Hums

some airlines operating fixed wing aircraft have adopted a master active approach to improve operational safety by analyzing feather data on a routine basis to provide part visibility of their operation In flight operations quality presumption (FAQ) programmer. A simple description of HUMS Is that It Is a schema for monitor the locating of technical components, principally shafts, bearings, gears and other rotating components. The level of vibration Is indicateed by accelerometers. The data is stored in a data card which is later taken out and brought too state station for reading off at the end of each flight.Operational information from the flight thus becomes available from the soil station via a terminal. The list thus printed also informs regarding any pay back values that have been exceeded and description of failures in HUMS. Most of the information is analyses manually and this provides valuable additional information during trouble shooting. Advanced helicopter observe agreements were Implemented In the early sasss quest aftering concern over the deject worthiness of helicopters and, at the time, technical defects were the mall Issue.The acronym HUMS, Health and usage monitor Systems, was introduced for these systems. With the introduction of HUM systems, the number of incidents relating to the chemical malfunctions decreased and as a consequence the proportions of incident relating to the aircrew error increased. Thus later a need was envisaged of developing a system called HOMO. AIM accepted handling in aviation and in context to India Air Force. WORKING The system consists of sensors, computers, softw be and analytical methods that, when taken in concert are able to record vibration and other parameters and thus deduce the health of the machine.The HUMS information is receive and processed by the Digital Acquisition and Processing Unit (ADAPT) in the beginning being stored on a charismatic card which is placed in the cockpit unit prior to flying. This card is taken out on loss the helicopter after the flight and data are loaded into a ground station for further electronic processing. A HUMS is like a doctor applying many stethoscopes to a patient continuously and keeping a constant check on his health. Helicopters having more rotating and moving parts, bequeath assume part if not properly maintained, hence their mechanical health is deprecative to the safety of flight.The deployment of HUMS as a life saving and cost hard-hitting equipment is a boon. There are number of sub systems in HUMS which arrest parameters and determines he health of the helicopters. We will be dealing with the most fundamental subsystems in the subsequent paragraphs. In HUMS the fatigue or damage to the components is set while in service itself. Inevitably components assume out or fail unexpectedly. The traditional monitoring techniques such as oil detritus and engine achievements trending are aimed at identifying these p roblems before they become hazardous.Techniques using pompous flight data quarter be used here, for example, engine performance trends can be calculated from engine parameters gathered in flight. hushed the traditional Accident Data is usually inadequate for monitoring wear in rotating components and so a host of specialized techniques have been positive to measure the health of the rotors and transmission. These rely heavily upon vibration measurement and lease special instrumentation and data acquisition systems. A PC establish ground station provides the aircraft operator and maintain the simple diagnosis of the aircraft and mandatory maintenance actions.Advanced mechanical of aircraft monitoring superior to any other monitoring system available. THE SUB SYSTEMS As stated earlier there are number of sub systems which gather information in flight skirmish the health and usage and wear and tear off the components and can be read over a ground station. Major ones are- (a) rot or Track and Balance. Each helicopter main rotor firebrand should follow one in front and along the same path, and blades should be place at equal angles. This track is measured in terms of blade height past a fixed point and the angle in the midst of the successive blades.A photo sensitive device on the nose looks at the blade tips at two points on the either side of the nose. The in the lead and the trailing edges of the blades can be detected, and the timing of their passes gives the blade eight. The interval between one blade passing over the sensor and the following blades gives the system lead/lag information. Infrared techniques can be used if the helicopter is to be flown at night. (b) Engine Monitoring. Engine Monitoring parameters include vibration, bobble temperatures and pressures, and shaft speeds. Engine Vibration can indicate ebullient wear on ball bearings or races.Small changes in the engine vibration speck must be recognized early. Two accelerometers are use d to pile up a good engine spectrum. The know frequencies of rotating components can first be used o detect simple imbalance. Then they are subtracted from the known spectrum. The remaining spectral lines are analyzed for more subtle defects. spoil temperatures are used to calculate thermal fatigue. High/Low temperature excursions, together with mean temperatures, are used to estimate damage caused by alloy expansion and contraction. (c)Gear Box Vibrations.The importance of gearbox vibration monitoring can not be over estimated. Cracks, broken gear teeth and excessive wear are critical areas that must be caught early. Gear vibrations are revealed by strategically positioned accelerometers. There might be 20 shafts in the gear box but fewer than half this number of accelerometers are needed to monitor them all. The problem is to separate very small signals caused by a single tooth defect from blown-upr signals (d) Oil Debris Monitoring. whatsoever moving metal surfaces in contac t with one another will produce debris.Most of it will end up in oil. Therefore, metal instalment detection is a useful means of monitoring wear in the engine and gear box. Particles lesser than ten microns are the result of prevalent wear and are no cause of concern, unless they are being ground down from larger particles. The presence of metal flecks greater than hundred microns in size indicates a serious wear problem. Particles that size are large enough to cause further damage to other parts of the engine, which in turn leads to creation of more large particles.Magnetic plugs were originally introduced to capture debris and prevent secondary damage. Today they have become an early ideal device for heavy wear. A refinement of this is the quantitative debris monitor, which consists of an electronic metal particle detector used in the place of the magnetic plug. The monitor uses an electromagnetic to attract debris. The debris causes a flux hoo-ha in the drive coil, which in t urn generates a voltage pulse rate that is proportional to particle size. A processor grades and counts the particles by size.