caused by a sudden reduction of engine power setting, reduce  power slowly. Shock cooling is generally considered to be the  outside components of an engine cooling much faster than  the truly hot parts inside the engine not directly exposed to  cooling airflow. This shock cooling allows the external parts  to cool faster and shrink more than the interior components  resulting in binding and scuffing of moving parts such as  piston rings and valves.  To reduce the possibility of inflight fire, the manufacturer  provides engine cool-down procedures for reducing engine  system temperatures prior to shutdown. Reducing throttle  setting allows the engine to begin a gradual cool down. The  GFM/POH may also instruct the pilot to adjust propeller pitch  at this time. Lowering the nose to increase airspeed provides  faster flow of cooling air to the engine cooling system.  Several minutes of reduced throttle and increased cooling  airflow are enough to allow the engine to be shut down. If the engine is retractable, additional time after engine  shutdown may be necessary to reduce engine temperature to  acceptable limits prior to retracting and stowing the engine in  the fuselage. Consult the GFM/POH for details.  [Figure 7-22] Retractable-engine self-launching gliders are aerodynamically  more efficient when the engine is stowed, but produce high  drag when the engine is extended and not providing thrust.  Stowing the engine is critical to efficient soaring flight. Prior  to stowing, the propeller must be aligned with the longitudinal  axis of the glider, so the propeller blades do not interfere with  the engine bay doors. Since the engine/propeller installation in these gliders is aft of  the pilot’s head, these gliders usually have a mirror, enabling  the pilot to perform a visual propeller alignment check prior  to stowing the engine/propeller pod. Detailed instructions for  stowing the engine and propeller are found in the GFM/POH  for the particular glider. If a malfunction occurs during engine  shutdown and stowage, the pilot cannot count on being able to get  the engine restarted. The pilot should have a landing area within  power-off gliding distance in anticipation of this eventuality. Some self-launching gliders use a nose-mounted engine/ propeller installation that resembles the typical installation  found on single-engine airplanes. In these self-launching  gliders, the shutdown procedure usually consists of operating  the engine for a short time at reduced power to cool the engine  down to acceptable shutdown temperature. After shutdown,  the cowl flaps (if installed) should be closed to reduce drag  and increase gliding efficiency. The manufacturer may  recommend a time interval between engine shutdown and cowl  flap closure to prevent excess temperatures from developing  in the confined, tightly cowled engine compartment. These  temperatures may not be harmful to the engine itself, but may  degrade the structures around the engine, such as composite  engine mounts or installed electrical components. Excess  engine heat may result in fuel vapor lock. If the propeller blade pitch can be controlled by the pilot  while in flight, the propeller is usually set to coarse pitch.  Some installations have a propeller feathering system that  reduces propeller drag to a minimum for use during non- powered flight. Some self-launching gliders require the pilot  to set the propeller to coarse pitch prior to engine shutdown.  Other self-launching gliders require the pilot to shut down  the engine first and then adjust propeller blade pitch to coarse  pitch or setting to a feathered position. As always, pilots must  follow the recommended shutdown procedures described in  their GFM/POH. Common errors during climb-out and shutdown procedures  include: If the self-launching glider is to land under power, the pilot  should perform the engine restart procedures at an altitude  that allows time to reconfigure. The pilot should follow the  manufacturer’s recommended engine start checklist. Once  the engine is started, the pilot should allow time for it to  warm up. After the engine is started, the pilot should ensure  that all systems necessary for landing are operational, such  as the electrical system and landing gear. Caution: Follow the manufacturer’s recommended engine  extension and restart procedures or a loss of situational  awareness could result in attempting a landing with the glider  a high drag configuration. The pilot of a sustainer or self- launching glider should plan for the engines to fail to start  and not have sufficient power to retract the engine and exhibit  a much higher drag coefficient. Should the engine not start  and retract, a glider pilot should have an alternate landing  area available with the decreased performance available in  the higher drag configuration.  The pilot should fly the traffic pattern to land into the wind  and plan the approach path to avoid all obstacles. The landing  area should be of sufficient length to allow for touchdown  7-21 •  Failure to follow manufacturer’s recommended  procedure for engine shutdown, feathering, and  stowing (if applicable). •  Failure to maintain positive aircraft control while  performing engine shutdown procedures. •  Failure to follow proper engine extension and restart  procedures. Landing