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A step in the right direction. Would be interested to know what the comparative energy ghg lifecycle costs for this fuel vs conventional fuel - and what prohib
by boringg 5y ago
A step in the right direction. Would be interested to know what the comparative energy ghg lifecycle costs for this fuel vs conventional fuel - and what prohibits them from using both engines. Is it just a liability / pilot test on the first go and then switch to both engines? Or are there concerns about going fully SAF?
- throwawayboise 5y agoAviation is extremely conservative when it comes to adopting any new technology. It is tested and tested and tested again. Allowing only 50% (or 100% on one engine) seems like exactly what they would do. Make a small change, test it for a while, tear down some engines and look for anything unusual, etc. If it's a drop-in replacement for Jet A, it needs to work in the newest modern engines as well as the 30 year old ones that are still in service. Look how long it took to get unleaded gasoline approved as an aviation fuel for piston-engined aircraft.
- sokoloff 5y agoPart of the difficulty is that the certifications for the (high-compression piston) engines were to run on 100LL, not to run on “a fuel with a lean mixture knock value of X and a rich mixture knock value of Y” and the specification for 100LL (ASTM D 910) is a formulation specification which includes tetraethyl lead rather than being a performance specification. Maybe the FAA could have been more aggressive in allowing a replacement fuel to be certified, but various fuels have been tested for over a decade now in experimental category aircraft, meaning they were not holding up development activities, just holding what seems like an objectivity reasonable hurdle for all-model STC approval (which still hasn’t been granted; we’re at the “many model” approval level right now).