Hello Folk,
The following is a series of raw conversations regarding TCFG members' thoughts/experience with flying/owning the Model 680FL Aero Commander. These conversations are sourced from the TCFG Chatlist in the early 2000's and are strictly the opinions of members at the time.
While I am sure the experiences discussed are still as relevant in 2015, it should be noted that some key members featured have since passed out of Commander ownership.
Wing Commander Gordon will undoubtedly recall the times...
Enjoy!
Cheers
Russell
VH-CAU
560E s/n 726
680FL
You'll love the 680-FL. If you've never flown the long body models, you'll
find it more of a "big airplane" both in feel and abilities.
For the first time, you'll have some fuel management procedures; using the
main system before switching to the aux. tanks (one of the few Commander
models with fuel switching).
The main difference in owning/operating an IGSO-540 powered model is the
Simmonds fuel injector. In my opinion, this unit is every bit as complex and
central to the operation of your engine as the FCU on a turbine engine, and,
in my opinion (again) can only be overhauled and calibrated by Central
Cylinder in Omaha, Nebraska.
If there is an Achilles heel to this model, it is the Simmonds. It will give
you fits when you get into hot weather -- you'll have to do the mixture dance
to keep the engine running during roll-out and taxi.
Also, nearly all these Commanders are fitted with Bendix fuel flow meters
that are run by transducers. The fuel flow gauge and the transducers MUST
be calibrated together; the gauge as an internal ac inverter and you can't
just swap transducers or gauges and have the system work. Also, if a shop
does the calibration of this system, it's done on a test bench using jet fuel
with a correction factor for avgas. Make sure they know this is an avgas
gauge or you'll get wacked-out readings.
As you can tell, this minutia is brought to you courtesy of my having nursed
along more than one FL and FLP models.
Figure 45 gph on fuel flow, 65% power, which I vaguely remeber as being 30"
and 2600 RPM. Depending on your cruise altitude preferences, flight plan at
185 kts in the 10,000 DENALT range, getting much faster in the mid teens, if
you're willing to go with oxygen.
You can run this engine at 25 degrees lean of peak at 65% power (and below),
but in my talks with the guys at Suburban Airfreight who operated a fleet of
-FLs, they decided to run 120 degrees rich to make up for the lower lead
content of our modern avgas; this engine was designed in the late 40s, /
early 50s and assumed a higher lead content for valve guide lubrication.
Just about everthing else is pure (geared engine) Commander.
Oh! And if you do get one, don't be alarmed on your first night flight when
you look out and see blue flames coming out of the exhaust stacks. This is a
real fire breathing dragon!
