Federal investigators said Tuesday that they are focusing on the condition of the pilot and the engine of a helicopter as they try to determine why the aircraft slammed into an Arlington Heights home, killing all four on board.
Witnesses interviewed by investigators reported seeing the helicopter flying at about 350 feet Monday when it suddenly rolled over on its left side, positioning its rotor blades perpendicular to the ground. Seconds later, the 1,600-pound aircraft crashed through the roof of a ranch home at 311 S. Fernandez Ave.
The helicopter’s air-speed gauge read 145 m.p.h. when investigators pulled it from the wreckage.
Officials of the National Transportation Safety Board said they have ruled out a malfunction of the 19-year-old helicopter’s controls or its rotor, which turns the aircraft’s large blades. Instead, they are training their attention on the possibility that the helicopter’s engine seized in flight. Investigators said that when they examined the engine after the crash, they couldn’t spin the turbine, which propels the helicopter.
The engine will be shipped back to its manufacturer, Allison Engine Co., in Indianapolis, where it will be dismantled and studied, said David C. Bowling, an NTSB investigator who spoke at a news conference at Waukegan Regional Airport, where the helicopter took off Monday and where the wreckage was taken for examination.
Bowling also said officials are trying to determine whether pilot Scott Maras suffered a medical emergency, such as a heart attack, during the flight.
A check of medical records showed that Maras, 40, had no history of serious medical problems, Bowling said. But he said investigators are awaiting results of final tests by the Cook County medical examiner’s office.
Initial autopsy findings released Tuesday indicated that Maras, of Lake Geneva, Wis., and his three passengers all died from injuries suffered in the crash. Also killed were two staff members of Chicago Futabakai Japanese School–Shinobu Sada, 49, and Kazuya Yamaguchi, 38, both of Arlington Heights–and Yasuo Sato, 62, a photographer from Wilmette.
Futabakai officials had rented the helicopter to take aerial photographs of the school, which recently had moved to a new location in Arlington Heights. The school is for children of Japanese nationals living and working in the Chicago area.
The helicopter was owned by Rotors in Motion, based at the Waukegan airport.
The failure of an engine in a helicopter such as the one that crashed Monday is extremely rare, occurring only about once in every 300,000 flights, said Tommy Thomason, who oversees light engine manufacturing for Allison Engine. Thomason disputed the suggestion that engine failure could have caused the helicopter to plunge out of the sky in Arlington Heights.
“Mid-air engine seizure could not explain a sharp bank to the left,” said Thomason, a pilot and former program manager for Bell Helicopter Textron, which made the model 206L-1 that crashed Monday.
But other helicopter pilots weren’t so ready to dismiss the possibility that a jammed engine could have caused the crash.
“If the rotors were not turning fast enough, they could not support the weight of the helicopter beneath it,” said Barry Desfor, a helicopter pilot for 30 years and co-owner of Helivalues Inc., a Lincolnshire-based company that publishes a book assessing the value of used helicopters. “That’s the reason for the bank, and he may have been turning to look for a clear area (to land).”
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Even when helicopter engines fail, aviation experts said, pilots can use an emergency procedure called “auto rotation” to descend safely to the ground. In the procedure, the updraft of air flowing through the rotor blades keeps them spinning like a pinwheel long enough to slow the helicopter’s descent for a safe, if bumpy, landing.
But Bowling said there is no way to determine whether Maras tried the procedure.
“He should have been able to bring the nose up. We have no evidence he did that,” Bowling said. He estimated that Maras would have had only about 15 seconds to initiate the procedure, which requires putting the aircraft into a sharp descent, and then leveling off.
The home that the helicopter struck, owned by James and Grace Stearns, suffered about $125,000 in damage and loss of property, Arlington Heights officials said. Both the couple’s cars were destroyed. Grace Stearns, who was shaken but unscathed, had been sitting in her study working on her computer no more than 10 feet from where the helicopter hit.
“She is feeling very overwhelmed. Four people died within 5 to 10 feet of her,” said Nancy Stearns Burgess, a daughter. “She still feels very fortunate to be able to walk out of the house. It’s pretty miraculous.”
Though a Bell Helicopter spokesman said the 17- to 35-m.p.h. winds Monday afternoon in Arlington Heights normally wouldn’t present a problem for the helicopter, Bowling said officials are investigating whether the wind played a role in the accident.
Bowling gave a clean bill of health to the aircraft’s maintenance, and NTSB safety records indicate that the Bell 206L-1, also known as the Long Ranger, has had a relatively low frequency of accidents.
Helicopter industry observers also praised the Allison engine that powered the aircraft.
“It’s an extremely reliable engine. When you go with a single-engine aircraft, you have to bet that engine is going to take you to your destination and back,” said former Army helicopter pilot Frank Jensen, former president of the Helicopter Association International.