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: imperfection Deficiency: lack of conformance to specs Fault: Cause of failure Malfunction: 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 5 years), proportional to the probability of service over a period of time, T.

fail in = performs stated function , without failure time.

(even with misuse) in the stated environment , for a specified period of

Vanderbilt: Reliability & Risk Engineering & Management

NSF IGERT awarded 2001 $2.7 M over 5 years BME/ChE/CE/EECS/MT/Math/ME/Owen 2 year support toward PhD Sankaran Mahadevan, CE

Infant Mortality Joints, Welds, Misuse <-Useful Life -> Contamination, Screening, Design, Burn-in Time -> Wearout Corrosion, Cracking, Wear, Crazing, Shorts -  Design, Preventive Maintenance, Replacement, Repair

Misassembly <- Useful Life -> Time-> Friction, Fatigue, Erosion, Corrosion, Cracking, Lack of PM PM, Replacement

Debug errors, Spec. Errors, Special Cases Time ->

QI Lawsuit Time -> QI PM Lawsuit

Is this a reliable ventilator?

Maude Complaints - XXX Series

2006 2005 2004 2003 2002 2001 2000 1999 1999 2000 t 2001 2002 2003 2004

Date complaint recieved

2005 2006

Product Liability

Negligence - legal Strict Liability - legal Breach of warranty – legal Defects Failure to warn

Negligence

You owe a duty of care to another The standards for that care have been breached As a result a compensable injury results There are damages or injury to the plaintiff

Strict Liability

The PRODUCT dangerous.

is defective or 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 expectations Risk/benefit State of the art Defective warnings Inadequate 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 recall Fluidized air therapy bed X-ray/Cobalt therapy accident Morphine infusion 3 hours not 24 LMA – cyanosis (see MAUDE)

Some final key phrases

Misuse Negligent selection Failure to inspect Use with knowledge of defect Alterations Disclosure through MAUDE (FDA) Disclosure through CPSC (non-FDA)