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Track 2 Session 8
2:20 to 3:20 p.m. Thursday March 27, 2008
Using FRACAS Data to Analyze the Achieved
Reliability for an Aircraft Radar Operated by the Swedish Air Force
During the period 1971-01-01 to
2000-12-31, more than 100 Saab AJ 37 Viggen aircraft were operated
by the Swedish Air Force. During this period, more than 212.000
flight hours were accumulated. All discovered failures were reported
using a Failure Reporting, Analysis and Corrective Action System
(FRACAS) called DIDAS. The reported failures were classified as
relevant or not relevant. The classification was carried out in
cooperation by representatives from the Swedish Air Force, the
Central Workshop and the producer of the radar system, i.e. Saab
Microwave Systems (formerly Ericsson Microwave Systems AB). This
case study illustrates how the analysis of FRACAS data can be a very
effective and important tool for reliability work employed by both
the user and the producer in order to address all failures reported
from operation and maintenance. It can help to:
- Analyse and correct failures
- Perform better predictions of
failure rates and MTBF by using field data in the predictions
according to similarity analysis
- Find out when infant mortality
period ends
- Find out the time for the best
period
- Find out if a wearout period
exists
- Calculate the need of spare
parts initially and later on
- Calculate the amount of NFF
(No Fault Found)
- Estimate reliability growth
period in theory and practice
- Define the need of design
changes
- Define need of preventive
maintenance
- Define safety-related failures
Key Words: FRACAS (Failure
Reporting and Corrective Action System), Reliability Prediction,
MTBF, MFTBF (Mean Flight Time Between Failures), Similarity
Analysis, Best Period, NFF (No Fault Found), Reliability Growth
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