Product Liability Committee

A product defect, a condition listed above, An Engineering Perspective could be the result of a manufacturing or pro- duction error. A defect could occur in a prod- uct’s materials, design, contents, construction, finish, packaging, warnings and/or instruc- Consumer tions. It is important to note that not all prod- ucts that present a risk of injury are defective. For example, the cutting ability of a kitchen knife is not a product defect for two reasons: Product Recalls 1) a dull blade inherently lacks utility, and 2) the risk associated with a sharp blade is con- sidered reasonable and obvious. by Jason L. Hertzberg, Ph.D., P.E. In determining whether a risk of injury makes a product defective, the CPSC consid- ers the following questions: • What is the utility of product (i.e., what The decision to notify the Consumer Prod- failing to inform the government in a timely is it supposed to do)? uct Safety Commission (CPSC) and inves- manner about products that allegedly posed • What is the nature of the injury that tigate the need for a recall of a consumer a danger to young children. See http://www. might occur? product is a very difficult one for any com- cpsc.gov/cpscpub/prerel/prhtml05/05138.html. • What is the need for the product? pany. In 2003 alone, 280 consumer product Given the trend outlined above and • What is the exposed population and po- recalls were issued. The Trouble with Recalls, the fact that only general CPSC reporting tential risk of injury? Consumer Reports, August 2004, pp.12–17. requirements exist, it is beneficial to review • What is the CSPC experience with the According to the CPSC, incidents involving both the existing requirements and factors product? consumer products account for over $700 to consider when deciding whether to report • What other information sheds light on billion dollars annually. See http://www.cpsc. to the commission and when it is necessary the product and the patterns of use? gov/CPSCPUB/PUBS/REPORTS/2005Plan.pdf. to initiate a consumer product recall. See http://www.cpsc.gov/BUSINFO/8002.html. In November of 2004, the U.S. Court While there are different requirements In determining if a substantial product of Appeals affirmed the CPSC reporting for reporting depending upon the circum- hazard exists, the commission considers the requirement and the ability of the commis- stances, this article will address only those following factors: sion to impose civil penalties for not report- pertaining to Section 15b of the Consumer • Pattern of Defect—Is there a product ing in a timely manner. The court agreed Product Safety Act (CPSA). The CPSA states defect that could or has directly resulted that the CPSC must be notified about poten- that manufacturers, importers, distributors in a “pattern” of failures? tially dangerous products even before they and retailers (MIDRs) must notify the CPSC • Number of Defective Products in Com- are found to be defective and that separate within 24 hours of obtaining information merce—One defective product can be offenses exist for every product not reported. that reasonably supports the conclusion that the basis of a recall if an injury is likely In addition, it was determined that proof of the product exhibits one or more of the fol- or could be serious. a defect is not required before a civil penalty lowing conditions: • Severity of Risk—Is there a risk of a seri- can be imposed. In March of 2005, a record • Fails to meet a consumer product safety ous injury? civil penalty of $4 million was levied against standard or banning regulation; • Likelihood of Injury—Consider the a large children’s product manufacturer for • Contains a defect which could create a sub- number of injuries that have occurred stantial product hazard to consumers; or could occur given the intended or rea- • Creates an unreasonable risk of serious sonably foreseeable use or misuse of the injury or death; or product as well as the population group • Fails to comply with a voluntary standard that is exposed. It is important to note upon which the CPSC has relied under that it is not necessary for any product the CPSA. failures or injuries to have occurred for a See 15 U.S.C. 2064. product to be recalled. Id. The remainder of this article outlines a basic engineering approach that can help Dr. Jason L. Hertzberg heads Exponent’s Mechanics and Materials practice in Chicago. to determine, from a technical perspec- His practice consists of product liability, product recall/CPSC issues, and engineering tive, when and if to report to the CPSC and support for industries ranging from consumer products to medical devices. Dr. Hertz- whether it is necessary to initiate a product berg also has a background in consumer electronics, having served as Director of recall. Reporting merely signals the begin- Competitive Analysis for Palm, Inc. and as a technical spokesperson for the company. ning of an investigation period and does not

December 2005 © 2005 DRI. All rights reserved. 59 Product Liability Committee necessarily result in a product recall. It must There are many aspects of an engineer- ings and labels on the product should be be mentioned that reporting is encouraged ing failure analysis investigation. Depending recorded, including serial number, model by the CPSC, even if it is unclear if a real upon the situation, certain information may number, product name and brand, and danger or hazard exists. It is imperative that not be available to the analyst. As would be batch information. This type of informa- the company seeks legal counsel to assist in expected, the more information that is avail- tion can sometimes be useful in limiting this decision. able for review, the more likely a complete the extent of affected product, as discussed In an engineering analysis of this kind, understanding of the cause of a product in a later section. It is also prudent to per- there are typically four basic questions that failure can be achieved. Some of the infor- form a thorough examination of damage need to be answered: mation that can provide insight during an to the product. Mechanical damage (e.g., • Why has the product(s) ‘failed’ or is likely investigation is listed below: impact, wear) can provide insight into the to fail? • Incident information including what is use or misuse of the product and the loads • How many products are affected? known about the events leading up to the or stresses that the product was subjected • What is the risk and severity associated incident(s), the incident itself, post inci- to during its lifetime. Thermal damage pat- with the ‘failure’ of the product? terns can provide insight into the origin of • What is the most appropriate Corrective Reporting is encouraged by heat, smoke or open flame. In some cases, Action Plan (CAP)? it is possible to narrow down the region or the CPSC, even if it is unclear if even the component responsible for a fire, Why Has the Product Failed depending upon the degree of damage to or Is Likely to Fail? a real danger or hazard exists. the product. It is important to note that In order to determine why a product has thermal damage patterns can sometimes failed, a multidisciplinary approach is typi- dent activities, eyewitness accounts, inci- be easily marred or removed during normal cally required. Many investigations of prod- dent reports, and photographs. handling or product removal from the inci- uct failures require expertise in a variety of • The “fingerprint” of the product includ- dent site. Careful attention should be given areas including materials science, corrosion ing the manufacturing date of product, to preserving both the product condition engineering, mechanical engineering, elec- serial number, specific model and batch as well as the surrounding environment for trical engineering, thermal sciences (i.e., fire numbers, and the manufacturing facility subsequent analysis of thermal damage pat- cause and origin), manufacturing processes where the product was assembled. terns. A powerful non-destructive method and human factors (e.g., man-machine inter- • Application specific information including used to examine the internal damage to a actions, evaluation of warnings, labeling, and how and where was the product used. product is x-ray imaging, a technique simi- instructions). In order to determine why a • Service/maintenance history of incident lar to that performed by medical doctors to product has failed, it is necessary to deter- unit(s) and similar models, including any look inside the human body without per- mine the failure mechanism and, in some reports of previous problems. forming surgery. This method utilizes the cases, the root cause. • Available documentation including de- fact that different materials of construction It is important to distinguish between the sign, subassembly, and manufacturing have different densities that show up as dif- failure mechanism and root cause. A failure assembly drawings, operation manuals, ferent shades of gray in an x-ray image. mechanism is the mechanism by which the warnings and instructions. As most products are comprised of vari- “failure” takes place while the root cause is • Timeline of product evolution includ- ous materials, including different plastics, the fundamental, underlying reason for the ing changes in materials of construction, metals and ceramics, it is possible, in many failure event. As an example, consider the product design, components, construc- cases, to look “inside” a product using x-rays hypothetical case of an electrical appliance tion, finish, packaging, warnings, and/or and determine the extent of damage to the that ignites, leading to a residential fire. In instructions. inner components without disturbing their this case, one potential failure mechanism • Quality control procedures implemented condition or position. is overheating from within a thermostat, from raw material vendors through man- In many cases, there is a limit to the which causes the component housing to melt, ufacturing and assembly lines, includ- amount of information that can be gained thereby exposing the hot, electrical contacts ing material certification sheets supplied from a non-destructive evaluation. After of the thermostat to the flammable plastic by vendors as well as other certifications all non-destructive methods have been cover of the consumer product. A possible (e.g., ISO certified). exhausted, a destructive examination is typ- root cause for this scenario would be corro- Aside from a review of the aforemen- ically in order. However, once a product is sion of the silver electrical contacts within tioned information, the first step in deter- altered from its original condition, valuable the thermostat that leads to a high-contact mining the failure mechanism of a product information can be lost if proper procedures resistance and the intense, localized heating is performing a non-destructive analysis are not followed. Therefore, it is very impor- described in the failure mechanism above. of the incident unit. This typically consists tant to carefully perform any disassembly of While it is always desirable to determine the of an overall visual examination and photo the product and photo document the indi- root cause of failure, in some cases identi- documentation of the product from various vidual steps of the destructive examination. fying the failure mechanism is sufficient in angles, as well as the surrounding environ- In addition, if legal action has been taken or order to implement an appropriate CAP. ment, if at all possible. All available mark- is pending as a consequence of the product

60 For The Defense Product Liability Committee failure, it may be necessary to perform any warning labels. For example, “Danger,” rials of construction? Is the problem with destructive analysis in the presence of other “Warning,” and “Caution” are terms used a defective component? Is this compo- parties in order to avoid problems related to to convey different levels of hazard. See nent single-sourced or multiple-sourced? evidence spoliation. ANSI Z535.4-2002, American National If the problem is with only one compo- After the product is disassembled, it Standard for Product Safety Signs and La- nent supplier, is there an easy way to sep- is useful to examine the components at bels, American National Standards Insti- arate out the unaffected population? high magnification using different types of tute, Inc.; • Is this a batch problem tied to a manu- microscopes in an effort to determine how • Ineffective usage of background color facturing process deviation or tempo- a component performed or how it failed. By or foreground text font and/or color for rary process change implemented based using different lighting conditions with an warning labels; on other constraints? optical microscope, for example, it may be Exemplar products (i.e., new and iden- • Is this a problem only with certain mod- possible to determine the origin of the crack- tical products) are very useful as bench- els of product? For example, are there ing, sequence of damage, or the nature of a marks with respect to construction and differences in product construction that failure (e.g., single overload event, repetitive function. In addition, laboratory testing of determine if the product is susceptible to loading). In addition, it may be possible to exemplar products makes it possible to gen- a specific failure mode or unsafe condi- determine the temperatures achieved during erate both normal use and abnormal use tion? Can this be verified empirically? an overheating event. For example, in some conditions. This can yield valuable infor- • Are there geographical considerations that cases, the color of a metal oxide is a sensi- mation and help determine the cause of the make it possible to rule out certain popu- tive function of the temperature at which it product failure. lations of product? For example, are prod- is formed. Once an optical examination has ucts much more likely to overheat and been done, it is sometimes helpful to exam- How Many Products Are Affected? cause fires in certain countries based on ine the failed or damaged component or Once a failure mechanism, and possibly the standard power outlet voltages (e.g., United product using a Scanning Electron Micro- root cause, has been established for a product, States 115 volts, Europe 230 volts)? scope (SEM). This type of microscope allows it is important to determine if this is an iso- for an examination at much higher magni- lated incident involving a single product or What Is the Risk and Severity fications than light microscopes since it is whether there is evidence of a “pattern of Associated with Failure? based on the use of electrons rather than defect.” A strict definition of a “pattern of In addition to determining the size of the light for imaging purposes. In some cases, defect” is not provided by the CPSC. There- affected population, it is necessary to assess it is possible to identify microscopic fea- fore, the existence of a “pattern of defect” the risk of product failure in the field. Is the tures at very high magnifications that indi- depends on the specific circumstances asso- hazard impossible, possible, probable or cate the nature of the failure or the existence ciated with a given product investigation. virtually inevitable? In determining where of a material or manufacturing defect. In Review existing databases including listings the risk falls within this spectrum, it is nec- addition, it is also possible to determine of product returns, customer complaints and essary to determine the conditions under the chemical composition of a component reported incidents should be conducted, pref- which a defect manifests itself. How many using Energy Dispersive X-ray Spectros- erably on an ongoing basis, in order to help independent steps are required for the fail- copy (EDS), a feature available on many determine the number of failures of a spe- ure to occur? Is this a single-step criterion or SEMs. This can be helpful in determining the cific product and compare this information are multiple steps required? If possible, it is materials of construction, as well as the exis- with historical data. Is this the first product advantageous to determine or approximate tence of contamination or corrosion prod- to come back or is this the 12th product in the probability associated with each respec- ucts which may have led to failure. the past three weeks to be reported? If there tive step or event, either analytically or Important insight into the foreseeable is a spike in the number of field returns, the empirically. The probability of a failure can use and misuse of a product can also be next question is whether the failures are sim- then be calculated by multiplying the prob- gained by reviewing the warnings, labels ilar in nature. This requires a detailed exam- abilities of each event. For example, if there and instruction manuals that accompany a ination of additional incident products. If is a 50 percent probability of occurrence for product in the marketplace. As mentioned additional incident products are not avail- each of the three separate events required to previously, a product defect can be the result able to examine, it is beneficial to review all produce a failure, the probability of failure is of inappropriate product labels or product available photographs and reports associated calculated to be 12.5 percent. This can help literature. Some of these problems include: with these incidents. to determine where the risk falls within the • Unclear or inaccurate description of re- If a “pattern of defect” is established after spectrum of occurrence. quired steps and/or precautions involved a review of the failed products, it is neces- It is insufficient to merely determine in assembly, operation, or maintenance sary to determine how large of a population the risk of a product failure and ignore of the product; of product is affected. Some of the impor- the severity of the hazard. For example, it • Ineffective placement of warning labels tant questions to consider in this determi- is much more serious to have 1,000 prod- on the product; nation include: ucts in the field that have a small chance of • Ineffective or inappropriate use of tex- • Is this an inherent design problem? For failure but would cause serious harm com- tual and pictorial components of the example, is the problem tied to the mate- pared with one million products in the field

December 2005 61 Product Liability Committee that will most likely fail but would cause lit- an “end point” (i.e., fire) is specified and to both assess the ease of implementation tle or no harm. In fact, in an extreme case then followed by identification of all of the and determine what can go wrong during such as that mentioned earlier, one defec- associated elements in the system that could the process. In the case of a field fix, provid- tive product can be the basis of a recall if cause this “end point” to occur. ing detailed instructions and schematics to an injury is likely or could be serious. In repair personnel or customers is important, order to assess the severity of a hazard, one What Corrective Action Plan and walking through these procedures with approach is to perform targeted laboratory (CAP) Is Most Appropriate? individuals unfamiliar with the product can testing of “worst case” scenarios using a If the decision to recall a product is made be an insightful exercise during the develop- conservative approach to foreseeable con- based upon the answers to the questions ment of these instructions. The bottom line ditions. This can be a very useful tool to listed above, it is necessary to consider the with any CAP goes back to the KISS princi- determine the “end point” in the event of a most appropriate CAP. A CAP refers to any ple of basic design, Keep-It-Simple-Stupid. failure. For example, this approach can be type of remedial action taken by a com- used in some instances to determine if the pany in response to a safety issue with one Summary malfunction of an electrical product that is of its products. Any CAP is called a “recall” Determining if a consumer product needs prone to overheating could lead to a fire, and for the purposes of public awareness. How- to be recalled from the field is a very diffi- if this fire would be contained within the ever, a CAP can be one of many different cult and important decision that involves product or could spread to its surroundings. actions, including a customer fix using a both legal and engineering considerations. This information can be a critical factor in repair kit sent from the manufacturer, com- While general guidelines exist in order to aid deciding whether or not to recall a product. plete removal of all products from the field, in this determination, every product and cor- In addition to an empirical approach, ana- or an exchange for a new model. Even if the responding set of circumstances is unique, lytical tools exist that can help evaluate the original hazard(s) will be sufficiently miti- which means that investigations typically risk and severity associated with various gated or eliminated by implementing the fix, need to be handled on an individual basis. failure scenarios. These tools include Fail- it is possible that new hazards can be intro- Although all valuable information may not ure Modes and Effects Analysis (FMEA), as duced as a result of the action. Therefore, it be available in all cases, a basic framework for well as Event Tree Analysis (i.e., visual rep- is prudent to evaluate a CAP using an FMEA conducting the technical portion of a product resentation of all events which can occur in or comparable approach, especially if a cus- investigation can be built around the four a system) and Fault Tree Analysis, whereby tomer fix is the preferred solution, in order basic questions outlined in this article.

62 For The Defense