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Feature Article 1

FEATURE ARTICLE

Matt Debski, Aircraft Owner WVFC tdebber@alum.mit.edu

 

Experimental Avionics for Certified Aircraft

 

Over the past few years, I've been slowly upgrading avionics in my 1976 Cessna 182 and 1979 Piper Archer II.  These planes are forty-plus years old.  While there areplenty of articles in AOPA Pilot and others about doing Glass Panel installs in planes of this age, I don't have the resources to spend as much or more than the planes are worth on upgrading their panels.  Fortunately, a kinder-gentler FAA policy and its results means that I can get the great functionality of modern avionics at lower prices than a few years ago.

 

Avionics installed in certified aircraft have been subject to strict certification requirements.  The process of certifying these avionics is expensive and time-consuming.  This has ledto a relatively slow pace of available innovation in avionics.  A manufacturer must recoup the cost of certifying each generation of avionics, as well as earn their profit, before it makes sense to release a new generation.  Additionally, the high cost of these certified avionics narrows the number of aircraft in which it makes financial sense to install them.  

 

The experimental aircraft avionics world has a large set of manufacturers that have been off-limits to the certified aircraft world.  Experimental aircraft have wide latitude in the avionics they install.  Because these avionics are not subject to the costly, strict certification requirements, the time it takes to recoup the cost of a generation of avionics is lower.  Additionally, incremental changes can be made on an existing model without having to go through the expense of re-certifying them.

 

A few years ago, the FAA in collaboration with various industry groups, approved an addition to its set of accepted standards for certification.  Under the old rules, avionics with software were required to have the software certified line-by-line.  The new standards generally involve demonstrating that the complete device performs to a set of requirements.  That change - to demonstrating performance instead of strict certification of each line of code - has reduced the cost of certification.  It has also enabled entities to obtain certifications for experimental avionics by demonstrating they perform to acceptable standards.

 

The approval process results in a Parts Manufacturing Approval (PMA) being issuedto the avionics manufacturer.  A Supplemental Type Certificate (STC) permits the installation of the avionics in a particular make and model of an aircraft.  In some cases, the entity obtaining the approval for certified aircraft is not the manufacturer.  For example, EAA STC owns the STC for the Dynon Avionics Electronic Flight Instrument System.

 

The upshot of all of this is that there are now many devices available through this alternative certification process that meet or exceed the performance of products certified under the previous system for much lower prices.

 

The Dynon D10A EFIS (Electronic Flight Instrument System) and Garmin G5 are both replacements for a vacuum-powered attitude indicator.  A separate G5 can also be used as a replacement heading indicator.  While the D10A and G5 are only certified to replace the attitude and/or heading indicators, they both also include indications for airspeed, altitude, vertical speed, heading and a variety of other flight data.  In other words, they contain all the flight instruments in one display in the center of the instrument scan.  The instruments are powered by solid-state sensors instead of spinning gyros.  These solid-state devices are more reliable than the vacuum pump and spinning gyros thatform the basis of the previous generation of attitude and heading indicator.  The electronic systems also contain standby batteries that will last for at least two hours.  This functionality is available for $2500 plus installation cost.  To me, that is a great deal.  As a point of reference, a new vacuum-driven attitude indicator will cost at least $1000.

 

Another set of products being certified under this new model are autopilots.  Garmin's GFC 500, TruTrak's Vizion, and Trio Avionics' ProPilot are all full-featured autopilots.  These two-axis auto-pilots include modern features such as auto-level from unusual attitudes, altitude pre-select, and the ability to fly coupled approaches and other maneuvers controlled by GPS steering.  However, they're priced in the $4000 to $7000 range.  The "low-price" autopilot from S-TEC is over $16,000.

 

Innovation in this area will surely continue.  Aspen Avionics has released a single EFIS that combines the attitude indicator and an HSI.  It also interfaces with the TruTrak Autopilot.  Its cost is $5000.

 

The new certification path is a game-changer for older aircraft constrained by a budget.  Upgrading to solid state flight instruments and a fully capable autopilot can be accomplished for a sane amount of money.  The cost of the avionics plus their installation no longer exceeds the value of the aircraft.  This makes the plane a much more capable aircraft and substantially increases safety.  The FAA's shift has helped it fulfill its mission of providing the safest, most efficient aerospace system in the world.

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