|
|
Posted for "Tracy Crook" <lors01@msn.com>:
Dr. Michael Seals and myself would recommend that if there is any
concern about enlarging the trailing spark plug hole, we suggest to have
a switch that if primary (leading) ignition were to fail you can turn on
the trailing ignition.
Without enlarging the trailing hole there will likely not be enough
power to land the vehicle safely. We are troubled with the idea of
someone using dual ignition on the leading plugs only. If a spark plug
fouls then there is no TRUE dual ignition.
Can't comment on the operating characteristics of the enlarged trailing
sparkplug hole (I haven't flown this configuration) but the last statement
is totally bogus.
At around 500 hours, I had an in-flight failure of the leading spark caused
by the opening of the leading coil ballast resistor. The only evidence that
this occured was an increase in EGT of about 30 degrees F. I noted this
during an instrument scan but saw no significant loss of power. I continued
my flight to the scheduled destination about 85 miles away from the point
where the failure occured.
The leading spark failure was not discovered until the following day during
preflight checks when I disable both coils (one at a time). The engine
stopped when the trailing coil module was disabled.
I do use a modified trailing coil ignition timing (same as the leading
timing instead of 15 degrees retarded) which prevents a large loss of power.
Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com
|
|