KLN94 to a KNI520?

[Darryl Snover]

Having trouble coming up with a definite answer to this one. I'm hoping the collective experience here may have an accurate answer:

My Cherokee 140 has a KLN94 GPS installed, but as VFR-only. It is not wired to an annunciator, nor a CDI.

The required annunciator is available at a reasonable cost (MD41-524), so that'll resolve that. However, while I have two CDI's (KI-209 - KNI-520), I know that the KI-209 will definitely NOT work (KI-209a would work, but that's not what I have). What is less clear is whether the KNI-520 can be driven by the KLN94. Documentation isn't clear on this.

Is anyone familiar with the KNI-520 enough to know if it is able to driven by the KLN94 GPS? If it is, then I have a reasonable path to get this GPS IFR capable without spending multiple AMU's.

* Yeah, I know. Install a 'modern' GPS. Except that a modern GPS would cost about a third of the value of the aircraft, and couldn't be installed until sometime in 2022 with all the avionics shops being completely booked. I'd love a GPS-175, but the cost......

 

[steingar]

I just didi this a few years ago and had to go buy the CDI. Think it was a 209a, I have a 209 in the hangar still for sale. What I recall was getting the right gizmo was painful, but didn't break the bank. I like the KLN94, it is long in the tooth but it works well, runs my autopilot and I can program from home, so I don't need to keep a computer at the hangar or routinely drag one to the hangar.

 

[Darryl Snover]

Based on what what I can figure out, the KNI-520 will work, but since the KLN-94 doesn’t output any vertical guidance, may not be the best choice, and that a standard VOR-only CDI like a KI-202 may be a better choice.

since I already have the 520 installed, I’m thinking I’ll go ahead and use it.

 

[gov98]

So um...well... in the um ahem... legal world (anyone feel free to correct me if I wrong) you're not going to ahem get your KLN ever certified by anyone for IFR operation at a reasonable price. Since they didn't do the original work they aren't going to sign off on the required documents to make it legal for IFR. (I'm betting dollars to donuts that your paperwork says VFR-only). Not saying it's okay or acceptable but VFR only vs operation that includes Approaches (i.e. "IFR") [but again NOT LEGAL FOR IFR] is just a setting on your KLN-94 as it is anyways, you can look that up if you want to take ALL and I mean ALL the risk associated it. All I am saying is that what your hoping to achieve (IFR legal KLN-94 operation) is not going to happen just by wiring in an annunciator and and a KNI-520. Especially since, you couldn't install it yourself legally anyway.

 

[midlifeflyer]

Wow! The aviation group mind strikes again! I've long had this theory that when someone says anything aviation related, it appears in many unrelated places.

Yesterday I went to look at an older 172 a flight school I work with acquired. In the cockpit, a VFR Only KLN 94!

 

[Darryl Snover]

So um...well... in the um ahem... legal world (anyone feel free to correct me if I wrong) you're not going to ahem get your KLN ever certified by anyone for IFR operation at a reasonable price. Since they didn't do the original work they aren't going to sign off on the required documents to make it legal for IFR. (I'm betting dollars to donuts that your paperwork says VFR-only). Not saying it's okay or acceptable but VFR only vs operation that includes Approaches (i.e. "IFR") [but again NOT LEGAL FOR IFR] is just a setting on your KLN-94 as it is anyways, you can look that up if you want to take ALL and I mean ALL the risk associated it. All I am saying is that what your hoping to achieve (IFR legal KLN-94 operation) is not going to happen just by wiring in an annunciator and and a KNI-520. Especially since, you couldn't install it yourself legally anyway.

The KLN94 is an IFR capable GPS, which in this case was installed without the required bits (annunciator, CDI), rendering its install VFR only - which indeed is placarded that way. However, working with an A&P/Avionics shop to get the install of those required bits taken care of, along with the necessary paperwork/tests/POH Supplement, and this is very do-able. Certainly not the first time that older equipment is re-used/installed in an aircraft. As to reasonable cost - that's part of the information gathering that I'm in the process of doing.

 

[Ryan F.]

I loved my KLN-94! It was a great little unit for its era, consistently undersung/undersold and always the David to Garmin's GNS430 Goliath. I used it to fly to all 4 corners of the USA and slightly beyond.

Like vintage arcade games, these electronics come into our lives and must inevitably leave again. The GTN650 that replaced its predecessor in 59Y is light years ahead in functionality and capability, but I still have a soft spot for the venerable KLN-94.

Wouldn't spend an extra dime on one at this point, though.

 

[Darryl Snover]

If I can meet my goal for an AMU or two, I’ll be thrilled. But anything more than that, and some other hardware will have to be installed. I admit I’d love a GPS-175 in its place!

I loved my KLN-94! It was a great little unit for its era, consistently undersung/undersold and always the David to Garmin's GNS430 Goliath. I used it to fly to all 4 corners of the USA and slightly beyond.

Like vintage arcade games, these electronics come into our lives and must inevitably leave again. The GTN650 that replaced its predecessor in 59Y is light years ahead in functionality and capability, but I still have a soft spot for the venerable KLN-94.

Wouldn't spend an extra dime on one at this point, though.

 

[Ryan F.]

If I can meet my goal for an AMU or two, I’ll be thrilled. But anything more than that, and some other hardware will have to be installed. I admit I’d love a GPS-175 in its place!

Your plan might be good, and I'm only throwing this out there because I've been neck-deep in avionics upgrades for the last few months, but... "hear me out" as my favorite fitness friend tells me when we're in the gym. I'm only attempting to provide a little context for your decision.

Let's assume you're able to hit your goal and get the KLN-94's VFR-only limitation removed for under $2k AMU.

You're now on a timer. The timer's countdown is much like Wheel of Fortune. You spin the wheel, and where it lands, no one knows. Let's say it lands on a display failure 6 months after the investment. (By the way, this is not a far-fetched scenario. I see failed KLN-94s on a regular basis.) Since these units are unserviceable, you have a new choice: replace the KLN-94 with another used unit (with an identical timer, which is to say, random) or replace. What do you do?

Because these units are now old, I think most folks would probably replace it with a modern Navigator. Of course the KLN-94 is LNAV only vs. the full, wondrous LPV capability of the GPS175, and you're out the labor to not only install the new gear, but uninstall the various components necessary to make your TSO-129(C) 129 GPS a "suitable RNAV system." I'm not sure it's investment which really pencils out.

But then again, you could hit the lottery. Maybe your display keeps on crankin' in the meantime, and you have multiple years of LNAV-only approaches ahead of you.

It's a thought process...

 

[gov98]

The KLN94 is an IFR capable GPS, which in this case was installed without the required bits (annunciator, CDI), rendering its install VFR only - which indeed is placarded that way. However, working with an A&P/Avionics shop to get the install of those required bits taken care of, along with the necessary paperwork/tests/POH Supplement, and this is very do-able. Certainly not the first time that older equipment is re-used/installed in an aircraft. As to reasonable cost - that's part of the information gathering that I'm in the process of doing.

Hey I mean I get it, and more power to you if you can get someone to sign off on it. I guess I just estimate roughly that the process of installing the wiring etc. is going to involve taking a lot of stuff out to put old stuff in. Which is great but I think you're looking closer to 3-5000 in labor to include the sign off. It's one of those once you break the "seal" might as well just do it right. (In my very irrelevant and humble opinion after all it's your money.) All I'm saying is...is that you can get your IFR capable GPS to display approaches and do everything that an IFR KLN94 would do by looking up on the inter webs how that can be done. No it won't be legal, and no it won't be driving a nav head, and it won't be driving independent annunciator lights. Just putting all those components in the plane and wiring them won't make the GPS display approaches either.

 

[Doug Reid]

There was a mid continent cdi with annunciators on ebay a few weeks ago for less than $500.. it was advertised as a working unit compatible.