Buying Used Avionics: Plan For Refurb Work

Installing used avionics and instruments could make sense for some, but consider testing fees, flat-rate repairs and installation hardware when shopping.

If you thought even a modest new avionics upgrade was in the budget, but proposals are proving otherwise, plan B might be buying used equipment. While this isn’t a bad plan, a hasty buying decision might end up costing more in the long run. This is especially true when buying complex instruments and avionics that require factory service. Worse is buying equipment, having it installed and paying for troubleshooting when it doesn’t work.

In this article, we’ll take a look at the current used avionics market, the potential costs of pricey factory service and some common traps to avoid at any cost. We can’t cover all equipment, but we’ll look at some that may cause problems.

Chasing the Paperwork

The first step is to differentiate marketing lingo from FAA airworthiness matters. And it does matter, because installing shops—especially FAA repair stations—will need supporting paperwork when it’s time to sign off the installation—whether they generate the paperwork in-house or acquire it from another shop.

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One marketing term that’s stuck around for years is the so-called yellow tag, a sticker that might be placed on the component representing it as being in serviceable condition. In the eyes of the FAA (and the technician endorsing the aircraft logbooks), a yellow tag affixed to the component means nothing unless it references a completed FAA form 8130-3. This is the form the technician or repair station representative completes and signs after a part has been tested, inspected (and perhaps repaired) and found to conform with manufacturer specifications. You might find 8130-3 forms attached to the logbook or placed in the flight manual.

Depending on its operating specification (aka ops specs) most manufacturers will provide an 8130-3 after reconditioning or remanufacturing a component to original specifications. Depending on its repair station procedures, some shops will assign a green tag to a component, which generally means the unit is expected to be serviceable or repairable, but it hasn’t been through the evaluation process yet. A red tag likely means the component is beyond reasonable repair or perhaps was cannibalized for parts, rendering it unfit for installation. If you source used avionics from an end user, it might not have any airworthiness documentation at all. Consider these avionics to be “as removed” and in unknown condition. Be ready to pay for bench time, which according to our research can be as little as $90 to as much as $150 or more per hour.

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It’s tough to say what, if any, warranty will come with used equipment. We found that equipment bearing fresh 8130-3 paperwork typically has a 90-day warranty. Reputable shops may warranty an overhauled component for as long as one year. You should get the specific terms in writing. This is especially important for more complex systems and those with high-price replacement parts, including weather radar, systems with CRT displays and complex gyroscopic instruments.

Kevin Helvey at Wentworth Aircraft in Crystal, Minnesota, told us missing paperwork isn’t a deal-breaker for the used equipment it sells, but that it could cost you more. “The majority of installers will end up testing the equipment before installing it anyway, so they can issue tags,” he told us. True, but that’s billable. Since Wentworth isn’t an FAA Repair Station, it doesn’t have the ability to issue an 8130-3. Instead, it places a 30-day warranty on used equipment it sells and (for an extra fee) can coordinate bench testing and certification through its network of shops.

S-TEC 30

Worth mentioning is the STC and installation requirement for the S-TEC line of autopilots—which Wentworth generally keeps in inventory. Helvey and shops we talked with stressed the importance of purchasing (through parent company Genesys Flight Systems) an applicable STC kit to support the installation at an approved Genesys dealer. Even if you have all of the correct autopilot components for a given aircraft (these systems are airframe-specific and have operating voltages, bracketry, wiring and other hardware that varies among airframe types) you could spend an additional $1500 or more on the STC paperwork package, which includes wiring schematics, blueprints, install documentation and other paperwork that comes with the system when sold new.

A Strong Market

We see a strong secondary market for used equipment, likely due to the high costs of new gear. According to a recent report by the Aircraft Electronics Association, retrofit avionics amounted to 46 percent of sales during the first six months of 2016, or more than $509 million. The rest came from forward-fit OEM sales, which was more than $1.1 billion.

To combat the slump, avionics shops are making used sales a larger part of their business. You’ll often find them selling on eBay,, in an online store and traveling to trade shows with used equipment to pedal.

Dave Fetherston, a principal at Nexair Avionics in Massachusetts, recognizes enough market demand to launch an online store for the variety of avionics his shop takes in trade. Fetherston offered several caveats.


“Buyers need to be aware that used radios must have traceability, and sometimes eBay sellers have broken equipment removed from their airplane,” he told us. He wasn’t the only one that stressed the importance of buying from a reputable shop that has a return policy.

What about sourcing your own equipment and carrying it into a shop for them to install? You might pay more for the labor—or be turned away. We’ve heard of shops slapping a premium on the installation of used equipment it didn’t provide. That makes sense because shops rely on the profit margin they make on new equipment sales.

“Good shops are busy right now and it’s understandable why some might instead choose a customer for new equipment over a direct labor job on someone’s used radio,” Fetherston acknowledged.

Like every other shop we spoke with, Nexair Avionics certainly will work with customers and their used equipment, but with guidelines. It’s made clear that the equipment must include complete installation kits. Lopped-off interface connectors don’t cut it.

avionics factory repair costs

Obsolete Parts

Every established seller we spoke with reported sizable demand for replacement navcomm equipment. This includes the popular Bendix-King KX155 digital radio. However, the extinction of the gas discharge display—a common failure component—makes buying this otherwise reliable radio a risky proposition.

Consider that the KX155/165 radios came to the market in the early 1980s—making some of them today over 30 years old. If by chance the radio has an original display, you could eventually eat a repair invoice that approaches $1700. That’s because the old gas discharge display has been replaced with a new LCD, requiring a field (or factory) mod for it to work. BendixKing recently created a factory refurbishment program (through a service bulletin) for the front end of KX155(A) and KX165(A) radios, which will carry a one-year warranty. The $1750 factory refurbishment includes a replacement bezel, lenses, knobs and of course the LCD display. Field replacement (less the bezel and knobs) could run $1300.

cathode ray tube

Just when we gave up on Narco support—particularly gas discharge display replacements for the venerable MK12D digital navcomm—we learned through several shops that a vendor is producing replacement displays. That may extend the useful life of the fleet of existing MK12D and other later digital Narco equipment. While support still exists, we don’t think buying them makes sense.

Aircraft and Avionics Sales in New Cumberland, Pennsylvania, specializes in Narco repairs. Company principal Paul Haubert told us his shop receives nearly a dozen Narco radios for repair each week. He quoted us $275, plus bench labor, to swap a failed MK12D display with a new one. Haubert also told us his shop has been performing all kinds of repairs on Narco equipment and sourcing parts isn’t a real problem. They can be reached at

But servicing other equipment like the UPS-AT GX-series navigators might be a problem. The display vendor for this system is gone. That could leave you scrambling to buy another unit to use for parts before you even have it installed. Who needs that hassle?

Instruments, Glass

You’ll find all sorts of flight instruments on the used market. This includes mechanical slaved HSIs, basic iron gyros, first-gen retrofit EFIS and even later-generation OEM and retrofit glass, including the popular Aspen Evolution PFD. There’s even Avidyne Entegra and Garmin G1000 components—most removed from wrecked aircraft. Pay close attention to factory repair pricing on any of these. If the equipment is out of a salvaged aircraft, you could be stuck with stuff that can’t even be installed and signed off.

BendixKing KX155/165(A)

Avidyne’s Tom Harper stated company policy that says any Avidyne equipment that was installed in an aircraft involved in an accident (as described in 49 CFR 830.2) shall not be serviced or recertified. If the aircraft was involved in an incident, the equipment may be repaired or certified, but only after a review of the situation and circumstances of the specific incident. Avidyne charges a flat-rate testing and recertification fee of $1300 for an Entegra PFD. Flat-rate repair pricing is $7800 and can depend on mod status. Avidyne’s testing/certification fee is $750 for the EX600 MFD, a TAS traffic processor and the DFC90 autopilot, but only if no mods or service are needed.

Avidyne has a sizable rotable pool to support its installed base of Entegra and retrofit avionics, but doesn’t sell factory overhauled equipment.

Installing a used Aspen PFD or MFD system requires the display to first be evaluated by the factory so the installing dealer can use the AML-STC. Aspen’s Michael Studley, director of field service engineering, recommended that the RSM (remote sensor module) be replaced due to the susceptibility of damage to the magnetometer during removal. The RSM is $440 for exchange, while servicing the display is on a case-by-case basis.

Narco MK12D navcomm

With a market flooded with aging HSI systems, it’s tempting to make a steal-of-a-deal on a BendixKing KCS55A HSI/slaved compass system, as one example. There are several critical and complex components in this system, including the KG102A remote gyro. These live hard service lives—not made any healthier by sitting in a box in a hangar or the closet. Before committing to this system or any gyro instrument, we strongly suggest having it bench tested by a shop that’s familiar with it.

Understand the true disposition of an instrument’s recent service history, and the difference between ones that are represented as being rebuilt and overhauled. There is a difference and it’s easy for uneducated sellers to falsely represent the instrument’s status. For instance, FAR 43.2 says, in part, that no person may describe in any required maintenance entry (or form) a component being rebuilt unless it has been disassembled, cleaned, inspected, repaired as necessary, reassembled and tested to the same tolerances and limits as a new item, using either new parts or used parts that either conform to new part tolerances and limits. Bryan Miner at Mid-Continent Instruments and Avionics in Kansas told us it doesn’t represent instruments as being rebuilt, despite tearing them all the way down, cleaning everything inside and replacing components needing replacing.

WAAS navigators

You can learn a lot about the status of an instrument by reading a shop teardown report, which you should ask for. A gyro overhaul generally includes replacing the bearings and any worn mechanical parts. It also includes disassembling the rotor assembly, while replacing any worn parts in it. It should also include calibrating the electronic outputs, if the instrument drives an autopilot. In many cases, you’ll have to pay extra to have the shop align the newly overhauled gyro with the autopilot flight computer it interfaces with. These are fine adjustments that command proper autopilot bank angles, roll rates and flight director command bar presentation. This is one of many reasons why it’s important to get an accurate proposal to install used equipment before the job starts, and after the shop has all of the required parts on hand. The last surprise you want is having to shell out additional money halfway through the job because you (and the shop) didn’t plan on additional accessories and parts.

For basic instruments like airspeed indicators and plain-vanilla directional gyros, some shops might perform basic repairs on a case-by-case basis. Again, read the teardown report for an idea of what was repaired. If done right, you could save money on a repair versus overhaul. As an example, Mid-Continent Instruments and Avionics quoted us $2400 as the average list price for repairing a Century NSD360A HSI, and $3548 to overhaul it. The warranty for the repair is 90 days on the specific parts that were replaced. It’s one year for a complete zero-time overhaul.

Last, you could buy something that’s not serviceable at all, even when buying a core unit with a plan of having it overhauled. Such deal-breakers include components with missing data/identification tags, those found to have excessive corrosion and early-production products with extinct replacement parts.

Is the Savings Enough?

In our view, only in rare occasions does it make sense to source the latest avionics from the used market. Reader Randall Dean’s experience proved that patience could pay off.

“I held out for most of the items I wanted to show up on eBay and was able to purchase a nearly new Garmin GTN750 with 23 months of warranty remaining, along with the Aspen MFD1000, a Garmin XM system, a WX500 Stormscope and even an S-TEC 55X autopilot,” he told us, admitting he spent north of $40,000, but still saved thousands. With the help of his shop, John Revere priced a used GTN750 and some other avionics for his Bonanza, but recognized only a $1200 savings overall. “The full-term factory warranty for the new equipment just made better sense,” he admitted. John Dendecker, the general manager at Carpenter Avionics in Smyrna, Tennessee, advises his customers to consider the warranty when making the decision.

“My rule of thumb is that the savings for used avionics has to be at least 20 percent less than new equipment to even think about sourcing current-production used avionics,” he told us.

Dendecker pointed out that the majority of factory-new equipment has a two-year warranty, sometimes longer. As the pricing chart on page 6 shows, out-of-warranty repairs for newer avionics can cost as much as you might pay for the equipment.

When it comes to installing used autopilot systems, Dendecker and other professionals suggested the cost savings should be at least 50 percent of a new system. Part of that has to do with sourcing hardware that might be missing from the supplied kit. This includes things like trim command and disconnect switches, servo mounting brackets, bridal cables, wiring harnesses and the previously mentioned STC and paperwork kit for S-TEC autopilots.

While the caveat applies to all used equipment, it’s even more important to make absolutely certain that autopilot components are fully functional before the job commences. And just because a component is functional doesn’t mean it’s up to the current mod status and software revision. These costs (not to mention freight charges to send equipment out for evaluation) add up in a hurry.

“If I’m installing a used system and find that it doesn’t work, I could be spending considerable amounts of time troubleshooting because I’ll assume the problem is related to the installation, only to conclude there is a problem with one or more of the components. The customer pays for this time,” Dendecker cautioned.

Advice from a Legacy Avionics Specialist

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In the early days of avionics retrofitting, guys like Harley Bennett were (affectionately, he says) called junkies. Now they’re referred to as legacy avionics specialists. Bennett fell into a nearly 50-year career buying and selling used avionics after equipping his flying club airplanes for IFR using more affordable used avionics. It was the used avionics listings in the publication Trade-A-Plane, plus a demand from avionics shops, that made him realize he could make a living in a business that does nothing but sell used avionics. Bennett has no interest in competing with avionics shops, so his company doesn’t sell new avionics and it doesn’t do installations.

“To our knowledge, we are the only established avionics company who deals only with used equipment. It’s this narrow focus that allows us to offer what we believe is the best service at affordable prices,” he said. Bennett was an early member of the Aircraft Electronics Association (AEA) and says his company has worked hard to create and foster a solid working relationship with traditional avionics shops around the world. That means if he doesn’t have an item a buyer is looking for, he knows where to source it. The company stocks and ships a wide variety of equipment—from navcomms to weather radars—from its East Granby, Connecticut, warehouse.

Selling only certified equipment with a 90-day warranty (or with a one-year warranty for an additional 10 percent), Bennett Avionics subcontracts all repair and certification work to a network of shops around the country and utilizes experienced techs who are open to working on older avionics. In our estimation, that’s one challenge in buying used equipment. The bench techs who were once skilled in repairing old equipment have been replaced with new talent who aren’t versed in older analog designs.

Bennett makes a reasonable case for buying used equipment. “For clients trying to decide on new or used avionics, I advise them to first establish a budget and consider how important it is to recover the investment when they sell the aircraft. They’ll likely recoup a larger percentage of the investment in used avionics because it took a hit in depreciation on someone else’s watch,” he told us. On the other hand, he acknowledges that used equipment isn’t for everyone.

Bennett said you should insist that any used equipment you buy is first tested, certified and comes with the appropriate installation hardware. Also, consider recommendations from fellow aircraft owners. “The avionics industry is a small one and the reputation of a seller (including shops) is enduring,” he said. Speaking of enduring, Bennett cautions against investing in stuff that’s just too old, or also too much. “After all, how many 40-year-old television sets are you watching in your home? Plus, when making a buying decision, think about the avionics you need for the mission, versus the ones you want,” he advised. In our view, that’s solid advice that applies to both used and new avionics. Contact Bennett Avionics.

Caveat Emptor

If you think used avionics make sense for your situation, our advice is to work closely with your shop when it comes to sourcing it— if they even agree to install it. They’ll spot red flags easier than you might.

Ask the seller to agree to returning your money (or make good on the repair) if a bench test reveals problems. Shy of buying new stuff from the start, that’s one more layer of protection in a deal that could cost more than you thought it would.

Editor in Chief Larry Anglisano has been a staple at Aviation Consumer since 1995. An active land, sea and glider pilot, Larry has over 30 years’ experience as an avionics repairman and flight test pilot. He’s the editorial director overseeing sister publications Aviation Safety magazine, IFR magazine and is a regular contributor to KITPLANES magazine with his Avionics Bootcamp column.