THE CONTRIBUTING CAUSES TO AERIAL FAILURES

THE CONTRIBUTING CAUSES TO AERIAL FAILURES

BY RALPH CRAVEN AND JAMES T. STEFFENS

Although aerial apparatus standards are continuing to improve with respect to safety-related design features, the American fire service continues to experience an inordinate number of aerial apparatus accidents and failures. Why? Within recent years, the National Institute of Emergency Vehicle Safety (EVS) has been maintaining a record of aerial incidents. The first documentation was begun in the late 1980s by Mission College in Santa Clara, California. The data were included in a video record of aerial incidents entitled Aerial Error. Distributed by a number of organizations as a public service, the original video–the only known existing visual record of aerial apparatus failures–is continuously revised and updated.

Subsequently, EVS has expanded its monitoring and recording efforts to include investigating aerial failures around the country. Eighty-six aerial incidents have been logged during the past four years. EVS also has in its database an entry for the recall of one aerial vehicle (tiller) and one aerial manufacturing defect, which together have had an impact on another 100 aerial units. The EVS database of aerial incidents is far from complete and is based on information obtained by or provided to EVS. Nevertheless, this informal data-gathering process has revealed that more than 180 aerial units have been affected by incidents, recalls, or manufacturing defects–a significant number of units. Yet, the fire service as a whole generally is unaware of this fact.

Unfortunately, when an aerial device fails, there are accusations of operator error, even by those unfamiliar with the specifics of the failure. EVS research regarding aerial failures, however, shows that a majority of aerial incidents are not the result of operator error. Actually, three primary areas (including operator performance) have been contributing to aerial failures.

PRIMARY CAUSES OF AERIAL FAILURES

The three primary causes of aerial failures as documented by EVS`s database are as follows:

Design, manufacturing, and purchasing weaknesses. Aerials manufactured since 1991 have been designed with a much higher degree of safety than those produced years ago. The newer design standards include increased tip load limits (minimum of 250 pounds at maximum extension and zero degrees elevation), improved ladder design (K-bracing), and other important features. Unfortunately, these increased standards do not always result in a nonflawed apparatus. It must also be remembered that the largest majority of aerial units in service were manufactured before adoption of NFPA 1901, Pumper Fire Apparatus–1991, and NFPA 1904, Standard for Aerial Ladder and Elevating Platform Fire Apparatus–1991. some of the design and manufacturing deficiencies that have contributed to aerial incidents have included the following:

–twisting of the aerial ladder (less than one year of age) to the extent that it could not be properly extended or retracted. It had to be disassembled and returned to the manufacturer for replacement.

–“peeling” or “gouging” of the metal structural members of the aerial; in some cases, the condition occurred during delivery tests or initial training on the unit.

–existence of water and extensive rusting on the interior of the ladder base rails of a new aerial ladder.

Other examples of aerial incidents related to the design, manufacturing, or purchasing process are safety recalls issued by the National Highway Transportation Safety Administration (NHTSA).

Another example of a serious problem that has not been the cause of a recall because it does not affect highway performance is the manufacturing defect found on the Hahn Firespire aerial. First identified by EVS in 1990 on a unit in Riverside, California, this defect affects 60 aerial units, including a number still in service today.

There also have been several cases in which departments sent an aerial unit back to the original manufacturer for repair. Unfortunately, the departments did not require an engineered repair and the manufacturer misunderstood the problem or inappropriately addressed it. In at least two instances, an aerial that had been returned by the manufacturer to the department failed because it had been improperly repaired.

Maintenance and inspection deficiencies. At least 15 incidents during the past five years have resulted from failure to adhere to a rigid inspection and testing program. In several other instances, it was impossible to determine if poor maintenance or inadequate inspection and testing contributed to the failure because the maintenance records for the unit were kept so poorly or did not exist.

Examples of how failure to inspect and maintain aerials has contributed to the conditions that caused their failure include the following:

–annealed aluminum that should have been identified during a regular testing program.

–cracks in and separations of welds, which, again, should have been identified during regular inspection/testing.

–extensive corrosion/rust in or on structural members, which should have been identified during inspection/testing.

–existence of structural fasteners with the markings to indicate their potential to be counterfeit and therefore substandard.

It can`t be stressed enough that regular inspection and testing are a shared responsibility between the independent organization and the owner of the aerial unit. Complete inspection and testing, including nondestructive testing–while conducted by many departments on an annual or biannual basis–are required only once every five years under the provisions of NFPA 1914. More important is the required operational, visual, and load testing required annually as well as after each time the aerial device is used under unusual conditions, excessive stresses or loads, or any other condition that might have exceeded the limitations set by the manufacturer. While a third-party testing organization can be retained, qualified fire department personnel can perform the required fire operations, visual, and load testing. In either case, performing these tests is essential to ensuring a safe aerial device.

When investigating an aerial failure, comments such as the following are often heard:

“Yes, the aerial is regularly tested by XYZ Company, and it was last tested two and a half years ago and is due again next year. We like to exceed the required NFPA scheduling of once every five years just to be sure. Have we inspected it? Well, not really; that`s the reason we use the testing company.”

“Maintenance records? You will need to talk to Technician Jones. He knows that aerial inside and out. Written documentation? No, except for those penciled notes in the file and the invoices for some purchased parts.”

In both cases, the department is unknowingly contributing to the potential failure of its aerial unit. It is vital that a department owning and operating an aerial unit supplement a nondestructive testing program performed by an independent-testing organization by doing the following:

keep detailed written records of all inspections, preventive maintenance, and repairs performed on the aerial unit.

ensure that the aerial unit is inspected regularly and thoroughly as part of an ongoing preventive maintenance program.

conduct the required operational, visual, and load testing on an annual basis and after any occurrence where the unit might have been subjected to conditions exceeding the limitations set by the manufacturer.

An aggressive and documented maintenance and inspection program is a vital and cost-effective component for any department wishing to minimize the potential for an aerial failure. Unfortunately, many departments are not performing these functions and are unintentionally contributing to aerial failures.

Operational errors. As with any multifaceted piece of equipment used under adverse conditions where life and property are at stake, operational difficulties or errors will occur. Aerial design within recent years has begun to minimize the difficulties with operational error through improved weight ratings (minimum 250-pound tip load) and interlocks that warn the aerial operator when the aerial is in a potential failure mode. Unfortunately, hundreds of aerial units still in service do not have these features.

Operational errors that result in aerial accidents usually can be classified into four general categories, as follows:

The aerial unit is used beyond its design limits. The newer aerial units designed in accordance with NFPA 1904 are intrinsically safer than many of the older aerial units. An improved design as well as a higher tip load (250 pounds) at any elevation or extension are incorporated into the manufacture of the unit.

Unfortunately, when that nice new unit goes out of service, such as for maintenance, the personnel now staffing the reserve unit expect that this 10-, 20-, or 30-year-old unit can perform in the same manner and to the same standards as their front-line aerial. Unfortunately, this is not the case. For example, some aerials designed under the older standards (prior to 1991) were to be used in a supported position–not cantilevered–at certain angles and extensions.

Within recent years, an aerial failed in an eastern city, causing a firefighter to be seriously injured. The aerial, a reserve unit of 20-plus years, was operating at a major fire with the ladder extended beyond 90 feet, raised to an elevation of about 40 degrees, and had water flowing. This positioning was well beyond the maximums recommended by the aerial manufacturer, as was noted on the aerial`s turntable plate. The maximum recommended extension at 40 degrees of elevation when the unit was functioning as a water tower (which it was) was 50 feet. As a result, when the firefighter began to climb the ladder to adjust the nozzle, the ladder buckled and collapsed.

The aerial is used as a demolition tool such as a crane. Depending on local policies and situations, a number of departments have used aerial devices in ways for which they were never designed. In the interest of convenience and speed, the aerial device was used to break out windows, enlarge openings in walls and roofs, and even to knock down masonry walls.

Obviously, many of these aerial de-vices do not hold up under this type of abuse and catastro-phically fail at the time of their im-proper use or at some later date. The aerial device design-ed for one application cannot effectively and continually be used for another without significant consequence.

The warning system is ignored or overridden. It is recognized that under emergency conditions, aerials will be used in the manner necessary to achieve a life-saving operation. Often, this ex-ceeds the manufacturer`s operational limitations. A catastrophic failure is avoided–not al-ways–but often because of safety margins built into the system.

Unfortunately, many aerial incidents do not occur during an emergency but during mundane nonemergency duties such as repairing a flagpole halyard, hanging a street banner, or operating a water tower at an incident at which no lives are threatened.

One of the difficulties is that older aerial units do not have the type of warning systems and interlocks included on aerials designed and built under the provisions of NFPA 1904. Often, aerial operators are not properly trained or “forget” that the unit they are operating is not designed to be put into the configurations they manage to find. Again, many times, no serious consequences result; but older aerials are failing more often, since they were not designed or built to function under the conditions in which we place them.

The stabilization system is not fully utilized. A review of the aerial failure database indicates a minimum of nine aerial incidents in which the stabilization system was not fully deployed or not deployed at all. In several of these instances, lives were threatened and the “short-jacking” was knowingly undertaken with a recognition of the potential for aerial failure. Unfortunately, several failures occurred during training exercises, maintenance inspections, and other nonemergency activities in which the operator or technician raised the aerial, intending to use it on a very limited basis, and then proceeded to raise it more fully and rotate the device. Without the stabilization system fully employed, the unstable aerial unit collapsed, chassis and all, onto its side.

Improperly uprighting the unit often increases the damage incurred when the aerial tipped over and destroys the structural integrity of the aerial device, the chassis (frame), or both.

It is imperative that all personnel who will operate an aerial device for any reason be trained in the proper procedures, including the deployment of the stabilization system, for placing it in service.

CONCLUSION

While operator error does contribute to aerial failures, many items ranging from the design and manufacture of the unit to the inspection and maintenance of the unit cause many failures. When an aerial fails, a thorough investigation must be conducted to determine the reason for the failure. It is not enough to “assume” operator errors. Many reasons for the failures are not readily obvious and cannot be determined without a thorough investigation that includes a metallurgical analysis. n


Photo by Bob Pressler.


n RALPH CRAVEN, based in Reno, Nevada, is a member of the NFPA Fire Department Apparatus Committee. He investigates apparatus, including aerial, failures across the country. He previously served for a number of years on the fire science faculty of Mission College in Santa Clara, California.

n JAMES T. STEFFENS is an independent consultant (JTS & Associates) to emergency service organizations based in Bradenton, Florida. He served on the NFPA Fire Department Equipment Committee (predecessor to the Apparatus Committee) from 1988 to 1992 and is very active in addressing a variety of apparatus issues.

Craven and Steffens are founding members and officers of the National Institute of Emergency Vehicle Safety (EVS), a nonprofit independent organization based in Reno, Nevada, dedicated to emergency vehicle safety.

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