Jug Scope Coming soon to the App Store

The 11-view borescope inspection.

A step-by-step guide to a complete cylinder borescope inspection, based on Savvy Aviation's standard protocol.

  • 3 groups
  • 11 views per cylinder
  • 66 images for a six-cylinder engine

What You Need

  • An iPhone or iPad with iOS or iPadOS 17 or later
  • A borescope (a WiFi borescope or the Ralcam F4A cable borescope), or the device's own camera
  • Access to the top spark-plug hole on each cylinder
  • A way to turn the propeller by hand
  • Jug Scope, with an Owner / Mechanic plan or a Shop plan

3 Groups, 11 Views

For each cylinder, capture all 11 views in order. The views are grouped by crankshaft position to minimize prop rotation.

  • 7 · Views at BDC Both valves closed. Piston, valve heads, cylinder walls.
  • 2 · Exhaust Valve Open Seat and stem inspection while valve is lifted.
  • 2 · Intake Valve Open Seat and stem inspection on intake side.

Bottom Dead Center — Views 1–7

Position the piston at bottom dead center. Both valves are closed. Capture all 7 views before rotating the prop.

  • Borescope reference image: piston crown at bottom dead center
    View 1 Piston CrownAim straight down at the piston crown. Look for unusual carbon patterns, erosion, or damage. Normal pistons show even carbon deposits. Hot spots or clean patches may indicate detonation.
  • Borescope reference image: exhaust valve head face
    View 2 Exhaust Valve HeadAim directly at the exhaust valve face. Center the valve in the frame. Look for erosion, pitting, or hot spots. The exhaust valve runs hottest and shows wear first.
  • Borescope reference image: intake valve head face
    View 3 Intake Valve HeadAim at the intake valve face. The intake valve typically shows less wear than exhaust but inspect for corrosion, deposits, or damage from foreign objects.
  • Borescope reference image: cylinder wall at 12 o'clock position
    View 4 Cylinder Wall — 12 o’clockPoint the borescope at the 12 o’clock position on the cylinder wall (top). Look for scoring, corrosion, or unusual wear patterns. Healthy walls show visible crosshatch honing marks.
  • Borescope reference image: cylinder wall at 3 o'clock position
    View 5 Cylinder Wall — 3 o’clockRotate the borescope 90° clockwise to view the 3 o’clock position. Check for scoring or rust that could indicate ring problems or moisture ingress.
  • Borescope reference image: cylinder wall at 6 o'clock position
    View 6 Cylinder Wall — 6 o’clockContinue to the 6 o’clock position (bottom of the barrel). This area can accumulate oil and deposits. Look for abnormal carbon buildup or wall irregularities.
  • Borescope reference image: cylinder wall at 9 o'clock position
    View 7 Cylinder Wall — 9 o’clockComplete the wall survey at the 9 o’clock position. Compare all four wall views for symmetry — uneven wear patterns can indicate piston ring or cylinder geometry issues.

Exhaust Valve Open — Views 8–9

Rotate the prop to open the exhaust valve fully. You will see the valve lift off the seat.

  • Borescope reference image: exhaust valve seat with valve open
    View 8 Exhaust Valve SeatWith the exhaust valve open, view the valve seat surface. Look for pitting, erosion, or uneven contact patterns. A good seat shows a uniform contact band around the full circumference.
  • Borescope reference image: exhaust valve stem and guide
    View 9 Exhaust Valve StemView the exhaust valve stem and guide area. Look for carbon buildup on the stem, guide wear, or evidence of oil passage past the guide.

Intake Valve Open — Views 10–11

Rotate the prop to open the intake valve fully.

  • Borescope reference image: intake valve seat with valve open
    View 10 Intake Valve SeatWith the intake valve open, view the seat surface. Compare condition to the exhaust seat. Intake seats typically show less thermal stress but may have deposits from induction system contaminants.
  • Borescope reference image: intake valve stem and guide
    View 11 Intake Valve StemView the intake valve stem and guide. The intake side typically shows less carbon than exhaust. Look for guide wear or unusual deposits.

Repeat this 11-view sequence for each cylinder. A complete 6-cylinder inspection produces 66 images. A 4-cylinder inspection produces 44 images.

Tips for Good Captures

  • Hold still for a second or two before you capture. Motion blur is the most common problem.
  • Clean the lens with a microfiber cloth between cylinders for consistent image clarity.
  • Adjust LED brightness for even illumination. Too bright washes out detail; too dim introduces noise.
  • With a WiFi scope, keep the phone or iPad close to it. Signal drops with distance.
  • Capture extra views if something looks unusual. More data helps Savvy's analysts make better assessments.
  • Work in shade or a hangar if possible. Direct sunlight makes the screen harder to read.
  • Insert slowly and avoid scraping the spark plug threads. Gentle, steady movements produce the best images.

Supported Borescopes

Jug Scope works with WiFi borescopes, the Ralcam F4A cable borescope, and the device's own camera. See which cameras work →

Getting Started

  1. Get the app. Coming soon to the App Store
  2. Sign in with Apple.
  3. Choose a plan.
  4. Add your aircraft: tail number, engine, and number of cylinders.
  5. Connect your borescope.
  6. Follow the guided capture, cylinder by cylinder.
  7. Review the set. Retake any view you need to.
  8. Send it to your shop or to Savvy, or export a ZIP. Each image is named for you.

Ready for your next borescope inspection?

Coming soon to the App Store See pricing

[email protected]