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Retightening a leaking non-self-sealing hose clamp in service

Aviation Mechanic General (AMG) practice question 14 of 17 on Fluid Lines and Fittings. ACS element AM.I.D.R5 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONDuring an inspection, a mechanic finds a clamp on a non-self-sealing hose that cannot be tightened with the fingers, and leakage is evident at the connection. What does the handbook direct for retightening this clamp?

  1. ATighten the clamp one-fourth turn
  2. BTighten the clamp finger-tight plus two complete turns
  3. CLeave the clamp undisturbed
Show the answer and explanation

Correct answer: A. Tighten the clamp one-fourth turn

  • A — correct For a non-self-sealing hose in service, the handbook says not to disturb a clamp that cannot be tightened with the fingers unless leakage is evident; if leakage is present, tighten one-fourth turn.
  • B — incorrect Finger-tight plus turns values apply to initial installation and are not to be used for loose clamps in service.
  • C — incorrect Leaving the clamp alone is correct only when no leakage is evident; with leakage present the clamp is tightened one-fourth turn.

BACKGROUND

Hose clamp tightening instructions must be followed carefully to ensure proper sealing and to avoid breaking clamps or damaging the hose. For initial installation a torque-limiting wrench (15 or 25 in-lb calibrations) is used when available, or the finger-tight-plus-turns method otherwise; because hose connections are subject to cold flow, a follow-up tightening check should be made for several days after installation. Those initial-installation values are not used for loose clamps in service. For retightening in service, a non-self-sealing hose clamp that cannot be tightened with the fingers is left undisturbed unless leakage is evident, in which case it is tightened one-fourth turn. A self-sealing hose clamp that is looser than finger-tight is brought to finger-tight and given an additional one-fourth turn.

STUDY TIP

Separate initial installation (finger-tight plus turns) from in-service retightening (one-fourth turn), and check whether the hose is self-sealing before acting.

KEY POINTS

  • In-service retightening of a leaking non-self-sealing hose clamp is one-fourth turn.
  • A self-sealing hose clamp looser than finger-tight is set finger-tight plus one-fourth turn.
  • Finger-tight-plus-turns values are for initial installation only.

SOURCES

  • FAA-H-8083-30B ch09 "Installation of Flexible Hose Assemblies - Clearance" (retightening loose hose clamps in service)
  • FAA-H-8083-30B ch09 "Hose Clamps"
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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.