Alternate Air; Heating & Ventilation; Cold Weather Operations - Lancair IV Handbook

ALTERNATE AIR

Alternate air is provided automatically from
a spring loaded door in the air filter box. This door
should open if the air filter is blocked, providing ample
induction air.
HEATING & VENTILATION
Cooling air. Your Lancair is equipped with a NACA
air intake scoop in the vertical stabilizer for cabin venti-
lation, simple eyeball vents are installed in the overhead
to control air flow through the cabin.
Heating. Cabin heat is provided by means of an intake
system using engine compartment air warmed by pass-
ing over/thru a heat exchanger where exhaust gases are
used as the heat source. This air-to-air heat exchanger
provides air which is either dumped overboard or into
the cabin. Due to the potential of a leak from the higher
pressure exhaust gases containing Carbon Monoxide
(CO) into the fresh air side of this heat exchanger, it is
necessary to inspect the structural integrity of the unit
periodically. Initial operation of the system for the win-
ter months should always include such an inspection.
A monitoring system should be considered for the cabin
air. These simple devices change color upon exposure
to CO. They are quite cheap and excellent insurance
against the effects of this odorless and deadly gas.

COLD WEATHER OPERATIONS

Preflight Inspections
Winter preflight inspections of the aircraft need to ac-
count for the accumulation of frost or ice on the exterior
of the aircraft. The Lancairs with their extraordinary
smoothness can suffer markedly from the effects of
such accumulations as they utilize laminar flow airfoils.
These effects result in significantly higher drag of the
airframe and wings as well as reduced lift and increased
weight of the accumulation. Once these deposits have
been removed (preferably by warming in a hangar) the
preflight should include special emphasis on freedom of
control movements.
ENGINE CONSIDERATIONS
Very cold temperatures require extra consider-
ations for engine starting and operations. The engine
oil will be significantly more viscous causing higher oil
pressures, slower indication upon starting, increased en-
gine wear, tappet noise, poor battery performance, etc.
During extreme cold weather it may be neces-
sary to preheat the engine, oil and battery before start-
ing. Since the engines are cooled by pressurized air
created in flight, ground operations must be minimized
at high ambient temperatures and conducted with care
at all times.
Engine operations should be into the wind
when possible. The mixture should be RICH. Avoid
prolonged idling and do not exceed 2200 RPM on the
ground. Warm up should be at 1000-1200 RPM. The
engine is warm enough for take-off when the oil tem-
perature has reached a minimum of 100 deg. F with a
turbocharged engine. Excessive oil pressure can cause
overboost and consequent engine damage.
CRUISE OPERATION
Cold weather operation may require an occa-
sional cycle of the propeller control. This could be
particularly true after long duration cruise just prior
to descent where lack of governor control could cause