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I received a post from someone flying the Blue Mountain EFIS Lite in
their RV and am passing it along to the list. Much thanks to Sam
Buchanan for the report. -Kirk
Forwarded Message:
--> RV-List message posted by: Sam Buchanan For the past six weeks I have been flight testing a Blue Mountain
Avionics EFIS/Lite in my RV-6. I first saw the BMA EFIS/One and Greg Richter at
OSH 2001 and was very impressed with the capabilities and potential of a gyroless IFR panel. The announcement of the EFIS/Lite coincided with my decision to upgrade the panel in 399SB so I could
regain IFR currency. I paid a deposit for the Lite in early January expecting delivery in
6-8 weeks, but it was not until the first of June that I actually got my
hands on a unit. The purpose of this post is not to expound on the various delays in receiving the product; I fully expected some delays
to occur as the Lite was brought to market, especially considering no
similar product had been introduced to the experimental aviation community. I have now flown three individual Lites in an effort to achieve
satisfactory and expected performance from the instrument. Unfortunately, none of
the units had all features working at the same time. Greg Richter, guru in chief at BMA, has been very receptive of
the multitude of observations and suggestions I made about the unit and incorporated many changes to the software code based on my flight
testing. The display is much more user friendly now than it was six weeks ago. Admittedly I received the first unit early in the production cycle, but
Lites and EFIS/Ones are presently being shipped to customers. However, the most serious problem is with the AHRS platform. This is
the solid state "gyro" system that forms the basis for the entire box. (By
the way, it is my understanding the AHRS in the Lite is identical to that
in the EFIS/One.) The benchmark I initially used to test the AHRS as to see if
the system could remain stable in a 360 degree standard rate turn. This is
an essential function since the standard rate turn is the maneuver upon
which all IFR flight is based. Unfortunately, the AHRS "cutout" after about
280 degrees of turn with a resulting drift into erroneous bank and pitch displays, and this problem was repeatable and predictable. What was especially troubling was that the error occurred with no warning flag.
Attempts by Greg to tweak the software were unsuccessful and this
problem among other AHRS and pitot errors was present in all three boxes I
flew. I have returned all the units to Blue Mountain Avionics. I still feel
very strongly that AHRS is the way of the future and I intend to have the technology in my plane; I would very much like it be from BMA. Greg Richter and I have a very pleasant relationship and hopefully I will be
able to fly a fully functional EFIS/Lite in the not-too-distant future. Greg emailed me today stating that he thinks he has a grip on the problems,
so I suppose time will tell. However, "flying" the unit on a bench cannot substitute for hundreds of hours in an aircraft in actual flight. The purpose of this post is to update those of you who are considering
the purchase of BMA or other AHRS technology. Please keep in mind this is
very new stuff and no doubt debugging time needs to be a part of your plans
if you decide to install this or similar equipment. Please keep in mind that
AHRS is the backbone of BMA's autopilot and terrain mapping equipment. I am
also going to be very interested in actual flight experience of builders who
are incorporating the new TruTrak auto pilot systems since it is my
understanding they also use AHRS. The most serious concern I have is for flight into IMC with new AHRS
boxes. As all IFR-rated pilots know, IFR flight is a very serious undertaking.
Personally, I am going to need to see the AHRS systems rack up a bunch of time before I point 399SB into the clouds with little but
AHRS keeping me safe. I will have some limited backups on board, but the
builders who are considering the EFIS/One with only the Lite for backup (or
similar systems from other manufacturers) are putting ALL their IFR eggs in one
AHRS basket! I will keep the RV community informed as to future developments of this
matter and I eagerly await the impressions of other builder/pilots who
develop a knowledge base of this new technology.
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