John Baker wrote:- snip
>
>Now about my previous message on engine priming before the first
>start. There were no comments, probably because I forgot to mention
>that the 'Oil' system needs proper priming. The procedure is not in
>the Rotax manual.
>
>Regards,
>John Baker.
There is a Safety Bulletin - number 150197 - put out by Cyclone Hovercraft
(the British distributor for Rotax) which we sent on to known Rotax owners.
In case you did not receive it I am reproducing it here. (Note that Rotax
use the word "venting" whereas we would prefer "priming"):-
"Rotax 912 and 914 engines - Venting of Lubrication System
TO BE CARRIED OUT BEFORE FIRST OPERATION. AFTER EACH OIL CHANGE. AFTER
ANY ENGINE RE-INSTALLATION AND AFTER ANY DISMANTLING OR MODIFICATION OF THE
LUBRICATION SYSTEM.
The Rotax 912 and 914 engines use a dry sump lubrication system. It is
essential that the feed line from the oil tank to the oil pump is filled
with oil and the pump is primed with oil before the engine is first
started, and after each oil change. This procedure for "venting of the
suction line" is explained in the engine operators manual, and if not
followed can result in severe engine damage when the engine is started.
Some installations using long hoses, non standard or raised oil coolers,
may require a more comprehensive venting procedure to ensure that the
lubrication system is adequately primed. Employing one of the two
following procedures should ensure that venting is correctly carried out.
METHOD 1
1a) Check that oil tank connections are the correct way round and secure,
and that the oil cooler (if fitted) is in the suction line between the oil
tank and oil pump inlet. Check that the oil tank is filled with oil almost
to its upper level.
1b) Block the return line from the bottom of the engine to the oil tank,
either by carefully clamping the rubber hose, or by disconnecting it at the
tank, and plugging the tank connection.
1c) Using a compressed air line, pressurise the oil tank through its vent
connection (on the neck of the tank). The air line pressure should be not
more than 3 bar (45 psi) and not less that 2 bar (30 psi). Maintain the
pressure for at least 30 seconds for normal systems with short oil lines
and oil cooler below the oil tank. For systems with a longer suction line
(more than 1 metre) or with oil cooler above the oil tank, or with a
non-Rotax oil cooler, increase the time to 60 seconds.
1d) Although not essential, the venting will be helped is you get an
assistant to turn the propeller in the normal rotation direction whilst the
pressure is held on (make sure that the ignition is off, and for ease of
turning, remove one spark plug from each cylinder).
1e) Unblock return line, refit vent line to tank, refit spark plugs if
removed. Spin engine on electric starter with ignition off, and observe
oil pressure reading. Pressure should rise immediately, but if it does not
rise within 10 seconds, stop and re-vent the system. Continue cranking
until a stable pressure of at least 1.5 bar (22 psi) is reached.
METHOD 2
To be used if a compressed air line is not available:-
2a) Carry out steps 1a and 1b.
2b) Disconnect the suction line at the oil pump inlet connection.
Pressurise the oil tank using a bicycle pump or other low pressure source,
into the vent connection on the neck of the tank. Continue with the low
pressure until oil flows freely from the hose which you disconnect from the
oil pump. Quickly reconnect and clamp up the hose and remove the pressure.
Rotate the engine several times with the propeller as described in step 1d.
2c) Carry out step 1e.
After venting, ensure that all oil pipe connections are secure and oil tank
is still full at least to its mid level.
After all other normal pre-start precautions, engine can be started. IF
OIL PRESSURE DOES NOT RISE IMMEDIATELY (WITHIN 3 SECONDS OF START) REPEAT
PROCEDURE. Run engine for a few minutes at 2500 rpm, continually checking
oil lines and connections for leakage before flying the aircraft."
Regards,
Roger
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