The above picture shows the fuel system for my
IO-470L right engine just after complete overhaul. This fuel system had 1900 SFRM in 1999 on it
and was definitely tired from the slop in the shaft and wear in the throttle arm
(shown below). The rubber diaphragm in the flow divider was very stiff.
The above picture shows a fuel
line watch out as regards aged fuel line hardware. Casually checking these
fittings from time to time can pay big dividends in finding a problem while it
is still small.
Below is a photo of the servo internals (not
mine), that is mounted onto the throttle body.
These components work very hard to feed your
engine and if you are going to blast past any published TBO numbers, give them
the respect they deserve. If all the inside parts of your engine have been
friends for a long time and have come to like each other, then extending your
engine service with component overhauls such as this could be a good move for
you. Don't forget to do all new hoses!
Below is a picture of an IO-470L Romec fuel
pump that came off my left engin. Removed in May 2013 after 1400 hours TIS as a
result of a deep dive into the back end of the engine to repair a broken exhaust
support stud that sits in the bottom of the intake plenum in the base of the
throttle body .
Below is a picture of the fuel pump shear pin
that is designed to break if anything nefarious happens in the pump to save the
engine driven gears from damage. Of course you will be a glider at that point
but that is what a boost pump is for!
The left engine fuel pump below was overhauled
in 2013. Below is a picture of the overhauled pump
re-installed into the engine
This is where your mechanic would adjust the
high side fuel flow of the pump, using the updated Continental SID.
Below you will see the impetus for all the
left engine work in 2013 - the broken exhaust hangar stud at the base of the throttle body plenum.
The airbox and throttle body had to be removed to allow access for the stud
extraction. My mechanic Dave had this piece extracted in about 35 minutes! The
reinstallation, however, was another matter entirely!
space and lots of little connections and routings to consider were very tedious.
Anything to do with removing the airbox on a B55 Baron is going to
be quite a chore - so be prepared if you set out to tackle it.
After fitting the newly overhauled pump and
fresh hoses we were ready to fire it up and set the fuel pressures/flows. When I
think about it, all this work resulted because of a broken exhaust hangar stud.
Because of the age of the hoses and the time on the fuel pump, I'm actually
pleased that this issue surfaced which allowed for a good freshen up of critical
components at the back of a fine running 1400 SMOH engine.
This is the stamped nut that simply shredded
apart after 48 years and caused all this rebuild - a blessing in disguise,
because it caused much closer inspection of things that are difficult to inspect
properly. My takeaway is to never curse something that causes you to dig deeper
into things that are difficult to get at, you may find things that need
These are now replaced with much more robust
12 point self-locking AN fasteners (see one in above picture).
Below are some helpful links that will guide
you in doing this rather complicated and somewhat convoluted process.
The latest TCM Fuel flow procedure is
SID97-3F. This is
the guiding principle document for the engine fuel flow set up.
Here is a picture of an awesome set of Fuel
Flow Set Up gauges built up by
Pedron Aircraft Works in Denton, TX 940-453-5324.
And no, this would not be their first rodeo with these gauges. I saw them set up
a C414 new fuel pump in about 45 minutes with this set up on the wing!
Below is an image showing where
to "T" the gauge for your metered fuel flow.
Mike Busch's Savvy Aviator article on the Fuel
Flow Set Up is
A primer on continuous flow fuel injection
Read the Tennessee Aircraft Services Article on
the TCM SID Set Up
An article in Aviator Pros website (formerly
AMT Online) is
Probably the best resource for doing the set
up, in my humble opinion, is the Aviator Pros 5-Part video series. Part 5 is the
typical warning that makes the lawyers happy.
Below is a picture of an in-flight B55 pump
fitting failure that was successfully saved by employing the boost pump during a
missed approach! Thank goodness the spewing fuel did not catch fire on the hot
exhaust pipes below the fuel pump.
This fellow will no doubt be doing a fuel flow
setup in the near future.
Read the entire BeechTalk thread on this
So there you have it, some of the best
resources for setting up your Beechcraft TCM engine's fuel system. All in one
place for the CSOBeech visitor!