Jump to content

Relocating SVS light and control knob bracket


adverseyaw

Recommended Posts

I have a Precise Flight standby vacuum (SVS III) in my J model and the bracket is right where my right knee goes. Does anyone have recommendations on alternate mounting locations? Moving them to the passenger footwell doesn't seem worth the hassle, since I'll just be making it a problem for whoever is flying with me. Is there another place to mount these that would get them further out of the way?

Maybe even moving them to the center of the footwell, immediately below the yoke, would be an improvement.

(Eventually I'm planning to lose the vacuum instruments but will be hanging on to them for at least a while.)

IMG_20180114_113336.jpg

Link to comment
Share on other sites

Are you considering an electronic AI for Back-up?

The world Is leaving the back up vac devices in droves...

Some older devices have limited skill at high altitudes...

Plan on moving on...

Or are you just looking to move an auxiliary control?  Seek help from your mechanic for that.

The stuff hanging below the instrument panel was added on by a mechanic after it left the factory...

PP thoughts only...

Best regards,

-a-

Link to comment
Share on other sites

52 minutes ago, carusoam said:

Or are you just looking to move an auxiliary control?  Seek help from your mechanic for that.

Yep, just looking to move the knob and light. Will definitely get an A&P to do the work, just wondering if anyone had inspiration on other locations before I get it off to him. :)

And yeah, the whole thing will eventually get tossed out for an Aspen or G5s or whatever else is the best choice when I upgrade. (I'm sure things will change by the time that happens, so I'm not really thinking about it until then.)

Link to comment
Share on other sites

48 minutes ago, N201MKTurbo said:

The knob will be hard to relocate. The light can go anywhere you want. See if you can get a new label or make your own with the same text.

Well, blarg. I know the pushrod has a z-bend with some room left (found the shuttle valve last time the cowl was off) so maybe there's enough space for my A&P to move it around a bit. Still scratching my head about where it could go, though. Under the yoke is the best I've come up with so far.

  • Like 1
Link to comment
Share on other sites

You can move the knob right under the yoke so that it is between your knees.  I have my light dimmers there and it is never an issue. As others suggested, move the light to the panel, where it is obvious....although maybe it will be seeable in the center....

  • Like 1
Link to comment
Share on other sites

I have the same Precise Flight system on my K model.  Actuating cable is mounted below the panel just to the left if the yoke.  Warning light is mounted on the left side of the panel below the fuel gauges. Position of the actuator has never been an issue. 

  • Like 1
Link to comment
Share on other sites

13 hours ago, Ned Gravel said:

The knob pulls a wire that moves a valve that shuts your (now dead) vacuum pump out of the system and allows your vacuum system to draw its vacuum from another source.  See the diagram.

 

5a5c68d3909f9_SVSdiagram.jpg.59ac91d632b1400785b8ada5e3b20ab5.jpg

Interesting, so not all standby vacuum pumps have a valve like that?  I forget what kind of standby vacuum pump I have, but there is certainly no diverter valve or anything...

Link to comment
Share on other sites

1 hour ago, jaylw314 said:

Interesting, so not all standby vacuum pumps have a valve like that?  I forget what kind of standby vacuum pump I have, but there is certainly no diverter valve or anything...

Precise Flight does not use a second pump.  When you pull the cable, the engine intake manifold provides the vacuum.  Depending on altitude, you may have to reduce power to get more suction.

Link to comment
Share on other sites

Precise Flight does not use a second pump.  When you pull the cable, the engine intake manifold provides the vacuum.  Depending on altitude, you may have to reduce power to get more suction.


And one of the reasons I was happy to lose it. The amount of power reduction needed to provide reasonable vacuum made it truly an emergency tool.

42a46fb6af071f84dc45f2c4e8836526.jpg


Sent from my iPhone using Tapatalk Pro
  • Like 3
Link to comment
Share on other sites

Time to look at what you have in the plane...

The precise flight system in the Long Bodies is an actual vac pump with an electric motor mounted in the rear...

A switch turns the pump on.  The electric switch is mounted amongst all the others like the fuel pump...

This can be tested on the ground.  The sound of the pump running is clearly Audible.

 

The older Precise Flight devices are the valve that opens up a line to the engine intake.  This system is a problem at high altitudes when it can't generate enough vacuum to operate the instruments.  A serious challenge flying in IMC can occur if you lose the vac pump there...

It is very important to know how this thing operates.  Closing the throttle can increase the vacuum, but it decreases the MP that keeps you aloft...

I'm only a PP, and have only tested the electric motorized version...

I think @Marauder May have written a paper covering...

dang here he is...   

I was too slow to type... (go up one post):)

Best regards,

-a-

Marauder, How Long ago did you collect that data?

  • Like 1
Link to comment
Share on other sites

My SVS control was at one time I attached to the side of the footwell near where your A/P is, then moved by a previous owner to just below the yoke.  I don't thonk you need to modify the cable to make it work.  I suppose the big concern is introducing slack on the cable that allows the cable to move and reducing effectiveness of the cable.

Link to comment
Share on other sites

When I had the same system installed in my 201 the mechanic installed the push pull cable in the panel under the prop control and the light next to my AI which to me made a lot of sense. I believe it is important to have the light located in close proximity to the AI because in IFR conditions this is the instrument your most looking at.

Link to comment
Share on other sites

1 hour ago, jaylw314 said:

Holy smokes, I didn't realize there was such a thing.  @Marauder 's numbers make it look kind of scary!

Yeah, its a "get on the ground" tool and nothing else. I hope people don't think the Precise Flight standby system is intended to allow you to continue on your merry ole way. It isn't. I think 4.5" is the expected "normal" vacuum. My flight test to calibrate it was sobering. That is why I said I was happy to lose it and replace it with an L-3 ESI-500.

 

Link to comment
Share on other sites

I removed the Precise Flight system from my C.  It didn’t work well enough to retain & the SVS valve can leak, disabling the sole vacuum pump.

An AHRS from a portable (Stratus, etc) is far more likely to help you out. IMO. 

If you do want to keep it how about putting a soft rubber ball over the knob to cushion your knee?

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.