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Smooth installation of a bladder fuel tank

Aviation Mechanic Airframe (AMA) practice question 4 of 12 on Aircraft Fuel Systems. ACS element AM.II.J.K2 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONA bladder fuel cell is being unfurled in a wing bay. Why must its bottom surface lie smooth and unwrinkled?

  1. ASo the cell holds its rated fuel volume
  2. BSo contaminants can settle into the sump
  3. CSo the cell stays wet and does not dry out
Show the answer and explanation

Correct answer: B. So contaminants can settle into the sump

  • A — incorrect The handbook gives contaminant settling, not volume, as the reason the bottom must be free of wrinkles.
  • B — correct Wrinkles on the bottom surface block fuel contaminants from settling into the tank sump, where they would otherwise be drained off.
  • C — incorrect Keeping a bladder wet applies to dry storage, which is handled by wiping the inside with clean engine oil, not by how the bottom lies.

BACKGROUND

A bladder tank, or fuel cell, is made of reinforced flexible material and can be rolled up and passed through a small opening such as an inspection hole, then unfurled inside a prepared structural bay. Bladder cells must be attached to the structure with clips or other fastening devices and should lie smooth and unwrinkled. A wrinkled bottom traps contaminants and keeps them from reaching the sump, where the drain valve removes them. Bladder tanks are used on aircraft of all sizes and have seams only around installed features such as vents, sump drain, and filler spout. A leaking cell may be patched per the manufacturer's instructions or sent to a repair station equipped for that work.

STUDY TIP

Tie every fuel tank feature back to the sump: the low point where water and sediment collect so they can be drained before flight.

KEY POINTS

  • Bladder cells install through small openings and are clipped to the structure.
  • The bottom must be free of wrinkles so contaminants reach the sump.
  • Dry storage of a bladder calls for wiping the inside with clean engine oil.

SOURCES

  • sources/ama-airframe/ch14.txt, "Bladder Fuel Tanks"
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MORE ON AIRCRAFT FUEL SYSTEMS

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-31B Aviation Maintenance Technician Handbook – Airframe, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.