U.S. agency issues safety warning for small airplane

SAN FRANCISCO — The National Transportation Safety Board is urging faster action to correct unsafe wiring found in a type of small airplane that crashed in Northern California, killing all four on board the medical transport flight.

The Piper PA-31T was carrying a flight nurse, transport medic and patient from Crescent City, near the Oregon border, to Oakland on July 29 when the pilot reported smoke in the cockpit and declared an emergency.

The transportation board issued an urgent safety recommendation Monday, asking the Federal Aviation Administration to issue an emergency directive that would require mandatory action and a shorter timeline for addressing the problem.

The transportation board’s recommendation is based on preliminary findings in an ongoing investigation of what caused the transport plane to break apart. Rescue teams found the wreckage in Humboldt County about 280 miles north of San Francisco.

Evidence indicates that an in-flight fire occurred in an area where electrical wires and adjacent hydraulic lines may have been in contact, a press release states. Investigation of six other planes showed electrical lines in direct contact with hydraulic lines, which could chafe and then arc, causing a fire.

“We think it’s a dangerous situation having electrical lines next to hydraulic lines,” said NTSB spokesman Eric Weiss, adding that the investigation is ongoing and no cause has been determined.

FAA spokesman Ian Gregor said in an email Tuesday that the agency is “actively working with Piper on possible additional safety actions” and that it had issued a “special airworthiness information bulletin” in December, noting the problem.

The special bulletin recommends inspections at the aircraft’s next scheduled maintenance visit.

The July crash came as the Federal Aviation Administration continues its efforts to improve the safety of the aircraft known as air ambulances. It began that effort after a series of deadly crashes. In 2008, there were five accidents that killed 21 people.

Piper Aircraft spokeswoman Jacqueline Carlon said in an email that the company has issued a “mandatory service bulletin” for operators. It is working with both agencies, she said.

There are more than 300 31T-series planes registered with the FAA.