Light Plane Philosopher
- Dec 16, 2007
- Port Townsend WA
I said significant crash structure. Many legal ultralights have had to eliminate such things as cockpit, brakes, turnover protection, crumple zone, shock absorbers....Huh? Ultralights are not allowed, by law, to exceed a certain empty weight. It's open to interpretation (and one's imagination and engineering skills) how much crash protection that empty weight allows.
I'm pretty familiar with Part 103 and AC103-7. I don't recall any prohibition on some certain level of crashworthiness or structure. What am I missing?
The FAA does not provide additional weight allowance for these crash structure items. In fact, AC103-7 defines roll cages, brakes, etc. as part of the structure with no extra weight credit. Many ultralights don't have these items, because to do so and still have the required 120 square feet of wing area and other flight structure built strong enough to handle normal air loads has been difficult. So many if not most go without these crash safety items.
The FAA does allow 24 additional pounds for a parachute. But a parachute only helps for structure failure at altitude, not hitting concrete barriers. I guess the FAA provided this parachute band aid because it's arbitrary weight limit has resulted in plenty of under strength ultralights that have had inflight structural failure. I would prefer a sound flight structure rather than a parachute. I have been reading the old Sport Aviation from the ultralight days in the 70’s and 80’s. It's astounding how many of these early ultralight designers were killed in those days.
So yes, in my interpretation, the law prevents my full freedom to add the needed crash devices.
p.s. My design will have crash structures. But it has taken me years to get there.