Method to detect mechanical faults and dynamic instability in rotor systems of helicopters, tilt rotor aircraft, and whirl towers

• US 8,041,520 B2
• Filed: 09/18/2008
• Issued: 10/18/2011
• Est. Priority Date: 09/26/2007
• Status: Expired due to Fees

• Current Assignee: Gilbert Ronald Mesec
• Original Assignee: Gilbert Ronald Mesec
• Inventors: Mesec, Gilbert Ronald
• Primary Examiner(s): Nghiem; Michael
• Assistant Examiner(s): Le; Toan
• Application Number:
  US12/284,100
• Publication Number:
  US 20090088922A1
• Time in Patent Office: 1,125 Days
• Field of Search: 702/58, 702 33- 36, 702 40- 44, 702 56- 57, 702/59, 702 65- 76, 702/79, 702/81, 702 84- 85, 702/87, 702 89- 91, 702 94- 97, 702/101, 702105-106, 702/108, 702113-114, 702/123, 702/127, 702141-142, 702144-147, 702150-151, 702/154, 702/159, 702/166, 702/168, 702/172, 702/175, 702179-185, 702/189, 702/193, 702198-199, 244/17.11, 244/17.13, 73/18.1, 73/18.4, 735/70, 735/79, 735/83, 736/49, 73653-654, 736/58, 73660-661, 356/4.01, 356/4.08, 356/6, 356/138, 35613904-13905, 356/139.1, 356/150, 356614-615, 356/620, 701/3, 701 8- 10, 701/14, 701/29
• US Class Current: 702/58
• CPC Class Codes: B64C 27/008 Rotors tracking or balancing devices
• CPC Class Codes: G07C 5/0816 Indicating performance data, e.g. occurrence of a malfunction
• CPC Class Codes: G07C 5/0858 wherein the data carrier is removable

Abstract

A method of processing revolution to revolution blade track height and timing data so that mechanical and dynamic stability, maladjustments, and defects are discovered in a rotor with a plurality of blades on a vertical lift aircraft. Tracking devices collect blade track height and timing data. That data are processed into track and lead-lag data sets. Data set values are sorted maximum to minimum, or in reverse order, to remove the chaotic character of the collected data, thereby adding coherence and linearity to it. Defects and maladjustments are found by analyzing processed aircraft flight condition data combined in various ways. Only ground and hover flight condition analysis is required. Data collection and analysis is very rapid and the analysis output is presented graphically. The analyzed data are available moments after collection. Significant operational, safety, and cost saving are achieved.

Claims

1. A method of processing blade tracking height and timing (lead-lag) data for a plurality of 50 or more revolutions of a rotor with a plurality of blades to detect defects, if any, in at least one rotor with a plurality of blades of a rotary wing or tilt rotor aircraft, where a defect corresponds to a fault or failure, including maladjustments, of any part of the rotor with a plurality of blades, comprising:

a. tracking data are collected and stored in a computer for each revolution of a rotor with a plurality of blades, and for each of one or a plurality of steady state flight conditions of the aircraft under test, for determining average track height and absolute lead-lag values for each revolution of the rotor with a plurality of blades and segregating the values into data sets of track height and lead-lag;

b. using the computer to sort the stored track heights and lead-lag data sets;

wherein

i. each data set of a rotor with a plurality of blades is sorted so the values of the individual blade track height or lead-lag, are arranged from maximum value to minimum value, or in reverse order;

ii. the distribution of values of each individual blade track height or lead-lag places anomalous or major variations values at its extremes;

iii. the distribution of individual blade track height or lead-lag reveals the motion of the blades on a rotor with a plurality of blades and the motion is defined by the variation about median values;

c. the collected data and sorted data are stored separately so that the collected data are preserved and sorted data are used to analyze the condition of the rotor with a plurality of blades;

wherein

i. the slope of the distribution of track height data defines the relative power necessary to drive each individual blade and blade tendencies to climb or dive on a rotor with a plurality of blades;

ii. the distribution of the lead-lag data defines the effectiveness of the damping system and the drag and weight imbalance in the lateral plane of rotation of a rotor with a plurality of blades;

iii. the distribution of individual blade track heights or lead-lag of individual blades of a rotor with a plurality of blades are compared one to another in either track height or lead lag or in combination to determine the dynamic tendencies of the blades or rotor, rotor component interactions, rotor or blades anomalous behavior, and defects of the rotor with a plurality of blades;

d. the distribution data of track heights and lead-lag are displayed graphically for use in maintenance or the safe operation of the aircraft.

2. The method according to claim 1, wherein using graphic displays to detect defects in a rotor with a plurality of blades, wherein distribution data of track heights and lead-lag from one or more flight conditions of a rotor with a plurality of blades are compared one to another, in track height, lead-lag, or in combination, and are displayed graphically such that defects of a rotor with a plurality of blades are identified.

3. The method according to claim 1, wherein distribution data of track heights and lead-lag from two aircrafts of the same model are compared to detect known defects, and the distribution data of a rotor with a plurality of blades used are from one aircraft where known defects exist and are compared against the distribution data from another aircraft rotor with a plurality of blades to determine the existence of the same or similar defects in its rotor with a plurality of blades where distribution data from both aircrafts are at the same flight condition.

4. The method according to claim 1, wherein distribution data of track heights and lead-lag from two aircrafts of the same model are compared and the distribution data from an aircraft rotor with a plurality of blades where no defects exist are used to determine the absence or existence of defects in another aircraft rotor with a plurality of blades and the distribution data from both aircrafts are at the same flight condition.

5. The method according to claim 1, wherein the median points of the blade height and lead-lag distribution data accurately represent track height and/or lead-lag values of a rotor with a plurality of blades, wherein the ability to properly correct maladjustments on a rotor with a plurality of blades depends upon the accuracy of the track height and lead-lag values derived, and wherein average distribution data of track height and lead-lag values can be inaccurate as large variations in track height or lead-lag skew average track height and/or lead-lag value calculations by increasing or decreasing the averaged value, wherein, large variations in the distribution data of track height and lead-lag values are at the extremes of the distribution data thereby making the median values at or closer to the actual steady state dynamic track height or lead-lag value of any blade on a rotor with a plurality of blades and provide for accurate corrections to maladjustments.

6. The method according to claim 1, wherein the sorted data are further processed to extract further evidence of mechanical defects or dynamic instability of a rotor with a plurality of blades or its individual or collective parts by analyzing the magnitude or variations in the distribution data of track height and lead-lag values around the median value of the blade track height and/or lead-lag distribution data as the variations in values represents the blade motion vertically and laterally, and the changes in values define the rate of change of that motion, thereby revealing the tendencies of one or more parts of a rotor with a plurality of blades to operate within, reach, or exceed the limits of motion imposed by the part or attached parts.

7. A method according to claim 1, wherein the degree of stability of the cord-wise centrifugal pitching moments of a rotor with a plurality of blades is determined by data from one or more flight conditions of a rotor with a plurality of blades, wherein the track height and lead-lag distribution data are compared one flight condition to another to determine track height and lead lag variations, distribution data slope, median distribution data crossing points, and other indicators of blade centrifugal pitching moment stability of a rotor with a plurality of blades wherein a wide variation in stability of the collective blade pitching moments render a rotor with a plurality of blades unstable.

8. The method according to claim 1, wherein vertical lift aircraft track height and lead-lag data from a rotor with a plurality of blades are combined with accelerometer data from the same aircraft processed to extract frequencies and their amplitudes to enhance the detection of defects of the rotor with a plurality of blades comprising:

a. collecting frequency data during the same period of time that the track height and lead-lag data are collected;

b. the accelerometer data are processed independently to extract frequency and amplitude of the data;

wherein

c. the track height and lead-lag data and the accelerometer frequency data and amplitude data are analyzed together to highlight, enhance and improve the detection of defects or maladjustments of a rotor with a plurality of blades; and

wherein

d. defects such as rotor shaft bearing wear, excessive rotor gyration, and/or blade attachment defects are revealed when accelerometer first and second harmonic frequencies have high amplitudes in combination with track height and lead-lag data showing abnormal data variation about the mean data values of a rotor with a plurality of blades.