The International Cessna^® 170 Association

Where do you place a CDI when all 7 holes are taken by ASI,T&B,ALT,AH,DG,VSI,RPM? Saw some pictures showing an 8th hole below the middle hole(seems like a difficult mod due to the strenghening required) and others beside the radio stacks panel covers. Picture attachment and explanation on the difficulty of installation appreciated. Is there a 2 1/2" CDI that can interface with kx170b's? Thanks!

Alvin, that "eighth hole" mod you refer to would require removing the overlay and then either adding a piece to the instrument panel or, probably easier, removing the existing instrument panel and fabricating a new one that included the piece that drops down in the center to accomodate the extra instrument. The 170 & 170A models had a couple different versions of the panel - one of which that included an instrument in that exact location. This was usually done when the compass was panel-mounted in the center (where one might usually fine the DG), so the VSI (I believe) was mounted beneath it. If you can find an instrument panel from one of those then it would already have the mounting hole you need for the CDI and all you would need to do is cutout the compass hole above it to accommodate whatever instrument you plan on mounting there.

Here are some shots from a TIC170A member (can't remember who - sorry) who performed the mod:

Instrument panel installed


Panel Overlay modified for extra hole


Panel completed

Alvin how much money do you have for that 2 1/2" CDI.

Viewing the panel picture Doug posted my CDI is located just about where the stall warning horn is located just to the left of the control column. I do not have either of the lower outer panel covers installed on my airplane which makes the panel flat in this area.

Also viewing his picture my radio stack is closer to the outside of the aircraft The right side of the CDI is flush to the right of the radio stack below it and there is enough room for the CDI. I have a GPS annunciator panel to the left of the CDI.

I also relocated my Mag switch to a lower sub panel so the my key ring wouldn't dangle in front of the CDI. I don't think I have a picture but if I find one I'll post it.

Alvin, here's an idea. I'm assuming you have the panel-mounted compass. Get a windshield-mount ot panel-top compass, pull the panel-mount compass, get a 2-1/4" VSI & mount in the compass hole. Pull the 3-1/8" VSI and mount your CDI in that hole.
My Spruce catalog lists some 2-1/4" VSI's at about $200, and some windshield mount compasses for somewhat less.
Mounting the CDI in a sub-panel would probably be easier & cheaper, maybe make up a flat sub-panel to replace the LH glovebox.

Eric

zero.one.victor wrote:Alvin, here's an idea. I'm assuming you have the panel-mounted compass. Get a windshield-mount ot panel-top compass, pull the panel-mount compass, get a 2-1/4" VSI & mount in the compass hole. Pull the 3-1/8" VSI and mount your CDI in that hole.
My Spruce catalog lists some 2-1/4" VSI's at about $200, and some windshield mount compasses for somewhat less.

Eric

D'oh! Funny how the passage of time fogs the memory. What Eric describes is how mine was setup when I purchased it.

Another possibility would be to replace your DG with an HSI. Then you would have DG, CDI all in one hole. This would be quite a bit more expensive , but would look really slick.

Actually, Becker (German mfr) makes an approved 2-1/4" CDI with GlideSlope, etc. but they are not the "low bidder" in any contest I've ever seen. (Their more common 3-1/8" indicators go for $2K, etc.)

This page has a pic of their unit near the bottom.
http://www.avionix.com/indicator.html