A Good Soaking

Thats whats likely to happen if you don't conduct a thorough avionics pre-buy on a used airplane. Heres what to look for.

My telephone rang early one Monday morning. It was a friend who wanted to share some news and ask for advice. After months of searching and disappointment, he had finally found what he described as a cherry, reasonable time and well-equipped early-model Saratoga.

Not having seen the aircraft in person yet, he was making judgments from afar, relying on the brokers spec sheet and the craftily written ad in Trade-A-Plane.

I could sense his excitement and dreaded the thought of bursting his bubble over an avionics issue. He wanted to verify that the avionics were making the deal even sweeter. Before I could finish my first question he answered, it has a full stack of Bendix/King IFR avionics, an autopilot and even a GPS.

I had him forward the spec sheet and after review, it turned out that the cherry Saratoga did have reasonable times, new paint and interior.

But the avionics were, well, not exactly up to standards. Nor were they we’ll represented in the spec sheet or the ad. (Gee, what a surprise, that almost never happens.)

The Toga had a full stack of Bendix/King IFR radios, but lovingly made in Olathe when Jerry Ford was president. One of the navcomms was only 360-channel and not likely to meet the FCC frequency tolerance specifications.

The transponder was an older model KT76 of questionable mod status and the autopilot was an ancient pneumatic wing leveler long since out of production.

I hesitated for a few hours before getting back to my friend but when we worked up the numbers for even a minimal upgrade of these systems, his budget was a shambles.

Sorry to say this isn’t a rare occurrence these days.

Pig in a Poke
In the airplane buying and selling business, there are few hard rules but one of them is that clean airplanes with low time get top dollar regardless of avionics.

Although the one with better avionics may bring a slight premium and sell more quickly, a nice airplane with an avionics museum wont necessarily be cheap. If you find one with a recently upgraded stack, you’ll pay more.

With so much high-dollar upgrading going on, we find that the avionics in some single-engine aircraft exceed the value of the airframe. This is great news for the buyer but not so good for the seller, especially since he did the upgrading.

Recently upgraded or not, caveat emptor when it comes to avionics in a newly purchased used aircraft. Avionics and related systems are often the most overlooked detail during the pre-buy process and its not at all unusual for a pre-buy to skip the boxes entirely, reasoning that compared to an engine overhaul or replacing a cracked spar, how expensive could it be to fix a few radio problems?

Maybe it wont be expensive. Then again, weve seen instances of avionics repairs requiring several thousand bucks just to get the panel up to minimum standards and make sure everything thats there works right, let alone upgrading anything.

Chances are, the used aircraft of your dreams wont have the panel of a new model. With that in mind, here are some avionics basics to consider when shopping for used aircraft.

If you keep the following items in check, you can dodge most of the surprises commonly encountered on the first trip to the avionics shop and have more money for goodies once you get there. At the very least, you can squeeze the seller on price a little and knock the bitter edge off the cost of necessary upgrades once you own the airplane.

The Basics
When you test fly the airplane ahead of buying it-and you do plan to test fly it, right?-turn on every box in the panel and make sure it works correctly, not just powers up. The DME should show distance, speed and time, the ADF should point at the station and the comms should transmit and receive intelligibly. Basic stuff, I know, but youd be surprised at the number of owners who say, I never tried the number 2 comm.

One pre-buy I was involved in turned out to be a hassle for the owner despite my advice on checking out the basics. He was serious about a 1980 Aztec and I warned him to make sure that the 24-month pitot/static inspection was properly complied with before delivery. Aztecs always seem to require repair of the static system at some point. Static lines get old and brittle; fittings crack and break loose. Its a big bucks fix.

This owner thought he was getting a fresh inspection but when I examined the logbooks after purchase, the system was overdue. And as I predicted, it needed a lot of work, requiring replacement of plumbing all the way out to wings.

A newly purchased aircraft without a relatively fresh pitot/static signoff raises some red flags. Its possible that the system has leakage and failed the certification and the owner left this problem to the future buyer. Or worse, the aircraft wasnt we’ll maintained and such inspections were ignored.

Hopefully, the test was actually performed and the entry simply overlooked in the logbooks. Its amazing the number of pilots who are unfamiliar with FAR 91.411 and 91.413 criteria.

If the aircraft is flown IFR, the transponder, altitude encoder, pitot/static and altimeter need to be inspected and certified every 24 months.

If the owner was a fair-weather pilot who never operated IFR-a common thing- the transponder is the only device required to periodically re-certified under the FARs.

A properly performed pitot/static check will also reveal defective flight instruments, specifically airspeed, VSI and altimeter. The big-dollar item here is an encoding altimeter, which can easily cost more $1000. If the altimeter fails the tolerance and/or friction part of the test, you can count on replacement or overhaul.

Age-related case leakage from the VSI and altimeter sometimes fail a system. In short, browse the logbooks and find the date and/or hours since the last replacement. And if replaced, were these instruments zero-time overhauled units or simply repaired?

A reputable instrument shop will provide a teardown report during the overhaul. Spray painting the case and cleaning the bearings doesnt count. The same holds true for vacuum-driven instruments, which probably fail more often. Bottom line: Know the condition of the static system before you buy.

Transponders, Encoders
Another item to address at biennial inspections is the transponder, along with the Mode-C reporting system or blind encoder. If you look through the logs and find the same serial numbered encoder for the last 15 years of inspections, its probably reaching the end of its service life.

Since encoders plumb into the static system, they can be another source of leakage. The cost of a new encoder is about $300, plus labor. The encoder certification checks the Mode-C reporting through all ranges to the service ceiling of the aircraft.

Any intermittence or erroneous reporting will fail that portion of the test and replacement is often recommended if not required. Incidentally, if your aircraft has an encoding altimeter and it needs replacement, do yourself a favor and switch to a standard altimeter and remote blind encoder.

The replacement cost of each unit is often less than replacing the single encoding altimeter. The regulations say that the entire instrument must function 100 percent so if only the altimeter section of the instrument is functional but the encoding is faulty, the entire instrument must be replaced or overhauled.

you’ll have to swallow the initial installation costs associated with the change over. But a standard altimeter and blind encoder are cheaper to maintain in the long run.

If the transponder is long in the tooth with no recent repairs or overhauls, it may or may not pass its required check. Plan on the worst case and a replacement or repair and factor that into your price negotiations.Upgrade and Priorities

So, you purchase an older but clean aircraft intending to upgrade the panel, expecting to retain at least some of the primary systems. You bought the aircraft right and actually have money left in the budget for avionics upgrade. (Trust me, you don’t have as much upgrade money as you think.)

Many new owners want to jump right in and install the latest and greatest color GPS navigator, a favorite toy. This is where an avionics shop sales department gets into tough-sell territory. What many owners fail to realize is that newer nav management systems that incorporate several primary systems will not perform we’ll when coupled with older equipment, especially indicators and audio panels.

Consider the audio control system, for example. The communications systems in newer NMS systems were engineered to play best with modern high performance audio systems.

You can certainly pipe a Garmin 430 through an ancient Cessna or Piper audio switching network with its awkward array of relays and wiring. But most reputable shops will balk unless the audio panel is upgraded, too.

Technical issues such as impedance mismatching, sidetone level imbalances and so on are clearly noticeable. Its almost like installing performance racing tires on a stock suspension system.

No problems, of course, with relatively recent audio panels, such as the Bendix/King KMA24. Replacing one of those when upgrading is purely an elective decision but audio panel technology has come so far in the past five years that it always makes sense to at least consider one. These days, you get a state-of-the-art intercom out of the deal, too.

In my view, however, its best to delay the installation of a newer navcomm and/or GPS and build the foundation with modern audio. As weve reported in past issues of Aviation Consumer, the market is packed with affordable audio options and by far, one of the leading complaints we hear about new radios is that they don’t sound right.

Also, you’ll save money on installation costs while changing audio and major systems while the panel is opened up.

Budget Damage Control
Does the aircraft have an avionics master switch? An older but recently upgraded ship usually will but many older aircraft still rely on power switches for each box. This adds to wear and tear and invites failures. Also, many older aircraft still have individual fuses instead of push/pull type breakers.

When adding an avionics master switch, expect to have the old-style fuses changed to breakers first. This is a sizeable and tedious task, as the main electrical buss needs to be opened up and reworked. Having fuses instead of breakers is often indicative of the condition behind the panel and you can just about plan on major rewiring work. Again, factor this into your price negotiations. It can easily cost $2000 in just wiring.

How about a cooling fan system? If you arent sure when you examine the aircraft, look for a circuit breaker labeled as such. You should also turn on the avionics master and listen for a blower. Most new systems shouldnt be installed without avionics cooling.

More often than not, older panels have outside air-cooling and the ducting is broken, decayed or missing. Add a fan to the list of upgrades once the airplane is yours. Plan on approximately $300 to $500.

Whats the style and condition of the aircraft antennas? If equipped with fiberglass comm antennas, is the coating cracked and ragged in appearance? Are the communications antennas older metal type rods?

If so, despite the condition of the airframe, its probable that very little upgrading has been done and you may have to spend the money yourself to get the airplane up to standards.

New replacement comm antennas can cost more than $500 for the pair. And for a real shocker, research the price of those flying-V antennas found on many Bonanzas. Whatever the case, do some quick math by looking at the ballpark costs for antennas and wiring.

Older Radios
We still see a lot of mid-1970s airframes with older Bendix/King or Narco radios. Its very common to see a KX 170B as the number 2 radio to a newer digital display model, such as a KX 155.

Some owners reason that they can buy the airplane and muddle through with one not-so-old radio and one ancient navcomm for a couple of years, then upgrade later.

Not a bad plan but make sure the number 1 comm really is up to snuff. How recent is the digital unit and does it have the most recent mods available from the factory?

Check the condition of the digital displays. A Bendix/King Silver Crown KX 155 navcomm display replacement can easily cost $200 per radio. I recall one case of a client picking up a clean later model Archer with a respectable avionics spec sheet.

On the way home from fetching the aircraft, he stopped midway to have almost $1000 worth of radio work done, much of it due to display failures and push-to-talk system repair.

Once on home turf, he replaced the directional gyro after suffering hopeless precession during the trip home. His first week of aircraft ownership cost him nearly $2000. And that was just to fix what was already there, no upgrading.

We see a few Collins Microline units in various airframe models, sometimes combined with Bendix/King radios. These were fine radios in their time but have been the subject of literally dozens of modifications. Without these, the radios performance will be substandard compared to modern gear. It could cost a couple of thousand to bring them into line, a sum thats most of the way toward a new navcomm.

As for KX 170s in the number 2 slot, these were also fine radios. But they are reaching the end of their service life. We caution owners not to spend too much repairing them, if they can even be fixed economically.

The same advice applies to older DMEs, ADFs and RNAV units. The Narco DME 190 was a fine unit in its day, but do you really want to repair one that doesnt work? How about a KNS 80, whose expensive display can set you back almost as much as the unit is worth.

When youre poking around the cockpit, make note of the type of VOR/LOC indicators. If you plan to immediately upgrade, you may have to replace these and your shop will want to know whats currently in the panel. Again, consider these items in your price haggling. Theyre fair game for knocking off a few bucks here and there.

Good Panels? Not Many
Aircraft with panels that have been regularly upgraded and cared for are few and far between, it seems. Most owners who invest the money and effort in regular retrofits are in it for the long haul. They have no desire to buy a different airplane every year, so they slowly build the panel of their dreams.

These are the airplanes that bring the big bucks when the owner finally moves up to that high-performance twin. They make perfect platforms for goodies without getting bogged down fixing the basics. If you find one of these-and they come along now and again-don’t expect to get it for a bargain price.

If you follow the steps and suggestions mentioned here, you may take less of a hit on the avionics once you fly your new airplane home. Better yet, have a shop you trust do an avionics pre-buy for you and make sure the items discussed here are covered. The inspection will cost a couple of hundred bucks, at most.

First, send a copy of the equipment list to your avionics shop. They can tell you if the aircraft is worth pursuing based on the level of upgrade required, even before spending money on a proper inspection. If the avionics credentials look good, set up an inspection. Get a written quotation for the upgrades you would have performed as a potential owner and ask the shop about the accessories mentioned here.

Bring the avionics quotation to the bargaining table. you’ll be surprised what a seller will deduct to make the deal work. The worst the seller can do is say no and walk away. In the end, he may be doing you a favor.

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by Larry Anglisano

Larry Anglisano is an Aviation Consumer avionics editor and a consultant for Exxel Avionics in Hartford, Connecticut.