TM 1-1500-204-23-1 · When  necessary  to  properly  evaluate  engine performance  or  when  icing  conditions  exist, inlet  duct  runup  screens  should  be  removed. Runup with screens removed shall be made in a designated, thoroughly cleaned area. CAUTION Inlet duct runup screens shall not be installed   and   removed   with   engine operating    above    Idle    rpm    Loose Items  of  clothing  shall  not  be  worn and  objects  which  might  be  drawn into   the   Intake   ducts   shall   not   be carried  when  installing  or  removing screens.  Damage to the engine may otherwise result. · Inlet  duct  runup  screens  may  be left off during taxiing to and from takeoff position when requirements or existing conditions     make     the     use     of screens impractical Since specific     conditions     warranting removal  of  screens  as  specified above  cannot  be  predetermined, specific conditions may be determined by each command as necessary to conduct their operation     Approval     of     screen removal should include any additional  precautions  necessary to assure safe operation of engine. j.      Use      only      nonmetallic-head      hammers      when required to install parts on engine. k. When possible, use appropriate hoist or lifting yoke on heavy or bulky parts, such as tailpipes. I.    Tighten  jack  screws,  attaching  screws,  bolts,  and nuts In small increments on opposite planes. WARNING Lead   poisoning   is   an   accumulative disease that can be fatal.  Preventive rather  than  curative  measures  shall be stressed. m.      A   turbine   engine   that   has   operated   on   fuel containing tetraethyl lead may have a yellow powder on those  sections  that  are  exposed  to  combustion  gases. for    example,    tail    pipes    and    combustion    chambers. Extreme  care  shall  be  used  by  all  personnel  handling such parts to prevent internal contamination of the body through  open  cuts,  sores,  or  inhaling.    Personnel  shall adhere to following precautionary measures. · Change clothes daily. · When possible, gloves shall be worn.  Wash or change gloves daily. · Hands    shall    be    thoroughly    washed    before eating, drinking, smoking, or using toilet. · Scrub body thoroughly each day. 8-5.    Turbine  Engine  Design  and  Construction.    A typical turbine engine consists of an air inlet, compressor section, combustion section, turbine section,   exhaust   section,   accessory   section,   and   the necessary  systems  for  starting,  lubrication,  fuel  supply, and  auxiliary  purposes,  such  as  anti-icing,  cooling,  and pressurization.      The   major   components   of   all   turbine engines are basically the same; however, the nomenclature of the component parts of various engines currently In use will vary slightly due to the difference  In manufacturer         terminology.      These   differences   are reflected in the applicable maintenance manuals. a.    Inlet  Ducts.    There  are  two  basic  types  of  inlet ducts,   the   single   entrance   and   the   divided   entrance duct.    Single  entrance  inlet  ducts  are  used  with  axial- flow engines, as shown in figure 8-3, to obtain maximum ram  pressure  through  straight  flow.    Divided  entrance inlet    ducts,    as    shown    in    figure    8-4,    provide    the opportunity  to  diffuse  the  incoming  air  so  It  enters  the plenum chamber with the low velocity required to utilize a  centrifugal-flow  engine  inlet  ducts  may  be  classified as: · Nose    Inlets,    located    in    the    nose    of    the fuselage or powerplant pod or nacelle. · Wing inlets, located along the leading edge of the wing, usually at the root for single-engine installations. · Annular  inlets,  encircling,  In  whole  or  in  part, the fuselage or powerplant pod or nacelle. · Scoop     inlets,     which     project     beyond     the immediate surface of the fuselage or nacelle. · Flush Inlets, which are recessed in the side of the fuselage, powerplant pod, or nacelle. 8-3