FAA Aviation Mechanic Airframe (AMA)Fuel, Cabin and Ice Control SystemsMedium
During refueling of a transport-category aircraft at a high flow rate, a technician notes that Jet A fuel contains a static dissipater additive (SDA). What is the primary purpose of this additive?
- ATo improve the lubricating properties of the fuel for the fuel control unit
- BTo inhibit microbial growth in the bottom of the fuel tank
- CTo lower the freezing point of any water suspended in the fuel
- DTo increase the fuel's ability to conduct away electrostatic charge generated during handling
Show answer & explanationAnswer & explanation
Correct answer: D. To increase the fuel's ability to conduct away electrostatic charge generated during handling
Static dissipater additive (SDA), such as Stadis 450, increases the electrical conductivity of jet fuel so that electrostatic charge generated by high-velocity flow through filters and hoses during fueling can dissipate quickly rather than accumulating to a dangerous level that could cause a spark.
Why the other options are wrong
- A. Lubricity improvers, not SDA, address fuel lubricating properties.
- B. Biocides control microbial growth, a separate additive from SDA.
- C. Lowering the water freezing point is the function of FSII, not SDA.
Static Dissipater Additive (SDA)
A fuel additive that increases the electrical conductivity of jet fuel to allow rapid dissipation of static charge generated during high-flow refueling.
- Common trade name is Stadis 450
- Prevents static spark hazards during fast fueling
- Different in purpose from FSII (anti-icing) and biocides
Memory trick: 'SDA Shields against Dangerous Arcs.'