Quality Control and Improvement, Reliability, Liability

P. King/Chapter 13 overview

Reliability is:

A characteristic that describes how good a device is.Must be planned for, designed in both in terms of the initial product and in maintenance of that product.

Failure is:

The degradation of the performance of a device (process) outside of a specified value AND non-performance or inability to perform its function for a given time period within specified conditions.Defect: imperfectionDeficiency: lack of conformance to specsFault: Cause of failureMalfunction: unsatisfactory performance

Failure Measures

Real life failure: fact of life, define normal operation, anticipate worst, try to design out.Failure rate typically = #failures/unit time = failures/million hours for devices.

Unreliability is:

A measure of the potential for failure of a device (or process.)Leads to high cost, wasted time, inconvenience, poor reputation, unsafe operation, … - 9/9/99 more than 10,000 stepladders recalled by Home Depot – steps too short, improperly attached (RIDGID ladders, Louisville Ladder Co, Louisville KY)

Quality is:

The ability to provide stated needs NOW (and is implied during warranty period.)Warranty period: that period of time that you guarantee to refund/replace/fix your product.

Safety & Quality in Health Care:

HHS Secretary Tommy G. Thompson today (10/11/2001) announced the release of $50 million to fund 94 new research grants, contracts and other projects to reduce medical errors and improve patient safety.This research initiative is part of HHS' broader efforts to improve the quality of care in America and better assure safety across health care settings. 

Reliability Implies:

MTBF of x years (for example, e-1 fail in 5 years), proportional to the probability of service over a period of time, T. = performs stated function, without failure (even with misuse) in the stated environment, for a specified period of time.

Vanderbilt: Reliability & Risk Engineering & Management

NSF IGERT awarded 2001$2.7 M over 5 yearsBME/ChE/CE/EECS/MT/Math/ME/Owen2 year support toward PhDSankaran Mahadevan, CE

Infant Mortality

<-Useful Life ->

Wearout

Joints,Welds,Contamination,Misuse

Corrosion,Cracking,Wear, Crazing,Shorts

Screening,Design, Burn-in

--Design,PreventiveMaintenance,Replacement,Repair

Time ->

Failu

re R

ate

Failu

re R

ate

Time->

Friction,Fatigue,Erosion,Corrosion,Cracking,Lack of PM

PM,Replacement

Misassembly

<- Useful Life ->

Failu

re R

ate

Time ->

Debug errors,Spec. Errors,Special Cases

Failu

re R

ate

Time ->

QI

QIPM

Lawsuit Lawsuit

Maude Complaints - XXX Series

1999

2000

2001

2002

2003

2004

2005

2006

1999 2000 2001 2002 2003 2004 2005 2006

Date complaint recieved

Date

of

Man

ufa

ctu

re

t

Is this a reliable ventilator?

Product Liability

Negligence - legalStrict Liability - legalBreach of warranty – legalDefectsFailure to warn

Negligence

You owe a duty of care to anotherThe standards for that care have been breachedAs a result a compensable injury resultsThere are damages or injury to the plaintiff

Strict Liability

The PRODUCT is defective or dangerous.Risk is too high (risk/benefit higher than competition, etc.)

Breach of Warranty

Implied Merchantability (“King’s Pacemakers”)Implied Warranty for particular purpose (pacemaker)Breach of express warranty (written or oral contract: cures 100%)

Defect

Actual defect (sharp edges, …)Consumer expectationsRisk/benefitState of the artDefective warningsInadequate guarding…

Failure to warn!

You have a duty to warn. If you do not warn that coffee is hot, you are likely to get in trouble…

Examples

Coffee burn“found with head trapped in side rails…”Stepladder recallFluidized air therapy bedX-ray/Cobalt therapy accidentMorphine infusion 3 hours not 24LMA – cyanosis (see MAUDE)

Some final key phrases

MisuseNegligent selectionFailure to inspectUse with knowledge of defectAlterationsDisclosure through MAUDE (FDA)Disclosure through CPSC (non-FDA)