PLT250: Fuel Grades and Contamination
What code PLT250 covers, why the FAA tests it, and how to study Fuel Grades and Contamination before your checkride.
Recall fuel - types / characteristics / contamination / fueling / defueling / precautions
What this means for your checkride
This covers aviation fuel grades and their dye colors, how contamination such as water, sediment, or the wrong grade gets into a system, and the fueling, defueling, and sampling steps that catch it before flight.
Contaminated or mis-fueled tanks are a direct cause of engine failure, so the FAA tests whether you know the correct grade, how to sump and inspect fuel, and the static-electricity hazards of fueling.
A common mistake is trusting a single sump sample. Water is heavier than fuel and keeps settling, so you sample again after fueling and after the airplane has been moved.
Where to study it
Practice questions on this code
Real questions from the Aviator IQ bank that test this exact area. Answer each to see the correct choice, the full rationale, and the FAA source.
If the proper grade of AVGAS for a reciprocating engine is not available, what does the handbook direct the pilot to do?
Under the fuel color-coding system that extends to decals and airport fuel handling equipment, how is all AVGAS identified?
Oral checkride defense
A code on your report is an area the examiner can revisit. Here is how an examiner might probe it, and how to explain it out loud.
The correct grade of fuel isn't available. What do you do?
Use the next higher grade the POH approves, never a lower grade, and note it. A lower grade risks detonation. Confirm the fuel is the correct color for its grade and that a sample is clear of water and sediment before you accept it.
How and when do you check for fuel contamination?
Sump every drain before the first flight of the day and after each refueling, checking for water (it settles low and beads), sediment, and the right color and smell. Sample again after the airplane has been moved, because water keeps settling to the low points.
A code on your test report is an area of deficiency. An authorized instructor must review it with you and endorse that review before you take the practical test, and the examiner may revisit it during the oral. Study it until you can explain it out loud, not just recognize the answer.