Because Owning And Flying Your Beechcraft Can Be Done Safely AND For Less Money!
  Your Collins 251 & 351 or NARCO MK12D Needs Digital Displays



Collins Display Replacement Source


Do you have the popular Collins VHF 251 and VIR 351 Digital Flip-Flop Nav/Com setup and flustered that the digital displays are always burning out?


Collins NavCom


Here is a posting from the Beech List for a contact to get the displays at something like $36 and the secrets to changing them out in about 5 minutes time:


Once or twice a year one of the display units will burn out and die. The five digits displayed in each of these radios are separate display units, so with dual nav/comms, this package has twenty individual display units. Every time I'd bring one in for repair, it costs close to $100 and seemingly without fail, two weeks later a different digit in the same radio would fail!


My avionics shop only charges a half hour labor and usually says "I'll have it done in an hour or so" I figured just how hard can it be! The next time it happened I figured I'd give it a shot by doing it myself. The avionics shop agreed to sell me a display unit ($63), but cautioned to be very careful, "there's a trick to getting that face apart without damaging it" (not that they offered to show me what it was!). So I was very careful, figured out the 'trick' without breaking anything, and changed the display.


It took about five minutes, including pulling the radio and reinstalling it in the panel. So with the help of a couple of electrical engineering buddies from Raytheon, I tracked down the manufacturer of the display units in hopes of getting a really economical fix to this recurring problem. I contacted them and they promptly responded with a note saying they'd be happy to sell to me and they'll even accept a credit card!



This is the reported display element removal procedure from two visitors:


Remove radio/nav. from aircraft using a standard avionics allen key. Undo the selector switches with a small allen key and gently remove. Undo the two screws that hold the plastic front plate to the frame and remove gently. Carefully pull out the failed display and replace with a new one, taking care not to bend any pins. Reverse the above to re-assemble.


The top of the front cover is flexible and has "hooks" on the inside.  Simply slip a thin putty knife under to unhook after removing the screws and knobs and the front cover slides off.  To verify that it was indeed the light assembly that was bad I switched the first and last and the problem went with the light.  I ordered one from Etsy for $35 plus shipping of $6.30 so it should be resolved shortly. Susan Shawlee of Sphere Research Corporation in British Colombia has them in stock for $49 plus $22 shipping via parcel post.


It has also been reported by avionics guru, John C., that the later Cessna 385 radios use the same display modules and if you find these radios on EBay, they can be a source for replacement displays. The Collins' DME DCE-400 unit reportedly contains these display modules as well.


NEWS FLASH November 2013: Latest report from Beech Talker Larry M. indicates:


"the supply line for the digital displays for the 251/351 Collins radios is drying up. The units are labeled a couple of different ways, but the Minitron 3015F part number is accurate. There is a supply of 20 units at $49.00, less than half of what the market price is, at Sphere Research."


Susan Shawlee

Sphere Research Corporation

3394 Sunnyside Road

West Kelowna, BC V1Z 2V4


Phone: +1 (250) 769-1834             Fax: +1 (250) 769-4106             URL:



Cessna radios, and other Collins units, such as their DMEs use these digits, and it can be even cheaper to find them used. I saw a DME for sale, EBAY buy it now, for $99.00, and the seven digits alone are worth $125.00, and you still have more parts!



Hopefully, these tips will extend the life of your Collins equipment but come on folks, at some point even the most hardened CSOB has to enter the 21st Century of Nav/Com technology



NARCO MK12D Display Replacement Source



Digikey PN: 541-1413-ND

OE PN: PD020D02505S51 or PD-20D025-5 and Datasheet is HERE



NARCO NCS812 Display Replacement Source




Digikey PN: 541-1414-ND

OE PN: PD-20D025-7 and Datasheet is HERE



KFC 250 Auto Pilot Annunciator Bulb in KAP310



KING 28V PN: 037-0026-11


Bulbs in KAP315 Panel are: OL-632


This is a conventional 28V Bulb: 8632 T1.25 available HERE or HERE for ~$2.50 on 9/23/2017


An Auto Pilot shop quoted the contributor $28.50 for the bulb. You decide.........


Contribution courtesy of Duke and Bonanza owner Ken R.

Matthias R. reports the following regarding bulbs for his KAP315 autopilot annunciator:

"We have to replace some of the bulbs in our KAP 315 autopilot annunciator panel of our KFC 250. I noticed that you had some information about them and two links to shops selling them -- one has gone dead and the other charges $80 for a 10-pack.

I found the same bulbs at Mouser for $1.30 a piece." HERE



NARCO Repair Sources


With NARCO having gone out of business, many of us with fully functional equipment may be wondering where to get repairs for the NARCO brand.

A few years ago, I had a Com failure on one of my MK12D+ radios and was able to identify Lafayette Avionics as a viable shop that could and would still repair the NARCO brand. Ron at Lafayette Avionics identified a shorted capacitor which was the source of my Com problem and made the repair.

I love my MK12D+ Nav/Coms and will keep them going as long as I can.


On 11/3/2018 Bill H., reports that Spencer Avionics in Spencer, IA has NARCO repair capabilities (as long as parts are available). They are located at KSPW and their phone number is 712-262-2364. You can also email them.


On 10/01/2022 these two shops were identified as NARCO repair capable:

RC Avionics  near Minneapolis/St. Paul

Mike's Avionics in Star Valley, Arizona (928) 474-5562

Mike is Not Quite Retired

If you know of other shops that are willing and able to repair NARCO equipment, please email me with their info.