TM  1-1520-240-10 2-3-6            and NO. 2 OIL TEMP circuit breakers on the No. 1 and No. 2 PDP. 2-3-23.  Engine Caution Capsules.    712   The follow- ing items are in reference to Fig. 2-14-5: a. NO. 1 (2) ENGINE OIL LOW.  This is illuminated when approximately 2 quarts of usable oil is remaining in the engine oil tank. b. NO. 1 (2) ENG CHIP DET.  This is illuminated if a  detector  is  bridged  by  ferrous  metal  particles  which may indicate impending engine or engine transmission failure. c. NO.  1  (2)  ENG  N1  CONT.  This  is  illuminated when the ECL is not in the STOP, GROUND or FLIGHT detent or when the ECL position does not agree with the N1 actuator position. 2-3-24.  Engine CAUTION/ADVISORY Capsules. 714A   The following items are referenced in Fig. 2-14-6: a ENG 1 (2) FAIL. Active when the engine failure logic in the DECU detects a failed engine condition. The engine failure logic is active when N1 is greater than 60% and the ECL position is greater than 50_(within 10_ of FLT position). The engine failure logic in each DECU is used to recognize any of the following: (1) Power  turbine  shaft  failure.  N2  is  greater than RRPM by more than 3 percent. (2) N1 underspeed. (3) Engine flameout. (4) Over temperature start abort (Primary mode only). (5) During normal shutdown as the N1 goes be- low 48 percent the ENG 1 (2) FAIL caution is illuminated for 12 seconds, this is a BIT self system check. b. FADEC 1 (2). Active if Primary FADEC System hard fails. c. REV 1 (2). Active if Reversionary FADEC system hard fails. d. ENG 1 (2) OIL LVL. Active when approximately 2 quarts of usable oil is remaining in the engine oil tank. e. ENG  1  (2)  CHIP  DETR.  Active  if  a  detector  is bridged by ferrous metal particles which may indicate impending engine or engine transmission failure. f. ENG  CONT  PWR.  Active  when  power  turbine inlet temperature is in the contingency power range. 2-3-25.  Engine Chip Detectors.   The engine accessory section oil sump and engine trans- mission chip detectors are electrically connected to the corresponding NO. 1 or NO. 2 ENG CHIP DET caution capsule on the master caution panel (fig. 2-14-6). If a detector is bridged by ferrous metal particles, which may indicate impending engine or engine transmission fail- ure, the corresponding NO. 1 or 2 ENG CHIP DET cau- tion capsule will illuminate. Also, the associated ENGINE CHIP DETECTOR or ENGINE TRANSMISSION CHIP DETECTOR magnetic indicator on the MAINTENANCE PANEL (fig. 2-9-2) will latch. Refer to Chapter 9 for emer- gency procedures. 2-3-26.  Engine Chip Detector Fuzz Burn-Off. Helicopters equipped with the chip detector fuzz burn -off system in the engine are identified by a module labeled PWR MDL CHIP BURN-OFF located below the MAIN- TENANCE PANEL. The chip detector fuzz burn-off sys- tem  employs  an  automatically  operated  fuzz  burn-off electrical circuit with the ability to eliminate nuisance chip lights caused by minute ferrous metallic fuzz or ferrous metallic  particles  on  the  engine  accessory  gear  box (AGB)  chip  detectors.  The  response  time  of  the  fuzz burn-off circuit is more rapid than that of the helicopter warning system; thus a successful fuzz burn-off will be accomplished before any caution capsule on the master caution panel illuminates. Should the particle or particles not burn-off, the NO. 1 or NO. 2 ENG CHIP DET caution capsule will illuminate. Also, the corresponding ENGINE CHIP DETECTOR or ENGINE TRANSMISSION CHIP DETECTOR magnetic indicator on the MAINTENANCE PANEL will latch. Power for the PWR MDL CHIP BURN- OFF is supplied by the No. 1 DC bus through the HY- DRAULICS MAINT PNL circuit breaker on the No. 1 PDP. 2-3-27.  Engine Interstage Air Bleed. NOTE Bleed band oscillations at low torque settings (approximately 30% torque per engine), indi- cated by fluctuating RRPM and torque, can occur and are not cause for engine rejection. To aid compressor rotor acceleration and prevent com- pressor stall, an interstage air bleed system is provided on each engine. A series of vent holes through the com- pressor housing at the sixth stage vane area allows pres- surized air to bleed from the compressor area. This en- ables the compressor rotor to quickly attain preselected RPM. The pneumatic interstage air bleed actuator con- trols operation of the air bleed by tightening or loosening a metal band over the vent holes. Should the bleed band malfunction and remain open, there would be a notice- able loss in power.  712   The interstage air bleed system operates automatically when the ENG COND levers or the engine beep trim switches are used to govern RPM. 714A   The interstage air bleed system operates auto- matically through the FADEC system. 2-3-28.  Engine Drain Valves. Pressure-operated engine drain valves are in the bottom of each engine combustion housing. The valves auto- matically drain unburned fuel from the combustion cham- ber following an aborted start or whenever the engine is shut down. One valve is at the forward end of the com-