Comment by tadruj | Hacker News Reader

Comment by tadruj | Hacker News Reader

Parent Full thread

They are still producing them because it's cheap due to "grandfathering" laws.

"grandfathering" means if you'd design an airplane like 172 today they wouldn't meet the safety standards and you wouldn't be able to produce them, but since they were designed back in the days, if they don't change the design, they can still produce them.

http://www.usatoday.com/story/news/nation/2014/06/14/unfit-f...

I fly 172 regularly. It's a safe plane, but you have to know quite a bit about engine and how it works to be really safe up in the sky. I had engine failure on take-off with extremely well maintained plane. Starting the engine is a pain in the ass for most civilians who don't understand 4 stroke engines.

Cessna 172 uses about 10 gallons of fuel per hour. That's quite a lot. I think in 2017 there's better options out there.

I had a partial engine failure in a fairly new fuel injected Cessna 172 during descent to landing... didn't overfly the airfield to check wind, but landed instead.

The article states:

> Luckily, the Cessna’s engine is about as reliable as aircraft engines gets.

Unfortunately, that's not that reliable. Statistics I've read (can't locate them now unfortunately) indicate about 2 to 10 inflight engine problems per 100,000 hours, which doesn't sound a lot. But if you fly two hours a weekend, making 1000 hours over a decade, that's a 2 to 10% chance of encountering engine problems right there.

Part of the grandfathering has to do with liability law: http://www.motherjones.com/kevin-drum/2013/02/odd-case-liabi...

Small plane / general aviation design is a complete mess. Even the fancy new 172SPs are still using engines with 1950s manual spark plug timing.

Fixed spark timing is not that big an engineering deficit for an engine that runs at a fairly constant power setting.

Road-going cars need variable spark timing because they are called upon to efficiently make wildly varying amounts of power. (Idle, cruise, accelerate are all part of the normal drive cycle.) Airplane engines, many racecars, and other similar applications that need to produce fixed, high power for prolonged periods of time often use fixed timing mechanisms.

Reply on news.ycombinator.com