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Rubber particles found in a main line strainer

Aviation Mechanic Powerplant (AMP) practice question 4 of 20 on Engine Fuel and Fuel Metering Systems. ACS element AM.III.I.K9 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Powerplant (AMP) practice mode.

Question bank updated 2026-09-22

QUESTIONWhile inspecting a fuel system, a mechanic finds particles of rubber in the sediment removed from the main line strainer housing. What does this most likely indicate?

  1. ADeterioration of a fuel hose
  2. BNormal wear of the strainer screen
  3. CCorrosion of the fuel tank interior
Show the answer and explanation

Correct answer: A. Deterioration of a fuel hose

  • A — correct The handbook states that particles of rubber in the strainer sediment are often early warnings of hose deterioration, so the hoses should be examined.
  • B — incorrect The screen is a metal filtering element that is removed and cleaned on schedule; it does not shed rubber particles as it wears.
  • C — incorrect Tank corrosion is checked by inspecting the tank surfaces and, on light alloy tanks, the inhibitor cartridge; it would not leave rubber in the strainer.

BACKGROUND

Inspection of a fuel system installation consists basically of examining the system for conformity to design requirements together with functional tests that prove correct operation. Water and sediment must be drained from the main line strainer at each preflight inspection, and the screen is removed and cleaned at the periods specified in the airplane maintenance manual. The sediment removed from the housing should be examined, because particles of rubber are often early warnings of hose deterioration. The strainer should also be checked for leaks and damaged gaskets. Elsewhere in the system, hoses are replaced if the plys have separated, if there is excessive cold flow, or if the hose is hard and inflexible.

STUDY TIP

Treat strainer sediment as evidence rather than waste; what you find tells you which upstream component is failing. Rubber points to hose, so trace the hose runs before signing off the inspection.

KEY POINTS

  • Drain water and sediment from the main line strainer at each preflight inspection.
  • Examine the sediment, because rubber particles warn of hose deterioration.
  • Remove and clean the strainer screen at the intervals in the maintenance manual.

SOURCES

  • amp-powerplant/ch02.txt "Main Line Strainers"
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MORE ON ENGINE FUEL AND FUEL METERING SYSTEMS

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-32B Aviation Maintenance Technician Handbook – Powerplant, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.