The pilots aboard a corporate jet that crashed last month at Hanscom Field, killing all seven people on board, may have failed to conduct a preflight check and possibly attempted to take off with the plane’s lift controls in a locked position, federal investigators have found.
The National Transportation Safety Board disclosed the new details Friday in a report on its preliminary findings in the May 31 crash that killed Philadelphia Inquirer co-owner and philanthropist Lewis Katz, three guests, and the three-member crew.
Pilots are supposed to check aircraft flight controls before takeoff by moving the control column from right to left and forward and back-ward and by moving the rudder pedals from side to side, said John Goglia, a former member of the NTSB and an independent safety consultant from Saugus. The check is part of a myriad of details that need to be verified before flying, he said.
Information from the flight data recorder, however, “did not reveal any movement consistent with a flight control check prior to the commencement of the takeoff roll,” the NTSB report said.
Goglia, after reviewing the report, said the findings suggest the pilots may have skipped a step in the preflight check. “If he had done that, he would have discovered that he had a flight control problem,” Goglia said in an interview.
The Gulfstream IV jet reached a speed of nearly 190 miles per hour on the runway, but never became airborne, according to the report. Rather, the jet left the runway, rolled onto the grass, struck an antenna, and burst through a chain-link fence before sliding into a gully, where it erupted into flames.
The federal report also raised a question about whether a locking system, which is intended to protect flight controls from damage when a plane is on the ground, was engaged when the pilots attempted to take off.
The mechanism known as a gust lock keeps the ailerons and rudders in a neutral position and the elevators in a down position to prevent wind gusts from damaging the aircraft when it is parked, the NTSB report said.
Investigators found the position of the elevators at the back of the plane was consistent with the gust lock being on, according to information from the flight data recorder.
Elevators, located on the rear wings of the plane, are crucial to lifting the plane’s nose to take flight. If the elevators were in the down position, the plane would not take off.
“The pilots should have disengaged the gust lock right when they started the engine; it’s not clear whether they did or not,” said Bruce Landsberg, president of the Aircraft Owners and Pilots Association Foundation in Frederick, Md. “It would be bad to try to take off with that engaged, because the flight controls would be immovable.”
Even though the position of the elevators suggested the gust lock was on, authorities discovered that the lock was off when they went through the jet’s wreckage, the report said.
The discrepancy raises the possibility that something else may have gone wrong, said R. John Hansman, a professor in the Department of Aeronautics and Astronautics at the Massachusetts Institute of Technology.
“Why was [the gust lock] off in the wreckage? I would still be looking for other potential causes of control malfunction,” he said.
If the gust lock was left on, the airplane also should not have been able to gain the power it needed to take off, experts said. When activated, the amount of thrust the plane can muster is 6 percent of the aircraft’s total power, the report said.
That’s enough to taxi the jet, but not enough to take off, experts said. “It’s designed to prevent exactly this kind of accident,” said Hansman.
The report also confirmed that the pilots tried to abort the takeoff, noting that tire markings consistent with braking began about 1,300 feet from the end of the runway and continued for about another 1,000 feet through the extra paved area at the end of the runway. The pilots also employed their thrust reversers, which are also used to slow down planes.
NTSB spokesman Peter Knudson had no comment on the report.
In briefings after the crash, officials from the NTSB described what appeared to be a normal takeoff up to the point where the plane was supposed to lift its nose and ascend. At that point, the officials have said, the cockpit voice recorder “captured comments concerning aircraft control.” The officials have not said what the comments were.
“Those are the million-dollar words right there,” said Gene Allen, a pilot from Fort Lauderdale, Fla., who has been flying the Gulfstream IV since 1995. “The words you really want to hear is what did they say when they couldn’t lift off.”
The jet was piloted by James McDowell, 61, of Georgetown, Del., who listed 18,500 hours of flying experience in his most recent application for a medical certificate from the Federal Aviation Administration, officials have said. His family declined to comment on Friday.
His copilot was Bauke “Michael” De Vries, 45, of Marlton, N.J., who had logged 11,200 hours in the air, according to authorities. His family did not return messages Friday seeking comment.
Katz’s son, Drew, did not return an e-mail seeking comment. A voicemail and e-mail seeking comment from a spokesman for Drew Katz’s company, Interstate Outdoor Advertising, LP, also went unanswered.