Terry Clark had similar problems.
He was advised by Skydrive that it was likely to be a broken wire just
inside the box, and tried to find the fault. He accepted that this could
cause the unit to fail completely. No faulty connection could be found and
the unit stopped working completely. The replacement cost over 400
He subsequently found that the other box still had an intermittent fault.
With further use the fault has become repeatable. When COLD the unit will
shut down, when the mag is grounded, but when HOT grounding the mag fails to
shut down the unit.
I and others have had considerable problems trying to find the fault.
During initial engine tests the engine would not shut down on some
occasions. The electrics were supplied and fitted by R.D. Aviation. They
supplied, no less than 3 ignition switches thinking that it could be the
problem. All the wiring was thoroughly checked. It was also impossible to
identify which magneto was at fault as it varied between failures, giving
support to the theory that it was the wiring. Under cowl temperatures have
been checked to ensure that they do not exceed the specified limits.
While, originally, the fault was intermittent it has now become repeatable
with the original module failing to shut down when HOT.
The conclusion is that both modules have been faulty since new (they are
consecutive serial numbers) with the switching transistor junctions failing
at higher temperatures. These modules, at their exceptionally high cost,
are expected to last the lifetime of the engine.
The story above is for information. I am sorry but it does not help solve
the problem. I am convinced these modules, are far less reliable than they
should be. They cost pennies to make and are sold at an insane prices as
high reliability aircraft parts. When they fail we are invariably told it
is the owners fault (too hot, wires allowed to vibrate etc).
Ian Rickard G-IANI XS Trigear, 200 hours
Europa Club Mods Rep (Trigear)
e-mail mods@europaclub.org.uk
or direct g-iani@ntlworld.com
|