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1

Application of electric capacity measurements to detecting delamination in blades of helicopter’s lifting and auxiliary rotors

100%
Gebura A.
Polish Maritime Research
|
2017
|
tom 24
|
nr 2
This paper represents a series of the authors’ publications concerning effects of atmospheric conditions on aircraft [5-6, 11]. Hazards connected with separation ( delamination ) of heating elements from blade’s spar , namely: increased susceptibility to ice formation as a result of change in aerodynamic profile, decreased deicing effectiveness, shortened life of heating elements , weakened strength of blade’s structure, are described. In order to monitor the above mentioned delamination process during its early phase, these authors proposed to measure systematically electric capacity between the heating element and blade’s spar by means of a technical method. The electric capacity measurements performed by these authors on blades both in laboratory and service conditions demonstrated their practical usefulness for assessing delamination extent as well as for identifying areas where heating element separation from spar occurred. The method in question is simple , cheap , fast and non-interferring (non-destructive) as well as it does not require dismounting the blades off the helicopter. As proved in practice , it is especially useful in sea-rescue or military operational conditions. Special attention was paid to application of the method to composite blades where coming-off the heating element tape causes local overheating the blade structure , that impairs flexibility of composite’s layers and may lead even to local cracks which may trigger helicopter crash. These authors desire to apply the method as a standard unit of on-board diagnostic system in the future
2

Diagnosing turbine engine bearing structures with the aid of FAM-C and FDM-A methods

100%
Gebura A.
Polish Maritime Research
|
2009
|
tom 16
|
nr 1
The diagnostic method FDM-A [2], based on the measurement of the pulsation component frequency modulation, and the FAM-C method, making use of the alternating current frequency, were developed in the Air Force Institute of Technology. The essence of their accuracy consists in “natural” synchronisation of the sampling signal with the angular velocity of the observed kinematic links. These methods make it possible to determine the level of wear of a subsystem and its location during normal operation of the power unit. They provide opportunities for determining numerous parameters of bearings, bearing structures, and the rotor unit. Moreover, the FDM-A method makes it possible to detect resonances in particular elements and their parameters - among others, they provide opportunities for assessing the level of the mechanic quality factor of the examined structure, i.e. the time margin of structure operation until the structure reaches the state of resonance. On the other hand, the FAM-C method provides opportunities for defining numerous parameters of the phenomena connected with the rotor unit. The diagnostic system is connected to an arbitrary point of the electric network (electric junction, for instance) supplied with the direct voltage1or the alternating voltage2 taken from the generators driven by the examined rotating system.The presented experimental material was recorded in operating investigations of the aircraft turbine engine unit, in which the role of “generators – observers” was played by: an aircraft DC generator and a three-phase AC rate generator. Generators of this type are also used in rocket cutters with turbine engines, this way the conclusions presented in the article can be easily transferred to those objects.During the measurements, performed on the decks of the examined airplanes and on engine test beds, the ranges and locations of assembly and wear defects were determined. Successive stages of wear of the rolling bearings were also observed
3

The diagnosis of onboard generators (alternators)

63%
Gebura A., Radon T.
Polish Maritime Research
|
2009
|
tom 16
|
nr 3
In the paper selected problems related to diagnostics of onboard generators and alternators fitted with control systems are discussed. Problems refer to commutator generators and synchronous single- and three- phase alternators. Special attention is paid to commutation effects. Results of incorrectness and possibility to detect them are discussed. There are also discussed effects associated with changes in a character of pulsation, which occur during shortings or insulation clearances in rotor or stator wiring. Possibility of diagnosis of generator’s or alternator’s parts by means of analysis of pulsation component parameters is indicated. In the case of alternators a number of diagnostic methods based on observation of changes in shape of voltage or frequency modulation, is discussed. This allows to detect many mechanical or electrical faults of generators, alternators or their control systems
4

Possibilities of FAM-C method in diagnosing ship power plants

50%
Gebura A.
Polish Maritime Research
|
2003
|
tom 10
|
nr 2
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