Chapter 1 · How a Propeller Makes Thrust
| Item | Fact / typical value | Topic |
|---|---|---|
| Blade angle | chord line ↔ plane of rotation | 17.1 |
| Angle of attack | chord line ↔ relative airflow = blade angle − helix angle | 17.1 |
| Element speed | 2π r n — highest at the tip | 17.1 |
| Best AoA | ≈ 2–4° | 17.1 |
| Geometric pitch | GP = 2π R tan β (75 % station) | 17.1 |
| Slip | geometric pitch − effective pitch | 17.1 |
| Efficiency | ≈ 80–87 % | 17.1 |
| Blade angles | reverse ≈ −2 to −8° · fine 10–12° · coarse 20–35° · feather 85–90° | 17.1 |
Chapter 2 · Forces, Torque, Vibration and Resonance
| Item | Fact / typical value | Topic |
|---|---|---|
| Largest force | centrifugal — blade out of hub | 17.1 |
| Thrust bending | tips forward | 17.1 |
| Torque bending | against rotation | 17.1 |
| CTM | towards fine pitch — larger than ATM | 17.1 |
| ATM | towards coarse pitch | 17.1 |
| Torque reaction | roll opposite to prop rotation | 17.1 |
| Gyroscopic precession | force acts 90° later in rotation | 17.1 |
| Resonance | forcing = natural frequency · red arc on tachometer | 17.1 |
Chapter 3 · Propeller Construction and Materials
| Item | Fact / typical value | Topic |
|---|---|---|
| Blade stations | measured from the hub centre | 17.2 |
| Face / back | face flat (towards cockpit) · back cambered | 17.2 |
| Wood | ≥ 5 laminations ~19 mm · birch, maple, cherry, ash, mahogany | 17.2 |
| Wood protection | metal tipping · tip drain holes · fabric sheathing · varnish | 17.2 |
| Metal blades | forged Al alloy · heat-treated · shot-peened · anodised | 17.2 |
| Composite | foam core + spar + carbon/glass/aramid · erosion sheath · lightning mesh | 17.2 |
Chapter 4 · Propeller Types and Installation
| Item | Fact / typical value | Topic |
|---|---|---|
| Fixed pitch | climb (low pitch) · cruise (high pitch) · standard | 17.2 |
| Constant speed | prop lever = rpm · throttle = power | 17.2 |
| Contra vs counter | contra: same axis · counter: opposite engines | 17.2 |
| Shafts | flanged (dowels) · tapered (key) · splined (front split + rear bronze cone) | 17.2 |
| Rear cone contact | ≈ 70 % minimum (marking compound) | 17.2 |
Chapter 5 · Governors and Constant-Speed Operation
| Item | Fact / typical value | Topic |
|---|---|---|
| Governor | flyweights (up) vs speeder spring (down) → pilot valve | 17.3 |
| Underspeed | flyweights in · valve down · finer pitch | 17.3 |
| Overspeed | flyweights out · valve up · coarser pitch | 17.3 |
| On-speed | flyweights upright · valve centred · oil trapped | 17.3 |
| Non-feathering hub | oil → increase pitch · CTM → decrease · oil loss → fine | 17.3 |
| Power changes | increase: rpm then throttle · decrease: throttle then rpm | 17.3 |
Chapter 6 · Feathering, Reverse and Overspeed Protection
| Item | Fact / typical value | Topic |
|---|---|---|
| Feather angle | ≈ 85–90° | 17.3 |
| Light-twin hub | oil → fine · counterweights + spring + N₂ → feather · oil loss → feather | 17.3 |
| Start locks | hold low pitch on shutdown; release by centrifugal force | 17.3 |
| Hydromatic | double-acting · feather pump · pressure cut-out · distributor valve | 17.3 |
| Autofeather | armed · torque loss → feather · other side disarmed | 17.3 |
| Turboprop ranges | alpha = flight (governor) · beta = ground (blade angle from lever) | 17.3 |
| Overspeed governor | ≈ 106 % rpm | 17.3 |
Chapter 7 · Synchronising and Ice Protection
| Item | Fact / typical value | Topic |
|---|---|---|
| Beat | difference between propeller frequencies | 17.4 |
| Synchroniser | master–slave · limited authority ≈ 1–3 % · off for take-off/landing | 17.4 |
| Synchrophaser | holds blade phase angle · pulse pickups | 17.4 |
| Anti-ice fluid | isopropyl alcohol · rheostat pump · slinger ring · feed shoes | 17.5 |
| Electric de-ice | timer → brush block → slip rings → boots · ammeter pulses | 17.5 |
| Boot removal | MEK / toluene · re-bond, roll out air, test resistance | 17.5 |
Chapter 8 · Inspection, Damage Assessment and Repair
| Item | Fact / typical value | Topic |
|---|---|---|
| Al blade crack | any transverse crack → reject | 17.6 |
| Wood charring at flange | loose hub bolts | 17.6 |
| NDT | penetrant (Al/steel) · MPI (steel) · eddy current · ultrasound · etch · tap (composite) | 17.6 |
| Prop strike | remove → approved shop + engine sudden-stoppage inspection | 17.6 |
| Minor repair | dress nicks: long shallow blend along the blade · protect | 17.6 |
| Major repair | straighten · shorten (all blades) · repitch — repair station only | 17.6 |
Chapter 9 · Tracking, Balancing, Ground Running and Storage
| Item | Fact / typical value | Topic |
|---|---|---|
| Track tolerance | ±1/16 in typical (light aircraft) | 17.6 |
| Protractor | universal propeller protractor · 0.1° · blade face at reference station | 17.6 |
| Static balance | knife-edge / suspension stand | 17.6 |
| Dynamic balance | accelerometer + phase · ≤ 0.2 ips | 17.6 |
| Hunting / surging | oscillation · flare from trapped air | 17.6 |
| Storage | wood horizontal · CPC not on rubber · non-hygroscopic wrap · desiccant | 17.7 |
| Hub / governor | preservative oil, rotate, cover, plug | 17.7 |