Propeller work

Six procedures. Procedure 0 applies to every one, and to anything else that puts your hands on a blade.

Procedure 0 — Before you touch a blade (R1, R2)

1. Ignition off, mixture idle cut-off, master off, chocks in.
2. Disconnect and ground the P-leads at the magnetos (PP-H Procedure 0).
3. Confirm both magnetos grounded.
4. Treat the propeller as live anyway — stand clear of the arc, move it in the direction of rotation.

Check — point at both grounded P-leads and say the propeller is live. Both, every time (PP-M Concepts §1).

Procedure 1 — Inspect a propeller (S3, S10)

1. Clean the blades so damage is visible.
2. Inspect leading edges for nicks, gouges and erosion — this is where damage concentrates.
3. Inspect face and camber surfaces, and the tip.
4. Inspect the hub: cracks, corrosion, oil leakage at seals, security of hardware.
5. Check for oil or grease leakage from a constant-speed hub, which points at seals.
6. Check blade shake and endplay per the manual's limits.
7. Check spinner and bulkhead for cracks — a spinner crack is a finding, and a departing spinner is dangerous.
8. Measure everything against the manual's limits.

Check — run a cloth or a gloved finger along the leading edge. Nicks catch it, and small ones are easy to miss visually against a painted or polished edge.

Procedure 2 — Dress a minor blade repair (S5, S11)

Read PP-M Concepts §3 first, and confirm this is within minor-repair limits.

1. Measure the damage: depth, length, location on the blade.
2. Check the propeller TCDS and manufacturer's manual for allowable damage and dressing limits at that location (S11).
3. Check cumulative removal from the blade's history.
4. Confirm the repair is minor, not major — an A&P may not perform major propeller repairs (GEN-I Concepts §2).
5. Dress with the specified tools and method — smooth files and abrasives, working along the blade, never across it.
6. Blend to the specified radius and length. The transition must be gradual.
7. Check the finished dimension against limits, and check the corresponding area of the other blade for balance requirements.
8. Restore the surface protection per the manual.
9. Record the repair, the amount removed and the cumulative total.

Check — run a fingernail along the blend. You must feel no step, no edge and no ridge. A short steep blend is itself a stress raiser and has not repaired anything.

Failure — filing across the blade rather than along it. It leaves transverse marks, which are stress raisers perpendicular to the load.

Procedure 3 — Measure blade angle (S4)

1. Position the propeller and aircraft as the manual requires.
2. Identify the blade station at which the angle is specified — an angle is meaningless without it, because the angle varies along the blade.
3. Set the protractor per its instructions, referencing the specified datum.
4. Measure at the station, on each blade.
5. Compare against specification, and compare the blades against each other.

Check — state the station before quoting the angle. An angle measured at the wrong station is a confident wrong number.

Procedure 4 — Remove and install a propeller (S1, K7)

1. Procedure 0.
2. Note hardware, orientation, index marks and any spacers or shims.
3. Support the propeller — it is heavy and awkward, and dropping it damages a blade and possibly you.
4. Remove per the manual, keeping hardware identified.
5. Inspect the mounting flange and bushings, and the rear of the propeller and the crankshaft flange faces — corrosion and fretting here are findings.
6. Install with correct index alignment, new O-rings or seals, correct hardware.
7. Torque in the specified sequence and to the specified value, and safety.
8. Check track (Procedure 5) and check for leaks.
9. Run and re-check per the manual.

Check — confirm index alignment before torquing. Many propellers are indexed to the crankshaft for balance and for clearance, and fitting one a spline out changes both.

Procedure 5 — Check static track (S2)

1. Procedure 0.
2. Set a fixed reference close to the blade tip — a block, a pointer, clamped so it cannot move.
3. Rotate the propeller by hand and note where each blade tip passes the reference.
4. The difference between blades is the track error. Compare against the manual's limit.
5. Rotate again to confirm.

Check — the reference must not move between blades. If it can shift, your measurement is of the reference, not the propeller.

Procedure 6 — Adjust a governor (S8)

Engine running. GEN-F Procedures Procedure 7 applies in full.

1. Get the target RPM from the engine and airframe data for that installation.
2. Warm the engine to the specified temperature.
3. Adjust in small increments, allowing RPM to stabilize between changes.
4. Check both the maximum RPM setting and the governing range.
5. Shut down, safety the adjustment, and re-check on a subsequent run.

Check — state the target RPM and its source before adjusting. "Until it sounds right" is not a specification, and an overspeeding propeller is a structural event.

The checks, collected

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