If there's a public manufacturer of only small aircraft you'd be able to see for certain on their quarterly reports, if insurance liability is one of their dominate expenses.
From the reference quoted above, looks like $218,000 per airplane is probably all insurance cost ($100,000 per plane in 1988 is $216,000 per plane in 2010 dollars).
"Product liability costs
Those manufacturers reported rapidly rising product liability costs, driving aircraft prices beyond the market, and they said their production cuts were in response to that growing liability.[3][16][18][19]
Average cost of manufacturer's liability insurance for each airplane manufactured in the U.S. had risen from approximately $50 per plane in 1962 to
$100,000 per plane in 1988, according to a report cited by the Bureau of Labor Statistics,[14] a 2,000-fold increase in 24 years.
Rising claims against the industry triggered a rapid increase in manufacturers' liability insurance premiums during the 1980s. Industry-wide, in just 7 years, the manufacturers' liability premiums increased nearly nine-fold, from approximately $24 million in 1978 to $210 million in 1985.[16]
Insurance underwriters, worldwide, began to refuse to sell product liability insurance to U.S. general aviation manufacturers. By 1987, the three largest GA manufacturers claimed their annual costs for product liability ranged from $70,000 to $100,000 per airplane built and shipped that year.[7][19]"
Also, insurance cost is only part of it. Agreements and lawsuits aren't 100.00% deterministic and predictable. There often remains troubling tail risk. Lawsuits and workings of agreements (including insurance agreements) are judged by humans according to written language, which is a lot more wobbly than a math equation. People who haven't been through bigger lawsuits often think that an agreement says X, which is 100.00% clear and certain, and will be 100.00% of the time judged as saying X in a lawsuit. However, judgements sometimes rule differently no matter how sure you and your lawyers were on what an insurance agreement says. You have to keep that in mind when making business decisions. Also, even if insurance does cover all nominal costs, they don't cover internal staff time and stress (which can be substantial in bigger lawsuits). Unless a product is making a lot of profit, if there is litigation risk, businesses often conclude it's not worth the trouble. To make it worth the trouble, you sometimes have to do something like, "Well, at what price is it worth doing this thing which we aren't so keen on doing? We'll sell it at that. If it doesn't sell, we will just cancel it."
