A few years ago, a routine assignment turned into a brief, bizarre and surreal experience. I was to inspect an engine-powered forklift that had exploded in flames as the operator was positioning a crated refrigerator. Firefighters extinguished the blaze that resulted in serious fire, smoke and water damage. The forklift was moved to a local forensic engineering firm's temporary storage facility.
Scene of the Crime
From the airport, my cab sped along following the arcane instructions provided. Avoiding a swerving car, we passed our turn-off, leaving us truly lost. I knew something was amiss when my cab driver began alternately praying aloud and calling his dispatcher for instructions. We finally stopped in a run-down residential/industrial neighborhood. I exited the cab, but didn't see any signs or business identification. I wanted to confirm the location, but before I could draw a breath to say, "Please wait a minute," the cab sped off.
While getting my bearings, I couldn't see or hear any people or activity close by or even a block or two over. The area seemed to be abandoned.
Stepping over the broken front steps and onto the porch of the ramshackle residence, I called out through the open front door, but no one answered. Pumping adrenaline with my senses on full alert, I kept calling out as I stepped into the house. I then noticed stacks of audio mixer boards, lighting control panels, huge concert speakers and musical instruments. This wide-open place was either a major rock band's warehouse or a stash of "hot" goods.
I turned and flew down the crumbling front steps. As I walked toward what I thought might be a main street, a UPS delivery truck miraculously appeared. I called the driver to stop. At the curb and composed, I asked where my destination was located. I had the right address, but had to walk through the alley to a rear garage. I learned that during lunch hour, the places here always closed up leaving a desolate appearance. Walking through the gritty alley, I could now hear sounds of activity. Finally at the storage area, and with my anxiety calmed, grubbing around a burned lift truck would be a welcome change from my brief adventure in the "Twilight Zone."
The Investigation
During my inspection, I noticed the most severe fire damage was to the right side of the forklift. Fuel hoses, and lift and attachment hoses showed surface charring, but were otherwise intact. Charred wiring appeared to be a result of the fire. Hoses under the floorboards were charred, but the right side tilt cylinder hoses were burned completely and only hose steel braiding and steel fittings remained.
When the fire started, the load was being back-tilted which required a pressurized hose feeding the piston rod side of the tilt cylinder. The remaining steel braid from that tilt cylinder hose had pulled free of its tilt cylinder fitting with its open end aimed at the engine exhaust pipe. A steel band, with the hose part number, remained on the hose braid. Not finding other probable causes, this hose, spraying pressurized, flammable fluid onto the exhaust pipe, seemed a likely cause of this fire. Gently lining up the braid with the fitting, I measured a tight two-inch radius bend from a bulkhead fitting to the tilt cylinder port fitting.
The Culprit
The burned hose part number matched the number in the parts manual. Manufacturer's specs recommended a five-inch minimum bend radius as compared to the two-inch installed radius I measured. I requested a system relief valve pressure test that proved normal, making it unlikely excess pressure blew the hose out of its fitting. My opinion report concluded that hose choice and installation with an undersize bend radius was a defective design. The resulting repetitive high stresses each time the hose was pressurized and the tilt cylinder moved resulted in hose failure. The manufacturer later settled with the dealer's insurance carrier.
As for my brief "Twilight Zone," misadventure — the storage supervisor told me that the audio goodies I saw belonged to a rental outfit. He later found out and then told me that the rental crew had left quickly the morning of my visit to bail one of their "roadies" out of a local lockup!
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