Start & Run-up

Hand Propping:

• Hand propping enables pilots to start engines of aircraft that lack an electrical system
• Even though most airplanes are equipped with electric starters, it is helpful if a pilot is familiar with the procedures and dangers involved in starting an engine by turning the propeller by hand (hand propping)
• Due to the associated hazards, this method of starting should be used only when absolutely necessary and when proper precautions have been taken
• An engine should not be hand propped unless two people (preferrably both pilots), both familiar with the airplane and hand propping techniques, are available to perform the procedure

• Hand Propping Precautions:

  • The person pulling the propeller blades through directs all activity and is in charge of the procedure
  • The other person, thoroughly familiar with the controls, must be seated in the airplane with the brakes set
  • Both participants should discuss the procedure and agree on voice commands and expected action
  • As an additional precaution, chocks may be placed in front of the main wheels
  • If an additional person is unavailable to help, the airplane's tail may be securely tied (with slack removed)
  • When hand propping is necessary, the ground surface near the propeller should be stable and free of debris
  • Unless a firm footing is available, consider relocating the airplane
  • Loose gravel, wet grass, mud, oil, ice, or snow might cause the person pulling the propeller through to slip into the rotating blades as the engine starts
  • To begin the procedure, the fuel system and engine controls (tank selector, primer, pump, throttle, and mixture) are set for a normal start
  • The ignition magneto switch should be checked to be sure that it is OFF
  • Then the descending propeller blade should be rotated so that it assumes a position slightly above the horizontal
  • The person doing the hand propping should face the descending blade squarely and stand slightly less than one arm's length from the blade
  • Never allow a part of your body to enter the prop arc
  • If a stance too far away were assumed, it would be necessary to lean forward in an unbalanced condition to reach the blade
  • This may cause the person to fall forward into the rotating blades when the engine starts
  • The propeller is swung by forcing the blade downward rapidly, pushing with the palms of both hands
  • If the blade is gripped tightly with the fingers, the person's body may be drawn into the propeller blades should the engine misfire and rotate momentarily in the opposite direction
  • As the blade is pushed down, the person should step backward, away from the propeller
  • If the engine does not start, the propeller should not be repositioned for another attempt until it is certain the ignition/magneto switch is turned OFF
  • The words CONTACT (mags ON) and SWITCH OFF (mags OFF) are used because they are significantly different from each other
  • Under noisy conditions or high winds, the words CONTACT and SWITCH OFF are less likely to be misunderstood than SWITCH ON and SWITCH OFF
  • When removing the wheel chocks after the engine starts, it is essential that the pilot remember that the propeller is almost invisible
  • Incredible as it may seem, serious injuries and fatalities occur when people who have just started an engine walk or reach into the propeller arc to remove the chocks
  • Before the chocks are removed, the throttle should be set to idle and the chocks approached from the rear of the propeller
  • Never approach the chocks from the front or the side
  • The procedures for hand propping should always be in accordance with the manufacturer's recommendations and checklist
  • Special starting procedures are used when the engine is already warm, very cold, or when flooded or vapor locked
  • There will also be a different starting procedure when an external power source is used

• Hand Propping Procedure:

  1. Person out front says, "GAS ON, SWITCH OFF, THROTTLE CLOSED, BRAKES SET"
  2. Pilot seat occupant, after making sure the fuel is ON, mixture is RICH, magneto switch is OFF, throttle is CLOSED, and brakes SET, says, "GAS ON, SWITCH OFF, THROTTLE CLOSED, BRAKES SET"
  3. Person out front, after pulling the propeller through to prime the engine says, "BRAKES AND CONTACT"
  4. Pilot seat occupant checks the brakes SET and turns the ignition switch ON, then says, "BRAKES AND CONTACT"

Aircraft Start-up Considerations:

• Priming is helpful for many engines, but the amount of priming is dependent upon the density of the air
  • Warm air requires less priming, cold air requires more, potentially twice as much
• When starting an engine, it is not necessary to advance the throttle far forward before start
  • Doing so may cause the engine to go from cold to an excessively high RPM on start
  • Often, a closed throttle is sufficient

Aircraft Run-up Considerations:

• Before conducting a run-up before takeoff, it is generally a good idea to point the aircraft into the wind while still able to see final
  • Doing so will allow you to monitor airport traffic and allow airflow over the engine during the run-up
• When advancing the throttle, pay attention to engine smoothness and consistency in operation
• Checking magnetos not only ensures smoothness of operation on a single magneto, but verifies proper timing and unfouled magnetos
• Checking propeller systems, if appropriate, verifies the functionality of the propeller system and the integrity of the lubrication system
• Checking carburetor heat verifies functionality should the flight experience or suspect icing conditions
• Confirming suction gauge reads properly verifies the vacuum system operation is healthy to provide accurate instrument readings for those instruments that require
• When retarding the throttles, pay attention to engine smoothness and consistency in operation
• Be mindful of surface conditions, such as ice, that could cause the aircraft to slide when at a high power setting
• Throughout the entirety of the run-up, pay attention to unusual noises or inconsistencies throughout all checks
• The manifold pressure (if gauge equipped) should be steady

Surface Area Dangers:

• Personnel must always be aware of the dangers associated with moving surfaces
• Rotor wash created by the blades of a rotary-winged aircraft or thrust from the exhaust section of a fixed-winged aircraft may cause severe personnel injury
• The proper safety equipment must always be worn when working on flight decks and flight lines

Cold Temperature Engine Starting:

• Starting an engine in the cold produces some challenges
• Components like metals contract in the cold, impacting how the engine performs as compared to when warm
• Low vapor pressure combined with reduced battery efficiency can make cold temperature start-ups more difficult
• Carburetor engines are more likely to experience difficulty starting as compared to fuel-injection
• Carbureted engines can benefit from a few pumps of primer during cold temperature operations
  • When engines fail to start, the chance of overpriming increases, and fuel may pool in the cylinders, disrupting the fuel/air ratio, posing a backfire or engine fire risk
• Consider an external observer when starting engines in cold weather to provide advanced warning of fires
• The aircraft's POH/PIM knows what is best for that specific aircraft but as a rule-of-thumb, cold weather starts can cause abnormal engine wear, reduced performance, and therefore decreased time between heavy maintenance like an overhaul
  • Some of this is due to metallurgy being out of tolerance, but also reduced oil flow
• Cold engine temperatures can be mitigated by storing aircraft in heated hangars, or absent that, using a device that heats the engine before starting such as a pre-heater blowing hot air into the cowling, or an electronic engine-mounted heater
• When using pre-heaters, follow the manufacturers guidance, to include your aircraft
  • Avoid excessive heat to non-metalic equipment
  • Do not leave the heater on for longer than recommended
• Once complete with pre-heating, inspect the engine for any foreign objects, and once clear, start the engine before the aircraft's engine cools down again

Aircraft Engine Flooding:

• An engine is considered flooded when too much fuel has entered the cylinder, thereby disturbing the fuel/air ratio
  • This can be caused by over priming or too many start attempts
• Cold weather makes an engine particularly susceptible to flooding with engine pre-heat being a preventative measure
• Aircraft manufacturers will have specific procedures to clear a flooded engine, but generally speaking, pilots may:
  • Reduce the mixture to idle and crank the engine (blowing fuel out of the exhaust)
  • Allow the aircraft to sit (for gas to evaporate)
• Of course, extra fuel in the system carries at least some level of risk and so engine fire procedures should be reviewed just in case

Safety Considerations:

• Pilots should always shout clear prop prior to starting the engine to not only make sure the prop area is clear of people, but that others around are not surprised when the engine starts

Starting An Aircraft:

• Most aircraft have starters that automatically engage and disengage when operated, but some older aircraft have starters that are mechanically engaged by a lever actuated by the pilot
• The starter engages the aircraft flywheel, rotating the engine at a speed that allows the engine to start and maintain operation

• 

• 

• Electrical power for starting is usually supplied by an on-board battery, but can also be supplied by external power through an external power receptacle
• When the battery switch is turned on, electricity is supplied to the main power bus bar through the battery solenoid
• Both the starter and the starter switch draw current from the main bus bar, but the starter will not operate until the starting solenoid is energized by the starter switch being turned to the "start" position
• When the starter switch is released from the "start" position, the solenoid removes power from the starter motor
• The starter motor is protected from being driven by the engine through a clutch in the starter drive that allows the engine to run faster than the starter motor [Figure 4]
• When starting an engine, the rules of safety and courtesy should be strictly observed
  • Clear the area visually and make a call, "Clear prop!"
• In addition, the wheels should be chocked and the brakes set, to avoid hazards caused by unintentional movement
• When using a starter, don't hold the started for more than a few seconds or it can burn out due to excessive heat
• To avoid damage to the propeller and property, the aircraft should be in an area where the propeller will not stir up gravel or dust

Private Pilot - Engine Starting Airman Certification Standards:

• To determine that the applicant exhibits satisfactory knowledge, risk management, and skills associated with recommended engine starting procedures
• References: FAA-H-8083-2, FAA-H-8083-3, FAA-H-8083-25; POH/AFM

Start and Runup Case Studies:

Conclusion:

• When hand propping, always be sure to follow the procedures listed in the pilot operating handbook
• To learn more about tie-downs after flight, see: AOPA's Training Tip: How to Tie Down an Airplane and read AOPA - Securing an Airplane on the Ramp
• Learn more about turbine engine start-up by reviewing hot, hung start
• Still looking for something? Continue searching:

References:

• Airplane Flying Handbook (Chapter 2) Hand Propping
• Federal Aviation Administration - Pilot/Controller Glossary
• Airplane Flying Handbook (10-5) Starting, Taxiing, and Run-up
• Pilot Workshops - Pilot Tip of The Week: Starting a Flooded Engine
• Reddit - Witnessed and accident today