Chapter 11. Safety, Ground Operations, & Servicing

Ground Movement of Aircraft

Engine Starting and Operation

The following instructions cover the starting procedures for reciprocating, turboprop, turbofan, and auxiliary power units (APU). These procedures are presented only as a general guide for familiarization with typical procedures and methods. Detailed instructions for starting a specific type of engine can be found in the manufacturer’s instruction book.

Before starting an aircraft engine:

  • Position the aircraft to head into the prevailing wind to ensure adequate airflow over the engine for cooling purposes.
  • Make sure that no property damage or personal injury will occur from the propeller blast or jet exhaust.
  • If external electrical power is used for starting, ensure that it can be removed safely and it is sufficient for the total starting sequence.
  • During any and all starting procedures, a “fireguard" equipped with a suitable fire extinguisher shall be stationed in an appropriate place. A fireguard is someone familiar with aircraft starting procedures. The fire extinguisher should be a CO2 extinguisher of at least 5-pound capacity. The appropriate place is adjacent to the outboard side of the engine, in view of the pilot, and also where he or she can observe the engine/aircraft for indication of starting problems.
  • If the aircraft is turbine engine powered, the area in front of the jet inlet must be kept clear of personnel, property, and/or debris (FOD).
  • These “before starting" procedures apply to all aircraft powerplants.
  • Follow manufacturer’s checklists for start procedures and shutdown procedures.

Reciprocating Engines

The following procedures are typical of those used to start reciprocating engines. There are, however, wide variations in the procedures for the many reciprocating engines. No attempt should be made to use the methods presented here for actually starting an engine. Instead, always refer to the procedures contained in the applicable manufacturer’s instructions.

Reciprocating engines are capable of starting in fairly low temperatures without the use of engine heating or oil dilution, depending on the grade of oil used.

The various covers (wing, tail, cockpit, wheel, and so forth) protecting the aircraft must be removed before attempting to turn the engine. External sources of electrical power should be used when starting engines equipped with electric starters, if possible or needed. This eliminates an excessive burden on the aircraft battery. All unnecessary electrical equipment should be left off until the generators are furnishing electrical power to the aircraft power bus.

Before starting a radial engine that has been shut down for more than 30 minutes, check the ignition switch for off; turn the propeller three or four complete revolutions by hand to detect a hydraulic lock, if one is present. Any liquid present in a cylinder is indicated by the abnormal effort required to rotate the propeller, or by the propeller stopping abruptly during rotation. Never use force to turn the propeller when a hydraulic lock is detected. Sufficient force can be exerted on the crankshaft to bend or break a connecting rod if a lock is present.

To eliminate a lock, remove either the front or rear spark plug from the lower cylinders and pull the propeller through. Never attempt to clear the hydraulic lock by pulling the propeller through in the direction opposite to normal rotation. This tends to inject the liquid from the cylinder into the intake pipe. The liquid will be drawn back into the cylinder with the possibility of complete or partial lock occurring on the subsequent start.

To start the engine, proceed as follows:

  • Turn the auxiliary fuel pump on, if aircraft is so equipped.
  • Place the mixture control to the position recommended for the engine and carburetor combination being started. As a general rule, the mixture control should be in the “idle cut-off" position for fuel injection and in the “full rich" position for float-type carburetors. Many light aircraft are equipped with a mixture control pull rod which has no detent intermediate positions. When such controls are pushed in flush with the instrument panel, the mixture is set in the “full rich" position. Conversely, when the control rod is pulled all the way out, the carburetor is in the “idle cut-off" or “full lean" position. The operator can select unmarked intermediate positions between these two extremes to achieve any desired mixture setting.
  • Open the throttle to a position that will provide 1,000 to 1,200 rpm (approximately 1/8 to 1/2 inch from the “closed" position).
  • Leave the pre-heat or alternate air (carburetor air) control in the “cold" position to prevent damage and fire in case of backfire. These auxiliary heating devices should be used after the engine warms up. They improve fuel vaporization, prevent fouling of the spark plugs, ice formation, and eliminate icing in the induction system.
  • Move the primer switch to “on" intermittently (press to prime by pushing in on the ignition switch during the starting cycle), or prime with one to three strokes of priming pump, depending on how the aircraft is equipped. The colder the weather, the more priming will be needed.
  • Energize the starter after the propeller has made at least two complete revolutions, and turn the ignition switch on. On engines equipped with an induction vibrator (shower of sparks, magneto incorporates a retard breaker assembly), turn the switch to the “both" position and energize the starter by turning the switch to the “start" position. After the engine starts, release the starter switch to the “both" position. When starting an engine that uses an impulse coupling magneto, turn the ignition switch to the “left" position. Place the start switch to the “start" position; when the engine starts, release the start switch. Do not crank the engine continuously with the starter for more than 1 minute. Allow a 3- to 5-minute period for cooling the starter (starter duty cycle) between successive attempts. Otherwise, the starter may be burned out due to overheating.
  • After the engine is operating smoothly, move the mixture control to the “full rich" position if started in the “idle cutoff" position. Carbureted engines will already be in the rich mixture position. Check for oil pressure.

Instruments for monitoring the engine during operation include a tachometer for rpm, manifold pressure gauge, oil pressure gauge, oil temperature gauge, cylinder head temperature gauge, exhaust gas temperature gauge and fuel flow gauge.

 ©AvStop Online Magazine                                                                                                                                                      Contact Us              Return To Books

AvStop Aviation News and Resource Online Magazine

Grab this Headline Animator