Engine Overhaul Manual
Jabiru Aircraft
Pty Ltd
Jabiru 2200 & 3300 Aircraft Engines
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ISSUE
1
2
3
4
5
6 7
Dated : 28/10/2014
Issued By: AS
Page: 129 of 201
L:\files\Manuals_For_Products\Engine_Manuals\Overhaul_Manual\JEM0001-7_Overhaul_Manual_DRAFT_(29_10_14).docx
Figure 159
– Universal Joint tool FU14B (FU16B for ½” Socket)
Repeat this process on all the remaining through-bolts and studs.
Rotate the crank inside the crankcase. Assess the force required to turn crank: excess friction indicates
that bearings have tightened up and minimum clearances have not been maintained. This may indicate
an error in measurements or
– in the case of a top-end overhaul – fretting damage to the cases.
Contact Jabiru Aircraft or our local representative for guidance. Assessing friction is an exercise in
judgement and overhaulers must develop a feel for this aspect. The engine being worked on may be
compared with another engine where practical.
Issue 1 of Service Bulletin JSB 031 noted that in some special cases where 12-point nuts are fitted to
older through-bolts the nut may overhang the thread of the bolts. This was due to the extra length the
12-point nuts. While this was acceptable in some cases for engines subject to the Service Bulletin
Issue 1 re-work it is
NOT ACCEPTABLE
during a normal engine overhaul. New design through-bolts
must be used which are long enough to accommodate the 12-point nuts.
WARNING
DO NOT EXCEED SPECIFIED TORQUE
– through-bolt damage will result.
ALL BOLT TORQUE SETTINGS IN THIS MANUAL ARE “DRY” UNLESS STATED OTHERWISE
Correct tightening procedures must be used. See Section 3.8.3.
Fitting cylinders & through-bolts is a critical operation & must only be attempted by trained
technicians.
Excess sealant can now be wiped off the cylinder bases and the crankcase join
– this is most easily
done once the sealants have dried.
7.8.1.1
Additional Information
– Through-Bolt Tension
Technicians reading this must understand t
he difference between “bolt tension” and “nut torque”.
Torque is the setting on the torque wrench & defines how much rotational force it takes to turn the nut.
Bolt tension is the actual tensile load in the bolt
– the force holding the parts together.
Tuning a guitar is a good illustration of the difference between bolt tension and nut torque
– for a given
torque on the guitar string adjustor the tone of the string might be too high or too low
– in that case the
musician can set the string tension directly by turning the adjuster until the string tone is right. For a
through-bolt we cannot measure the tension directly and we are forced to make assumptions of the
relationship between nut torque and bolt tension
– in effect we are trying to set the guitar string tone
indirectly by assuming that a given torque on the string adjuster will give a certain string tone.
Testing has shown that assembling these parts dry gives good, repeatable results for bolt tension.
Altering these parameters has unpredictable effects and is not recommended.
7.8.2 Option
– Fitting Oil Pump
It is possible to fit the oil pump now rather than later. This allows the overhauler to turn the cam by
hand as the oil pump housing is being tightened to check for binding between the oil pump gears.
Full fitting details are given in Section 7.8.17.
