Difference of a new panel vs. a panel overlay.

[edessa]

School me on the difference on a new panel vs. a panel overlay to go from a standard six pack to a G3x or Dynon 10" display?

I started doing avionics work a few years ago after mainly turning wrenches for 25 years on airliners and corporate jets. I mostly have been installing GPSs, G5s, AV-30s, GI275, engine monitoring systems and such as a side hustle. I never had the opportunity to do a complete panel replacement and was wondering what the difference of the two are.

 

[Jeff Oslick]

Going from 6-pack to a glass panel, you will need a new panel, as the structure for the 6-pack is different than what is required for a large display. Overlays generally only work if you're going to "glass" via equipment that will fit in the standard round instrument holes (i.e. GI275).

 

[WDD]

Think of an overlay as a veneer you'd put over plywood. It looks great, but by itself isn't structural.

 

[Bell206]

I never had the opportunity to do a complete panel replacement and was wondering what the difference of the two are.

Are you asking about the differences in the structure panel the avionics mount to vs the panels used to cover over that structural panel; or, are you asking about the different types of structural instrument panels? If that makes sense.

 

[edessa]

Going from 6-pack to a glass panel, you will need a new panel, as the structure for the 6-pack is different than what is required for a large display. Overlays generally only work if you're going to "glass" via equipment that will fit in the standard round instrument holes (i.e. GI275).

That makes sense. I see a lot of posts around the web say that people have gone from a steam to 10" glass and say they just did an overlay out of 0.080" or thicker aluminum. Some of those claimed this was the work around to avoid an STC or field approval for their new panel and I always wondered how thick the total panel was.

 

[bonefishpete]

Aluminum > Royalite

 

[Bell206]

Some of those claimed this was the work around to avoid an STC or field approval for their new panel and I always wondered how thick the total panel was.

There's no work around if you modify the primary structure. Some panels have a structural frame that ties into the fuselage bulkheads and provides support to flight controls, etc. which in turn supports screwed on sub-panels. If you can keep all your mods within those sub-panels it tends to be viewed as a minor alteration. However, modify the frame portion and its a major alteration. But not all panels have sub-panels. So its specific to the aircraft in most cases. Any panel work I did, I always did as a major with a 337.

Regardless, the majority of panel work usually falls under a major repair and depending what data you use will determine if you need a field approval. Unfortunately, some the "work around" type installs I heard of got pinged during prebuys where those installs were found to be without the proper approvals. Something to consider.

 

[Jesse Saint]

Most panels themselves are nonstructural, but the surrounding structure is. A new panel would attach to the existing structure. Some may call that an overlay. Others would call that a new panel. As was stated, technically an overlay is like the plastic pieces that cover everything except the gauges and knobs. Very few shops do that any more.