Piper Aircraft Corporation Malibu Mirage PA-46-350P, Airplane Maintenance Manual

Page: 877 / 1956

PAGE 1
Feb 28/07 4H3
33-40-00
PIPER AIRCRAFT, INC.
PA-46-350P, MALIBU MIRAGE
MAINTENANCE MANUAL
EXTERIOR
External lighting consists of anti-collision strobes, landing, taxi-pulse, position, and wing inspection
lights. All lighting is 24 Vdc, except for the anti-collision strobe lighting, which is powered though a power
supply, which converts 24 Vdc, received from the aircraft bus power, to a very high voltage required to
flash the lights. Refer to 91-33-40 for electrical schematic details of these lighting systems.
1. Strobe Lights
A. Description (See Figure 1 and 91-33-40.)
Each wing tip strobe tube is powered by its individual power supply. Both power supplies receive
power from the main bus through the 5 amp STROBE LIGHTS circuit breaker, and are controlled by
the strobe light switch. If both strobe lights exhibit a fault, first verify that the STROBE LIGHTS
circuit breaker has not opened (reset, if necessary), and then check integrity of the strobe light
switch (replace if required). If either strobe is operating correctly, the strobe switch is considered
good. Check wiring from the strobe light switch to each strobe power supply to verify system wiring
integrity.
The strobe light assembly functions as a capacitor high voltage discharge system. An audible tone
of 1 to 1.5 K Hertz is emitted during the charge cycle of the strobe power supply in a normally
functioning unit. However, the audible tone does not necessarily mean the power supply firing circuit
is good. A voltage of approximately 450 volts is developed on the capacitor, after which the audible
tone ceases. The capacitor is paralleled across the Xenon flash tube which holds off the voltage
until the tube is triggered by a separate pulse generated by a solid state timing circuit.
After the trigger pulse causes ionization of the Xenon gas in the envelope, an intense light is given
off for a brief moment as the capacitor discharges. Following discharge across the tube, the
oscillator again chops up the dc aircraft current into alternating current, and again develops a higher
voltage through transformer action. After full voltage is again impressed on the capacitor the cycle
repeats itself occurring at about 50 flashes per minute.
Since each wing tip strobe is powered by its own power supply, and if both power supplies are
emitting audible tones, simply switch power supplies from each wing tip. If the trouble is one of the
power supplies, replace it. If the faulty strobe still malfunctions replace that strobe tube. Refer to
Replacement of Position / Strobe Lamps and to Replacement of Strobe Power Supplies.
B. General Service Information
(1) Never reverse power supply input connections for even an instant. Reverse polarity will
permanently damage the circuitry. Even though damage may not be immediately apparent, the
power supply will fail in use.
(2) Wait five minutes for high voltage bleed down to occur, before handling a strobe power supply
to avoid electrical shock.
(3) Never allow connection between pins 1 and 2 of the flash tube connector, since this will
discharge the capacitor and destroy the trigger circuit in the power supply.
NOTE: All of the following conditions, except item (6), are considered to require replacement.
(4) A Xenon flash tube can be photo-sensitive. Some may flash normally when exposed to light,
but may become difficult to fire in darkness.
(5) Xenon flash tubes become more difficult to fire with age, or when exposed to very high
temperatures.
(6) A tube with most of the service life left in it, should fire on a reduced voltage of 22 volts.
(7) A tube with little service life left in it, will fire with an engine running, but refuse to fire on battery
voltage.