Table of Contents
Advertisement
Page 34 of 136
Chapter 3 — Spares planning
553-3121-100
Standard 2.0
F — The failure rate of a particular spares item.
T — The turnaround time for repairing a failed spares item in hours.
The formula produces an NFT value. The number of spares required for a one
year period may be found by looking up the NFT value in
of spares required," on page
Procedure 1 provides an example of spares planning for the NTMW07 card.
Procedure 1
Determining spares quantities for a one year sparing interval
1
Determine the number (N) of the particular item that is being serviced
by the depot.
For example, a single depot services 10,000 Universal Trunk Cards.
2
Determine the failure rate (F) for the specified item.
From the Failure rates listed in
Universal Trunk Card is 0.44.
3
Determine the turnaround time (T) in hours.
Assume a centralized depot with a turnaround time of 48 hours.
4
Calculate the NFT value by multiplying N x F x T.
NFT = (10,000 units x
From the NFT values in
NFT value 0.21= 4.
Therefore, four NTMW07 cards are needed to last an interval of one
year when servicing 10, 000 NTMW07 cards.
—————————— End of Procedure ——————————
September 1998
37.
Table
20, the failure rate for the
0.44
x 48 hours)/1,000,000 = 0.21
Table
21, the number of spares required for
Table 21, "Number
Advertisement
Table of Contents
