Rob Wolf wrote;

I agree with almost everything Bill Hannahan said.  We SHOULD be allowed to buy non-certified aircraft from professional builders…

 

It may be faster, quieter and more efficient, but it will not be safer.

 

I have been a homebuilder for over a decade, and a lurker for two decades before that.  I have been a senior engineer at a certified airplane company for four years.  The FARs governing certification virtually guarantee that certified airplanes are safer.  The rules do not make them less likely to break, but they ensure that the consequences of failure are commensurate with their likelihood.  (Put it simply -- if the effect of a failure are "minor", it's allowed to happen more often than failures whose effects are "hazardous".)  This characteristic of the cerification process dominates virtually every element of certified airplane design…

 

So I agree with BIll that good things will happen if we take the shackles off of the professional builder community, and transfer some responsibility from the government to the individual, but I disagree that homebuilts are safer.

 

 

Rob

 

I understand what you are talking about, homebuilts have always had a much higher accident rate than certified airplanes, but does that always have to be the case in the future?

 

What percentage of accidents are caused by the failure of kit components? What percentage of homebuilt accidents would be prevented if kit components were designed to certification standards? I think those numbers are small. What percentage of accidents are caused by faulty workmanship of the homebuilder? Probably a larger number but still small.

 

I believe that the higher accident rate is largely due to the fact that homebuilts tend toward high performance and require a higher level of flying skill and flying judgment than the average spam can. Some airplanes that are challenging to fly have been certified, Globe Swift, MU-2, certified Pitts, even the Cirrus have racked up a substantial accident rate despite certification. Perhaps the biggest benefit of certification from a safety standpoint is that it pushes designers in the direction of less spirited airplanes that are more tolerant of imprecise flying and poor judgment, a modest benefit, at enormous cost.

 

The F-15 has much higher performance than the P-51. Chuck Yeager has said that a child could fly the F-15 but when he straps into a P-51 he reminds himself, “Yeager, this thing will bite you in the ass if you’re not careful.” Rob, engineers like yourself worked very hard to make the F-15 easy to fly, giving the pilot more time for situational awareness and weapons management.

 

I believe we have reached the point where we can use technology to improve the safety and performance of GA aircraft at a reasonable cost, by establishing a non-certified category. The hypothetical future Lancair jet (not just a 4P with a turbine glued on) could be such an aircraft. For example, consider an airplane that;

 

Refuses to stall/spin

 

Refuses to fly into terrain, except for landings on runways

 

Refuses to pull excessive G

 

Refuses to exceed Vne

 

Slows down for turbulence

 

Calculates its weight and CG taxiing out and refuses to takeoff if it’s out of limits

 

Refuses to takeoff if there is inadequate fuel reserve

 

Refuses to takeoff if the airframe is not configured for takeoff

 

Refuses to takeoff if engine parameters are not correct

 

Folks like JFK jr, John Denver and many others could have survived in such an airplane.

 

I am not suggesting fly by wire, that is too big a step. I call it SAP “Super Auto Pilot”. The pilot would still have a stick and rudder pedals mechanically connected to the control surfaces.

 

SAP could;

 

Fly the plane from takeoff to landing, or

 

Run in the background taking action only when it detects danger, or

 

Be turned off when you want to buzz your girlfriend’s house, but if you screw up the accident report will note that you turned it off.

 

This may sound like pie in the sky but no breakthroughs are required to do it. The hardest part would be writing the software to accomplish these goals under any combination of conditions and not screw up. One could start with the easiest functions and add on as experience is gained. The software for true fly by wire is much more critical and has been successfully accomplished by several engineering groups on several aircraft, with some bumps along the way.

 

SAP is beyond the capability of the average double garage homebuilder. It would be expensive and time consuming in the certified world, but a well financed kit company or Raytheon or Boeing or Honda could do it in a new non-certified category faster and cheaper.

 

Using modern technology we can have non-certified planes that are faster, more efficient and safer than the clapped out Baron.