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Reference before mixing AVGAS and turbine fuel

Aviation Mechanic General (AMG) practice question 10 of 26 on Ground Operations and Servicing. ACS element AM.I.F.K11 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONBefore any mixing of AVGAS and turbine fuel is considered for an aircraft engine, the mechanic must refer to

  1. Athe Type Certificate Data Sheet for the powerplant.
  2. Bthe fuel supplier's blending chart.
  3. Cthe airport fuel vendor's quality-control test records.
Show the answer and explanation

Correct answer: A. the Type Certificate Data Sheet for the powerplant.

  • A — correct The handbook directs the mechanic to the Type Certificate Data Sheet for the respective powerplant before mixing AVGAS and turbine fuel.
  • B — incorrect The handbook does not refer to a supplier document; the approved fuels for an engine are found in its Type Certificate Data Sheet.
  • C — incorrect Vendor quality records address contamination of delivered fuel, not whether a given engine is approved to use a fuel mixture.

BACKGROUND

Only approved grades and types of fuel are to be used in an aircraft engine. The handbook states that before mixing AVGAS and turbine fuel, the Type Certificate Data Sheet (TCDS) for the respective powerplant must be consulted. The consequences of an unapproved mix are severe: adding jet fuel to AVGAS decreases the power developed by a reciprocating engine and can cause engine damage through detonation and loss of life, while adding AVGAS to jet fuel can cause lead deposits in a turbine engine and reduced service life. The fueling checklist also states simply: do not mix AVGAS and JET fuel.

STUDY TIP

When a question asks which document approves a fuel for an engine, think of the powerplant Type Certificate Data Sheet.

KEY POINTS

  • Consult the powerplant Type Certificate Data Sheet before mixing AVGAS and turbine fuel.
  • Jet fuel in AVGAS reduces power and can cause detonation damage.
  • AVGAS in jet fuel causes lead deposits and reduced service life.

SOURCES

  • FAA-H-8083-30B ch01 "Types of Fuel and Identification"
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-30B Aviation Maintenance Technician Handbook – General, 14 CFR part 43 and part 65. Regulations and handbooks are revised; confirm details against the current edition.