20psi in it for some reason??
i tried footpump handpump and even my dewalt 120psi compressor i use for light mechanic work still nothing. i use robart airline retainers everywhere and have also brass T fitting everywhere with a cylinder to retract tailwheel. have not maiden the plane yet to this issue.

Johnnie Red

Check the retainers!!!! You have put them backwards!!! It happened to me as well about 20 years ago!!!!

Greg Wright

My Feedback: (6)

Get rid of the retainers. It sounds as if you might have cut thru the hose some where with one of them. They aren't needed.

warrenmiller11

you can put retainers backwards?

Johnnie Red

Yes Warren. Get rid of them and you'll see that everything will be ok!

SWORDSN

My Feedback: (13)

Retainers? Are you talking about the knurled nuts?

warrenmiller11

yup

raptureboy

I've never made a conscious effort to put the retainers on one way or the other and have never had this problem. My guess is you have a major leak or pinched line leading to the tank.

warrenmiller11

so are these things like useless or what?? how do you guys secure the line with like glue or what??

ForcesR

More than likely the brass T-fitting connected to the airline that is connected to the airtank is almost completely blocked by flashing left over from the manufacturing process. The T-fitting is acting as a pressure restrictor due to the left over flashing. Take a small drill bit and run it through all three openings of the T-fitting. I have experienced this same issue in the past with the brass T-fittings. I now run a small drill bit through every T-fitting to get rid of any left over flashing before T-fitting installation.

Drill bit size - .039(# 61) max.
- .036(# 64) min.

P.S. I use retainers (knurled nuts) on all connections and have never experienced any problems with using them.

Roger

Instructor

My Feedback: (16)

Take a pair of forceps and pinch off the tube from the tank to the retract valve and see if you can build up pressure. If not, then you will have to go back from the retract valve to every connection you have and pinch off the tube before the connection, starting from the tank first. Do this until you build up pressure, then you will know what connection is giving you the problem.
Correct that connection and you will have no problems.....


Larry/Instructor

Chad Veich

My Feedback: (60)

I'm betting on Roger's assesment on this one. I have had the same issues with fittings as well as the little brass restrictors.

raptureboy

Good to know about he fittings. Have not had the problem yet but now I know to look there when it happens. The free exchange of ideas is always great. Let us know if this fixes it.

warrenmiller11

good stuff ill check all of the above guys

LDM

My Feedback: (15)

There is another possible problem, when you tighten the pump to the air valve and turn it , at time it will turn in airline inside the plane, if this occurs you will not get air into the tank, same exact process about 20 psi and it seems so difficult to fill .
If this happens you have to disassemble the internal line, unkink the line, retighten and if possible carefully expoxy the internal nut to the frame so it can not turn as you tighten the pump to the valve.

warrenmiller11

ok cool thanx for the heads up i already removed all retainers and unkinked everything so ill check make sure my fill valvle doesnt twist

Greg Wright

My Feedback: (6)

Yes the knurled nuts are pretty useless. Most modelers usually just push the hose all the way onto the Nipples and once it is on it stays on for a long time with no issues.

I myself have gone and used safety wire on most of the fittings just for a more secure connection.

Chad Veich

My Feedback: (60)

I've never used anything but friction to retain the hose and in 20+ years of using pneumatic retracts it has not been an issue. Just be sure you always keep fresh hose on the nipple. In other words, if you remove the hose for any reason always cut it back to make sure you have fresh, unstretched hose going back on the nipple. It doesn't hurt to change out your air lines every decade or so too!

radfordc

My Feedback: (14)

I did have an airline blow off of a fitting recently. I made some knurled fittings to clamp the airline in place. Probably not needed often, but it makes sure the line stays in place.

prop wash

Make sure that your "tank" is glued in and not twisting when the engine running and vibrating,the tank will tend to twist from vibrations.Use foam spray insulation to lock the tank in place.
Tom

warrenmiller11

cool thanx for the foamspray tip

warrenmiller11

so i removed everything and checked everything, nothing. so i finally hooked up the airtank alone to the fill valve and still not filling past 20psi enough for 1 1/2 cycle at the most. my wild guess here is FAULTY AIR TANK so im ordering a bigger one than the one that came with the package vavle and all that hopefully it will work if not electric retracts here i come

ForcesR

warrenmiller11, then the brass fitting that is connected to the air tank is partially blocked with flashing left over from the manufacturing process. Take the small drill bit and run it through the tank fitting to remove the flashing. A faulty tank is one that will not hold air due to leaks, in this case the tank will not take the required air pressue due to a partial blockage. As I mentioned before, flashing in t-fittings and or straight fittings acts as a pressure restrictor. Remove the flashing and you will have a serviceable air tank.

Drill bit size - .039(# 61) max.
- .036(# 64) min.

Roger

Greg Wright

My Feedback: (6)

Its not a blockage in the fittings. If there was a blockage then you would have immediate air pressure at the pump. There is a leak in your compressor or your air source some where that you are not finding.

warrenmiller11

thanx for the head up guys