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Posted: Feb 3, 2015

Emergency Response Vehicles and Failure Analysis

Analyzing why certain parts or systems fail in today's emergency response vehicles (ERVs), commonly referred to as failure analysis, should be considered one of the most important functions of any maintenance organization and should be part of its preventive maintenance program.
Chris Mc Loone   Christian P. Koop

I think some failures are too easily relegated at face value to normal wear and tear when the actual problem may go much deeper. Departments should address why it failed. It can ultimately save the organization unnecessary equipment downtime and save big dollars at the same time. Additionally, it could lead to eventual equipment improvements industrywide.

Most in the ERV maintenance field should already have an adequate understanding of failure analysis and its importance. The main purpose behind this article is to discuss the basic failure analysis steps for those readers who may not be aware of them. I will also cover some of the common terminology associated with failure analysis and the steps involved in the process that departments sometimes do not follow correctly.

Underlying Problems

Finding out why a component or system failed catastrophically or had a shorter-than-normal service life is something that should be ingrained into a maintenance organization's operations and its technicians. It should not matter whether the maintenance operation is private, municipal, or governmental. The curiosity alone of finding out the reason behind a failure-not just making repairs or replacing parts-will separate the average technicians from the good ones. In some cases, a design or manufacturing defect may actually be the culprit. On the other hand, it could be a training issue involving misuse of the equipment leading to early failure. Keep in mind that equipment misuse or improper operation by the driver/operator can lead to instant failures. Many times an ERV will continue to operate normally, but eventually the part or system affected will fail prematurely. It could also be that equipment was not specified or built for the level, severity of service, or even the climatic conditions of an ERV's location.

The level of maintenance and the intervals may not be frequent enough or may not meet the basic minimum schedule recommended by the original equipment manufacturer (OEM). Keep in mind that most OEM-recommended maintenance schedules are minimum requirements and may need to be exceeded. The use of incorrect lubricants and fluids is another cause of failures and shortened service life. Yet another critical factor is operating ERVs beyond gross vehicle weight ratings (GVWRs), which will negatively impact entire drivetrain and chassis componentry service lives. Careful study and investigation of failures with the objective of finding the root cause will eventually point to one of the items mentioned above.

Don't Assume

To properly begin failure analysis, you must take on the role of investigator and never assume that the failed part is the problem. Taking notes to document the process is very important and a basic requirement. Speaking to the driver, if possible, and asking the proper questions should also provide useful information. Many times a good visual inspection by an experienced technician can quickly find the cause. However, in some cases, it may be difficult to find and may require consultation with the OEM or the parts manufacturer or even using specialized equipment.

Determining whether a part failed over time or experienced a one-time catastrophic failure is very important in failure analysis. Depending on what parts failed, do not clean them before the inspection, and leave them on the vehicle. Fo

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Posted: Feb 3, 2015

Apparatus Purchasing: Make It Simple, Part 2

Fire apparatus specifications (specs) have been characterized as proprietary, open, generic, manufacturers', design, performance, contractors', bid, purchasing, and even deceptive. Individual authors and speakers have their own descriptions for each that are often influenced by personal experiences and occasionally prejudiced by personal agendas.

By Bill Adams

That's life. This article will not address the content, intent, or partiality of any specification or the ramifications of using one in lieu of the other. That's a local matter-do what's best for your fire department. It does address the format in which a specification, and in particular a purchasing specification, is written. The objective is to make the document less confusing and easily readable.

A purchasing specification is a document written by an apparatus purchasing committee (APC) and promulgated (put to bid) by the authority having jurisdiction (AHJ) describing a fire apparatus it wants to purchase. Some commentaries portray writing fire apparatus purchasing specifications as an overwhelming task so technically oriented that only highly trained professionals should be allowed to undertake it. That is not necessarily true. Although there are specific legalities and guidelines APCs must follow, purchasing specifications that are overly lengthy and not easy to understand can cloud the process and discourage APC members. There may be spec writers who, for pecuniary reasons, may intimidate purchasers when describing the process.

Playing on Emotions

Beware of questions and statements such as, "Would you spend hundreds of thousands of dollars for a new home designed by a self-proclaimed architect with no credentials, no experience, and no education in engineering? Would you let an apprentice electrician design and install your home's electrical system? If you were an employer, would you let an employee lacking technical expertise spend half a million dollars of your money on a piece of intricate machinery? Why would you let any of those three write a set of purchasing specifications for your fire truck? Let a professional do it."

Playing on Expertise and Knowledge

Read between the lines when you are told, "You've got to be very careful writing specs for a fire truck. New apparatus must meet the requirements of no less than 10 National Fire Protection Association (NFPA) minimum standards with the primary document being NFPA 1901, Standard for Automotive Fire Apparatus. NFPA 1901's Chapter 2 makes reference to more than 70 publications from 15 organizations ranging from the Society of Automotive Engineers to the United States Government. NFPA 1901 sentence 2.1 says: ‘The documents or portions thereof listed in this chapter are referenced within this standard and shall be considered part of the requirements of this document.' So you'd better know what you're writing."

Purchasers shouldn't be intimidated. It's doubtful anyone working in the apparatus industry can name all the referenced publications or even the applicable NFPA standards! Most of the hard work has already been done-it's all inside NFPA 1901. Consequently, an APC doesn't have to concern itself with whether some component part meets a voluntary or a consensus standard of the American Society for Testing and Materials (ASTM), the American Society for Nondestructive Testing (ASNT), or a mandatory requirement by some obscure government agency.

For obvious reasons, vendors will write a purchasing specification for a fire department for no charge. For a fee, consultants and professional spec writers will also write them. Kudos and good luck to fire departments that write their own specs. As long as specifications are precise, concise, and understandable, it is immaterial who puts the pen to paper. Choosing a spec writer is a local decision. Making specifications easy to read is a smart one. Read more

Posted: Feb 3, 2015

Keeping the Lug Nuts Tight and the Wheels On

WESLEY D. CHESTNUT

Emergency vehicles are some of the heaviest vehicles on the road today. With water, aerial devices, and various types of equipment, some emergency vehicles can weigh 80,000 pounds.

This massive amount of weight rests on the tire and wheel assemblies of these vehicles, which are held to the axles by several wheel-attaching nuts, more commonly known as lug nuts. Having something so small, in comparison to the overall size of emergency vehicles, to keep critical components attached to the vehicles is quite impressive. It takes all of the lug nuts working together at the proper torque to keep the tire and wheel assemblies attached to the vehicle.

Importance of Proper Tightening

The required torque equates to clamp load, which keeps the wheel attached to the emergency vehicle. It takes appropriate torque on all lug nuts to keep the wheel attached. A single lug nut coming loose may have a domino effect on the remaining lug nuts or lead to damage on the wheel or wheel stud.

Inspecting the lug nuts and verifying torque are critical to the integrity of the wheel mounting. If a loose lug nut goes without notice and damage to the wheel stud or wheel occurs, a wheel could separate from the axle. The National Highway Traffic Safety Administration (NHTSA) has investigated previous incidents in which this may have occurred, and manufacturers have issued safety recalls in certain cases.

New Vehicles

During assembly, a new emergency vehicle's wheels and tires are installed on the axles, then tightened to the appropriate torque. In many cases, the axles' supplier may specify the appropriate torque for the lug nuts. These torque values equate to the clamping force intended to keep the tire and wheel assembly attached to the axles. Manufacturers may use a calibrated torque tool to achieve the appropriate torque in the appropriate sequence. After the emergency vehicle has gone through the assembly process and subsequent road testing, manufacturers ensure the lug nuts are tightened, again using a calibrated torque tool.

In certain cases, an emergency vehicle may be built in two or more stages, with the chassis cab being built in one facility and final assembly occurring at a separate facility that may be miles away. The chassis cab manufacturer may recommend that the lug nuts be inspected and torque verified on all lug nuts after receipt of the chassis cab and prior to delivery to the end customer. This is a precautionary measure to ensure the lug nuts have remained properly tightened to their recommended torque value.

Once "In Service"

After the vehicle is placed in service, it is even more important to inspect, or verify torque on, the lug nuts. The wheel studs and lug nuts often experience dynamic conditions such as impacts from traversing various types of terrain and heat generated by vehicle braking. Over time, these conditions may adversely affect the wheel, wheel studs, or lug nuts.

National Fire Protection Association (NFPA) 1911, Standard for the Inspection, Maintenance, Testing, and Retirement of In-Service Automotive Fire Apparatus, indicates that lug nuts are to be torqued to the manufacturer's recommendation. The frequency of this inspection may depend on an emergency vehicle's use. However, there is guidance within the standard that suggests verifying torque between 50 and 100 miles after wheel removal.

Federal regulations promulgated by the Federal Motor Carrier Safety Administration (FMCSA) include a minimum periodic inspection standard that departments can use as baseline criteria for emergency vehicles. This standard includes inspecting wheels and fasteners for loosening, cracks, stripping, or elongated holes in the wheels.

Lug Nut Torque Indicators

There are various methods of inspecting for loose lug nuts that include visual inspection or applying a

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Posted: Feb 3, 2015

Not So Fast

As I write this, an apparatus crash involving a ladder truck that overturned en route to a reported structure fire is still fresh in my mind. The accident occurred at the end of 2014, and a mechanical failure led to the apparatus operator having difficulty steering the vehicle, resulting in the rollover.
Chris Mc Loone   Chris Mc Loone

There was also an unfortunate coincidence in that this was the second time in several months a rig from this station was involved in a rollover. There were many who jumped to conclusions regarding this most recent incident. Although it's easy to make assumptions, it's important to remember not to react so fast.

Whenever an accident occurs, a department will conduct its own investigation to arrive at the accident's root cause. In many cases, this will involve an emergency response vehicle failure analysis, which columnist Chris Koop covers in this month's Apparatus: the Shops.

The fire department here conducted an investigation quickly and determined the cause of the accident to be the failure of five spring hanger bolts that connect the truck's frame to the axle. According to media reports, the apparatus's operator and passengers heard a pop, then felt the truck sag. The spring hanger bolt failure caused the axle to move slightly inward, resulting in the tire rubbing against the wheel well and making it extremely difficult to steer.

There are a number of lessons to be learned from this incident. First, I believe the injuries sustained in this accident were not more severe because the operator was driving the truck in a controlled manner. It was responding to a reported structure fire, but had he been driving recklessly, the results may have been much worse. My high school English teacher was fond of relating Latin expressions to us. One of his favorites was "festina lente," which translates to "make haste slowly." We all have a job to do, but we have to get there to do it. Should the unexpected occur, being in control of the vehicle will help reduce the chances of severe injuries or death.

Second, know your trucks. I know that sounds obvious, but who among us doesn't know our personal vehicles well enough to know when there is an odd vibration that wasn't there before or notice when a new sound emanates from the engine compartment? One of the items Koop discusses is that when investigating the failure of an apparatus component, a department must ask the right questions, and the apparatus operator can be of great help. In the above example, the operator and firefighters were all able to cite very specific things that occurred prior to losing control of the vehicle. Although they were very specific items, when you know your trucks, you'll know every shimmy and every odd sound. Report them immediately.

I will never forget when I had a truck stall on me, luckily in our highway yard, on a fuel run. The truck just died and would not start again. As I was driving it to the yard, I noticed it was hesitating-not enough to make me really nervous, but enough to be noticed. After it died, and was subsequently flatbedded to the repair facility, I relayed this to my chief engineer, who replied, "Do me a favor. The next time it's doing that, turn it around and bring it back."

The third lesson is not to jump to conclusions too quickly. No department wants to experience an apparatus rollover, much less two within months of each other. Operator error was not to blame in this rollover. Moreover, I believe the operator saved the four firefighters riding that truck from more severe injury. As difficult as it was to steer the truck, had he been going too fast, the crash would

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Posted: Feb 3, 2015

Technical Rescue Rigs at the Ready for Complex Incidents

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Many fire departments and districts around the country have technical rescue vehicles and tractor-drawn trailers to handle specialized rescue situations that go beyond the capabilities of a traditional rescue truck.

By Alan M. Petrillo

Technical rescue trucks often carry collapse and trench rescue equipment, urban search and rescue (USAR) gear, hazmat gear, high-angle rescue equipment, water rescue and dive gear, or an assortment of those types of equipment needed for specific disciplines.

Although the latest technical rescue rigs being built are used by departments and municipal task forces across United States and from the Canadian to the Mexican borders, the equipment they are carrying and their specific missions vary by locality.

Kevin Arnold, rescue and specialty vehicle product manager for Ferrara Fire Apparatus, points out that technical rescue vehicles are usually very different from each other. "It might be a USAR truck, hazardous materials truck, a command vehicle, dive truck, or a combination of those that define its mission," he says, "but in the end it still is pretty much a big rescue vehicle-a specialized toolbox on wheels."

Disaster Response

Arnold says that technical rescue vehicles often are designed to respond to natural disasters. "Their use seems to revolve around disasters like wildfires, hurricanes, tornados, and flooding conditions," Arnold says. "After Hurricane Katrina hit the Gulf Coast in 2005, departments and fire districts went wild buying technical rescues and command trailers."

Arnold points out that technical rescue vehicles can be either self-propelled or tractor-drawn trailers, and the type purchased by a fire department or municipal entity depends on how the vehicle will be used. "Typically, a technical rescue vehicle will sit somewhere and not be used a lot," Arnold observes. "So, many fire departments choose to base their technical rescue equipment in a trailer that will sit for a while until needed yet can be pulled by a variety of vehicles."

Slide-Outs

Ferrara built a technical rescue vehicle for San Francisco, California, Arnold says, that doubles as the mayor's mobile command center, complete with several slide-out sections. For Louisiana's homeland security agency in West Baton Rouge, Ferrara built a technical rescue on a tandem-axle Freightliner chassis that also duplicates the agency's dispatch center in the truck with three slide-out sections, Arnold says.

Slide-out sections are popular in combination technical rescue and command vehicles, says Scott Oyen, vice president of sales for Rosenbauer. "Technical rescues need a lot of storage room to haul all the equipment that departments want to put on them," Oyen says. "When there's a command center built into the vehicle, you need the slide-outs in order to provide the space necessary for them to function. We're building a technical rescue and command vehicle right now that has the incident command inside with four slide-out sections and a lot of electronics gear, while the technical rescue equipment is stowed in compartments around the outside of the vehicle."

Equipped for All Hazards

Oyen notes that Rosenb

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