Aspen RSM

I don’t have the answer and, fingers crossed, I have not had any issue with my Aspen PRO fully integrated with the autopilot, the altitude preselect and the Garmin 750 and 430 navigators. I did purchase extended warranty to cover for such events.
Our RSM was placed well aft of the baggage compartment on our P210 to ensure no luggage-caused magnetic events. My kids tend to have some strong magnets in their toy-arsenal.
Are you being taken care of properly by Aspen? Are you happy with the dealer who is taking care of your problem?

Googling on this, I find only this vague description, and loads of people asking the same Q

because RSM failures are clearly common – despite denials within the industry.

The Aspen RSM heading sensor appears not to be the normal fluxgate magnetometer used in GA. A fluxgate is a form of saturable reactor, where the earth’s magnetic field, when suitably aligned, causes a piece of ferrous material to saturate sooner (under excitation from a 400Hz waveform) in one orientation versus another. I reckon Aspen may be using something like Hall effect sensing, but google turns up nothing on that either.

I think the warnings listed in post #1 are mostly bollocks. If the thing is so sensitive that power tools can’t be used, it won’t be fit for the intended purpose because it might be parked in a steel hangar which has got magnetised over time, and anyway it should not be destroyed by this. A heading error, maybe. Same with the mag field produced by the wire going from the battery to the starter motor (with the return distributed via the airframe, usually) – you get a helluva field during starting. The “not using the aircraft” is especially bollocks; did that come from Aspen directly?

From speaking to many owners, and having received a fair few photos of EFDs showing the “big X”, I think the problem is just poor QA. There are some videos online showing the Aspen factory and they are not hugely inspiring. When they started, and for years, they had so many failures they started soak testing (running it and letting it get hot; the EFD unit does run very hot due to an AHRS temp stabilisation oven; you can barely touch it) their stuff for many hours. This takes out most infant mortality, but temperature cycling is always the #1 enemy of electronics so anything that runs hot will fail much sonner than the same circuit running cool. But anyway the RSM doesn’t run hot; it could not be used to measure OAT if it did. It does suffer from mounting problems, where heat conduction from the cockpit affects the OAT reading even during flight.

It is also possible that the RSM is sensitive to mechanical stresses when mounted; most roofs are curved and if you screw it down tight, the package will be stressed. This is not a known-big failure mode in GPS antennae but they contain either no circuitry or just a little bit. The RSM has loads of stuff inside. This is from the IM (below link)

and I bet most installers don’t follow it because it is a bit complicated; at its simplest it means using spacers (washers, or custom-machined spacers; I had to machine some up specially for mounting a TAS605 antenna on the TB20GT composite roof) to take up the roof curve (the silicone seal should cover the gap ok).

Certainly Aspen have blamed RSM failures on incorrect installation but it was never clear (at least publicly) what exactly is happening IF this is true.

Digging around some more, I find loads more RSM reports, like this one from an installer: The RSMs had a problem with water intrusion… they updated them a couple years ago (changed the potting on the bottom) and it got a bit better.

Then there is this warning in the EFD1000 IM which makes sense but that simply means that mounting any heading sensor on the roof is a really stupid idea.

This is curious since the wingtips are normally the best place for a heading sensor

The IM contains a huge list of where to not install the RSM, but all these are to do with magnetic fields affecting it.

Some of the prohibited installation areas relate to lightning certification, not magnetic interference. In the Aurigny Trislanders, we mounted the RSM in the nose, forward of the undercarriage, as we couldn’t find anywhere else on the fuselage that was magnetically quiet.
We had our far share of failures and were never able to pinpoint a common reason.

Peter I know you are not a big fan

I don’t think you are being fair to me on this, Rate2. I happen to be a mod/admin on EuroGA so I get “attacked” (there are various degrees of this, from gentle criticism, all the way to quite vicious personal attacks) for posting negative stuff on some product. So let me look at this, taking what you posted above

• my fourth Aspen RSM (Remote Sensor Module) fitted
• The failure modes are varied and some go well beyond red X and cross check attitude messages to really get your attention
• The most exciting was instant AI inversion followed by dramatic swirling patterns across the whole screen
• I just got the Aspen switched off before I became disorientated.
• I pushed quite hard for an explanation
• assumed that Aspen had a bad batch of units
• When it came out its issue was a 30 degree heading error in some quadrants
• both suffered some common magnetic event
• suspect it will just be a replacement RSM and no explanation

If anyone read this, they would conclude the product is a complete joke!

My inbox contains a fair number of similar stories which can’t be posted – well not in any identifiable way. And one pilot who got through 3-4 of these things, and sent me some fun photos, is dead now (a CFIT; probably unrelated).

The “industry” claims that these were “teething troubles” in the early years only, but it doesn’t quite sound like that… At the same time an installer at one of UK’s biggest shops was talling me they got through a load of the EA100 autopilot adapters, but the shop can’t be identified either.

The product has been a success because it delivers a lot of “bang for the buck” and is fairly easy to install. It arrived in the market at an opportune moment.

I know there are dealer relationships to deal with but in general it is right to discuss this stuff. What wigglyamp posted above

We had our far share of failures and were never able to pinpoint a common reason.

is in line with my thinking: a product which either (a) has manufacturing QA issues or (b) subtle / undocumented installation-related issues, or possibly both.

I’ve been in electronics design and manufacture since mid-1970s so have seen plenty of ways to screw up. And everybody has a screw-up at some point. I once (20+ years ago) sent out a few hundred products with a reversed tantalum capacitor, which, ahem, basically explodes, but only if the conditions are right What sets apart one company from another is how they deal with it. We sent out replacements by DHL the next day and gave everyone a DHL account on which to return the duds. It cost us many thousands…

The problem is that since almost everybody is trying to look after a dealer relationship, stuff doesn’t get discussed (I mean this in the widest sense, GA / internet, etc) so a recurring issue may not get fixed for ages, if ever.

One could argue that the product did deliver a lot bang for the bucks back when it was introduced and was pretty much the only game in town. With the many new products (G5, GI275, G3X Certified, Dynon HDX Certified) we now have many more options, and luckily not all of them are from Garmin.
Same can be said, albeit to a much lesser extent, about autopilots (from the fully integrated Dynon, the GFC500, all the way to the TruTrak and Trio).
Not really on topic, but one can see why Aspen is looking at drones.

The most exciting was instant AI inversion followed by dramatic swirling patterns across the whole screen

I had the same behavior and my guy doing the avionics work for me thought also first it would be the RSM. But before ordering a replacement he crosschecked with Aspen and with the cryptically numbers they could tell him that it was the unit itself not the RSM.

Good luck for me, it was still in the extended guarantee period and so I got the MAX upgrade very cheap.

When one reads GA social media – especially in the US – it is quite obvious that Aspen rode an anti-Garmin sympathy wave, just like Apple (who back then was a “small” company) rode an anti-Microsoft sympathy wave. Then, the principle that “in the land of the blind, the one-eyed man is King” remained quite helpful, as it always is in GA. Finally, in GA, all but the brave try to protect their dealer relationship which in practice means that problems are not openly discussed if the product is within warranty, and since the warranty could be an extended one… you get the idea. Everything I see points to a product which is not well designed (for volume production and a long service life), probably not well manufactured, and which most likely has a sensitivity (in the RSM) to non-obvious installation issues. I would also predict a sensitivity to how much ventilation there is behind the panel.

That said, they have had some years to fix things.

Apart from the temperature cycling of the main box, which is always a difficult thing. On a bench setup at Aero Friedrichshafen the unit reached something like +50C (too hot to touch, and this was sitting on a table, at ~ +20C, so imagine how much hotter it gets behind a panel) and I reckon the internals reach perhaps +80C which will dramatically impact electronics reliability. Some AHRS stabilisation ovens run at +90C and there is no way to avoid this solution with present-day solid state AHRS technology, but you want to put the oven somewhere where it doesn’t heat up everything else. For example Sandel in their SG102 have the same thing but it is inside a thermally insulated module and the box runs only just barely warm. But then this is bigger, more expensive, harder to install, so doesn’t sell anywhere near as well