טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentWeizer Erez
SubjectAvailability Improvement of an Impermeable Power Unit for
Small Vessels of the Israeli Navy
DepartmentDepartment of Quality Assurance and Reliability
Supervisor Dr. Abraham Rotem


Abstract

For the past few years the Israeli navy has been operating a relatively small number of unique and fast naval vessels.

These vessels are unique due to their method of operation, their small quantity and the special and extreme conditions under which their propulsion systems are expected to operate.
Recently, malfunctions occurred more often and it seems that the availability and the preparedness of these vessels were unsatisfactory and that the main reason for this was failures in the Impermeable Power Unit.
This study's goal is to reveal and examine the main causes for the decline in the availability and operability of the vessels, and to recommend ways to improve the situation. 
The study included an attempt to reveal the causes for the situation from both a technical and a procedural point of view.
The method of study included gathering historical data. We divided different malfunctions into categories such as fuel system, oil system, propulsion system and miscellaneous malfunctions.
Our conclusion from this study is that the Impermeable Power Unit malfunctions were the main cause for the decline in the availability and condition of the vessels.
 An additional mapping of the reasons for malfunction in the Impermeable Power Unit took place. We attempted to classify the engines into 3 types: good, poor, and good with poor maintenance.
All the findings of the study were classified into subjects and causes for failure were examined and analyzed thoroughly. After careful examination of the malfunctions we found out that most of the engines were poorly maintained and that the engines quality was not the main source for the malfunctions.
The reasons and findings regarding bad maintenance were classified into 2 categories: technical and administrative/ procedural.
In parallel we attempted to examine if there was a common factor/ distribution for all the engine types mentioned above as a group and separately.
We did this in attempt to develop a method of forecast for engine malfunction which could help us foresee engine part consumption, develop work plans, and examine worthiness of technical improvement and more.
 
We used the Maximum Likelihood Estimators method in relation to the distribution of exponent and weibull.
The examination included classifying the engines separately and as a group into the categories mentioned above. The results of the comparison did not allow classification into whole groups but rather into sub groups of the mentioned distribution. 
 The amount of engines is too small for us to achieve well-based results especially when the only relation we found was in the sub-group level.
After analyzing the findings we submitted recommendations for improvement divided into technical and procedural categories.
 After finishing the study we prepared a follow-up plan for examination of the implementation and efficiency of our recommendations for a period of one year.