BRP-Rotax
MAINTENANCE MANUAL LINE
Part number Description
n.a
Orifice jet*, of 1 mm (0.04 in) inner diameter and 3 mm (0.12 in)
length. * or equivalent e.g. orifice diameter 0.040 in., long 0.0250
in., 60° degree approach angle according to AC43.13, latest
issue.
n.a
Adapter to spark plug thread.
n.a
Connect line.
Instruction Testing is carried out using the differential pressure test procedure.
Step
Procedure
1
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).
2
Starting with cylinder head 1 move piston to TDC position.
3 Remove the upper spark plugs. Prevent dirt or other foreign particles from
penetrating the engine (A).
4
Screw adaptor (1) into the spark plug thread and connect up the two pres-
sure gauges (2) with the orifice jet (3) between them (B).
5
Now put constant pressure, between 5.5-6 bar (80–87 psi) on the line and
take readings at pressure gauge (C)..
6 Repeat this procedure on all 4 cylinder heads.
Value The maximum permissible pressure drop is 25 %, e.g. from 6 to 4.5 bar (87 psi to 65 psi)
(D).
If the pressure loss is less than 25% then the valve seats and piston rings are working
properly. The spark plug has to be installed according to Chapter 12–20–00 section Instal-
lation of spark plugs.
If the value is over 25% inspection, repair or overhaul must be carried out in accordance
with the BRP-Rotax instructions for continued airworthiness.
• Detailed inspection of affected engine components.
COMPRESSION CHECK FOR FAULT-TRACING
General note Official and accepted measurement method is the differential pressure check, it is possible
to check the engine with a compression check method when differential pressure check
reading is unclear. Mainly - always perform the differential pressure check. In the course
of fault-tracing a compression check can also be performed.
A compression tester is required to check compression. The compression should be be-
tween 9 and 12 bar (130 psi and 174 psi).
Instruction Compression check for fault-tracing.
12–20–00
Page 8
January 01 2020
Effectivity: 912 Series
Rev. 0
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