1. Cummins ISB LTMS2
This package contains charts and figures that supplement the LTMS2 template put forth by Statistics Task Group.
LTMS2 Template document name:
“Cummins ISB LTMS Version 2 Proposal.docx”
The LTMS2 template contains possible values for the various chart limits. Page 2 of this document summarizes these values.
Pages 3-11 show the control charts and alarms of LTMS1 and proposed LTMS2.
Pages contain some comments on Excessive Influence calculations and alarms in LTMS1&2.
Art Andrews
November 30, 2010

2. LTMS1 LTMS2 lambda=0.2 No Fast start
Fast start with three reference oil results
No e alarms
Level 1 e limit = (e.g. hardware change)
Level 2 e limit = (reduced interval)
Level 3 e limit = (immediate re-reference)
No Z alarms
Level 1 Z limit = (dead band)
ACWS
Level 2 Z limit = +/ (immediate re-reference)
ATWL
Level 2 Z limit = +2/-1.5 (immediate re-reference)
Shewhart severity (Y) limit = +/-1.96
(immediate re-reference)
No Y Alarms
No Excessive Influence calculation
Excessive Influence calculation; uses Level 3 e limit as its tolerance
No extended reference intervals
Ee = 1.05
Ez = (eligible for +20% and +40% reference intervals)

3. focus: Shewhart severity (Y) alarms
LTMS1
focus: Shewhart severity (Y) alarms

4. ACSW

5. ATWL

6. LTMS2
focus: e alarms

7. ACSW

8. ATWL

9. Comparisons LTMS1 / LTMS2
focus: number of reference interval extensions and reductions

10. Reference Interval Extensions and Reductions
37 total reference oil results
12 were calibration tests
37-12=25 tests were eligible for extended intervals
9/25 (36%) received extended intervals in LTMS2
7/37 (18.9%) failed in LTMS2

11. RMSE
overall for all labs
RMSE
by lab

12. Comments on Excessive Influence and Alarms
Appendix
Comments on
Excessive Influence
and
Alarms

13. Tappet weight loss severity charts showing Excessive Influence calculation
Excessive Influence calculation adjusted Y results from green filled circle to cyan circle.

14. The dotted line is Level 2 e alarm, and solid line Level 3 e alarm
Tappet weight loss precision charts showing e
These are examples of results that trigger alarms in LTMS2 but not LTMS1. While their Y results are not excessive, their e values are high (~1.1) because they outlie the lab’s Z baseline (~-0.9).
This is an example of a result that would trigger alarm in either LTMS1 and LTMS2. It has a high Y value that exceeds LTMS1 limit. It has a high e value because its result (~2.8) outlies the lab’s Z baseline (~0.1).
The dotted line is Level 2 e alarm, and solid line Level 3 e alarm