Three years ago, Ameren (St. Louis, Missouri) began modifying its boom-truck fleet testing and maintenance procedures. Sherry Moschner, fleet services manager, wanted more consistent training for staff mechanics and field crews who service and inspect the booms. Boom cleaning is a major component of the new four-part program that specifies guidelines for field crews and shop personnel.

Mechanics Become Certified

Ameren's first step was to develop a standardized testing and training procedure for its mechanics. Ameren runs two shifts at most of its garages, with the majority of its mechanics working the evening shift. All new or noncertified Ameren mechanics are now required to complete 15 inspections on a variety of equipment with a journeyman mechanic before they can do testing on a boom truck by themselves. To become certified to complete their own inspections, mechanics also must perform a physical exam of an entire boom truck. All mechanics also must attend industry-sponsored manufacturer boom-truck training to enhance their skills.

The second step, initiating a nondestructive material-flaw detection system, began about 18 months ago when a boom section failed after a visual inspection was completed. A crack in the boom that was not visible on the outside caused the failure.

Determined to institute a more rigorous testing procedure, Ameren added an acoustic emissions test. This test is used to uncover hidden damage and cracks in the fiberglass or metal boom that could not be discovered by the typical visual inspection. Readings are generated by placing a series of sensors on the boom. The data is transmitted to a computer housed in the mobile testing vehicle. The test reads like a seismograph displaying the condition of the boom.

The acoustics testing is still evolving. There is no consistency within the industry on testing frequency, so Ameren is conducting pilot tests, taking into account the make, model and year of boom trucks. This will help establish the parameters for a regular routine of how often to conduct the acoustics test. Other utilities that use this type of testing often do so because of similar undetected failures in the boom.

A third part of Ameren's boom maintenance plan includes a diagnostic method for locating cracks called magnetic particle testing. It serves as another enhancement to Ameren's physical inspection of the boom. A magnetic particle tester is a handheld tester that uses an electromagnetic field and a colored cast-iron powder dusted on the surface of the boom to identify suspected cracks in the metal boom sections. All of Ameren's mechanics have access to this testing equipment.

Crew Maintenance Guidelines

Finally, Ameren has made daily inspections and periodic boom cleaning an integral part of its boom-truck maintenance program. Utilities have a variety of programs to maintain the integrity of their boom trucks, but sometimes the regular maintenance and cleaning between scheduled dielectric testing and service is overlooked.

Dirt accumulated during normal use can affect the dielectric properties of a boom. This includes road debris, salt spray, hydraulic fluid, grease, pine pitch and creosote. When residue builds up on the boom, water sheets out rather than beading up and running off. This sheeting or pooling of water on dirty booms can prevent booms from meeting dielectric standards and potentially pose a hazard in the field.

Ameren cleans its booms according to the manufacturers' requirements every three to six months, depending on the condition of the boom, and every time the boom undergoes inspection. To address this important procedure, the company recently produced a boom inspection and cleaning video for its field crews. The video includes steps on how to perform a comprehensive daily boom inspection and lists the stock-code numbers of the approved products for proper cleaning.

Approved Cleaning Solutions

Many crews have access to solvents. While they know how well these solvents remove grease, they may not know the harmful effects solvents can have on the fiberglass portion of the boom arm or bucket. Common degreasers or solvents can harm and strip the boom's gel coat, causing weak or soft spots. Some cleaners contain abrasives and leave a considerable residue. Other cleaning solvents, such as acetone, xylene and toluene, can cause permanent damage if left in contact with the surface too long. Many of these solvents are flammable and pose other hazards.

Ameren makes sure all products used on the boom trucks are formulated specifically for the type of boom being cleaned (metal or fiberglass) and approved by the aerial-lift manufacturer. For the hard-to-remove dirt that needs to be removed before washing, crews use the B-1 Boom Wipe from American Polywater Corp. (Stillwater, Minnesota). Ameren crews never use abrasive pads, which can scratch the boom and remove the protective gel-coat layer. The B-1 Wipe is a large towel saturated with a cleaner that will not harm the gel coat or leave a residue. It does a great job on the tough contaminants. It comes in a ready-to-go wipe package convenient for line personnel to carry on the truck for immediate usage.

Once a boom is properly cleaned, a good wax is used to protect the surface and force water beading during misty or wet weather. Specialty fiberglass boom waxes are available in pint cans and individual towelettes. The new training video addresses these approved products and the proper cleaning procedures and application of any chemical used on the boom.

Ameren relies heavily on past performance, input from its maintenance staff and feedback from its field personnel when developing maintenance specifications. The utility meets with all the garage supervisors monthly who pass the information along to the mechanics. With Ameren's procedures for sharing of information, along with its four-point plan for training and testing, the utility is well on its way to improved safety and function of its extensive boom truck fleet.

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Steve Hampton, superintendent of the Missouri Fleet Services Division of Ameren Corp., manages a team of seven transportation supervisors in Missouri who oversee nine garages. SHampton@ameren.com