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Source of engine instrument range markings

Aviation Mechanic Powerplant (AMP) practice question 9 of 9 on Engine Inspection. ACS element AM.III.C.K5 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Powerplant (AMP) practice mode.

Question bank updated 2026-09-22

QUESTIONThe actual oil pressure range markings for a specific aircraft may be found in the aircraft specifications or in what other document?

  1. AThe engine overhaul record
  2. BThe Type Certificate Data Sheet
  3. CThe applicable airworthiness directive
Show the answer and explanation

Correct answer: B. The Type Certificate Data Sheet

  • A — incorrect The overhaul record documents the work performed on the engine; it is not the source of approved instrument range markings.
  • B — correct The handbook states that the actual markings for a specific aircraft may be found in the aircraft specifications or Type Certificate Data Sheets, because the gauge dial itself does not show the range or limits for all installations.
  • C — incorrect An airworthiness directive corrects an unsafe condition and is not where instrument ranges and limits for an installation are published.

BACKGROUND

Engine instrument dials are often produced for a family of installations, so the oil pressure gauge dial does not show the pressure range or limits for all installations. The handbook states that the actual markings for specific aircraft may be found in the aircraft specifications or Type Certificate Data Sheets (TCDS). On a typical reciprocating engine oil pressure gauge, the lower red line at 25 pounds per square inch (psi) indicates the minimum oil pressure permissible in flight, the green arc between 60 and 85 psi shows the desired operating range, and the red line at 100 psi indicates the maximum permissible oil pressure. The mechanic confirms markings against the approved data for that aircraft rather than assuming the printed dial is correct.

STUDY TIP

When a question asks where approved values for a particular aircraft come from, think aircraft specifications and the TCDS, not the gauge face or the shop records.

KEY POINTS

  • Instrument dials do not show the limits for every installation
  • Approved markings come from the aircraft specifications or the TCDS
  • A typical oil pressure gauge shows red at 25 psi, green 60 to 85 psi, red at 100 psi

SOURCES

  • amp-powerplant/ch10.txt "Oil Pressure Indicator"
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MORE ON ENGINE INSPECTION

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.