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DESCRIPTION AND OPERATION.
The airplane is equipped with retractable, tricycle air-oil strut type landing gear which are hydraulically operated by an electrically powered reversible pump.
Gear positions are indicated by three green lights located above or below the selector lever for gear down and locked, and a red light located at the top of the instrument panel (pilot’s side) for gear unsafe positions. There is no light to indicate that the gear has fully retracted other than all lights are out. As the landing gear swings to the down and locked position and each downlock hook moves into its locked position, a switch at each hook actuates to the switch normally closed (NC) circuit to indicate by a green light that the individual gear is safely down and locked. The activation of all three downlock switches will also shut the hydraulic pump off. As the instrument lights are turned on, the green lights will dim. When the gear begins to retract and the downlock hooks disengage, the down limit switches actuate to the NC circuit and in series with the NC circuit of the up limit switch allows the gear unsafe light to come on. The gear unsafe light will remain on until the gear is up and all up limit switches are actuated to their normally open (NO) circuit.
Each landing gear is retracted and extended by a single hydraulic cylinder attached to the drag link assembly of the nose gear and the side brace link assembly of the main gears. Gear doors partially enclose the gear and operate through mechanical linkage with each gear. The gears are held in their up position by hydraulic pressure alone within the cylinders. There are no uplocks and loss of hydraulic pressure will allow the gears to drop. It is preferred that the gears be extended and retracted with the use of the gear selector handle; however in the event of hydraulic loss or electrical failure, they can be lowered by pulling on the emergency extension knob which will open a free fall valve between the two hydraulic lines to the nose gear cylinder thus allowing hydraulic pressure to neutralize between each side of the cylinder pistons and allowing the gear to free fall to the downlocked position. To assist nose gear extension under these conditions, two springs, one inside the other, are mounted on arms above the gear links. The main gears require no assist springs. Once the gears are down and the downlock hooks engage, a spring maintains each hook in the locked position until hydraulic pressure again releases it. A further description of the hydraulic system may be found in Chapter 29.
The nose gear is steerable through a 60 degree arc by the use of the rudder pedals. As the gear retracts, however, the steering linkage becomes separated from the gear so that rudder pedal action with the gear retracted is not impeded by the nose gear operation. A shimmy dampener is also incorporated in the nose wheel steering mechanism. A single bungee spring unit is incorporated between the rudder pedals and nose gear.
The two main wheels are equipped with self-adjusting single disc hydraulic brake assemblies. Hydraulic fluid for the brake cylinders is supplied by a reservoir installed at fuselage station 49.50.
TROUBLESHOOTING.
Mechanical and electrical switch troubles peculiar to the landing gear system are listed in Chart 3201. When troubleshooting, first eliminate hydraulic malfunctions, then proceed to switch malfunctions and last to the mechanical operation of the gear itself. Always place the airplane on jacks before attempting any troubleshooting of the gear.
32-00-00 Page 32-7 Revised: December 6, 2002
THE NEW PIPER AIRCRAFT, INC.
PA-44-180
AIRPLANE MAINTENANCE MANUAL
CHART 3201. TROUBLESHOOTING (LANDING GEAR) (Sheet 1 of 5)
Trouble Cause Remedy
Red gear unsafe light out Indicator lamp burned out. Replace lamp. while gear is in transit.
Indicator light ground in-Check ground circuit. complete.
Indicator light circuit wire Check wiring. broken.
Indicator light circuit Reset circuit breaker and breaker open. determine cause for open circuit breaker.
Red gear unsafe light on One or more up limit Isolate and replace switch. though gear has retracted. switches failed.
Nose gear up limit switch Check gear up adjustment out of adjustment. and readjust up limit switch.
Main gear not retracting Check gear up adjustment.
far enough to actuate
switch.
Red gear unsafe light on One or more down limit Isolate and replace switch.
though gear is down and switches failed.
locked.
Nose gear down limit Readjust down limit
switch out of adjustment. switch.
Main gear down limit Readjust down limit
switch out of adjustment. switch.
— Note —
The out of adjustment or failed switch may be determined by noting which down light is not lit.
Red gear unsafe light Light circuit wire loose. Check wiring.
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