For The Love Of God, Update Your Avionics!

Written by: James Brewer, Your Guy on the Inside

James “Jamie” Brewer, SEA Avionics Tech

Avionics can easily be overlooked when budgeting for an airplane.  It’s happened to everyone I know, and I’m sure if you have a plane it has happened to you.  You start thinking about replacing your radio after getting that repair bill, but then you notice a low oil pressure indication on your next weekend outing.  Shortly after that, the money you had to use for a replacement radio is going into your engine.  And although I have an affinity for all things electronic in an aircraft, engines tend to be a higher priority.

>>>> Why should you bump up the priority of updating your avionics beyond the ADS-B mandate?  The same reason anything gets bumped up in priority – cost.

The avionics of the mid 80’s to late 90’s were phenomenal.  Then again, that can be said for every era of avionics with their respective pushes of technologies to further limits.  But the convergence of small scale integration circuits such as logic gates and basic processors, predecessors to the revolutionary 8088 microprocessor that really kicked off home computing in the 80’s, made for some of the most inventive and flexible circuits ever.  Autopilots that processed analog signals to provide accurate acceleration curves to the servos are works of art.  It’s literally using analog devices to perform calculus.  And they have worked.  For decades.

But the world marches on.  Now the functions of entire circuit cards are contained on one small section of a chip that does thousands of other functions.  The amount of data available to a pilot or flight crew is akin to having an AWACS at your disposal.  And for a fraction of the (inflation adjusted) cost of the older units.  But with that aging beauty of analog / digital hybrid electronics comes a lack of availability of parts.  There’s not a big market for standalone components any more.  Some of the same transistors used in those giant home stereo systems are also used in avionics components from that era.  The stereo systems are gone, but the avionics are still functioning.  With a lack of demand, manufactures have moved on to bigger and better things (or rather smaller and better).  Look around your own environment outside of the cockpit.  What’s the oldest electronic device you have that you use regularly?  I’m going to go out on a limb and say it’s less than 20 years old.  Here is an autopilot that was last checked by the factory in 1978, the 24th week (June 12th through June 18th) of 1978 to be exact. I couldn’t tell you when it was manufactured; the date codes were so old the ink had degraded to the point of illegibility.

Fortunately, this unit was able to be repaired. But more and more, parts are no longer available for these aging works of art.

Gas discharge displays that were used for every radio ever known are as rare as winning at black jack when you hit on a 20.  The units that have early microprocessors are the same way.  And even if the part is available, it’s often more expensive than a new radio, and has been sitting on a shelf atrophying since Michael Jordan was the king of basketball.  Ultimately, the cost has gone up, and the reliability has gone down on the individual components inside radios.  As a technician I like to think I can fix anything, but the sad truth is without good parts, there’s nothing I can do.  Even when parts are available, the cost has gone up so much that paying the repair cost over the remaining life of the unit vs. the cost of a new replacement unit, means that a repair may be more costly than replacing the unit.

There is a convergence in the near future.  The old radios still have value, but that is diminishing quickly.  The new avionics are coming down in price, especially for the added features.  And I expect that trend to continue with a far shallower curve than normal consumer electronics. I can’t say when exactly that convergence will be perfect for updating an airplanes avionics systems, but it is within the next 5 years given current trends.  Of course that is also dependent on individual and/or company budgets.  Parallel to those trends is installation costs.  Currently, they are quite high relative to normal conditions, but shortly after the ADS-B crunch, there may be some opportunities for discounted installation costs.

There’s a multitude of other factors involved with deciding to change out avionics systems, but value of old equipment, price of new equipment, and cost of installation are the primary influences on the market that I see from my point of view, sheltered in a nice and cozy avionics shop.  But in the end, please for the love of God, update your avionics soon, and quit expecting a unit that was manufactured when Donna Summer was topping the charts to work as if it were a brand new fully integrated avionics package.

As an aside:  I still have my first computer, a Tandy CoCo2 manufactured in 1983 and it still works.  But I know the day is coming where I can’t keep it going anymore either, nor do I rely on it for anything important, such as safety of flight.  And no, I did not write this on that computer.


Autopilot Troubleshooting

By James Brewer

Your guy on the inside at SEA

As an avionics tech, I have specialized in autopilots primarily. I find it quite fascinating using electronics to do motive work in flying the aircraft, and how interesting it is using the electromagnetic force to overcome gravity! At least, when it’s all working well.

When there is a problem with an autopilot, it helps to have an understanding of the system. All autopilot systems have the same basic tasks to perform and so have (mostly) the same type of components involved. In short, they need to know what the airplane is doing and what it is supposed to be doing. It does this through the use of sensors and feedback loops. (With feedback loops nested inside feedback loops and more feedback loops inside of those feedback loops.)

Let’s get into the basic components that an autopilot needs to function.

  • Gyro. Typically a spinning mass to let the autopilot (and pilot) know that attitude ofAuto pilot the aircraft. Although accelerometers are beginning to replace the spinning mass, they provide the same type of information to the autopilot. You could say it is the heart of the system, but in staying with the biology metaphor, it is more like the inner ear where we get our positional information from.
  • Computer. Something has to do all the thinking! They take on many forms, but like all computers they take in information and output control data. Newer ones are real computers with processor chips, but the older ones are able to process the data without changing it to 1s and 0s.  (personally, I find that quite amazing)
  • Control mechanism (servo). The muscle of the system. The part that changes electronics to motion. Yes. I know that technically the electronic and the mechanical energy both come from the electromagnetic force, so it’s still fundamentally the same thing being used, but it is a conversion none the less. It’s all the more fascinating when it’s a vacuum servo! I wish I could have been there the day those were invented! “Hey, why don’t we use this whoopee cushion to fly an airplane?” “Great idea! Let’s get started!”

That really sums up the basics for an autopilot system. Everything else is another layer added on to the system to change what the computer thinks it needs to do. If there is an autopilot problem, the basic system needs to be checked since all other functions are dependent on them.

In flight, the best way to check the basic system is to get the aircraft straight and level and engage the autopilot with no modes (or only flight director mode) in clean air. At this point the basic feedback loops are in use and under control by the autopilot. Any deviation will be an indicator of a problem. Such as:

  • A slow wing rock or a pitch porpoise can indicate a problem with the control mechanism; be that a drive motor, bladder, feedback motor, or loose control cables.
  • A fast wing rock or pitch porpoise indicate a problem with the gyro. This failure mode is faster because it is reacting to the feedback loop that is the airplane itself. Autopilot 2The gyro is putting out information saying that it is moving and the computer is commanding the control mechanisms to drive quickly to get back to where it is supposed to be.
  • Drifting or climbing / diving uncommanded. Just like the wing rock and pitch porpoise, this one has degrees of difference separating the failure modes. A quick turn or dive indicates a problem with the gyro, where as a slow change indicates a problem in the control mechanism.

If the autopilot system handles basic flight with no problems, add in some offset by changing the aircraft attitude. Or more simply, grab the wheel push it. Change the attitude and see how it responds. It should return to straight and level flight. If not, see the above points for suspected problems. If no problems exist, check the modifier buttons; UP and DOWN. These are generally part of the computer and change its internal settings. A failure here indicates a problem in the computer itself.

If everything is still checking out OK, you can move on to the additional layers of complexity and additional components (sensors). Start with Heading mode. If it does not follow the bug correctly, there is most like a problem in the component that provides the heading information (HSI, DG). Next move on to the Course/ NAV mode. If the system doesn’t follow the CRS pointer, then the most likely culprit is the component that has the course data (HSI/DG). If it does not follow the NAV needle it’s likely the NAV source (radio or GPS).

Staying with the roll axis, move on to Approach if the Course/NAV modes pass. If this fails but NAV was OK, it can likely be a faulty computer. There are gains in the feedback loops that are changed inside the computer when switching to approach mode. Move on to Back Course to check that the system knows the difference. Again, a failure here is likely the computer if all other tests have passed.

Moving to the pitch axis, engage Altitude Hold mode and make sure it holds. Manually change the altitude and see if the autopilot recovers correctly. Next, adjust the speed of the aircraft. This will cause the autopilot to adjust the attitude of the aircraft to compensate to maintain the correct altitude. Failures here indicate a problem with the autopilot system altitude sensor (generally not the same as an altimeter). Likewise if the autopilot is equipped with an Indicated Airspeed mode. The aircraft will adjust as necessary to maintain the indicated speed. Failures here indicate a problem with the airspeed sensor (most likely) and just as with the altitude sensor, it is probably not the same as the airspeed indicator.

Glideslope mode can be difficult to troubleshoot. But as with most inputs to the autopilot computer, it is likely the sensor (GS antenna and or NAV radio.)

Most autopilots go through quite a bit of Pitch Trim testing as part of their initial internal tests. And quite often it is manually tested on the ground as part of a preflight. Testing it in the air is the same as on the ground. Set the autopilot up for straight and level flight, and then offset the pitch axis with the control wheel. The auto trim should kick in to recover the aircraft. Just don’t offset it too much! (Not that I speak from experience with that. Many years ago. With reoccurring nightmares.) A failure here actually indicates the pitch servo as the main culprit as the sensors that tell the computer that it needs to adjust the trim setting are located in the pitch servo, not the pitch trim servo.

Aside from some other less common options, that sums up most checks and in general the additional modes are going to be related to their unique sensors. (½ Bank mode is just a nightmare so I don’t want to talk about it. Suffice to say, it’s probably the computer, or the servo, but maybe the gyro)

PanelThis of course is by no means a comprehensive troubleshooting guide, and comprises thousands of pages of technical information along with too much tribal knowledge compressed as densely and as concisely as practical. The purpose of this being to give an understanding of how an autopilot tech thinks about the system and provide a means of communicating a failure mode as precisely as possible to eliminate troubleshooting time and expenses. One of the good and bad things about autopilot failures is that they generally manifest themselves in flight. This is bad because it can be expensive to troubleshoot an odd problem, and good in that I enjoy test flights.

Of course all of the information above presupposes correct wiring and structural integrity. If there has been major work done to an airplane, check that area first before troubleshooting the autopilot. For example, if a wing has recently been replaced, it’s a good idea to pass that information on if there is a wing rock problem in the autopilot; before two techs spend 40 hours each troubleshooting, scratching their heads since it passes on the ground and fails in the air then finding out about the wing replacement and finding a loose connector that would have been looked at in hour one had that knowledge been available. Hypothetically of course.

Below is a quick checklist that I have used when checking out an autopilot system in flight. It’s quick and paints the problem with a broad brush, but it does help to narrow down complicated problems into manageable sections that can be addressed individually.

In flight (assuming self-tests pass)

  • straight and level
    • AP eng – level flight
    • Offset aircraft – recover
    • Maintain offset – trim function
    • UP / DN modifier
  • Roll tests
    • HDG mode
    • NAV
      • CRS pointer OK
      • NAV needle OK
    • APR – gains
    • BC – opposite gains
  • Pitch tests
    • ALT HOLD
      • offset aircraft / recover
    • GS – capture and follow

And as always, make sure to follow all applicable flight instructions, operating handbooks, pilot’s guides, and other such directives when flying.

P.S. I wanted to write about the recently discovered (maybe) 5th fundamental force that will (possibly) add to gravity, electromagnetism, the weak nuclear force, and the strong nuclear force. Unfortunately I couldn’t find a way to relate it to aircraft. Unless it’s the force that causes avionics to fail….hmmmm

My ADS-B Experience

_MG_2201.jpgBy James Brewer

An Avionics Technician & Aviation Enthusiast

I know, I know. You’ve been hearing about ADS-B non stop for the last 5 years or more. I know you’ve heard every single reason to get a system installed; from the benefits to the requirements. I know you’ve heard that at midnight of 2019, your airplane will magically never be able to fly again. You’ve no doubt heard all the regulations and requirements over and over again, as well as the applicable air spaces. I know I have long since reached saturation on the subject some time ago. More importantly, I know what the burden means to you. Really, I do.

I have the opportunity to live a dual life. One half as an avionics technician, and the other with a small partnership on an airplane so I understand the myriad of costs associated with airplanes from both sides. The hanger fees, the maintenance costs, the fuel, tie downs, endless inspections, and of course, that bulb that keeps blowing right before you want to get in the air. Every time you turn around, there’s some other thing you have to comply with. So adding on yet another burden is less than pleasant. Don’t tell anyone else in the industry, but I really disliked ADS-B when it was announced. I saw it as another overbearing requirement to fleece “the rich guys with airplanes.” Especially when you hear comments like “well, it’s only $5000. Be glad you don’t have (insert fancy jet name here) its $100,000 on one of those.” That’s great. But on a $15,000 Cessna 150, $5000 is a big chunk! Or the classic “well if you can afford an airplane, you can afford (insert outrageously priced aviation item here).” I hate that one.

But. I have become a convert and I am singing the praises of ADS-B now. All it took was one flight.

I have a friend who was looking to upgrade his aircraft to be compliant. It just so happens I was attending an ADS-B training session at the same time. Fortunately my boss, Joe Braddock, pulled me aside and told me about the Freeflight RANGR products. He knows I have a tight budget so he presented them to me as an affordable solution. I’m not yet at the point of doing the upgrade myself, (like I said, tight budget) but I did pass the information on to my friend, and for a lot less than he was expecting to pay, he had an ADS-B solution.

Fast forward a few weeks and we go up in his ADS-B (in and out) equipped 172. Wow. It was cool! I really stink at spotting traffic, but having that Ipad displaying the aircraft with their info and velocities right there in front of me, it was like a whole new world opened up. We had WAAS GPS, traffic, and weather! In a 172! For less than 5 grand! With no weight or amperage penalties from a heavy radar. Win-win-win! Plus there were no functional changes in cockpit duties. We still set the transponder when we had to and the ADS-B updated its information accordingly with no input from us. The amount of information and situational awareness we had was amazing for that price. Being a bit of a tech geek, it was a lot of fun to play around with too. I’m glad I was in the right seat!

As we were flying, the technician side of me came out too. The install was a lot faster than we expected, and a lot simpler with digital communication instead of big round bundles of wires and adapter modules. I was pleasantly shocked at the minimal panel real estate that the ADS-B control head took. We were both smiling big on that flight.

On the other hand, I also get to back seat a Super Decathlon from time to time. There is something beautiful about a small bird with minimal distractions and a lack of flashy electronics to take away from actually flying. If that’s you, then I have nothing constructive to offer. Flying like that is a treat in life and on the ADS-B ruling, you’re getting the short end of the stick. The only consolation is that the prices for minimal systems are coming down and there’s still enough competition for your business to keep labor costs reasonable. For now. But as a guy with an inside view of the avionics world, that tipping point is coming soon.

If you have the opportunity to go up in an equipped airplane, by all means do it. Take the right seat and play around. I’m sure you will be very pleasantly surprised and the pain of upgrading will be lessened significantly.

Stay tuned for an informational chart to help guide you to the right system for your needs and budget.

Modifying Older Aircraft


By Nathan Hernandez

So you find your aircraft. You’ve wanted one, looked for one, and finally found one. It’s a great aircraft and was a great deal but the avionics are old and maybe outdated. Where do you start?

421c-beforeMost people start looking at before and after pictures on various websites and get some ideas. Then they get a quote for that full glass panel upgrade they saw online and….once their heart starts beating again and the sticker shock sinks in you ask the real question – what do I really need?

First of all, please remember this is about avionics. If your engines are past TBO, then get that done ASAP!

Avionics can perhaps be broken down into 3 sections- radios, flight instruments, and your autopilot. I tell people that electronic flight instruments and a great autopilot are wonderful tools but they are not practical without a good foundation. Your foundation tends to be the radios. That is, your audio panel, GPS, NAV, COMM and transponder. Those are the foundation of a good avionics package.

Start with your audio panel and transponders when you shop. You can have the biggest and best GPS/NAV/COMM on the market but if you cannot communicate with tower due to a failed audio panel or report altitude due to a failed transponder, well, then you’re grounded. That big awesome display means nothing at that point. Make sure your installers are putting in all new wiring and jacks for your intercom. The transponder needs a good serial encoder. This will reduce the risk of failures later and good shops will require it. No one wants to spend good money on their aircraft and have issues because they saved421c-after a few bucks with old wiring or an old encoder.

After those important details, at this point, you can look at the new displays with the GPS/NAV/COMM all built in. Personally, I recommend you aim for one really good unit and a strong secondary. Most of us are not going to buy an aircraft and spend the aircraft’s value on new avionics. Installing 2 large GPS/NAV/COMMs is great and looks cool but one with a solid back up will save you money and keep money in your pocket for the EFIS, autopilot, or maybe something like fuel? Just a thought.  Great avionics manufacturers like Garmin, Aspen, Sandel, Universal, Rockwell Collins, etc. have done their homework and produced systems with not only great features but great reliability and quality.

Don’t let yourself get caught off guard when you look to modify your aircraft. It’s always fun to go big and your avionics shop will be happy to help you do that. Make sure the shop you go to is looking out for your best interest. I have had clients ask me to install a nice EFIS with old unsupported radios. That does not help when you’re on final approach and your audio is not clear enough for ATC to give you clearance. What’s behind your panel or not in directly in your field of vision can be as critical as that nice looking big display in front of you.

For questions, comments, or even just to chat about anything avionics related, feel free to give me a ring or shoot me an email whenever you want.

Nathan Hernandez (321)255-9877 ext.291


Garmin Makes Major New Product Announcements

Garmin has once again taken the aviation world by surprise providing new, exciting products and updates to existing products that make sense, help pilots, and invigorate the market. Below is a list of some highlights of the announcements:

FLIGHT STREAM 510 Garmin 510.PNG

The new Flight Stream 510 will revolutionize how Garmin users manage databases with wireless technology.

The Flight Stream 510 is an SD card with built-in Wi-Fi and Bluetooth capability. The card installs into the existing card slot of the GTN series units and updates the databases throughout the cockpit between GTN units as well as G500/600 glass displays. Other added features of the Flight Stream 510 include two-way flight plan transfer between GTN 650/750, sharing of traffic, weather, GPS info, back-up attitude info,
and text messaging though a compatible mobile device.

The Flight Stream 510 will be available in early August for a list price of $1495. Normal terms and conditions of Garmin Dealer Installation Policy apply.


Garmin GTN 560

Improving on an already powerful, capable product, Garmin announced new, expanded features for the popular GTN 650/750 touchscreen navigators.

New features include:

•Voice command control: Over 300 spoken commands at the push of a button through the GMA 35/350 auto speech recognition
•Pinch to Zoom Interface: Similar to features on smartphones or tablets; zoom in/out on pages now with this feature
•Flight Stream 510 capability: Incorporate wireless technology into your aircraft with software update and the Flight Stream 510
•Text & Voice Call Control: Also with Flight Stream 510 and update, users can pair to an Apple mobile device for text and voice via GSR 56 datalink

Also additions with the software update include radio availability during power-up before engine start, flight track vectors, clear-all function, and pilot selectable SafeTaxi diagram descriptions.


New, more cost effective options are now being given to Garmin users through Garmin’s new OnePak Database bundling.

OnePak bundles allow customers to download datbases to multiple Garmin avionics and portables for one low price. Now updates for the GTN 650/750 as well as GNS 430W/530W range from a single update of $129 to an annual subscription of just $299. Bundle updates including all data (nav, obstacles & terrain) range from $449 to $649 for annual subscriptions. In addition, OnePak can cover your entire Garmin avionics package in your aircraft for one low price. From $649 to $924 including FliteCharts.

Garmin has not only made the database updating process easy but very affordable now.


Garmin Rebates

In addition to announcing new products and updates, Garmin is offering big savings on ADS-B products and other product packages. Some of these special offers include:

•Up to $2000 savings on various Garmin products when purchased with an ADS-B product such as the GTX 335/345, GDL 84/88 or GTX-330/33ES
•GTN 625 / GTX345R package for $9940 List or Aera 660 / GTX345 package for $6195 List
•$500 Off List Price for the GDL 84/88 series ADS-B products
•$100-$200 seminar bucks during EAA AirVenture Oshkosh
For complete details on any of these products or special offers, please contact Southeast Aerospace today.

SEA Tech Talk

Continuing with our series of avionics technical topics that we’ve encountered during the week, we cover an ongoing support issue with the RDR-1400 radar system.

IN-2025BRDR-1400 Radar Support Decreasing

Support for the Telephonics (formerly Bendix) RDR-1400 radar system has become an issue.  Over the past few years, one of the main subassemblies that fails in the system (the High Voltage Power Supply or HVPS) has become increasingly difficult to obtain.  Recently, it has been discovered that this HVPS will no longer be available at all.  Therefore, units (especially IN-2025 series indicators) with a power supply failure are not repairable.  Unfortunately, there is not a direct upgrade or replacement path for this system.

The First Edition of SEA Tech Talk


We are introducing a weekly post that expands on the avionics technical topics that we’ve encountered during the week.

This week’s Tech Talk includes: KT-74 ADS-B STC,  KHF-950 SB notes, Cage Locking Attitude Indicators.


Bendix/King is shipping and SEA has started selling the KT-74 transponder. The KT-74 is described as “ADS-B Ready” and the install manual provides instructions to install it as such.

However, at this time the KT-74 is only a Mode S Transponder replacement for the KT-76A & KT-76C. Although the KT-74 has ADS-B capabilities, there is no STC currently available for the transponder.

Bendix/King has informed us that an AML-STC will be issued soon. SEA will announce the KT-74 as ADS-B Ready once the STCs have been released.

A Few Notes on the KHF-950 SB

Why is the mod level important on the KTR-953 and KAC-952 HF components?

Previously, SEA answered the FAQ: “Can the KTR-953 and KAC-952 be mounted in different locations in an aircraft?“. The answer to that question details the service bulletin (mod) levels that each unit must have incorporated for this installation scenario to be possible.

In addition to what these service bulletins offer in the way of installation flexibility, improper performance and actual unit failure can occur if the units are mismatched. That is, using a KTR-953 unit without SB 8 connected to a KAC-952 unit with SB 9,10 is not ideal. Southeast Aerospace has actually seen units fail in the field when mismatched in this manner as well.

Cage Locking Attitude Indicators

Should all cage-able attitude indicators be locked when handled, transported, or stored?

No, not all and they could be damaged if you do.

Many legacy electromechnical attitude gyroscopic instruments include a caging device to hold the gimbals in place and ‘force’ the gyro gimbals to return to their home position. This instantly erects or resets the unit by pulling the caging knob. Some caged gyros include a cage lock mechanism, some do not. Some people believe that a cage-able gyro should always be in the locked position when handling, transportation, or storage takes place. This is not always the case. Continue Reading>>