Accessing rear of instrument panel

[Tokirbymd]

Have a Seneca IV. I am looking to replace the 760 JPI with a 790. From instrument perspective should be a simple plug and play as the connectors are the same. I am trying to gauge the level of difficulty for planning for either doing myself with A&P supervision, or how much time/effort to expect for the A&P. The 760 is mounted high on the left side of the panel. The maintenance manual describes removal of face mounted instruments with 4 screws and tinnerman nuts. However there is no mention of how to get access to behind the panel in any of the maintenance manuals or parts manuals. It appears the panel is somewhat modular but different than the older Piper panels with the plastic overlay. Is there a way to release the panel enough to get behind it? Looks like multiple screws around the edge but not sure how it would slide out over the yoke. Or is this all done by reaching up under and behind the panel leaving it in place? Any pointers to how to do this appreciated.

 

[Hang 4]

Can't speak to the Seneca, but in my Cherokee, best approach is to remove the front seat and lie on your back and reach up. Also, removing adjacent stuff can improve access. I have a G500 and there's tons of access if the display is out.

 

[wilkersk]

I second removing the front seats. It only takes a few minutes and makes it easier to get yourself into position.

But, I have yet to find 2 aircraft of the same model that look identical behind the panel. You could have a complete rats nest back there. Or, you could have vacuum lines that make it difficult to access the back of your engine monitor. You might have to cut a bunch of zip ties, or you might disturb some long hidden wiring nightmare that will expose itself with catastrophic results on the very next power up. By the same token, you might find it to be easily doable and maybe even enjoyable. You never know.

Wiring mystery exposed: 2hr job that turned into a much longer re-wire.

"No I will NOT just re-pin the connector. Yes, I will charge shop rate to install all new wiring."

 

[Bell206]

Or is this all done by reaching up under and behind the panel leaving it in place?

To add, this is the most common way. Each aircraft is different, but seats out with anything else that can make your access easier and more comfortable. Thin dense pads to lay on are also convenient to have. Sometimes if the instrument you want is at the top it helps to remove items under it. Unfortunately there's usually no simple alternative. Its one of the reasons it take more hours to perform avionics work. Good luck

 

[Llk]

CHT and EGT as a pigtail is interchangeable 700-800-900 and the part numbers are the same.

JPi articulates cleverly how the part numbers for the primary devices must be different- RPM, MP, etc.

No to repin’s? Find another shop.

Or learn to do it yourself. Don’t feed the beast. DB9’s / DB connectors are not new and they’re not difficult.


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[Llk]

Oh. I have a seneca II also Senecas rule the world lol


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[Tokirbymd]

CHT and EGT as a pigtail is interchangeable 700-800-900 and the part numbers are the same.

JPi articulates cleverly how the part numbers for the primary devices must be different- RPM, MP, etc.

No to repin’s? Find another shop.

Or learn to do it yourself. Don’t feed the beast. DB9’s / DB connectors are not new and they’re not difficult.


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Yeah if it was sitting out on a bench would not be difficult to figure out. Its contemplating doing all this behind the panel with unknown amount of service loop working material that has me worried.

 

[sourdough44]

You have to contort your body. Try to have whatever tools near before you get in position, or a helper.

 

[Ed Haywood]

See if the glare shield is easily removable. Then you can look down through the windscreen and get a good look at everything to plan your assault.