Engine Overhaul Manual
Jabiru Aircraft
Pty Ltd
Jabiru 2200 & 3300 Aircraft Engines
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ISSUE
1
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6 7
Dated : 28/10/2014
Issued By: AS
Page: 36 of 201
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3.8.2 Torque / Tension Wrench
Figure 39
– Torque Wrench & Crowsfoot Adaptor Setting 1
Figure 40
– Torque Wrench & Crowsfoot Adaptor Setting 2
A good torque wrench is an essential tool for maintaining and overhauling Jabiru Engines. It’s
important to realise however that even the best wrench needs calibrating occasionally. This can be
done using a dead weight on the end of a known arm or
– preferably – sending the wrench away to be
calibrated. Note that Civil Aviation Authorities generally require that the tool be calibrated in a way
which is traceable to a NATA-standard laboratory.
A “Crowsfoot” extension as shown in Figure 31 is also necessary – it allows high torque settings to be
used on small nuts without damaging them. The crankcase through bolt nuts used on Jabiru engines
are a good example of an application suitable for a crowsfoot extension. However, when using the
extension as shown in Figure 39 the extra length will throw off the torque setting of the wrench. This
must be corrected using the following formula:
𝐴𝑑𝑗𝑢𝑠𝑡𝑒𝑑 𝑇𝑜𝑟𝑞𝑢𝑒 𝑆𝑒𝑡𝑡𝑖𝑛𝑔 = 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑇𝑜𝑟𝑞𝑢𝑒 𝑆𝑒𝑡𝑡𝑖𝑛𝑔 × (
𝐿1
𝐿1+𝐿2
)
.
L1 is the distance from the middle of the grip of the handle to the centre of the wrench drive lug
L2 is the distance
in the direction of the handle
from the centre of the wrench drive lug to the centre of
the nut socket of the adaptor.
For example: a nut needs to be tensioned to 30lb.ft. The torque wrench is 12” long and the crowsfoot
extension is 2” long. The extension is oriented as shown in Figure 39. This means that the torque
wrench must be set to:
𝐴𝑑𝑗𝑢𝑠𝑡𝑒𝑑 𝑇𝑜𝑟𝑞𝑢𝑒 𝑆𝑒𝑡𝑡𝑖𝑛𝑔 = 30 × (
12
12 + 2
)
𝐴𝑑𝑗𝑢𝑠𝑡𝑒𝑑 𝑇𝑜𝑟𝑞𝑢𝑒 𝑆𝑒𝑡𝑡𝑖𝑛𝑔 = 30 × 0.857 = 25.7𝑙𝑏. 𝑓𝑡
If the extension is oriented at 90° to the wrench as shown in Figure 40 then no correction is needed
because L2 is zero.
L1
L1
L2 = 0
L2
