KAP 150 "HDG" Light Burned Out

[MisfitSELF]

I have a KAP 150 autopilot.  Just yesterday when I went to heading hold I noticed that the "HDG" light didn't illuminate (it definitely worked during pre-flight).  The function still worked as it followed my heading bug but it didn't light up even after a couple of autopilot disconnects and a reset of the trim power. 

What are my options to fix this? (and yes I'm even considering 'GFC-500' as an option (-; ).

 

Bruce

[LANCECASPER]

4 hours ago, MisfitSELF said:

I have a KAP 150 autopilot.  Just yesterday when I went to heading hold I noticed that the "HDG" light didn't illuminate (it definitely worked during pre-flight).  The function still worked as it followed my heading bug but it didn't light up even after a couple of autopilot disconnects and a reset of the trim power. 

What are my options to fix this? (and yes I'm even considering 'GFC-500' as an option (-; ).

 

Bruce

@Jake@BevanAviation This is the man that knows

[jlunseth]

Yeah just go to your local avionics shop and have them change the bulb. Had the same problem a few years ago on my KFC200. It was confusing because I did not know without watching the aircraft's reaction, whether I was or was not in HDG mode and since I have a separate GPSS (Icarus SAM) that works through the HDG mode, that meant that I did not know whether the 750 was in charge or not. Not  a big deal, just go get it fixed. While you are at it, get them to check all your other bulbs on the panel and in the instruments. Was told years ago they all need to work for the aircraft to be airworthy.

[kortopates]

Personally I vote for GFC-500! They're awesome.

But for a few dollars the bulb can be replaced. Any avionics shop can do it, but I recall the unit needing to be pulled to get the faceplate off - which is a bummer because doing so opens the static system requiring a leak test when putting the AP back in.

[Jake@BevanAviation]

@MisfitSELF  You could try and swap the lamp with a different one and see if the problem follows the lamp.  If the lamp fails to illuminate during PFT the lamp has failed.  If the problem doesn't follow the lamp it could be a logic problem with the flight computer.

[Pinecone]

I had this issue with mine.  When I took the plane to Sarasota Avionics to swap the 650 for an Xi, I mentioned this (and the KAS-297B display was dim), and they fixed both in an extra hour or so, and for a quite reasonable charge.

[Jerry 5TJ]

15 hours ago, kortopates said:

but I recall the unit needing to be pulled to get the faceplate off - which is a bummer because doing so opens the static system requiring a leak test when putting the AP back in.

It is often possible to pull the unit out of the panel about an inch and expose the four screws on the side of the front panel without disconnecting the static port hose. 

[Jake@BevanAviation]

To remove the bezel the unit will have to be removed from the rack and the static line disconnected.  There are 4 screws on the side of the unit that hold the bezel to the frame and 4 screws on the inside of the unit that hold the bezel to the motherboard.  To remove the 4 screws on the inside you have to take the top cover off and take the screws out of the top motherboard.

[moosebreath]

You access the bulbs exactly as Jake describes.  They simply plug into sockets on the front of the unit. The hardest part is getting the static line off if it has not been disconnected recently.  The rubber will be old and not want to slide off the metal tube on the computer.

Mouser part number 606-CM7376 will work.  They are currently less than $2.00 each if you buy ten.  It might be a good idea to simply replace them all at the same time.  

[LANCECASPER]

On 4/1/2023 at 9:02 AM, MisfitSELF said:

I have a KAP 150 autopilot.  Just yesterday when I went to heading hold I noticed that the "HDG" light didn't illuminate (it definitely worked during pre-flight).  The function still worked as it followed my heading bug but it didn't light up even after a couple of autopilot disconnects and a reset of the trim power. 

What are my options to fix this? (and yes I'm even considering 'GFC-500' as an option (-; ).

 

Bruce

Since your airplane (N57082) is 14v I'm not sure if the bulbs need to be 14v or 28v, my guess is 14v. Your KC192 autopilot box for the KFC150 will probably say 14v. 

Here's a spec sheet on the different bulbs and their voltage: https://www.mouser.com/datasheet/2/423/T-1_3_4_BiPinBase_.125in-1064891.pdf

Aircraft Spruce also sells a few of these: https://www.aircraftspruce.com/search/search.php search "bi-pin"

[Kefferch]

Can this work be done by an A&P and is this 100% legal to be done without going back to the factory?