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lbleriot a écrit:Pour les autorisations, c'est loin d'être évident: par exemple, SI1070 autorise UL94 (Swift, Danemark) dans un moteur mais CS-STAN ne permet pas UL94 dans un avion Fox: seulement UL91 (Total, France) et 91/96UL (Hjelmeco, Suède)
lbleriot a écrit:Si ton TCDS ne mentionne pas SI1070 en noir et blanc, tu fais quoi? bah tu fais comme pour 100LL: tu le mets sans mention noir/blanc sur ton certificat de type et sans STC, CS-STAN
lbleriot a écrit:Au pire, il y a cette STC de Swift pour UL94 dans un avion November, mais elle doit être validée par AESA sur un avion Foxtrot:
Manu a écrit:Si c'est dans la SI c'est autorisé.
FbS a écrit:Question : si mon manuel de vol de 1960 dit « 100LL selon SI1070 », est-ce que cela m’autorise aux autres carburants approuvés depuis par la fameuse SI1070 ?
lbleriot a écrit:En pratique, ça ne sert à rien d'acheter et valider une STC pour G100UL de GAMI ou 100R de Swift en France, quand Total ou Hjelmeco sortiront un 100UL Sans Plomb on aura un CS-STAN gratuit, ça deviendra même obligatoire (il resterai les avions November ou CDNR? mais si on regarde UL91 de Total, il est déjà consomé sans STC FAA ou STC DGAC).
lbleriot a écrit:Heeuh, alors pourquoi on a besoin d'une STC Auto-Fuel pour mettre Mogas dans nos avions?
Aviathor a écrit:Je pense que GAMI sait ce dont il en retourne, mais ce n'est pas à eux de se prononcer et qu'il s'exposerait juridiquement en le faisant.
Paul Millner a écrit:This is an exact parallel to the exhaust valve seat recession we saw in automotive engines in the 1980's that was associated with the phasedown of lead in mogas. But it wasn't the lead, it was the associated impact on fuel octane rating. Let me explain.
Blending gasoline in the 1970's, adding lead was the easiest and least expensive way to raise octane rating. But the octane engines used to measure octane rating were manually operated back then, and somewhat subjective. So two runs on the same sample could give an octane rating as much as 1 octane number apart. Also, the fine for selling gasoline that tested below the advertised number on the pump was as much as $1,000/gallon. So blenders would add extra lead, just in case. As a result, though regular unleaded might be labeled 87 octane on the pump, the actual octane of the fuel could be as high as 89 or 90 on any given day.
As the lead phasedown began in the 1980's it became more and more difficult to achieve octane... very expensive (platinum and rhenium catalyst) and energy intensive technology was required to boost gasoline octane. So blenders sharpened their pencils, and *delivered* octane began to decline while the number on the pump stayed the same.
Finally, the EPA accepted an industry proposal to exonerate blenders from government grab-sampled octane numbers that were too low, as long as the blender could demonstrate that they were in statistical process control (Edward Deming) of their blending process. This lowered delivered octane even more, to the pump stated number plus or minus a few tenths of an octane number.
As this process progressed, some engines without computerized controls began to show distress. The octane the engines were actually running on was declining, even though the number on the pump stayed the same. Fairly extensive work demonstrated this was so by the 1990's, but by then, no one cared anymore, as lead had been outlawed.
It appears the same thing happened to the UND engines... Although they were certified on 91/96 octane avgas in 1962, the Lycoming O320/O360 series engines hardly ever operated on that fuel. Most major blenders ceased making 91/96 by 1964. And, back then, no one leaned very much... they ran their engines rich. So the "91/'96" engines built most of their operating experience running on 100/130 or 100LL (that is rated 100/130).
At UND, however, all of a sudden these "91/96" engines were operating on 94 octane instead of 100 octane. And UND's practice is to lean to peak in cruise, which offers much less detonation resistance than the rich mixture settings of old. It's not surprising that engines began to suffer distress when the delivered octane declined (by six numbers) and the operating conditions were more severe than during the certification of those engines sixty years ago.
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