The method of estimating lifetimes of aircraft devices operating under ageing-attributable wearing conditions

Ważny, M.

doi:10.15632/jtam-pl.54.1.981

Cited by 1 publication

(1 citation statement)

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“…The method for determining the time distribution of exceeding the limit state by a diagnostic parameter, described in point 3, allows to define the readiness function of the time of reaching a limit state. By knowing this function, it is possible to determine the reliability of the selected commutator machines, the technical condition of which is assessed based on the considered diagnostic parameter [34,37]:…”

Section: Reliability and Durability Of The Selected Devices In Terms Of Changes In A Diagnostic Parametermentioning

confidence: 99%

Reliability Assessment of Aircraft Commutators

Wawrzyński

Zieja

Michalski³

2021

Energies

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The article describes the method of predicting the reliability and durability of an aircraft commutator, which is a primary source of electric energy in helicopters. Tests were conducted for 10 starter-generators. From this research it follows that the technical condition of brushes and bearings has a significant impact on the reliability of starter-generators. The reliability of starter-generators was determined based on the method consisting of two stages that was adopted: the first stage involved determining the density function of changes in diagnostic parameter depending on the operating time, but the second stage included the assessment of the reliability of bearings of the starter-generator taking into account the real flight profile. The first stage of the adopted method consisted of defining the dynamic model of changing the length of the starter-generator’s brush, which became the probabilistic model. Subsequently, based on differential equations, Fokker–Planck partial differential equation was derived, which describes the process of increasing the brush wear in a probabilistic way. This method enables the prediction of the residual durability of the helicopter’s starter-generator due to the change in a diagnostic parameter which is the wear of brushes during starter-generator operation. The second stage of this method allows determining the durability of starter-generator’s bearings building upon the average helicopter’s flight profile. Owing to the difficulty in measuring the wear of bearings, the relation between the durability of bearings and the temperature of surroundings can be applied by replacing the flight altitude with temperature. The reliability of the helicopter’s starter-generator was determined based on the serial-type reliability structure.

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Section: Reliability and Durability Of The Selected Devices In Terms Of Changes In A Diagnostic Parametermentioning

confidence: 99%