Lycoming and Continental Differ on 100LL Replacement
(FLYING eNewsletter, 6/09) According to a story posted on Avweb, Lycoming has gone on record opposing the development of 94UL as a replacement for 100 low lead (100LL) aviation gasoline. Continental supports development of 94UL, and is currently experimenting with modifications to its engines to accommodate the lower octane level — approximately 8 octane points less than leaded fuel. Both engine manufacturers acknowledge that many of their engines will perform satisfactorily on 94UL, but the higher-power, higher-compression engines are problematic. Computerized ignition (IE2 from Lycoming; Powerlink from Continental), knock-sensing technology and in some cases, lower-compression engine overhauls are among the fixes proposed to bring older engines into line with reduced octane levels. But Lycoming warns that the drop in fuel octane cannot be made up without potentially serious impact on engine performance. Lycoming believes that 100-octane lead-free aviation fuel is an attainable goal and should be pursued.
-------------
AOPA Videocast
AOPA Videocast: Issues with Leaded Avgas
-------------
Notes on Above VideoCast: Issues with Avgas.
Why do we need to replace 100LL?
-30% of the piston fleet need high octane fuel to prevent engine knock and detonation
-that 30% actually uses 70% of the avgas consumed
-many commercial piston aircraft like the DC-3/4/6 series need higher-octane fuel
-70% of the fleet may not need it, but it is not practical to have two fuel grades
-EPA demands it for the environment (lead is a proven carcinogen)
What does a suitable replacement for 100LL need to do?
-have good cold and hot start behaviors
-have similar weight to 100LL
-be affordable
-have good freezing point
-have stability over time
-not leave post-burn deposits
-provide octane sufficient to prevent detonation
-be cheaply and easily manufactured
-be transportable
-be environmentally friendly
How soon is an avgas replacement coming?
-it is too early to make a decision now (ie. Swift, UL94, engine modifications, etc.)
-the solution may not include only a fuel swap; it may include engine modifications to reduce detonation
-when all issues (economic, technical, and certification) are answered
-FAA has the final say
What are some problems with going to a new avgas?
-avgas refiners refuse to make more than one grade of avgas, because the volume is small. Shipping, refining, and tanking all costs money and avgas represents only around 0.5% of all transportation fuel sales.