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Yak 52 Start Up procedure

Before commencing the start up procedure, complete the following preliminary checks:

IMPORTANT NOTE:  Ensure magneto selector switches in both the front and rear cockpits remain on "0" until the propeller pull through procedure is complete, then SET THE MAGNETO IN THE REAR COCKPIT TO "1+2" POSITION before attempting to start the engine.



1.  Pre-start checks

The following checks must be completed in the front cockpit before the engine start up (going from left to right):




2.  Priming the engine

Prime into the cylinders (primer turned to the right) as required according to cylinder head temperature (CHT).  To identify the required number of primes use following basic rule: When the CHT showing on the CHT gauge is 100o C or above - no priming into the cylinders required, for the CHT below 100o C you will need one prime per each 10o below than 100o (e.g. CHT=40:  6 primes required, CHT=60:  4 primes).

IMPORTANT NOTE:  Do not prime more than required as above because fuel may wash off the oil from the cylinders' internal surface, which then may cause their damage.  Fuel may also accumulate in the bottom cylinders which may cause the hydraulic lock during start up. Maximum amount of primes given by the original Yak-52 Flight Manual is 12.

1. Make sure both magnetos in front and rear cockpits are on "0" and ALL switches are OFF, brakes are ON and locked, rudder pedals set to neutral.
2. Ask ground crew member to turn the propeller and confirm to him that magnetos and switches are OFF.  Pulling through must be done in the direction of propeller rotation.
3. Prime to the cylinders as the propeller is turned, one prime per half turn.  Only start counting primes when the primer is full of fuel (normally it takes a couple of shots), you will be able to feel resistance as the primer goes in.
4. When priming is complete start the stopwatch (right button on the clock).  The best timing between priming and actually pressing the start-up button is about 2 minutes to let the fuel to evaporate to some extent inside of the cylinders.
5.  Ensure that magneto in the rear is set to 1+2 position.

IMPORTANT NOTE:  When the engine is cold it is mandatory to turn the prop before the start up, if CHT is above 80o - it is forbidden to turn it.



2.  Starting the engine

1. Call "CLEAR PROP".
2. Put "Master Switch", "Generator" and "Ignition" switches ON (Up position).
3. Prime into the fuel system (always required irrespective of CHT).  Turn primer to the left and pump until pressure shows towards 0.5 kg/cm2.  Normally that requires 2-6 pumps.
4. Check that primer is closed (fully forward) and locked in the upright position.
5. Without delay after priming the system open starter cover with left hand and press the starter button with left thumb.  After 1/2 to 1 turn of the prop flick magneto switch to "1+2" position with left fingers.  DO NOT RELEASE START UP BUTTON IMMEDIATELY AFTER SWITCHING MAGNETO ON 1+2.  The button must be released only after the engine has started.  Normally it takes 3-5 seconds, maximum permissible duration of button pressing is 15 seconds.
6. When the engine is running steady set RPM to 38-41%.

NOTE:  When starting cold engine (CHT <= 20-30o C) and having difficulty with the engine "picking-up", use priming into the cylinders at the same time as you keep the button pressed and Magneto switch in 1+2 position.  Normally 3-5 extra primes are sufficient in this situation.  Do not forget to put primer back to fully forward, vertical and locked after that!
 

It is also permissible to aid start up with the throttle movements forwards and backwards in the range of 1/3 - 1/2 of its full movement (frequency about 1.5 - 3 seconds).  That works well with two people on board: one on the primer and the other on the throttle.  Do not over push the throttle, this will cause a power surge which over stresses parts of the engine.

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3.  Post-Start Checks

1.   Ensure that primer is fully forward, vertical and locked, then cover the start up button with its cap.
2.   Check the oil pressure.  If the oil pressure has not increased up to 1 kg/cm2 within 15-20 seconds after start up, switch the engine off immediately and find out what the problem is.
3.   Warm the engine up initially using RPM 41-44% until the oil temperature starts raising.  After beginning of the oil temperature increase use RPM 44-48% (up to 51% in winter) to continue the engine warm up.
4.   If the external power was used, put the Master Switch ON (up) then disconnect the power cord.
5.   Check that generator is on line by: a) Red lamp (Generator Failure) is out, and b) Needle on Volt-Ammeter is to the left of the zero marker, and then switch ON the rest of the circuit breakers on the left horizontal panel (switches 3, 5, 7 & 8).  It is recommended to fully press and release the knob on Attitude Indicator before putting the above switches ON.
6.   Press the Lamp test button and check if all lights are functioning.
7.   Monitor oil and fuel pressure, oil temperature, cylinder head temperature.
8.   The engine is considered as "warmed up" when CHT is above 120o and the oil temperature is 40o.
9.   The Oil Temperature must reach at least 40o C before you may commence engine power checks.
10. Operate Engine Cowl Flaps throughout engine warm up procedure to keep Cylinder head temperature within limits.
11. Carry out engine power checks.
 
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