EADS Socata TB 20 Pilot's Information Manual page 258

SECTION 7
DESCRIPTION
ENGINE
SOCATA
MODEL TB 20
The TB 20 airplane is powered by a six-cylinder, horizontally opposed, direct
drive LYCOMING IO-540-C4-D5D (or IO-540-C4-B5D, if the starting
vibrator, optional equipment A86500M is installed) engine rated at 250 BHP
at 2575 RPM, It is provided with a starter, a 24-volt / 70-amp alternator, an
all-weather shielded ignition harness, a dual magneto, a vacuum pump
drive, a fuel pump and a manifold air filter.
The engine cowl is a laminate cantilever structure, fixed on the firewall and
made of two elements, The upper cowl is fitted with an inspection door
provided to check oil level; it can also be fitted with an access door to the
propeller deicing fluid tank. The lower cowl is fitted with incorporated air
intakes and may be fitted with an inspection door to easy quick drain. Both
cowls are completely removable without requiring removal of the propeller.
The engine mount is made of steel tube, rigidly attached on firewall. Engine
attachment is provided by dynafocal mounting brackets to attenuate
vibrations.
Engine and accessories cooling is provided by a downwards airflow. Air
penetrates through holes located on each side of the propeller cone, is
guided around the engine by airproof deflectors, then conducted to two air
outlets located on the lower cowl.
Engine inlet air penetrates through an air intake located at the front of the
lower cowl and goes directly through a filter, before being admitted in the air
duct under the injection unit.
The air duct can also be air-feeded by an alternative air supply source
"Alternate air" which is mechanically actuated by pushing the control lever
located on the R.H. side under the L.H. instrument panel. From SIN 948
push central knob before pulling control lever rearward or pushing it back
I
forward. This air source provides the injection unit with heated air if icing
conditions are unintentionally encountered.
7.30 June 30, 1988
Revision 11