"CASA is responding to a high, and increasing, rate of engine
failures among aircraft that are powered by engines manufactured by,
or under licence from, Jabiru Aircraft Pty Ltd (Jabiru). Such
aircraft are referred to in this document as 'Jabiru powered
aircraft'.
The issues appear to be the result of several failure modes, which
require separate investigation.
CASA has formed the view that its functions under the /Civil Aviation
Act 1988/ require it to mitigate certain risks to passengers, trainee
pilots and persons on the ground.
Accordingly, while CASA works with Jabiru to identify the causes of
these engine failures and to implement appropriate corrective
actions, CASA proposes a set of operating limitations on Jabiru
powered aircraft."
https://www.casa.gov.au/standard-page/consultation-draft-%E2%80%93-cd1425ss-0?WCMS%3ASTANDARD%3A%3Apc=PC_102279
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Time for an all aluminium one rotor In Australia.
The Jabriu was based on the VW crank, rods and pistons I suspect.
There is not enough cylinder to cylinder spacing on a VW to get
adequate cooling fins on the heads.
I also suspect the through bolts are resonating.
The Australian aviation magazines are filled with Jabriu products
for sale.
Paul Lamar
Hi Paul, hope Robin is feeling better. The VW head might have been
ok at 25 to 36 hp with forced air cooling but it has more problems
than bore spacing; because of port layout and keeping engine width
and valve length down there is very little fining and airflow area
over the top of the combustion chamber so the heads run hot and the
CR must be kept low and the engines run rich so they don't blow up
so the efficiency is poor. For a late 1930's engine it is ok but
today?
Murry Rozansky
Paul, please keep us posted on Robin's progress.
I don't think there is anything in common between Jabiru and VW. There
are mostly GM/Holden and Honda parts in the Jabiru, and the cylinders
are individual units. Jabiru claims their crank and cylinders are
machined in-house from 7" diameter 4140 billet. Most of the problems
have been with the 6-cylinder versions, the 4's have not had the same
issues. There is a 3-way tussle as I understand it between CAM it that
makes the engine, Jabiru that integrates it and Rotec that makes
aftermarket water cooled heads. Most of the problems I have seen are due
to improper installation integration and poor understanding of cooling
airflow. The through bolt issue is separate.
I agree there is a need for a light-alloy single rotor, in Australia and
elsewhere. With properly engineered gearbox, turbo, EFI and ignition it
could be a serious challenger. You have to sell it to the market that
pays for these (military drones.)
David Josephson
Robin is fine and she is getting a lot test so the doctors can figure
out what
happened hopefully.
The bore and stroke are very much like a VW.
Here is a forged VW crank with the same stroke as a CAMit!
More evidence the cylinders are too close together.
The centre cylinders have worse cooling prospects.
The CAMIT engine has entirely different cylinder heads with more
and larger fins. However with roughly the same cylinder spacing.
These engines start having problems with as little as 300 hours.
The power ratings are optimistic.
A successful air cooled aircraft engine is one half HP per cubic inch
for a very good cooling reason. In air cooled aircraft piston engines
there is no replacement for displacement :-)
The CAMit 4 is 134 ci and 81 HP at 3300 RPM rating. If you run a prop at
3300 RPM it is very inefficient. It is probably a fair engine at 65 HP
and 2800 RPM or so. The weight is 140 pounds.
Paul Lamar
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