case study

Industry: Airline

Improving Aircraft Engine Disassembly

FOCUS: Improve NOEF (NO Evidence of Failure) rate.


Turnaround time (TAT) for engine repair and overhaul was taking a business on the average of 62 days. The critical-to-quality (CTQ) was 45 days. The customers had to compensate for the poor TAT by having more engines in inventory. Not only was the customer dissatisfied, the business had to keep excess inventory on hand to prevent further degradation of the TAT.


Using QFD and following guidance from the steering committee, the team determined they should focus their attention on the engine disassembly process. A goal was set to decrease engine disassembly by 50%. In the Measure Phase the current state was mapped and validated. It was determined that the team would focus on the time it took to break down the engine and clean each part. The upper spec limit was set at 10 days. After conducting a Measurement System Analysis (MSA), it was decided that the material routing process exhibited excessive variation. Data showed that 90% of the time the process exceeded the 10-day performance standard. In the Analyze Phase, among the tools used, was the cause-and-effect diagram. The two most significant areas highlighted were the disassembly variation and late material routing. Most of the tools used in the Improve Phase were Lean … flow of material, spaghetti diagrams, Standard work, kanbans, 5S, and visual management. Standard Operating Procedures were developed and communicated throughout the process and control charts were implemented at key points.


Variation in the cleaning and inspection process was reduced by 57% (surpassing the goal). The overall engine repair and overhaul TAT was reduced 37%. The reduction in parts inventory and Work-in-Process (WIP) and an increase in labor productivity produced nearly $6 million in savings.

* For additional information see iSixSigma Magazine, January/February 2006, pgs 45-51, “Improving Aircraft engine Disassembly” by Jonathan Atwood.