MOONEY
M20TN - MODEL TYPE-S
SECTION VII
AIRPLANE AND SYSTEM DESCRIPTION
7 -- 24
AIRPLANE FLIGHT MANUAL
ORIGINAL ISSUE -- 04-02-2008
ENGINE STARTING SYSTEM
Engine starting is provided by a 24 volt starter. The starter engages the drive shaft with a spring
clutch. Avoid manually turning the propeller backwards as it may damage the clutch. A starter
engaged warning light (START POWER) is incorporated in the annunciator panel.
Ignition is provided by an impulse coupled magneto. The engine firing order is 1--6--3--2--5--4.
The ignition harnesses are connected to the magnetos so the right magneto fires the upper plugs
on the right side and lower plugs on the left. The left magneto fires the upper plugs on the left and
the lower plugs on the right.
ACCESSORIES
EXHAUST GAS TEMPERATURE PROBE
The exhaust gas temperature (EGT) probe measures exhaust gas temperature as it exits the
exhaust valves into the exhaust manifold. The EGT probe varies electrical current (milliamps),
based on exhaust gas temperature, and displays this data on the Garmin GDU 10(XX) Multi--
Function Display.
TURBINE INLET TEMPERATURE (TIT)
The TIT (Turbine Inlet Temperature) indicator displays the temperature at the turbine inlet in de-
grees Fahrenheit. A green bar indicates “Normal” operating range of 1000 to 1750 degrees
Fahrenheit. A red “Warning” bar indicates 1750 degrees Fahrenheit. The TIT gauge is used as
the primary source to lean fuel mixture.
PROPELLER
HARTZELL THREE BLADE PHC--J3YF--1RF/F7498 or PHC--J3YF--1RF/F7498(B)
The (B) denotes a booted prop (for TKS)
The propeller is a three--blade, 76 inch (193 cm.) diameter, constant speed unit that features
aluminum blades in an aluminum hub. The spinner is fabricated from aluminum alloy. A more
detailed description is found in Hartzell Manual 115N (Propeller Owner’s Manual).
Centrifugal twisting moment acting on the blades moves the blades to a low blade angle (low
pitch) to increase RPM. Since the centrifugal twisting moment is only present when the propeller
is rotating, a mechanical spring is installed within the propeller to assist movement of the blades
to a lower pitch position as RPM decays, and to reduce the propeller pitch to the low pitch stop
when the propeller is static. With the blades at low pitch, the load on the starter when starting the
engine is reduced significantly.
Oil pressure opposes the spring and centrifugal twisting moment to move the blades to a high
blade angle (high pitch), reducing engine RPM. If oil pressure is lost at any time, the propeller will
move to low pitch. This occurs because the spring and blade centrifugal twisting moment are no
longer opposed by hydraulic oil pressure. The propeller will then reduce blade pitch to the low
pitch stop.
In cruise, always use the power setting charts provided in SECTION V.
Revision B -- 11-21-2014
