M

Mike@Crossbow

Member
I've been following some posts in this and some other aviation forums lately and I would like to post a friendly note to any of our customers that may currently be running the Crossbow NAV425EX.

As I'm sure most of you know, we have had some very unfortunate problems with our first release of the NAV425EX. We have detailed a number of problems that our customers have experienced and have described the process of identifying and fixing these problems in our service bulletins.
Link to Service Bulletins

We recently started upgrading these units, free of charge for our customers and will continue to support the NAV425EX as we move forward. If are interested in this upgrade, please contact me directly with the serial number of your unit and shipping information so that we can schedule your upgrade.


Mike Smith
Field App Engineer
Crossbow Technology
[email protected]
 
Crossbow Upgrade/Direct2Avionics

I have been in contact directly with Mike Smith and the team at Crossbow to update the system purchased from Direct2Avionics which is a component of the Chelton Sport EFIS package.
Mr. Smith and Crossbow have been upfront and informational on the issues surrounding the ADHARS recall and the solutions offered. Personally, I have chosen to send my unit back to Crossbow for the updated exchange rather than change several components in the plane and start all over with another *new* (system) unit using the Pinpoint Inertia GADHARS, which is the current offering from Direct2Avionics.
I appreciate Crossbow outlining the problem at hand (written and posted on their web site) and offering a firm solution (free upgrade exchange) with a specific timeline on the first phone call, at no additional cost or alteration to the plane.
I was convincingly told that my exchange will be back to me in 2-3 weeks.

Direct2Avionics, however, would not give me a firm (suggesting 60-90 days but not real convincing) timeline for an exchange to the Pinpoint Inertia GADHARS system, did not have installation drawings to send for review, did not discuss the additional parts involved (magnometer?) or the changes necessary and promised an e-mail direct to outline the exchange process with delivery instructions which I never received.

The decision to accept the upgrade with Crossbow was in direct relationship to the excellent service and solutions offered by Mr. Smith.


Patrick N. Garboden
Ozark, MO
builder #90203
 
Exactly the opposite

Patrick, I found exactly the oppposte in my dealings with D2A.

Here is a note I got from Kirk Hammersmith this morning. A couple of pre-notes. When at SNF, they were discussing this "demolition team". At that time, they were talking in terms of 30-60 days to get the initial "pre-production" units and get them in airplanes. It seems they are right on that schedule.

Our "demolition team" is assembled! Six aircraft have been outfitted with pre-production Pinpoint Inertial GADAHRS, one of them with two GADAHRS side-by-side (and providing comparative data for attitude and airdata). Four of the aircraft are airborne and testing the units and the other two aircraft should have their install completed in the next couple days. These will be long-term test aircraft, putting the Pinpoint through any and all conceivable situations, the goal being to uncover "gotchya's" before they get us (again). Also interesting is two of the aircraft in this group were recently involved in testing the latest "fixed" 425 from Crossbow, which again failed in both aircraft.

The following "demolition team" aircraft have Pinpoint Inertial GADAHRS installed:

Lancair Legacy
Lancair Legacy FG
Lancair IV-P
RV-10
L-39
Baron (in experimental category)

Integration and testing has also been completed in two EPIC aircraft.

Long-term testing will continue in our company Lancair ES, and we are preparing a seventh aircraft to add to the demolition team, which will be a Lancair IV-P Propjet.

We've instructed the pilots of these aircraft to document their flights and journal their testing and results.

Thank you for all of your support! You are welcome to post this info as you see fit.

Kirk Hammersmith
President
Direct-To Avionics, Inc.
www.d2av.com
(541) 504-8300 office
Click to expand...

I will also offer the following.... I find it interesting that there are 2 airplanes noted above that were in the Xbow testing program and their "Fixed" units continued to fail. I know one of the owners personally. In fact, he was one of the "problem airplanes" back when this issue first came to light.

I also talked with him at SNF, he had just gotten a new version of the 42x unit back and had flown to SNF from TX. It had been failing on him at that time. This was suppose to be the final "version". Perhaps Xbow resolved that issue, I don't know.

As for documentation, yes, they have been finalizing it based upon these intial installations. I have it, have had it since January. I'm happy to discuss what I know of it. I think I can tell you what "additional" would be required (not much btw). Also, unless I missed it, the documentation *is* on there website, ya just have to know where to look for it.... Incase, it's not for public consumption (because it's changing), I won't post the link, but if you'd like it drop me an email.

These guys are not very hard to work with. They actually have been very forthcoming and easy to work with IMHO. I'm not sure who you have been talking with, but I'm happy to help you with contacts if that's what you need. Again, drop me a private note.
 
Crossbow used three test pilots in addition to our own in house testing and verification on our aircraft. The first pilot has not had any problems with his unit at all and as far as I know has been 100% satisfied.

Our second pilot has continued to have intermittent GPS issues. We personally visited this customer to ensure that he had a proper install. Crossbow did not ship any GPS antennas with the NAV425EX, however we are recommending a high quality externally mounted Antcom unit at this time (2G15A-XS-1) which you can purchase at www.antcom.com. The mounting location of this antenna is in the tail section of a Lancair and in theory composite aircraft should be transparent to GPS signals but like most theory's this turns out to not be 100% accurate. We are currently recommending that this customer mount the GPS antenna externally for optimum performance and it is important to note that as far as I know there isn't one internally mounted GPS unit that is certified for general aviation. Every GPS unit i've seen has been an external mount.

Our third pilot seemed very happy with the unit in the early phases, although on one occasion he did have a heading drift problem which after speaking to him was the result of not remaining stationary for 60 seconds upon startup. This period is necessary in order to establish an appropriate base for the DMU signals and is noted in the NAV425EX user manual. This gentleman has also experienced a "stall warning" on a strong crosswind departure, however we do not provide airspeed data so I cannot comment on the cause or solution to this problem.

Crossbow is confident in the fixes that we have implemented in the NAV425EX and are moving forward with the upgrade process. We have already upgraded approximately a dozen of these units and will be upgrading more as the weeks go bye. Crossbow has been producing some of the best inertial systems on the market since ~1995 and we have our units in UAV's, personal aircraft, commercial airliners and even tractors (if you ever want to see a scary application, watch a tractor using autopilot at 40mph with 30ft booms on each end). We have been very forward with the problems that we had with the NAV425EX and although we will never be able to apologize enough for the inconvenience that we have caused our customers, we will do our best to correct the problem.

Mike Smith
Application Engineer
Crossbow Technology
 
Thanks

Mike,

Thanks for taking the time. Yes, the one person I know personally has the 42x in the back of his legacy. I wasn't aware that he used an internal GPS antenna back there.... Most of the Legacy's use an internal gps antenna in the wing tip and have no problems. Another challenge with this said airplane is that the owner wanted no external Comm/Nav antennas and is using the hidden composite type folded dipole antennas, which are also located in the rear of the airplane. If I remember correctly, the 42x series is not "hardened" right? So EMI, RFI, etc in close proximity may result in installation challenges?
 
With respect to the antenna issue, I can certainly understand the desire to have an internal GPS antenna. I wasn't aware of the internal GPS antenna that was mounted inside the wing, but I'll certainly look into it and see if we can do some testing in house down the road. Another possibility which I suggested to our test pilot, would be to mount the unit below the windscreen. This should give significantly better visibility for GPS acquisition, although still not as good as an external mount.

I'm not too sure what you mean by "hardened". Typically, we hear that term from our military customers and that usually refers to a permanently sealed unit that is pretty much immune to EMI, RF. The AHRS500GA unit that we sell (available in the Chelton Pro I believe) is a good example of what I would consider a "hardened" unit. The NAV425EX is not permanently sealed which reduces the cost of manufacture but requires the user to be a bit more careful about placing it near large sources of EMI,RF. We had a few customers that showed a lot of drift/noise from the when using the mic for certain frequencies (~119.0-120). We have made some hardware tweaks to significantly reduce the RF, EMI noise on the NAV425EX and I doubt that anyone would see any harmful affects from these sources now unless you were really bombarding the unit from a very short distance away.

Mike Smith
Field Application Engineer
Crossbow Technology
[email protected]
 
Crossbow update

I have received my updated and replacement Crossbow system, within the time frame quoted. I have also received my Antcom GPS antenna (which I purchased independantly) that was recommended by Crossbow for improved signal and performance.
Now to finish installing and proceed with testing.

Gorbak
Ozark, MO
 
Mike@Crossbow said:
With respect to the antenna issue, I can certainly understand the desire to have an internal GPS antenna. I wasn't aware of the internal GPS antenna that was mounted inside the wing, but I'll certainly look into it and see if we can do some testing in house down the road. Another possibility which I suggested to our test pilot, would be to mount the unit below the windscreen. This should give significantly better visibility for GPS acquisition, although still not as good as an external mount.

I'm not too sure what you mean by "hardened". Typically, we hear that term from our military customers and that usually refers to a permanently sealed unit that is pretty much immune to EMI, RF. The AHRS500GA unit that we sell (available in the Chelton Pro I believe) is a good example of what I would consider a "hardened" unit. The NAV425EX is not permanently sealed which reduces the cost of manufacture but requires the user to be a bit more careful about placing it near large sources of EMI,RF. We had a few customers that showed a lot of drift/noise from the when using the mic for certain frequencies (~119.0-120). We have made some hardware tweaks to significantly reduce the RF, EMI noise on the NAV425EX and I doubt that anyone would see any harmful affects from these sources now unless you were really bombarding the unit from a very short distance away.

Mike Smith
Field Application Engineer
Crossbow Technology
[email protected]
Click to expand...


Mike, thanks again for taking the time.

Couple of quick notes, but these are not RV specific, so I'll be quick.

The Carbon Legacys have their wingtips made out of fiberglass and not carbon (the only piece that isn't carbon). So, most builders put the GPS antenna out there and it works just fine. The one owner that had the problems, I do not know where his GPS antenna was originally located, but I DO know that his COMM antenna was located inside the fuselage behind the baggage bulkhead and near the 42x unit.

As for the other comment about putting the GPS antenna up on the glare screen, that won't work on a Legacy. The carbon surround on the lower part of the canopy/windshield acts as a huge Faraday cage and blocks the RF signal from the antenna. This is especially noticable in turns hence the need to put that antenna in the wing tip.

Lastly, yes, I used "hardened" to describe EMI, RFI, and Lightning. And if I understand you correctly, you answered the question, that basically the 42x is a lower cost unit that is not protected from those items, including the environment. The 500 series is...

Thanks tons and good luck with the upgrade deployment
 
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Everyone, I have the upgraded Crossbow 425EX and had another failure on the way home from OSH. I don't usually rant and rave, but I really am tired of the long distance troubleshooting and lack of timeliness with which this problem has been dealt. So to be clear, I am posting my letter to Mike at Crossbow.

Vic
*********************************************************
Mike, this is accurate. For the record, I had a continuous rotating heading indication in flight, and I reset the entire avionics suite in flight to no avail. I landed, and removed all metal objects out of the baggage compartment, and when power was reapplied it worked fine, and did so for the remaining 2 legs. Looking back on it, I don't believe the baggage had anything to do with it. The unit was powered off for about 10 minutes, which must have allowed it to properly initialize.

However, let's cut to the chase here. I spent Sunday after I got back trying to duplicate the problem. I even used a 20 lb magnet outside of the aircraft above the AHRS to try to induce the problem to no avail. All metal objects in my baggage compartment were at least 24" to 36" away form the AHRS.
I removed stuff from the baggage compartment because early on when the AHRS was mounted in a different location I had a 30 degree heading error induced by the tow bar being placed in the baggage compartment. But this was a heading error, NOT a continuous rotation.
So now I have had 2 unexplained failures on the updated 425. To tell you the truth I am shocked at the lack of response from Crossbow to get to the bottom of this. I don't understand why someone isn't out here flying my airplane to try to fix this.
Let me put it in perspective. I spent $175K on an airplane that took 2400 hours to build. I put what I thought was the BEST avionics suite in it and I have been on a VFR LIMITATION for almost a YEAR! And you want to keep pointing at customer problems? Then don't sell it to us!
I've now spent the last 2 days of my vacation ripping out the wiring for the crossbow and am hoping that Kirk will get me my Pinpoint within 2 weeks as he promised.
I've really had enough of the long range, armchair diagnosis going on here. I have yet to see one problem caused by me other than the tow bar, which I fixed without telling anyone.
I've tried to be quiet and work with you and your team along the way, but this is now above and beyond.
Vic
 
Curious?

I have been talking to my buddies building and flying composite airplanes and have heard of 3 composite airplanes and 1 metal one (vic's above) that got their revised 42x and had it fail with similar problems as the originals. Most of these guys are working to identify these problems if possible, and I'm hopeful they will be resolved. But I'm curious. Of the mostly metal airplane population (this is an RV focused site correct? :). Has anyone recieved the update and had it function correctly with no failures?

Curious minds want to know so they know what to expect. :)

Mike, any updates on your side? We talked at OSH about a certain eglass Legacy, but now I've heard of an ES and another RG Legacy, and Vic's above that seem to have had problems. I'm also checking with one other friend of mine who also has an eglass legacy to see if he's upgraded and what his results were.
 
Sorry for the late reply to your post and it was great to talk to you in Oshkosh.

In regards to Vic's plane, we initially suspected that his heading error was due to ferrous material located in the baggage compartment that was not there previously. This was based upon a phone call to Vic the same night of his flight from Oshkosh. A day or so later I saw his post on this forum and called again to find out what was happening. After reviewing the data from his EFIS, he was seeing intermittent GPS signal loss/corruption from his GPS antenna. Crossbow did not provide a GPS antenna with our kits, however we have noted in our service bulletins that our customers should use the Antcom 2G15A-XS-1 antenna (www.antcom.com), which is an aviation grade external mount antenna for proper performance. In Vic's case, the EFIS data showed over 150 kts of error which in turn caused the problems reported. As far as I know, Vic's problem is cleared up at this time.

I did get a call yesterday from a Legacy owner having similar problems and he has the same antenna that caused the problem in Vic's plane. I have asked the owner for some EFIS data, however we may have missed that opportunity (only the last four flights are recorded). We're still working on this customer's issue, but I'm confident we can resolve it.

If any of our customers are having difficulty, Crossbow would like to hear from you. We are confident in the fixes we have in place and have yet to see a reoccurrence of any of the issues noted in our service bulletin.
 
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