Beechcraft C-12C Operator And Technical Reference Manual

Contents

Beechcraft C-12C Operator And Technical Reference Manual Manual pdf 89 page image

TM 1-1510-218-102-73prefixed to the digital display will be removed. Allevent data is still available for playback until the data iserased. The display will be prefixed with an "E" againon the next power up cycle if the old data has not beenerased or if another event is recorded.NOTEPressing the EXCEEDENCE ERASE switchfor 0.2 seconds or longer will cause allevents to be erased from non-volatilememory. There are not provisions forerasing individual events.The Propeller Speed Tachometers are eachprotected by 1.0-ampere circuit breakers located onthe pilot’s left subpanel and placarded PROP RPM #1and #2.Section VII. UTILITY SYSTEMS2-59. DEFROSTING SYSTEM.a. Description. The defrosting system is anintegral part of the heating and ventilation system.The system consists of two warm air outlets connectedby ducts to the heating system. One outlet is justbelow the pilot's windshield and the other is below thecopilot's windshield. A push-pull control, placardedDEFROST AIR, on the pilot's subpanel, Figures 2-6and 2-8, manually controls airflow to the windshield.When pulled out, defrosting air is ducted to thewindshield. As the control is pushed in, there is acorresponding decrease in airflow.b. Automatic Operation.1. Vent blower switches – As required.2. Cabin Air Mode switch – AUTO.3. Cabin Air Temp control – As required.4. Cabin air, copilot air, pilot air, and defrostair controls – As required.c. Manual Operation.1. Pilot air, copilot air – In.2. Cabin air and defrost air controls – Out.3. Cabin air mode switch – MAN HEAT.4. Cold air outlets – As required.5. Cabin air manual temp switch – Asrequired.2-60. SURFACE DEICER SYSTEM.a. Description. Ice accumulation is removedfrom each inboard and outboard wing leading edge,and both horizontal stabilizers by the flexing of deicerboots which are pneumatically actuated. Engine bleedair, from the engine compressor, is used to supply airpressure to inflate the deicer boots, and to supplyvacuum, through the ejector system, for boot holddown during flight. A pressure regulator protects thesystem from over inflation. When the system is not inoperation, a distributor valve applies vacuum to theboots for hold-down.b. Operation.(1) Deice boots are intended to remove iceafter it has formed rather than prevent its formation.For the most effective deicing operation, allow at least1/2 inch of ice on the boots to form before attemptingice removal. Very thin ice may crack and cling to theboots instead of shedding.NOTENever cycle the system rapidly, this maycause the ice to accumulate outside thecontour of the inflated boots and preventice removal.(2) A three position switch on the overheadcontrol panel, placarded DEICE MANUAL / OFF /SINGLE CYCLE AUTO, C D T1 and DEICEMANUAL SINGLE CYCLE AUTO T2 controls thedeicing operation. The switch is spring loaded toreturn to the off position from SINGLE CYCLE AUTOor MANUAL. When the SINGLE CYCLE AUTOposition is selected, the distributor valve opens toinflate the wing boots. After an inflation period ofapproximately 6 seconds, an electronic timer switchesthe distributor to deflate the wing boots and a 4-second inflation begins in the horizontal stabilizerboots. When these boots have inflated and deflated,the cycle is complete.(3) If the switch is held in the MANUALposition, the boots will inflate simultaneously andremain inflated until the switch is released. The switchwill return to the off position when released. After thecycle, the boots will remain in the vacuum hold downcondition until again actuated by the switch.