Helllo All,
Piston driven Aircraft engines are designed with a dual
ignition system (Twin Magnitios, and two spark plugs per cylinder). The
ignition switch has positions that allow each of the magnitios and spark plug
banks to be checked out individually, (commonly known as left and right).
Before takeoff the engine is run up to about 1500RPM and the ignition switch
is turned to the left and right positions and the RPM drop is noted, normally
it should not be more that 50 to 100 RPM, (if the engine should quite on one
of the mag checks the pilot would never take off). HOWEVER, the aircraft is
always run with the switch in the BOTH position, using both mags and both
plugs in each cylinder.
I don't know why Iridium plugs would be changed every
100 hours, I don't do that with normal plugs if they are in good shape.
Jim
Lempe, FAA Certified Flight Instructor and A&P licensed mechanic.
A penny
saved is a government oversite!
________________________________
From:
"corvallis@peoplepc.com" <corvallis@peoplepc.com>
To: spridgets@autox.team.net
Sent: Thu, April 15, 2010 9:22:31 AM
Subject: Re: [Spridgets] Iridium Plug
Question
Some of the plugs will 'glue' themselves in if you leave them the
full
100,000-miles.
Air planes used to use dual sparkplug systems to take off,
when the most
power was needed. Do they still do this today? ...bill in
oregon
======================================================
-----Original
Message-----
From: spridgets-bounces@autox.team.net
[mailto:spridgets-bounces@autox.team.net] On Behalf Of CosmicMag1380
Sent:
Thursday, April 15, 2010 9:46 AM
To: Larry Daniels
Cc: Spridgets
Subject: Re:
[Spridgets] Iridium Plug Question
On Thu, Apr 15, 2010 at 5:26 AM, Larry
Daniels <ladaniels@sbcglobal.net>
wrote:
What do y'all think of Iridium spark
plugs? My brother asked me about
them for his airplane.
He has a flat six
motor with a second, redundant ignition system. So,
12 plugs at $7.40 ea. and
he changes them every 100 hours. It gets
costly. Are iridium plugs worth the
extra cash?
A couple of thoughts come to mind... My GM cars came with iridium
plugs and the service interval is "inspect at 100K, replace as
necessary". I
have never "had" to replace them but I did at 50K just
because I wanted to.
That being said, iridium plugs are reliable. A
good thing for an airplane.
Because your brother's life depends on the
engine running well. the price of
the plugs should not be a factor!
If I am correct, a redundant ignition
system on an airplane engine
only fires one or the other system (6 at a time
not all 12 plugs
firing) when the engine is running. If so, suggest to him to
replace
the primary set with the iridium plugs and keep the standard plugs in
reserve as he always has...
--
Kent
1960 Bugeye
1967 Sprite - following in
the 73's footsteps to the boneyard...
1969 Midget - just a shell of its former
self
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