California regulators on Tuesday temporarily grounded helicopters working on construction of a nearly $2 billion transmission line east of San Diego after a newspaper found that two accidents went unreported.
The California Public Utilities Commission's stop-work order came days after the San Diego Union-Tribune reported that in recent months, helicopters struck a boulder and a fence post during construction of a 117-mile network of towers to transmit power between San Diego and Imperial counties and Arizona.
No one was injured in either mishap.
San Diego Gas & Electric, which is building the Sunrise Powerlink project, initially told the newspaper that it wasn't clear whether it was required to report the rotor strikes.
Watch Wednesday for more on this from KPBS Reporter Amita Sharma.
"The pattern of Sunrise Project helicopter incidents is troubling to the CPUC and is of serious concern due to the safety risks such incidents impose on the residents of Imperial and San Diego counties and project personnel," commission director Julie Fitch wrote to SDG&E.
The commission's order requires the utility to ground its helicopters while pilots undergo safety reviews.
SDG&E's president and CEO said in a statement that the utility will comply with additional training. Construction will continue on the project's non-helicopter activities.
"Our goal is to make any necessary changes to ensure helicopter operations for construction of (the project) proceed safely for the benefit of our employees, contractors and the public," the statement said.
Construction of the power line relies heavily on helicopters. An average of 14 to 21 helicopters are used per day to build the overhead portion of the project.
