Abstract: A method of zeroing displacement data derived from a rotor having an array of features monitored by an array of stationary timing probes. The method includes steps to calculate the displacement at each probe for each of at least two measured revolutions from time of arrival measurements. Each displacement is defined as a sum of a common term and a unique term. The set of displacements is solved for the common term and the unique terms. A probe offset is calculated from each unique term. The zeroed displacements are determined by subtracting the common term and probe offset from the calculated displacements for each probe.

Abstract: A rotor arrangement and method by which a time reference is provided for a rotor. The rotor includes N time of arrival features. The method includes steps to: provide a plurality of time of arrival probes spaced apart circumferentially outside the periphery of the rotor; for each revolution of the rotor, measure a time of arrival of each feature at each probe; select N time of arrival measurements at each probe; derive a best fit of the measured times of arrival measured at all the probes against angular position; and set the time reference for the next revolution of the rotor equal to the best fit at the end of the current revolution of the rotor.

Abstract: A method is provided for identifying resonant frequency vibration events in an assembly of rotating blades mounted on a rotor. A plurality of circumferentially spaced stationary timing probes associated with the blades detect the times at which the blades pass the respective probes. The method includes the steps of: obtaining blade timings detected by the probes, determining, for successive rotations of the assembly, respective correlation factors for one or more of the blades, each correlation factor quantifying the degree of correlation between the blade timings detected by the probes for a particular blade on a particular rotation and the blade timings detected by the probes for that blade on the previous rotation and identifying a resonant vibration event when the one or more correlation factors cross a predetermined threshold.

Abstract: A boroscope has a first end and a second end, and the first end of the boroscope has an optical fiber and light source. A working head is attached to the first end of the boroscope. The working head has an electrical motor, and a tool is attached to and is arranged to be driven by the electrical motor. The boroscope carries a cable extending from the electrical motor to the second end of the boroscope.

Abstract: A method of providing a time reference for a rotor, for example a once per revolution time reference. The rotor includes N time of arrival features. The method includes steps for each revolution of the rotor. Provide a plurality of time of arrival probes spaced apart circumferentially outside the periphery of the rotor and measure a time of arrival of each feature at each probe. Select N time of arrival measurements at each probe. Derive a best fit of the measured times of arrival measured at all the probes against angular position. Set the time reference for the next revolution of the rotor equal to the best fit at the end of the current revolution of the rotor. Also a rotor arrangement for the method.

Abstract: A method of analyzing blade displacements detected by circumferentially spaced stationary timing probes associated with an assembly of rotating blades mounted on a rotor, including (a) identifying a possible resonant vibration event in the assembly of rotating blades; (b) zeroing the blade displacements on the rotations identified with the resonant vibration event to remove invariant blade displacements; (c) fitting modelled blade displacements corresponding to possible blade vibrational deflections at various frequencies to the zeroed blade displacements; and (d) characterizing the resonant vibration event by identifying at each rotation the frequency having modelled blade displacements which correlate best with the zeroed blade displacements. Step (c) includes performing at each individual rotation the sub-step of fitting the modelled blade displacements at each frequency to the zeroed blade displacements for successive rotations which include that individual rotation.

Abstract: A method of zeroing displacement data derived from a rotor having an array of features monitored by an array of stationary timing probes. The method includes steps to calculate the displacement at each probe for each of at least two measured revolutions from time of arrival measurements. Each displacement is defined as a sum of a common term and a unique term. The set of displacements is solved for the common term and the unique terms. A probe offset is calculated from each unique term. The zeroed displacements are determined by subtracting the common term and probe offset from the calculated displacements for each probe.

Abstract: A boroscope (60) has a first end (62) and a second end (64) and the first end (62) of the boroscope (60) has an optical fibre (66) and light source (68). A working head (70) is attached to the first end (62) of the boroscope (60). The working head (70) has an electrical motor (72) and a tool (74) is attached to and is arranged to be driven by the electrical motor (72) and the boroscope (60) carries a cable (76) extending from the electrical motor (72) to the second end (64) of the boroscope (60).

Abstract: A method for analysing blade displacements detected by circumferentially-spaced stationary timing probes associated with a rotating blade assembly, the displacements corresponding to times at which the blades pass the probes.

Abstract: A method of analysing blade displacements detected by circumferentially spaced stationary timing probes associated with an assembly of rotating blades mounted on a rotor, including (a) identifying a possible resonant vibration event in the assembly of rotating blades; (b) zeroing the blade displacements on the rotations identified with the resonant vibration event to remove invariant blade displacements; (c) fitting modelled blade displacements corresponding to possible blade vibrational deflections at various frequencies to the zeroed blade displacements; and (d) characterising the resonant vibration event by identifying at each rotation the frequency having modelled blade displacements which correlate best with the zeroed blade displacements. Step (c) includes performing at each individual rotation the sub-step of fitting the modelled blade displacements at each frequency to the zeroed blade displacements for successive rotations which include that individual rotation.

Abstract: A method is provided for analysing blade displacements detected by a plurality of circumferentially spaced stationary timing probes associated with an assembly of rotating blades mounted on a rotor. The blade displacements correspond to the times at which the blades pass the respective probes.

Abstract: A method is provided for identifying resonant frequency vibration events in an assembly of rotating blades mounted on a rotor. A plurality of circumferentially spaced stationary timing probes associated with the blades detect the times at which the blades pass the respective probes. The method includes the steps of: obtaining blade timings detected by the probes; determining, for successive rotations of the assembly, respective correlation factors for one or more of the blades, each correlation factor quantifying the degree of correlation between the blade timings detected by the probes for a particular blade on a particular rotation and the blade timings detected by the probes for that blade on the previous rotation; and identifying a resonant vibration event when the one or more correlation factors cross a predetermined threshold.

Abstract: A single link digital telemetry system transmits data in serial form from a sending station. The data clock signal is recovered at a receiving station for data synchronization purposes. To achieve recovery of the data clock signal the incoming data is synchronized with a high frequency clock of n times the original data clock frequency; the fast clock is utilized to drive a data latch so that on each positive incoming data edge the latch produces a synchronized data pulse for feeding to a recirculating shift register n bits long, which is also driven by the fast clock. The original data pulse can be recovered merely by tapping off from a chosen location on the register.