Ed,

Exhaust:

1- exhaust hardware fails.  2- exhaust pipes fail.  3- a little motion at the engine translates to a (relatively) lot of motion at the end of the exhaust.  And I’m pretty sure there are no Lexus engineers staying up at night in fear that a Lyco clone is going to be smoother than one of their engines.  The bottom line is that if you have more pipe on the back of that collector than the 6 or so inches that were on the 4-to-1 collectors that I’ve used when making headers, I’d use the clamp.  Optimally, it should limit (but not totally prevent) motion of your exhaust pipe aft of the collector.  And if your header designer thinks that is a good idea, I’d go with it.

EFIS:

Let’s start with the fact that you’re dealing with a non-DO-160 certified system.  Now, that doesn’t mean it’s a piece of crap (actually I’m impressed with the functionality Dynon can offer at their price), but it DOES mean that there’s been no objective measurement of how much environmental abuse these systems can take or at what point they’ll fail. The Dynon units themselves had an interesting failure mode early in their development – with a certain engine/prop/RPM combination (and don’t ask me what it was), the unit would display a slow roll, while the aircraft was sitting firmly on the ground (to their credit, Dynon quickly fixed this with a software update).  Colyn has mentioned a bunch of events that can take out both systems (the common failure mode), and I’ll add another one:  E-glass planes like the LNC-2 can generate significant P-static when in IFR conditions (think dragging your rubber-soled shoes across the carpet at 200 mph) and the resulting electrical field can wreak havoc with electronics – search the archives for examples.  And if (more likely when) that static discharges somewhere inside the plane, you’re now into one or more of the circumstances Colyn mentioned.  You really don’t need to kill entire EFIS systems, all you have to do is kill the sensor to render them useless. 

                I spent 7 years working on instrumentation and control systems in the semiconductor industry, and I’ve seen solid-state sensors go bat-$#!^ crazy from everything from moving a refrigerator magnet too close to the vibrations caused when a train passed 100 yards away.  I wouldn’t think of building a plane to be used for IFR with a non-DO-160 certified system and no backup that works on a different principle (spinning mass vs. solid state sensors).  Come to think of it, I wouldn’t do it with a system that WAS DO-160 certified, either.

                One last thing – with all of its high-end avionics, the F/A-18 (including the E and F variants) has steam gauges as backups.  I’m just sayin’…

Gary Fitzgerald

LNC2 ~70%

St. Charles, MO

Looking for a rebuildable (I)O-360

…or a good deal on a used one…

…  Is this clamp necessary?

I just have completed the install of a 2 screen Dynon Skyview system with ap and Dynon txpd with traffic, Garmin SL30 radio to give ILS presentation on the Dynon screen.  I have no steam gage backups.  With dual screens, backup batteries and dual ADHRS I feel that I have enough redundancy.  Does anyone have input or comment?  This plane may be one of the first with no round gauges anywhere.

Ed Gray, Dallas