Patent Publication Number: US-6983648-B2

Title: Component management system

Description:
This application is the US national phase of international application PCT/GB01/02461, filed in English on 5 Jun. 2001, which designated the US. PCT/GB01/02461 claims priority to GB Application No. 0013936.0 filed 8 Jun. 2000. The entire contents of these applications are incorporated herein by reference. 
   This invention relates to a component management system and particularly to such a system for managing components subject to wear e.g. components in or related to a braking system such as an aircraft braking system. 
   Airline operators, in the management of spare parts, traditionally have to use very general and usually somewhat inaccurate information upon which to calculate spares requirements for the replacement of components. Such systems can lead to either too many or too few of a particular component being held, can lead to components being held in the wrong place at the wrong time and can generally cost the airline operator a lot of unnecessary money. 
   It is an object of the invention to provide a system for management of components subject to wear which will overcome the difficulties of the prior art 
   According to one aspect of the present invention there is provided a system for management of components subject to wear including measuring wear rate of another component whose wear rate is related to the wear rate of the said component and using the measured wear rate to determine the predicted life of the said component. The said component may comprise an aircraft tyre and the other said component may comprise a brake operable to brake a wheel upon which the tyre is mounted. 
   The invention can thus provide a system, which is beneficially in the form of a computer database, allowing operators of aircraft or any other equipment where components are subject to wear to manage all the maintenance, analysis and provisioning aspects of such components, such as brake and wheel components, with the unique feature of being able to predict component, e.g. tyre life to a high degree of accuracy based on the measured wear rate of the component or a related component such as each tyre&#39;s related brake unit. From the predicted life of the component, spares requirements for that component may be determined, e.g. by determining the number of spares required and/or the location at which they will be required to be kept. 
   Inspection of the said component for a final determination as to whether replacement is required may thus be limited to a much narrower time band and the determination of when to change the component is therefore made a much easier and more certain step. 
   A formula, according to the invention, which has been used to predict expected tyre life for a given tyre is as follows:
 
Predicted Tyre Life=(( A/B )×( C−D ))+ D 
 
Where
 
   
     
       
         
             
             
             
           
             
                 
                 
             
           
          
             
                 
               A = Fleet average brake wear rate 
               (inches/landing) 
             
             
                 
               B = Brake wear rate for subject wheel 
               (inches/landing) 
             
             
                 
               C = Fleet average tyre life 
               (landings) 
             
             
                 
               D = Minimum tyre life 
               (landings) 
             
             
                 
                 
             
          
         
       
     
   
   The system of the invention may have the following features:
     Input of Brake Wear Indicator pin dimensions;   Historical record of maintenance performed on wheels and brakes;   Current status of each wheel and each brake unit fitted to each aircraft;   Automatic forecasting of wheel and brake unit changes;   Wear rate calculations for components, e.g. wheels and brake units, revealing any wear imbalances (for example for wheels on the same axle),   Predicted lives of components, e.g. installed wheels or brake units;   Reporting of reliability and maintainability statistics;   Automatic forecasting of component, e.g. wheel and brake unit spares requirements.   

   Some examples of aircraft component costs are set out below: 
   
     
       
         
             
             
             
           
             
                 
                 
             
           
          
             
                 
               Brake spacer 
               £800 
             
             
                 
               Tyre (remould) 
               £400 
             
             
                 
               Brake set 
               £12,000 
             
             
                 
                 
             
          
         
       
     
   
   A tyre may last about 400 landings, or about 2 months on average, for normal schedules. We have seen from the programme one tyre wearing at twice the normal rate but were able to correct the aircraft fault before the tyre was ruined and were able to get two thirds or more of the life out of the tyre. 
   Hence for a 10 aircraft fleet, times 6 tyres, times 6 for a years use, gives 360 tyres or £144,000 per year spent on tyres. 
   A brake set may last on average one year, and with 4 per aircraft for a 10 aircraft fleet, that is 40 brake sets per year or £480,000 per year. 
   Thus it can be seen that even a five per cent annual saving on these costs will amount to over £25,000. 
   According to another embodiment of the invention there is provided a method of determining wear imbalance in components by comparing predicted lives for at least two said components operating on a single piece of equipment. For example a malfunctioning component in a brake or anti-skid system may be identifed, according to the invention. Established wear patterns may be used to help make this determination. 
   Data input into a software programme according to the invention to predict wear life of aircraft tyres may include brake wear pin fitting date; date of commencement of monitoring of the components; number of aircraft landings at the commencement date of monitoring; the date when the brake or wheel was last changed; brake wear indicator pin dimensions. 
   Other factors which may be introduced into the system of the invention, when related to brakes and tyres, include brake hydraulic pressures; anti-skid control systems features; runway types; weather: temperatures etc. 
   The system of the invention can learn from updated tyre wear rates in making its component wear predictions.