Boeing airplanes typically use a 0-5 scale for cockpit display of vibration. These units represent the peak amplitude of the velovity of the vibration sensor. Signals from accelerometers are converted into velocity, measured in inches per second (ips). These units represent the physical displacement of the vibration sensor. Signals from velocity pickups are converted into vibration displacement, measured in 1/1000 of an inch, peak to peak (mils double amplitude). Two types of vibration pickups have been used on Boeing airplanes, the electomechanical velocity pickup and the piezoelectric accelerometer. I could find this quote on, but I cannot verify it: The vibration level is more than 4.0 unitsĪs to what the actual number really means, the FCOM does not say.The QRH defines High Engine Vibration as: The amber warning line ( 2) shows the limit of 4.0 units. (Boeing 737 NG FCOMv2 - 7.20.1 Engines, APU - System Description) ![]() Pointers/digits for all engine parameters. The engine start switch to GRD supplies electrical power to the EEC and displays When the EEC is not powered, N1, N2, oil quantityĪnd engine vibration are displayed directly from the engine sensors. The EEC must receive electrical power to supply engine operating data to theįlight deck engine indications. Engine vibration indications are displayed with a round dial/moving pointer. Oil pressure, oil temperature, oil quantity, and engine vibration are the secondaryĮngine indications. The value comes either from the EEC (Electronic Engine Control) or the sensor directly: (Boeing 737 NG FCOMv2 - 7.20.1 Engines, APU - Over/Under - Displays) The image you show is the Compact Engine Display: The increasing gas pressure will close the OVERHEAT pressure switch and further on the FIRE pressure switch.These are engine vibration measurements. If both loops in one engine sense a fault in one of its detectors, the FAULT light on the flight deck illuminates and the system is inoperative.Ī temperature rise inside and around the engine will cause the gas in the tube to expand. However the OVERHEAT/FIRE detection system will take the fault into account. ![]() Except for the OVHT/FIRE test, there is no flight deck indication of single loop failure. A leak in the sense tube causes the gas pressure to decrease and opens the FAULT pressure switch. Gas in the sense tube is charged with a minimum pressure to keep the FAULT pressure switch closed. In each section, two detectors (one of each loop) are mounted around the engine and make an assembly. The detectors monitor four sections of the engine the upper and lower fan case and the left and right core section. ![]() Each detector is connected to an individual stainless steel, gas charged sense tube. The detector consists of a 3-level pressure switch. I found a very good explanation of the system in PPRuNe forum: Įach engine has eight OVERHEAT/FIRE detectors, four in loop A and four in loop B. > Go to the ENGINE FIRE or Engine Severe Damage or Separation () checklist If the ENG OVERHEAT light stays illuminated: Engine Fire, Severe Damage or SeparationĮngine Overheat Autothrottle (if engaged).Cabin Altitude Warning / Emergency Descent.We just have to find out the correct NNC (Non Normal Checklist) and then we just read it and execute it.įor some of these checklists, we have memory items, meaning we have to know by heart some actions. When something goes wrong while flying on the Boeing 737, we use the QRH (Quick Reference Handbook).
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