TM 1-1520-238-10 Change 9 8-19 Section V. ADVERSE ENVIRONMENTAL CONDITIONS 8.35 GENERAL This section informs the crewmembers of the special pre- cautions and procedures to be followed during the various weather and climatic conditions that may be encountered. This material will be additional to that already covered in other chapters regarding the operation of various helicop- ter systems. 8.36 COLD WEATHER OPERATION. Helicopter operation in cold weather or an arctic environ- ment presents no unusual problems if the flight crew is aware of the various changes that occur in low tempera- ture conditions. 8.37 PREPARATION FOR FLIGHT. CAUTION Ice removal shall never be done by scraping or chipping. Remove ice by ap- plying heat or de-ice liquid (TM 1-1500-204-23). In addition to doing a normal preflight in Section II, the ro- tor head, main rotor blades, tail rotor, and flight controls should be free of all ice and snow. Failure to remove snow and ice accumulations while on the ground can result in serious aerodynamics and structural effects in flight. Check that all fuel tank vents, static ports, pitot tubes, en- gine inlet, APU inlet, ENCU inlet, and heat exchangers are free of snow and ice; and that tires, landing gear struts, and the hydraulic accumulator are properly serviced. a. If ice or snow is found in engine inlets and exhaust, remove as much as possible by hand and thaw engine out with hot air before attempting to start. Actuate PWR levers for freedom of movement before starting main engine. b. Attempt to turn rotor system by rotating APU drive shaft by hand in the direction of rotation. If rotor cannot be turned, apply heat to main transmission area. c. As long as fuel will flow freely from the drains in the tanks, it can be assumed that the system is free of ice. Any indication that flow is restricted is cause for applica- tion of heat. CAUTION Fuel draining from the affected compo- nent after several minutes of heat ap- plication does not necessarily indicate that all ice has been melted. Ice may still remain in the unit, and it could be a seri- ous hazard to flight operations. Heat should be applied for a short time after fuel begins to flow from the drain, and the drainage should be checked fre- quently until it is evident that all water has been removed. d. If water collected in sumps has frozen (indicated by a lack of flow from drain), apply heat liberally and open drain frequently. Catch all drainage in a clear container and inspect for water globules in the fuel. Continue sam- pling until fuel is free of water globules. CAUTION Due to an elapsed time requirement, it is recommended that the tail rotor teetering bearings warmup procedure be accom- plished as the last item of the exterior check during the flight crew preflight in- spection. At –31 C (–24 F), the helicop- ter must be started and the tail rotor must be turning within 5 minutes of tee- ter bearing warmup. Below –32 C (–25 F), elapsed time is reduced to 2 minutes. At a temperature of –32 C (–25 F) or be- low, the tail rotor must be cycled by an applied force no greater than 75 lbs. The tail rotor teetering bearings are made of elastomeric material which prior to certain cold weather flights require special warmup procedures as follows: e. One crewmember should apply a teetering motion by manually pushing back-and-forth at the tip of the tail ro- tor blade until the blade has reached its teetering stops. When the blade can be pushed to the stop, the bearing has been sufficiently warmed up.