2) Diaphragm; 3) Jet Needle - Rotax 912 Series Maintenance Manual

00356
fig. 039
04973
fig. 040
Effectivity: 912 Series
AIRCRAFT ENGINES
MAINTENANCE MANUAL II

13.1.2.2) Diaphragm

See fig. 039.
The diaphragm is linked to the plunger (carburetor piston). Depend-
ing on the pressure prevailing the plunger is moved up or down. For
checking, remove the 2 countersunk screws Q M5x12, the cham-
ber top W and the spring E. Check tight fit of the cover R on
chamber top. Wash chamber top with cleaning agent and blow the
inside venting bore with compressed air, then check.
Remove plunger from the carburetor housing and remove 4 Allen
screws T M4x12. The diaphragm Y is fixed by the retaining ring U
to the carburetor piston I. The position of the carburetor piston is
controlled via the diaphragm. On the diaphragm Y there are 2
positioning noses. The nose O fits exactly in the recess in the
plunger, nose P must engage in the recess in the carburetor
housing.
Check diaphragm for cracks or brittleness, replace if necessary.

13.1.2.3) Jet needle

See fig. 040.
The jet needle controls the fuel consumption at part load. It may be
regulated by choosing position of jet needle between 1 and 4.
Standard the needle is set to position 2. Modifications are allowed
only after consultation with the engine manufacturer.
Remove fixation screw { and check jet needle } with circlip q and
i
O-ring for wear.
NOTE:
Pay special attention to the grooves and the taper of the needle. At
visible wear the jet needle must be exchanged and refitted in the
same position.
NOTE:
Visually check outside of plunger I and the two inside compensa-
tion bores.
i
O-ring is only used in 912 ULS/S.
The jet needle fitted must move freely.
page 37
Initial issue, Jan. 01/2002