Deadstick landings occur when the aircraft's power source stops in mid air, forcing a glide down to earth. For deadstick landing technique refer to the article Deadstick in the In Flight:Fixed Wing Powered category.
Deadstick landings although often benign, are not without risk and so are best avoided. Being aware of the following list of causes and fixes, allows the model pilot to minimise those risks.
| Cause | Fix | Detail | |
| 1 | Lean Run | Richen high speed needle valve setting | High speed needle valve settings can become disturbed. Suggested protocol: |
| 1. Warm the engine by running near full thottle. | |||
| 2. Lean out the engine past the too lean position until you hear the engine note fall, (RPM decrease), very briefly, then quickly back again to a slightly rich position. This allows the model pilot a feel for the change in needle valve settings he is working with. | |||
| 3. Close the needle valve slightly until engine produces max RPM and holds it. This setting is too lean. Measure the RPM. | |||
| 4. Reduce the RPM by say 1000 rpm., by measurement or two 'clicks' on the needle valve. This will probably be near optimum. | |||
| 5. Hold the aircraft vertical for twenty seconds on full throttle. Engine note should pick up to maximum and hold. If there is any sign of struggling or no engine note increase then the mixture is still too lean. Reason for the pick up in RPM is the engine has to do more work against gravity to draw in the fuel, effectively leaning the mixture. | |||
| 6. Do the pinch test. i.e. pinch the fuel line, engine should pick up the same way, if not, then still too lean. | |||
| 7. Use the RPM meter at each flying session to ensure the settings are still optimum. If disturbed then reset to the RPM levels you now know to be correct for the engine/ prop combo. | |||
| 2 | Out of fuel. | Check fuel, Check full tank run time, Use timer. | |
| 3 | Debris in fuel lines. | Filter fuel. Use carb cleaner to blow out the carburettor. Check and clean filters regularly. | |
| 4 | Engine over heating. | Airflow through cowl inadequate. Open cowl. | |
| 5 | Glow Plug failure. | Check and replace plugs regularly. | 1. Once the engine is warm removing and replacing the glow starter should make no difference to the engine note. Should the correctly tuned engine show reduced RPM when the starter is removed the glow plug is deteriorating and should be replaced. |
| 2. After hard landings, nose overs etc. Glow plugs can become mechanically damaged but still glow when starter is used. Damage typically is seen by the coil being assymetrical. The glow plug should be replaced. | |||
| 3. Some glow plug filaments develop a white powdery appearance rather than the shiny metal appearance of a new plug. If this happens the filament has exceeded it's efficient lifetime. | |||
| 6 | Glow Plug loose in cylinder head. | Tighten Glow Plug. | |
| 7 | Cylinder head is becoming loose. | Check cylinder head screws. | |
| 8 | Marginal power, leading to lean run. | Increase power source rating, (engine size). If power is marginal, takeoff speed is first to be affected adversely. Realising this it is easy to see how every last ounce of performance could be asked from from the power source by the modeller. This in turn could lead to a lean run. | |
| 9 | Incorrect fuel tank location. | Correct fuel tank location | Avoid long fuel line runs, unless a pump is used. |
| Avoid wrong elevation of fuel tank centre line. i.e. should be horizontally in lne with. Carburettor. | |||
| If long lines are needed fit a fuel pump to avoid the large differences in pressure which will occur with vertical motion, i.e. gravity. | |||
| 10 | Fuel tank clunk foldback. | Fit brass tube extension in fuel line. | If the fuel tank clunk sticks in the forward position say due to a heavy landing then fuel starvation can occur on the next flight while climbing. Fitting a brass tube extension in the fuel line can prevent clunk foldback. |
| 11 | Fuel Foaming. | Airframe vibration can cause fuel to foam in the fuel tank. This can lead to dead stick events. Packing the fuel tank in foam rubber can reduce/eliminate this risk. The packing should be firm enough to hold the tank but not packed so tight that the cushioning effect is negated as will allow the vibration to continue to transmit to the tank and fail to reduce/eliminate the problem. | |
| 12 | In line fuel filter loose. | Tighten filter. | Loose filters can admit air into the fuel lines and cause fuel leanout and deadsticks. Better still remove the filters as they represent a possible failure point and filter the fuel separately before or while filling the aircraft's fuel tank. |
| 13 | Inline fuel filter dirty. | Clean filter. | Debris in in-line fuel filters restricts fuel flow leading to deadsticks. Better still remove the filters as they represent a possible failure point and filter the fuel separately before or while filling the aircraft's fuel tank. |
| 14 | Carburettor assembly is bad. | Reassemble carburettor | Carburettors can be wrongly assmbled at the factory, or components can become loose due to vibration. This can mean air ingress through loose seals and/or misaligned jets, which in turn can lead to deadstick conditions. |
| 15 | Stale Fuel. | Cycle fuel correctly. | a. Adding new fuel to a container that contains residual fuel not yet used, runs the risk of allowing the gradual deterioration of fuel to affect all the fuel in the container. |
| b. Any contaminants in the fuel as a result of blending cleanliness by the supplier get continually added to. | |||
| Eventually this contaminated fuel gets into the the engine's fuel tank and stops it, usually in the air with a deadstick event. | |||
| Solution: Filter all fuel before it reaches the the engine's fuel tank and make sure all fuel is used before refilling your flying field container. Finally clean fuel filters regularly. | |||
| 16 | Long steep descent at idle, causing fuel to pool in the crankcase. | Avoid long descents at idle. | Long steep descents at idle raise the head of fuel as seen by the engine. This leads to unburnt fuel accumulating in the crankcase. This in turn makes it difficult for an engine to throttle up, and can lead to a deadstick event close to the ground, i.e. just when you need to gain height. |
| If you choose to fly long descents at idle, keep the aeroplane level to avoid the increased head effect, i.e. not nose up and not nose down, and use on board glow or permaglow to maximise combustion at idle. | |||
| 17 | Long vertical spin with a near empty fuel tank. | Avoid spinning towards the end of a flight. | With standard fuel tank orientation, the clunk will likely be in fresh air during spinning if the tank is near empty towards the end of a flight. Left long enough, i.e. spinning from a great height the engine will be starved of fuel and stop. |
| 18 | Idle RPM setting set too low | Adjust throttle trim to set idle at 2500 RPM for a fully run in engine, or 3000 RPM for an engine just run in. | |
| 19 | Slop or backlash in the throttle actuator set up. | Remove the backlash. | |
| 20 | Carburettor barrel setup error, or carburettor barrel has loosened and slipped. | Check carburettor barrel setup and correct as needed. | |
| 21 | Carburettor 'O' ring seal between carburetter and engine case perished or split. | Replace 'O' ring | An 'O' ring in poor condition will allow air to enter making the engine difficult to tune and running eratic. Deadsticks may be reasonabley anticipated if this condition exists. |
| 22 | Plug becomes cold at idle because of reduced heating of combustion, and/or unburnt fuel cooling the plug element. | Fit On Board Glow or PermaGlow. See Engine Cuts Out After A Short Idle Time, Leading to Deadsticks On The Landing Run - The Use Of Glow Assist. | |
| 23 | Running rich. | Correct the mixture settings. | Can lead to unburnt fuel in the crankcase. Engine stops when full RPM is called for after a short run at idle. |
| 24 | Engine Wear. | Fit On Board Glow or PermaGlow. | Reduced compression due to cylinder bore wear reduces the ability of the engine to idle well. |
Comments
2nd. May 2016.
Adde points 23 and 24.