My only comment would be that I would think the AP in single pilot operation would be more of a “single pilots friend ” than the GPS.  Anyone?

 

Yep, that is a good idea.  After all, the auto pilot (wing level function) is my backup for the loss of the vacuum instruments.  However, the S-Tec 50 is not a good wing leveler in turbulence so I would say that it also has shortcomings. 

 

I also failed to mention that the pitot heat is only present on the main bus.

 

The reason some of these things are left off the essential bus is because of the two major failure modes I considered:

 

1.  Alternator/regulator problem.  Left with only the battery, I have two choices after pulling the field breaker. Massive load shedding by operating on the essential bus or selective shedding by powering down devices as necessary.  Even operating on the essential bus, as I approach the landing area, I can determine whether or not to turn on the master to energize the "nice to have" things.  The essential bus gives me many options.

 

2.  Some unspecified catastrophic electrical failure or smoke in the cabin.  There probably is a hint as to what caused the problem but chances are that it wasn't  one of the items on the essential bus if I keep the number of items on the bus to a minimum.  What I would feel comfortable with in such a dire emergency was also a consideration.  If I were to look at rewiring the system again, I would seriously consider adding both the auto pilot and pitot heat to the essential bus.  Of course, I have to consider the new wire size to the essential bus and the logic of using a diode to isolate the bus. 

 

In my case, if the battery failed, I am in serious trouble.  This is why a monitoring system is so important.  It is also why idiot lights (annunciator panel) are very useful in pointing out some abnormal condition. The more complex in-flight systems either require more intense scanning of displays or some more automatic warning of out-of bounds conditions.  In my old Skymaster, I found it incredulous that the vacuum gauge was down by my left knee and out of instrument scan range rather than next to the attitude indicator - by the way, that AI was the very same device that managed the auto pilot. 

 

Since I am the manufacturer of my aircraft, I did the risk analysis within the context of the mission and use of said powered lawn dart.  I considered the interaction of all the systems to help reduce exposure to single fault catastrophes.  I examined redundancy by trying to balance safety and weight, safety and weight (oops, that's redundant).  There are some conditions under which the probability of death are high.  It has no air conditioner, no backup engine, no required copilot, no ice protection, no lightning shield, no totally idiot proof devices.  It can't land on rough fields and it would be courting disaster if the canopy is opened for entry or exit in a driving rain (unlike a turkey, don't look up).  There is no need for a parachute for I have not figured out what unusual attitude is necessary to get the canopy open.  All in all, the POH recommends that situations that would expose the design deficiencies outlined above are to be avoided by the reasonable judgment of the pilot.  If that fails, declare an emergency and do something different than that which got you to the scene of the sin.

 

 

PS Remember, in a Lancair you can go down or you can slow down, but you can't do both.