Rotax 912 Series Maintenance Manual page 119

5.1) Compression check for fault-tracing
In the course of fault-tracing a compression check can also be per-
General note
formed.
A compression tester is required to check compression. The compres-
sion should be between 9 and 12 bar (130 and 174 psi).
Instruction Compression check for fault-tracing.
Step
1
2
3
4
Measurement Individual readings for the cylinder must not differ by more than 2 bar
(29 psi).
If the value is below 6 bar (87 psi), inspection, repair or overhaul must be
carried out in accordance with the BRP-Powertrain instructions for contin-
ued airworthiness.
- Detailed inspection of affected engine components.
Graphic Compression check for fault-tracing
Fig. 6
Effectivity: 912 Series
Edition 3 / Rev. 1
BRP-Powertrain
MAINTENANCE MANUAL
Operate the engine until the temperatures have stabilized for a period of 5 min
(engine oil temperature between 50 to 70 °C (122 - 160 °F).
Unscrew and remove top spark plugs.
Press compression tester (1) over the spark plug hole and use the starter to
turn the engine over with open throttle until maximum pressure is reached.
Successively take readings on all four cylinders and compare results.
Part
1 Compression tester
Procedure
A
B
1
Function
12-20-00
08651
page 15
January 01/2013