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Engine Overhaul Manual
Jabiru Aircraft
Pty Ltd
Jabiru 2200 & 3300 Aircraft Engines
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ISSUE
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Dated : 28/10/2014
Issued By: AS
Page: 76 of 201
L:\files\Manuals_For_Products\Engine_Manuals\Overhaul_Manual\JEM0001-7_Overhaul_Manual_DRAFT_(29_10_14).docx
5.11.3.1 Inspection and repair
Figure 87
– Valve Damage
Figure 87 shows various types of valve damage. From left to right they are:
1. Valve stem necking caused by the exhaust valve operating for some time with poor sealing. The
exhaust gas leaking past the seat overheated the valve stem with the result as shown.
2. A valve showing burnt residue on the valve seal face and rust on the valve stem from incorrect long
term storage.
3. A non-sealing valve.
4. A badly burnt valve
– this has run for many hours, allowing the exhaust gas to burn away the
sealing face.
5. A failed valve. This can occur due to the valve sticking and being struck by the piston (intake valve)
or by the valve being overheated and cracking (exhaust valve).
WARNING
Damage caused by valve sealing is a progressive process. If caught early the fix will be simple and
cheap
– if allowed to develop the repairs can be major and expensive.
As a part of the daily inspection the engine must be turned over (or “pulled through”) by hand while it is
cold. This allows the operator to feel the compression of each cylinder in turn and assess if any
cylinder is leaking. Tests like this will normally catch a poorly sealing valve before damage becomes
critical.