TM   1-1500-204-23-1 (6) Avoid snow and slush blown by preceding (2) aircraft by increasing distance between aircraft when Inspect oil and fuel drains and crankcase taxiing. breathers for ice or frost. Remove any existing frost or ice. (7) Reduce taxi speeds to ensure safe stop- ping. (8) Exercise care when pulling out or turning from parking line to ensure that other aircraft will not be damaged or covered by snow and ice from propeller blast. (9) Avoid  taxiing  into  deep  snow  or  snow  drifts, as steering could become difficult, brakes could freeze, and damage to propellers could result. (10) Unless aircraft is equipped with an auxiliary power unit, use only essential electrical equipment to preserve battery life while taxiing at low engine speeds. b.   Taxiing. The following are general procedures for taxiing: (1) Only personnel authorized to taxi as speci- fied in AR 95-1 may taxi Army aircraft. (2) Do not taxi aircraft on any taxiway which runs within 100 feet of active runways unless necessi- tated by terrain or directed to do so by proper authority. (3) Upon approved signal from flight compart- ment, approach and remove wheel chocks. Exercise caution and consideration for operating propellers, tur- bine inlet, and exhaust areas. (4) Use only sufficient engine power to gain roll- ing momentum when taxiing aircraft from a row of parked aircraft. When it is necessary to turn aircraft, gain required  momentum  in  straight  movement  to  permit  mak- ing turn with reduced power. (5) Under normal operations, wing guides will not be mandatory. However, when an aircraft is maneu- vered in proximity of other aircraft, buildings, or obstruc- tions, or in gusty or high wind conditions, there shall be wing guides to ensure adequate guidance. c. Postflight and Parking. The following procedures are listed to prevent abortive flights following the last flight of the day, and to protect parked aircraft: (1) Drain oil tank sump and main oil drain before condensation freezes. (3) Inspect  battery  for  charge  at  least  once     a week.  If  layovers  are  to  be  over  4  hours  and  temperature is below -20°F (-29ºC), remove battery and store in a warm  place. (4) Drain oil system when there is no provision available for preheating oil and a long layover period is anticipated. (5)  When  temperature  rises  above  freezing during a long layover, drain fuel and oil tank sumps of water before temperature drops. 3-12. Test Flights and Maintenance Operational Checks. Maintenance test flights are categorized as general test flights and limited test flights. Specific and mandatory requirements for accomplishment of aircraft test flights and maintenance operational checks are found in Section III, TM 55-1500-328-23. a.    Test Flight Safety Maintenance  test  flights  will  be accomplished with assistance as necessary from the most proficient flight crew available; i.e., copilot, techni- cal  inspectors,  and  observers.  Aviators  who  are  not  grad- uates of The Aircraft Maintenance Test Flight course may be  designated  as  Maintenance  Test  Pilots  upon  success- ful  completion  of  an  evaluation  administered  in  accor- dance with FM 1-544. Minimum crew possible will be aboard aircraft during test flight. b.   Maintenance Operational Checks. Maintenance operational checks (MCCs) are accomplished on the ground through engine runup, aircraft taxiing or use of auxiliary power or testing equipment, in such a manner as to simulate conditions under which the system is to operate. The purpose of an MOC is to assure that aircraft systems or components which have been disturbed dur- ing an inspection or maintenance action have been repaired, reassembled or adjusted satisfactorily. c. Carbon Monoxide Detection. Determine  the  car- bon monoxide concentration in aircraft after every major overhaul.  Follow  the  procedures  and  limits  in  the  instruc- tions packed with the carbon monoxide detector. Change 2 3-19/(3-20 blank)