984 K Road
Minden, Nebraska 68959
308/832-22OO



MODIFICATIONS

Installation of an auto fuel STC on a low compression 80/87 octane engine is an uncomplicated procedure. No major modifications are needed on this type of engine. We supply all placards and paperwork. An IA mechanic must "install" the STC by adding the new fuel placards and an engine placard. He then fills out a log book entry and form 337. The whole process takes approximately 30 minutes. No additional modification is required on this type of engine.

The same holds true generally for the higher compression Lycoming 0-360 and 0-320 engines depending upon the airframe in which they are installed. Generally speaking when these engines are mounted in an airframe equipped with a gravity feed fuel system (no fuel pumps), installation of the STC's consists only of paperwork and placards, with no modifications made. Some people then reason why buy an STC if it's only paperwork and placards. Installing the STC makes it possible for you to use an octane different than what was called for on the original Type Certificate while remaining in compliance with FAA regulations. Insurance companies expect you to be in compliance with the FAR's and we are able to contact you if we become aware of any changes in the fuel which could effect your airplane. For more info on this check out FAR's: Part 43, App. A (2) (vi), 43.3 (a), 43.12, and 21.183 (d) (1).

In some airframes equipped with suction lift fuel systems (pump fed systems), different electric fuel pumps may need to be installed to insure adequate fuel flow, and/or the fuel pump locations must be moved. The STC for the PA-28-160, -161, -180, -181 requires the removal of the factory installed electric pump. This pump is replaced with two completely different pumps and the fuel system is rebuilt. Installation on this airplane takes between four and six hours, approximtely double that on 24 volt PA-28's. Click here for more info on the Piper PA-28, -160 thru -181

OCTANE

The low compression auto fuel STC's approve the use of 87 and 88 octane automotive fuel, regular or unleaded. These are minimum octanes so you can also use premium fuel. High compression STC's require the use of 91 octane (minimum) premium unleaded or leaded automotive fuel.

Installing the auto fuel STC does not restrict you to using only auto fuel. Avgas can still be used, and it can be mixed with auto fuel if you wish. Without the STC, you are limited to only avgas. The use of gasoline which contains alcohol must be avoided. Gasohol can damage aircraft fuel systems, decrease range, and significantly increase the tendency toward vapor lock. Instructions for constructing an alcohol tester are included with each STC, or you can order a reusable alcohol test kit from us by clicking here.

We recommend that you purchase fuel only from major manufacturers rather than from cut rate stations. The quality of fuel obtained from major manufacturers is generally superior to that found at less expensive outlets. By using fuel from a major manufacturer you are more likely to obtain fresh fuel as opposed to fuel which was intended for use the previous season.

It is important that the fuel be fresh because of the Reid Vapor Pressure (RVP). Auto fuel has a RVP of between 7 and 9.3 in summer and it can go as high as 15 in winter. The exact change to the RVP varies from one part of the country to another. Some states have limited maximum RVP's to reduce air pollution and so historically RVP's have been moving toward lower numbers. Vapor lock is not a common occurrence, but it can develop during hot temperatures if the airplane has been serviced with winter blend fuel (high RVP), or with alcohol based fuel. Fuel volatility also affects carb ice. Carb ice can occur more quickly on higher volatility fuel.

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