Yak

Globaltec Ltd

Yak checkouts and interest

Full Yak conversions carried out, including comprehensive technical and operational instruction, flat spinning and safety training. It will include a differences training sign off if required.

BI-ANNUAL. Revalidations and renewals. You will know longer need to hire a club aircraft. The dual check and renewals can be done in your own aircraft.

The following are Word or Excel documents available for download.

YAK 52 General information. IAN AUSTIN November 2001.

Electrics:
24v battery, Push button on volt/ammeter, will give 24v with engine off or at idle. Generator fail light comes on any time bus. is being supplied by battery.
28v generator. Push button on volt/ammeter, will give 28v with engine running.
Master switch down for ground power. Always leave master off in neutral position.

Oil:
Min 8, min 10 aerobatics; max quantity 16, but anything above 13 tends to vent. Ideal 10-12. Burn rate +/- 1 litre/ hour depending on how it is flown.
Type: W100 summer UK, W80 winter UK. For running in straight oil with same grades.
Always watch oil pressure after start, especially on a radial. Leave drain mod open overnight.

Hydraulic lock.
2 separate problems:
1- Oil/ fuel already present in cyls. not compressible.
2- Oil/ fuel in induction manifolds being induced at start to cause lock.
Remedy: Always pull through, if locked or suspect excess oil problem, use drain mod or drain manifolds, remove front spark plugs on bottom cyls.
Safety: Check mags off, treat prop as live. Air on, brakes on.
Leave drain mod open overnight. Do not turn propeller in reverse direction.

Fuel:
100LL. MOGAS not recommended. Burn +/- 45 litres/hr at 6/60. Up to 80 per hour during aerobatics. Priming 2 positions.
1- Carb or (main pipe) for fuel pressure.
2- cyls for main priming.
Venting: vent located centre fuselage belly. May vent on ground if wing gets hot. Open tank filler to release pressure.
Small holes at filler necks to drain excess fuel if over filled.
Fuel drain under belly.
Fire valve is firewall shut off. Leave open except in an emergency.

Pneumatics:
Main system; bottle charged by engine compressor or ground charge point.
Emergency system only charged at ground charge point. (except yak 50).
Water drain on firewall to be drained after each flight.
If it is not closed after draining, the main bottle will not charge when the engine is running.

U/C system:
Pneumatic. VLE 200 kph. Lever has 3 positions- never stop in middle U/C relies on back pressure to control travel speed. If you get it wrong, go back to where you started and reselect.
Gear semi-retractable. Leave up for forced landing unless surface condition is good. (Reduces possibility of flipping over).
If gear does not extend: Leave circuit.
1. Check pressure,
2. Check soldiers
3. PTT lights and change bulbs if necessary
4. Reselect, perhaps use G-forces.
5. If unsuccessful put lever in neutral and open the emergency air tap with positive movement.

Flaps:
Pneumatic 2 position (up or down). Drag or landing flaps only ie. Not used for take off! VFE 170 kph.

Brakes:
Pneumatic. Drum. Suffer fading. Use cadence only. Differential. Remember, they do not work without air, or the air tap closed! Care should be taken when operating from wet grass. A/c may slide sideways due to torque reaction, or will weathercock into wind.

Starting:
Check that the air pressure is sufficient, main air tap is open, and the brakes are on. You may have enough air in the pipe work to start the engine and start taxiing, but it won’t be long before brake failure occurs.

Pneumatic. When button is depressed 2 things happen.
1- Air solenoid opens. Air is directed to cylinders via a distributor. Manual override exists if battery power is low by means of a tag on the side of the solenoid. Solenoid is mounted on inside of the firewall just forward of the left pedal, and must be pushed down whilst at the same time depressing the starter button for the sparks.

2- Shower of sparks energised. High intensity sparks directed via L/H magneto, also retards ignition to TDC. Engine should run on sparks before switching on mags.
There is no gearing to damage on start as is the case with a starter motor. Starting problems are often the cause of pilots releasing the start button prematurely.

Cooling:
Shutters control the cylinder head temp. Always scan the CHT instrument, especially at high power settings and after take off. Oil temp is less critical. Oil cooler under STBD wing has a separate control.
An important check is to ensure that the shutters are open and locked before take off.

PUFA is the most important check when flying the Yak. (Finals check).

P: Prop fine (as late as possible).
U: Latched, 3 Greens, 3 soldiers.
F: Flaps down.
A: Altimeter set.

G limits +7 -5.
Max x-wind 12kt Stall 105kph. Max manoeuvring speed 360kph.