installed in a system, it should be supported with rubber-lined  supporting clamps at regular intervals. Before installing metal tubing with threaded fittings, ensure  the threads are clean and in good condition. Apply sealing  compound, of the correct specification for the system, to  the threads of the fittings before installing them. While  connecting metal tubing, follow the same careful procedure  for connecting hose fittings to prevent cross-threading and  to ensure correct torque. When connecting the starter, generator, or various other  electrical units within the nacelle, make sure that all lead  connections are clean and properly secured. On leads that  are fastened to a threaded terminal with a nut, a lock washer  is usually inserted under the nut to prevent the lead from  working loose. When required, connector plugs can be  safetied with steel wire to hold the knurled nut in the full- tight position. Electrical leads within the engine nacelle are usually passed  through either flexible or rigid conduit. The conduit must be  anchored, as necessary, to provide a secure installation and  bonded when required. All engine controls must be accurately adjusted to ensure  instantaneous response to the control setting. For flexibility,  the engine controls are usually a combination of rods and  cables. Since these controls are tailored to the model of  aircraft in which they are installed, their adjustment must  follow exactly the step-by-step procedure outlined in the  manufacturer’s instructions for each particular model  of aircraft. Figure 8-11  illustrates a simplified schematic drawing of a  throttle control system for a reciprocating aircraft engine.  Follow a general procedure for adjusting throttle controls.  First, loosen the serrated throttle control arm at the carburetor  and back off the throttle stop until the throttle valve is in  the fully closed position. After locking the cable drum into  position with the locking pin, adjust the control rod to a  specified length. Then, attach one end of the control rod to  the locked cable drum, and reinstall the throttle control arm  on the carburetor in the serrations that allow the other end of  the control rod to be attached to it. This correctly connects  the control arm to the cable drum. Now, loosen the cable turnbuckles until the throttle control  can be locked at the quadrant with the locking pin. Then, with  both locking pins in place, adjust the cables to the correct  tension as measured with a tensiometer. Remove the locking  pins from the cable drum and quadrant. Hoses used inside low-pressure systems are generally  fastened into place with clamps. Before using a hose clamp,  inspect it for security of welding or riveting and for smooth  operation of the adjusting screw. A clamp that is badly  distorted or materially defective should be rejected. Material  defects include extremely brittle or soft areas that may easily  break or stretch when the clamp is tightened. After a hose is  The exhaust system should also be carefully connected  to prevent the escape of hot gases into the nacelle. When  assembling the exhaust system, check all clamps, nuts,  and bolts, and replace any in doubtful condition. During  assembly, the nuts should be gradually and progressively  tightened to the correct torque. The clamps should be tapped  with a rawhide mallet as they are being tightened to prevent  binding at any point. On some systems, a ball joint connects  the stationary portion of the exhaust system to the portion  that is attached to the engine. This ball joint absorbs the  normal engine movement caused by the unbalanced forces  of the engine operation. Ball joints must be installed with  the specified clearance to prevent binding when expanded  by hot exhaust gases. The filters in the air induction system must be cleaned to  ensure an unrestricted flow of clean air to the engine and  its units. Because methods for cleaning air filters vary with  the materials used in the filtering element, clean them in  accordance with the technical instructions for the aircraft  being serviced. The system of ducts for routing air to the engine varies with  all types of aircraft. In connecting them, the goal is to fit the  ducts closely at all points of disconnect so that the air they  route does not escape its intended path. The duct systems of  some aircraft must be pressure checked for leaks. This is done  by blocking the system at one end, supplying compressed air  at a specified pressure at the other end, and then checking  the rate of leakage. There are no hard-and-fast rules that direct the order in which  units or systems should be connected to the engine. Each  maintenance organization normally supplies a worksheet  or checklist to be followed during this procedure. This list  is based upon past engine installations on each particular  aircraft. If this is followed carefully, it serves as a guide for  an efficient installation. The following instructions are not a  sequence of procedures but a discussion of correct methods  for completing an engine installation. Mounting the engine in the nacelle is, of course, only the  beginning. All the ducts, electrical leads, controls, tubes, and  conduits must be connected before the engine can be operated. Connections and Adjustments 8-11