Decision making process and manual for diagnostic trend analysis

A decision making process for evaluating performance shifts identified during a diagnostic trend analysis of data obtained from a gas turbine engine, said process comprising the steps of:

• determining whether each performance shift can be attributed to a cause not related to an engine condition requiring maintenance;
• for performance shifts that cannot be attributed to a cause not related to an engine condition requiring maintenance, checking the persistence and magnitude of each performance shift;
• for performance shifts not having a sufficient persistence and magnitude, determining for each performance shift whether said gas turbine engine data indicates that an urgent condition may exist;
• for performance shifts having a sufficient persistence and magnitude or where said gas turbine engine data indicates that an urgent condition may exist, determining whether said gas turbine engine has been subject to a recent maintenance action;
• where said gas turbine engine has been subject to a recent maintenance action, determining if each performance shift can be attributed to said recent maintenance action;
• for performance shifts that cannot be attributed to said recent maintenance action and that have a sufficient persistence and magnitude, determining for each performance shift whether said gas turbine engine data indicates that an urgent condition may exist;
• for performance shifts that cannot be attributed to said recent maintenance action, using traditional and historical performance shift patterns to identify potential causes of each performance shift;
• and
• subsequently ranking said identified potential causes in most likely order.

A manual for guiding a user through a decision making process for evaluating performance shifts identified during a diagnostic trend analysis of data obtained from a gas turbine engine, said manual comprising:

• a flow chart flow chart setting forth the steps of said decision making process;
• a false data check table having a number of questions designed to determine whether performance shifts can be attributed to a cause not related to an engine condition requiring maintenance;
• a persistence and magnitude table for indicating whether a performance shift's persistence and magnitude is sufficient to consider taking action on said performance shift;
• a notification criteria table having a number of questions designed to determine whether said gas turbine engine data indicates that an urgent condition may exist;
• and
• traditional and historical pattern match tables that identify potential causes of performance shift.