3 ms·

Just because something is old doesn't mean it should get a free pass on continuing to use leaded fuel though... there must be other reasons why leaded is still

• Baeocystin 5y ago
  Exhaust valve seats. If you don't use appropriately hardened seats, you need lead to help cushion the wear between the exhaust valves and their seats in the head. If your perfectly reasonable next question is, why aren't standard aircraft engines just built with the appropriate seats, well, then... The answer is low market volume coupled with high regulatory hurdles. There aren't any villains here, just written-in-blood safety regs coupled with a small enough market that there is a lot less money available to fight inertia.
  • mateo1 5y ago
    Exactly. Flying for sport is expensive as it is today because safety has to be a priority (as it should). Add a requirement for new engines or major overhauls on old planes and the cost will spiral out of control. Besides, leaded fuel was a problem when literally every single car on the street was burning it. The total volume of fuel consumed by aviation piston engines is a joke compared to that.
  • ericpauley 5y ago
    In the case of Lycomings at least these valve guides have been hardened on cylinders produced since 1998, without having to certify a new type. On the Lycoming engines approved for 94UL I'm not aware of a restriction that these new guides must be installed for unleaded use.
  • User23 5y ago
    > just written-in-blood safety regs To be clear, this is literally true. Those safety lessons were paid for in blood.