# Manual for Life Cost Based FMEA

3.

Number of components in each beam line In order to count the number of components in each previously specified category, the FMEA team will have to consult with drawings and lattices of the beamlines.

4.

Number of components in the ILC

To predict the frequency of failure for the ILC we need to know how many components of the same categories there will be in the ILC.

Step 4. Fill out the Availability table as shown in Table 8 for each type of component in a separate table. Within the table each row corresponds to a particular beamline’s running period.

Beam line, operation hours (Run hours), and number of components in the beam line are all found in the previous steps.

•

Component hours is the product of Run Hours and # of Components in the listed beamline. This is a parameter created to calculate the average availability of a single component at SLAC.

•

# of failures indicates the number of component failures that occurred during that operation period as found by searching the CATER/AREMIS databases.

•

MTBF is calculated by dividing Component hours by the # of failures during that period. The unit is in hours.

•

TR is the total repair time for all of the failures during that period. This is the sum of beam loss time for that period. The unit is in hours.

•

MTTR is total repair time (TR) divided by the number of failures for that period. The unit is in hours.

•

Availability is calculated using Equation 6. This calculation yields the empirical availability for one component of certain type at SLAC.

Table 8. Availability Table

Date

Beam

Run

# of

Component

# of

MTBF

TR

MTTR

Availability

Line

Hours

Components

Hours

Failures

(hr)

(hr)

(hr)

5/1/97

SLC

8828

2300

20,304,400

15

1,353,626

136

9.06

0.999771

~ 6/8/98

Step 5 Calculate Availability for the entire system

The average availability of a single magnet can be calculated by adding the total Component Hours and MTBF for the entire year period. Most of the components in the ILC are run in series without redundancy. Thus, if one fails, the whole

FMEA MANUAL By S. Rhee and C.M. Spencer

18/26

January 2009