There were hundreds of ways they could malfunction or be improperly maintained, tested and operated.

A city agency later determined that the boiler had been improperly maintained and operated.

Firestone concluded that the tires had been improperly maintained, Mr. Descheemaker said.

Another common source of indoor pollution is improperly maintained or improperly used heating units.

Among other equipment said to have been improperly maintained was landing gear, radar and fuel systems and automatic pilots.

On the other hand, an improperly maintained aircraft could get in trouble - or crash - within minutes.

Bilge pumps are prone to failure because they're so overworked and sometimes improperly maintained.

However, 20 years after installation the control system was analyzed and uncovered that the detention dams had been improperly maintained, resulting in sediment detention failure.

That's the smell of ozone, and ionizers make some but not enough to be unhealthful, the experts say, unless they are improperly maintained.

If the equipment fails or is improperly maintained, who is responsible?