Availability
Availability is the probability that a spare part will be available in the spares pool when demanded to carry out a repair during the Repair Delay period. For example, a stock-holding of 10 spare parts might have an Availability probability of 90% in a 30-day Repair Delay period. This would mean that 9 times in 10 Repair Delay periods the demand for a spare part would be satisfied and 1 time in 10 it would not.
Daily Operating Hours
The Daily Operating Hours is a measure of the number of hours the equipment will operate for each day. For example, a power amplifier in a mobile phone antenna mast might be powered 24-hours per day.
Equipment
The Equipment is the name of the equipment under analysis.
Fleet Operating Time
The Fleet Operating Time is a measure of the total number of hours that the whole fleet of equipment that is supported by the store or depot will operate for during the Repair Delay period.
Manufacturer
The Manufacturer is the Original Equipment Manufacturer (OEM) who produces the equipment.
MTBSO (Mean Time Between Stock-Out)
The MTBSO is average time that should elapse before a stock-out situation should be experienced. For example, a component with a 90-day Repair Delay and a 10% Stock-out-Risk should experience 1 stock-out situation in 10 Repair Delay periods. Therefore, we would expect one stock-out situation in 900 days (10 repair periods x 90 days). Therefore, the MTBSO would be 900 days or around 2.5 years.
MTBF (Mean Time Between Failure)
The MTBF is a measure of the reliability of a product or component and is usually provided by the Original Equipment Manufacturer (OEM).
MTBR (Mean Time Between Return)
The MTBR is derived by combining the MTBF and NFF Ratio and is equal to the average number of hours that will elapse before a component is returned for repair. Some of the returns will be true failures and some may be No Fault Found.
NFF Ratio (No-Fault-Found Ratio)
The NFF Ratio is a measure of how many components will be returned for repair which are not really broken. The NFF Ratio depends on several factors such as the experience and training of users and support staff, the accessibility of the product, and the availability of tools, test equipment and facilities for testing the component prior to return. In specialist installations where the end user is supported by a team of highly experienced well trained and well-equipped engineers the NFF ratio can be as low as 1-2%. In consumer applications or in installations where there is a high degree of user interface or where the component is easy to remove and return to the supplier this figure could rise to as much as 600% or more.
Part Number
The unique part number of the equipment under analysis.
Project
The name of the project under analysis.
Repair Delay
A measure of how long it takes for a spare part to be dispatched for repair and returned to the user’s store once it has been repaired.
Stock-Out-Risk
The probability that a spare part will not be available in the spares pool when demanded to carry out a repair during the Repair Delay period. For example, a stock-holding of 10 spare parts might have a 10% stock-out-risk in a 30-day Repair Delay period. This would mean that 9 times in 10 the demand for a spare part would be satisfied and 1 time in 10 it would not.
Store or Depot
The store that supports the systems under analysis.
Systems in Service
The number of systems supported by the store. For example, imagine a certain store or depot supported 2000 mobile phone antenna masts and each antenna mast had 6 power amplifiers. The Systems in Service would equal 2000 and the Units Per System would equal 6.
Total Units in Service
The total number of operational units supported by the store. If there were 2,000 Systems in Service and 6 Units Per System, then there would be 12,000 (2000 x 6) Units in Service.
Unit Cost
The cost of the product or component being analyzed.
Units Per System
The number of systems supported by the store. For example, imagine a certain store or depot supported 2000 mobile phone antenna masts and each antenna mast had 6 power amplifiers. The Systems in Service would equal 2000 and the Units Per System would equal 6.