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For owners

Engine health: oil analysis and compression checks

Updated 4 min read

Engines rarely fail without warning — they leave a paper trail first. The Engine Health tab tracks the two record streams GA owners actually use to read that trail: oil analysis and differential compression checks.

What gets tracked

  • Oil analysis — spectrometric metal levels in parts per million: iron, copper, chromium, silicon, lead, tin, and aluminum, plus viscosity, the lab name, the report number, and the tach time when the sample was pulled.
  • Compression checks — per-cylinder differential readings over a reference pressure (72/80, for example), with the cylinder count configurable to match your engine.

Getting records in

  1. Enter manually or upload the lab report

    Type the values in yourself, or upload the lab's report and let the AI parse it into the entry form.

  2. Review before committing

    Parsed values go through a review step — check them against the report before they enter the record. The AI drafts, you confirm.

  3. Watch the trend build

    Each committed entry extends the engine's history, and the trend over time is where the signal lives.

Why there's no pass/fail coloring

You'll notice TachMinder deliberately does not paint these numbers green or red, and sets no thresholds. That's a design decision, not a missing feature. Compression limits are engine-manufacturer-specific — the same reading can be acceptable on one engine and actionable on another. And oil analysis numbers are meaningful mainly against the same engine's own history: a value that would be unremarkable for one engine can be a step change for yours. The app shows you the trends; your mechanic interprets them. An amber note in-app reminds you to verify readings against the manufacturer's service information.

Oil analysis and your maintenance schedule

If you've set up an oil-analysis reminder with your own interval, committing an oil-analysis entry can advance that reminder clock — so the record you just added and the "next sample due" reminder stay in sync. See How next-due dates work for how owner-set intervals behave.

TachMinder is an informational tool only. It is not a substitute for a certified A&P mechanic or IA. Only certificated mechanics and appropriately rated repair stations can approve return-to-service. Always verify Airworthiness Directive data with the FAA AD database (drs.faa.gov). TachMinder does not certify airworthiness.

Track your aircraft maintenance with TachMinder.

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