Pilot's Operating Handbook for the Piper PA-25 Pawnee

Dope sealer is applied to the frame at points where fabric at- taches. The wing framework consists of riveted aluminum ribs mounted on extruded aluminum spars with tubular drag and compression struts and high strength stainless steel drag wires. Aluminum sheet is used to form the leading edge and the false spars. An ash wing-tip bow provides a light tough member which can withstand considerable wing tip shock with- out failing. The wings are attached to the fuselage at fittings on the lower longerons, and by means of compression struts which bolt to upper fuselage members and wing spar fittings. The rear struts may be adjusted by means of a threaded attachment fitting at the outboard end of the struts. This adjustment is used to set the rigging of the wings, LANDING GEAR The Pawnee "C" landing gear employs two air-oil shock absorbers designed for minimum maintenance operation. (Con- sult Section IV for shock absorber maintenance.) The only maintenance normally required is lubrication of the hinge bolts and each end of the shock struts according to the lubrication chart. The steel hinge bolt bushings should be in- spected and replaced if worn. 5 671030 PAWNEE "C" SECTION II The Scott 8" steerable, full-swivel tall wheel is standard equipment on the Pawnee. This unit is combined with steel leaf springs which are easily replaced if needed. The main wheel assemblies are Cleveland Products 40-84A with Cleveland 30-41 Disc Brake Assemblies. The tires are 8:00 x 6 four ply rating. Tires should be inflated to 25 psi to prevent slippage and to produce even wear, EMPENNAGE The fin, rudder, stabilizers and elevator are all constructed of tubular steel with steel channel ribs. The control surface hinges have bronze bushing inserts and should be oiled accord- ing to lubrication chart. The elevators and the rudder are de- signed with an aerodynamic balance to increase stability and lighten control forces. Double stainless steel tie rods and fittings brace the stabilizers to the fin and fuselage. The tail brace wires should not be used for lifting or ground handling of the air- plane. CONTROL SYSTEM Conventional flight and engine controls are provided in the Pawnee. The flap lever has three positions, full up, half, or full down. The flaps are provided for an increased angle of descent only and should not be used for take-off or climb. The elevator trim control is located on the left side of the cockpit and consists of a two-spring system with an irrever- sible geared crank mechanism. This system normally requires very little maintenance except for inspection and lubrication according to lubrication chart. 671030 6 SECTION II PAWNEE "C" FUEL SYSTEM Located in the first fuselage bay aft of the firewall is a 38 gallon, non-corrosive, fiberglas reinforced, plastic fuel tank incorporating a polyurethane and nylon liner. The liner is a safety feature incorporated to prevent fuel spillage in the event of a severe impact. The fuel quantity gauge is a float-type direct indicating unit installed in the top of the tank within easy view of the cockpit. The fuel shut-off valve is controlled by a "T" handle on the right side of the cockpit, The fuel strainer, on the lower forward side of the fire- wall in the engine compartment, traps water or sediment that may collect in the system. Additional fuel screens are pro- vided at the tank outlet and in the carburetor. The quick-drain valve on the strainer should be checked daily for water or dirt. The fuel tank itself has an external vent line, and a non- vented fuel cap is used. The engine primer pump on the left hand side of the in- strument panel takes fuel from the top of the fuel strainer and pumps directly to the cylinders of the engine. The primer should be locked in at all times except when in use, to pre- vent malfunctioning of the engine. An idle cut-off is incorporated in the mixture control. The engine should be stopped with the idle cut-off. ELECTRICAL SYSTEM A 12-volt 25-ampere hour battery, voltage regulator, am- meter, starter solenoid, alternator, circuit breakers, stall warning light, switches, and related wiring are all included as standard equipment on the Pawnee. The battery is located in a box in the fuselage just forward of the horizontal stabilizer. It is accessible through the re- movable turtle deck. The master solenoid and an energizing diode are located on the forward side of the battery box. The diode excites a circuit permitting a completely dead battery to 7 671030