FPS Maintenance
The aircraft uses a high-performance carbureted, two-stroke internal combustion engine mounted at the rear of the fuselage in a pusher configuration. The engine assembly includes all electronics, RPM sensor, ignition module, vibration mount, and propeller. Fuel is held in an integral composite tank located within the fuselage. The tank is equipped with anti-slosh baffles and an internal fuel filter.
The engine should be inspected before each flight during the Preflight Inspection. Additional maintenance procedures are performed according to the Maintenance Schedule or as needed. There is also an additional maintenance schedule specifically for engine components.
Contents
Engine Maintenance Schedule
Each engine requires an additional maintenance schedule for subcomponents every 50, 100, and 300 hours. After 300 hours, the engine must be removed and sent to the OEM for overhaul to replace the engine core, harnesses, injector, throttle servo and more. Items like the ECU and fuel pump can go multiple overhaul cycles before replacement is recommended. The maintenance schedule for a specific engine is reset after an overhaul.
| Item | Preflight | 50 Hours | 100 Hours | 300 Hours |
|---|---|---|---|---|
| Inspect/Torque Propeller | ✓ | |||
| Propeller Replace | ✓ | |||
| Engine Oil Pre-Mix | ✓ | |||
| Spark Plug Replace | ✓ | |||
| Fuel Filter | ✓ |
Engine Hardware
| Item | Fastener | QTY | Torque | Threadlocker |
|---|---|---|---|---|
| Spark Plug | NGK CM-6 | 2 | 90 in/lbs | n/a |
| Prop Bolts | M6 x 60 SHCS | 6 | 90 in/lbs | n/a |
| Muffler Bolts* | M5 x 20 SHCS | 4 | 60 in/lbs | n/a |
| Cylinder Base Bolts | M6 x 20 | 8 | 110 in/lbs | Blue Loctite 243 |
| Crank Case Bolts | M5 x 25 | 4 | 90 in/lbs | Blue Loctite 243 |
| Carburetor Mount Bolts | M5 x 85 SHCS | 2 | 70 in/lbs | n/a |
| Engine Standoff Mount | M6 x 25 SHCS | 4 | 65 in/lbs | Blue Loctite 242 |
*Use Permatex 81630 Ultra Red High Temperature Gasket Maker between cylinder and muffler.
Tools needed: socket wrench, flathead screwdriver, 9/16" or 14 mm spark plug socket, 90 in/lbs torque wrench.
- Ensure the aircraft is powered off, all batteries are disconnected, and the engine is cool.
- Unscrew the hose clamp around the spark plug boot.
- Disconnect the spark plug boot from the spark plug.
- Remove the spark plug.
- Inspect the spark plug and insulator for damage and wear. The insulator should not be cracked. A normal spark plug will have brown or grayish-tan deposits on the side electrode. Burned plugs, or those with carbon fouling or oily residue, indicate a problem with the fuel/air mixture or fuel/oil mixture. Worn electrodes will appear eroded. Use the original spark plug if the condition is good or replace it with a new one.
- Ensure the spark plug gap is between 0.018 to 0.020 inch (0.38 to 0.5mm).
- Install the spark plug.
- Torque the spark plug to 90 in/lbs.
- Reconnect the spark plug boot.
- Reinstall the hose clamp around the spark plug boot.
Propeller Replacement
The FPS uses a 32 x 18 wood 2-blade propeller.
Tools needed: 5 mm hex driver, 90 in/lbs torque wrench.
Removal
- Ensure the aircraft is powered off, all batteries are disconnected, and the engine is cool.
- Note the propeller orientation and direction before removal.
- Remove the propeller bolts and propeller plate.
- Remove and discard the old propeller.
- Inspect the engine shaft hub thread and propeller bolts for damage. Replace any bolts that are bent.
Installation
- Insert the new propeller onto the propeller hub. Ensure the propeller is not mounted backwards.
- Align the propeller and compression stroke in a way that is ideal for hand propping.
- Reinstall the plate and prop bolts. Gradually hand-tighten each bolt using a star pattern before torquing to 90 in/lbs. Do not apply thread locker.