Using gas with odor to troubleshoot Wing Leveler leak?

[corn_flake]

I have been brain storming how best to get the wing leveler back to life in my M20E.  It darn on me we could borrow an old idea of using gas with odor.  For example, natural gas is normally odorless, but mercaptan is added to alert people of a leak.  I wonder method can be applied when troubleshooting vacuum line leak in wing leveler.  It won't tell you exactly where the leaks are, but it will sure narrow it down to a general area.  

What do you guys think?  Any gas you can think of that's readily available?  

[RLCarter]

Use smoke, no chance of blowing up you plane 

[Prior owner]

This might work. Probably very safe, too!

[Yetti]

Hand vacuum pump  Lines junction the baggage compartment port wall.   Start pumping you will find it.   Hint from Brittian is the red lines fail the most.

[Pasturepilot]

Yetti is on the right track. By trying to use a scented gas... were you going to pressurize the system that is normally vacuum-driven?   
 

I’d hesitate putting any fume or smoke through that system since it all gets pulled through the vacuum pump at some point. 
 

The red lines do fail most rapidly. Per Brittain, find a local Parker Store to source replacements lines. A leak in the red system would cause a right turning tendency.  Check where the lines pass through the gear well. Years of degreaser and being bumped by a cleaning brush cracked my red line where it passed through the gear well. Replacing the entire line in the wing is about an hour’s work if you’re working with any real purpose. 
 

I think I was right at $60 to replace most of the nylon lines. 

[corn_flake]

1 hour ago, RLCarter said:

Use smoke, no chance of blowing up you plane 

Thanks!  I knew better not to pump natural gas into the line....  

I was hoping for something like argon.  Used in welding.  Completely inert.  But, I will settle for skunk scent, human fart if it can be purchased in large quantity.   

[corn_flake]

25 minutes ago, Pasturepilot said:

Yetti is on the right track. By trying to use a scented gas... were you going to pressurize the system that is normally vacuum-driven?   
 

I’d hesitate putting any fume or smoke through that system since it all gets pulled through the vacuum pump at some point. 
 

The red lines do fail most rapidly. Per Brittain, find a local Parker Store to source replacements lines. A leak in the red system would cause a right turning tendency.  Check where the lines pass through the gear well. Years of degreaser and being bumped by a cleaning brush cracked my red line where it passed through the gear well. Replacing the entire line in the wing is about an hour’s work if you’re working with any real purpose. 
 

I think I was right at $60 to replace most of the nylon lines. 

My leak line is actually the green.  Are you sure about right turn tendency if the leak is red?  My green is leaking and my M turn right if the wing leveler is left active. 

[Yetti]

7 minutes ago, corn_flake said:

My leak line is actually the green.  Are you sure about right turn tendency if the leak is red?  My green is leaking and my M turn right if the wing leveler is left active. 

If you know it is leaking why have you not replaced it.  buy it and get busy.   The ailerons are connected by tubes to the yoke.  The servos can only pull down.

[211º]

Don’t forget that there are at least a couple of fillers so it’s not a closed system and the smell will leak out in the areas of the filters.

+1 for the t-connections in the baggage area. From this location with a hand vacuum pump you can test both directions of the rudder and both ailerons.

Pump to a 5 psi reading and see if it holds for 1 minute.

[corn_flake]

@Yetti  I know the green side is leaking, but I still can't identify if it's the line or the aileron servo.  I got as far as removing the inspection panel for the right aileron servo, but I did not remove the servo for vacuum test.  It seem like it would require removal of aileron linkage.  

@211º Is the t-connection in the baggage area under the carpet or side plastic panel?  

[carusoam]

Don’t put anything into the vacuum system of the wing leveler...

Because it is connected to your vacuum instruments...  anything going in will probably spread pretty well through the system...

Smoke particles are tiny solid bits... that would be bad for bearings...

There is a leak detection liquid used for the O2 system that  at be helpful to use... search for Snoop...

 

The idea of using mercaptans... is interesting... but once you get some in your nose... you have about a second to find the leak... if you miss it... your nose won’t recover for a day... or two...

You may get to test your natural poison defense system too...

Getting the odor out of the plane will most likely require removing all the tubing... PVC is pretty porous and can collect a lot of chemistry....

Why get creative for something that is supposed to keep the wings level in IMC?

There has got to be a manual for this ancient system... And procedures that work...

And drawings... 

Expect to be removing a lot of panels and inspecting the tape on each Servo device...

Looking at each tube connection that is safety wired on a barb...

Check and see if this on the list of PP maintenance... you may want to perform this with a mechanic near by... to check your work and log your changes...

Opening this many panels makes doing this a good idea around annual time...

Expect PVC tubing to stay flexible for about a decade... after two it’s starts drying out and getting rigid... at 50, fixing one problem will generally cause another one down the line...

Buy some new tubing from Celia... just to use as a comparison to what you have in your plane...

Chances are, you will want to replace the tubing and tape instead of spending time searching for the problem...

Biggest challenges come from rips in the rubber diaphragms...

The Brittain is a really cool system... keep it working... 

PP thoughts only... not a mechanic..

Best regards,

-a-

[N201MKTurbo]

You guys are over thinking this way too much.

just stick the tube in your mouth and suck real hard then stick your tongue on the tube. If that circuit is leaking, the tube will fall off your tongue in short order. If it is good, it will stay stuck forever.

[211º]

If you’re kneeling rearward on the rear seat, it is on the pilot’s side wall near the floor in the cargo area. The side panel should have screws that permit it to “swing” forward.

If you open the large access panel outside on the pilot’s side, peak in to the immediate left, you should see the red and green tubes traversing from the cabin floor.

Also there is a thread around here that contains the schematics.

[211º]

Brittain Autopilot Systems
https://r.tapatalk.com/shareLink/topic?share_fid=55491&share_tid=285&url=https%3A%2F%2Fwww%2Emooneyspace%2Ecom%2Findex%2Ephp%3F%2Ftopic%2F285-Brittain-Autopilot-Systems&share_type=t&link_source=app

This post has tons of info. I summarized my lessons learned in response 195. There are many other tidbits in this thread as well.


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[Pasturepilot]

6 hours ago, corn_flake said:

My leak line is actually the green.  Are you sure about right turn tendency if the leak is red? 

I’d had three hours’ sleep in the last 48 hours.  I want as sure about anything as I thought I was.  Thanks for catching that. 
 

The red side runs to the left aileron, and the vacuum force pulls it down, which would turn the airplane to the right. So the side that leaks (most) will be the heavy wing.

So yeah. Green system  = Drifting to the right. 
 

I had lost track of all the troubleshooting and adjustments on mine. I’ve fixed a number of leaky boots and cracked hoses over the last year or so. 
 

Good luck! It’s a great system once it’s operating properly. 

[takair]

7 hours ago, Pasturepilot said:

Yetti is on the right track. By trying to use a scented gas... were you going to pressurize the system that is normally vacuum-driven?   
 

I’d hesitate putting any fume or smoke through that system since it all gets pulled through the vacuum pump at some point. 
 

The red lines do fail most rapidly. Per Brittain, find a local Parker Store to source replacements lines. A leak in the red system would cause a right turning tendency.  Check where the lines pass through the gear well. Years of degreaser and being bumped by a cleaning brush cracked my red line where it passed through the gear well. Replacing the entire line in the wing is about an hour’s work if you’re working with any real purpose. 
 

I think I was right at $60 to replace most of the nylon lines. 

My local Parker store stopped talking to me the moment I told them I was sourcing lines for an airplane. It was really odd since they have an aerospace division. Anyway, if this is really their policy, you might tell them it is for your refrigerator ice maker or some such story. I had to source my parts On line after that. 

[tmo]

My go-to explanation is that I'm restoring an old American tractor. I figured if I have to lie, I'll try to lie as little as possible

[RLCarter]

If I think there is going to be an issue ‘cause of being an airplane, I offer no information other than I was sent to pick it up, but you have to go in with part numbers and quantities 

[corn_flake]

Thanks for all the great suggestions. 

@carusoam  Thanks for catching PVC can absorb odor.  Whatever I happen to use, I wouldn't want the smell to linger for the next 10 years....  

@211º Thanks for sharing the thread.  In fact, that was the thread that inspired to start look into the wing leveler issue.  And thank you for the detail explanation on where to find the T-connection.  The green is leaking so badly when I apply vacuum using a hand pump, the vacuum gauge never move above zero.  Frankly, I don't think I'm dealing with a small leak.  It is likely tubing has disconnect or a major crack some where on the green circuit.  

I got as far as having my hand around the right aileron servo feeling for the rip.  None was found.  I would like to remove the servo for inspection, but couldn't find a way to get my wrench on the nut behind the servo can without disconnecting the aileron linkage.  

[211º]

When I was looking - I also had an issue on the right/green side. Knowing what I know now, if there isn’t a reason to think that there is an abrasion in the green line, odds are better that it is the servo.

There is another thread around here that indicates the size of the nut for the servo and for green line out - if you don’t want to look for that thread, look in the tail section for the two servos (smaller ones if you also have altitude hold) and the wrench sizes should be the same.

The only way that I know to remove the servos is a lot of before you start photos, an imagination of what your hand is feeling, a small handled ratchet, a little swearing, a little pain from the edge of the Inspection portal, and some luck.


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[carusoam]

+1 for lots of pics...!

If you ever wanted to buy a dental camera from Amazon... you might chase all the tubing around corners with a little more ease...

Some idea I got from somewhere around here...

Best regards,

-a-

[corn_flake]

@211º  Yes, I do know the size for both the nut that secure the servo and the b-nut for the hose.  I'm sure can find a wrench small enough to remove them.  But, I'm not so sure how you were able to reattach the nut to reinstall the servo.  Perhaps you are better at contouring your wrist?