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The NTSB said the helicopter suffered an inflight upset for undetermined reasons before it crashed outside of a church in Drexel Hill, Pennsylvania on Jan. 11, 2022. Almost two years after the crash, the NTSB is unable to determine a reason for the sudden altitude change which caused the rotor system to speed up and engine power loss. The medical flight was transporting a young patient to a nearby Children's Hospital. The pilot suffered serious injuries and the three passengers, including an infant, were unharmed.
On Jan. 11 an Airbus EC135 P2+ (N531LN), operated by Air Methods as LifeNet and conducted as a helicopter air ambulance, was transporting a young patient to the Children's Hospital of Philadelphia. The NTSB said the flight track data indicate that while the copter was in cruise flight at about 1,500 feet mean sea level it departed from normal cruise flight with a sudden increase in altitude, followed by a dive. The report said that recovered data from different sources on the helicopter did not explain why the aircraft rolled inverted during the altitude excursion, relayed crewmembers. Surveillance footage showed the copter in a near-vertical, nose-down, spiraling descent. The NTSB said the pilot arrested the rotation and recovered the helicopter from the dive but could not climb or hover without sufficient engine power, resulting in a hard landing next to a church.The report said the examination of the helicopter did not reveal any evidence of a malfunction that would have resulted in an abrupt departure from the cruise flight. The NTSB said that due to the limited control authority of the Stability Augmentation System (SAS) actuators, it is not likely that a malfunction of the SAF actuator would result in an inflight upset before the pilot was able to react to the malfunction. The malfunction of a trim actuator would also not result in an inflight upset since the pilot would have noticed an attitude deviation before the trim actuator, with a rate of movement limited by design, would move the copter into an unusual attitude.
Data indicated that the main rotor system overspeed that likely occurred during the dive maneuver resulted in the overspeed of both engine power turbines. This was due to the sudden reduction in load from the main rotor. With the power turbine overspeed, both of the engine control systems, functioning independently of each other, would function as designed and revert to manual mode while at a minimum fuel flow rate. The NTSB said that both of the engines continued running at low power without automatic governing, which resulted in insufficient power to continue a normal flight and the engine twist grips remained in a normal fly position during the rest of the flight.
The NTSB determined that the probable cause was an inflight attitude upset "for undetermined reasons" that resulted in a rotor system overspeed, a power reduction in both engines and a subsequent hard landing. Despite a nearly two-year investigation, the reason for the crash has not been fully identified. The NTSB included a similar crash with another EC135 in Romania. According to that report, the helicopter had a malfunction of the autopilot, caution displayed "YAW SAS" and "ACTUATION" followed by a "brutal movement to the right with aggressive roll and descending with diving."
CBS News Philadelphia reported that the pilot, Danial Moore, was seriously injured during the crash. The news station released information about the 911 call following the crash, with on-flight medic Kevin Chaffee calling for help. The patient on board was a two-month-old baby girl, flying with the pilot, nurse and medic. Chaffee called 911 and told the dispatcher that everyone was conscious but the pilot was not alert. He said his main concern was the two-month-old patient and requested an ambulance right away. With the landing in a highly trafficked area and next to a church, the pilot skillfully maneuvered the copter and avoided life-threatening injuries for everyone on board and on the ground.
"It's really a testament to the pilot and what he was able to do in keeping everyone safe," Delaware County Council Chair Dr. Monica Taylor said to CBS News. "It's amazing, it's a miracle that there are no major injuries that occurred from this accident."
According to the NTSB, Moore made himself available for an interview from his hospital room the day after the event. At the time he could not remember the flight and was very uncomfortable. The interview was postponed due to his medical condition but later conversations over the following month revealed he had no memory of the crash. Chaffee told investigators the ride was a little bumpy after takeoff, which he thought was turbulence. He heard a loud bang from directly above him and the copter began a hard right bank and right roll, described as a maneuver someone would make to avoid a bird. He could not confirm, but Chaffee told investigators the helicopter rolled inverted numerous times before regaining control. The in-flight nurse, Kristopher Lawson, also told investigators there was an abrupt right turn and it felt like avoiding a bird.
Lawson said the aircraft was inverted and both he and Chaffee were pinned to the ceiling. After the aircraft was brought under control the crewmembers returned to their seats and strapped in, putting their hands over the infant to secure her. The NTSB said interviews with Chaffee and Lawson were consistent, however, Lawson did not remember hearing a bang but did not rule it out either.
In September 2023, the NTSB interviewed Moore. He said it was a nice day so he opted to fly at about 5,000 feet instead of the usual 2,000, to which he said he was glad he did since he did not think he would have been as successful if it was at 2,000 feet when the incident occurred. Moore said he had no memory of the initial incident but remembers being on the controls and fighting the aircraft in a dive.
"As we were descending, I caught a glimpse of a road to do a run-on landing," Moore said. "At 300-400 feet I noticed wires on the road and people around. I decided not to land there to avoid damage or hurt anyone. I thought I would ditch the aircraft somewhere else. I saw a patch of grass and aimed for it squeezing between trees."
Moore told investigators he did not recall any audios, cautions or instrumentation. He does remember previous SAS issues, but not any other aircraft issues. Two years later, the question as to why the aircraft lost control remains unanswered.