Preliminary Reports
MD500 Loses Firefighter on Rescue Run
MD Helicopters MD500, Sept. 2, 2016, Honolulu, Hawaii—An MD500 registered to and operated by the city of Honolulu was completing a hiker rescue mission near the Diamond Head state trail when a ground-based firefighter participating in the sortie was thrown from the rescue net and fell 25 feet to the ground, sustaining serious injuries. The flight, which originated from Honolulu International Airport, was in VMC. The crew had been scrambled to rescue an injured hiker. Local ground-based firefighters had reached the scene first and stabilized the hiker for transit. The hiker and a firefighter were lifted into a rescue net that was attached to the helicopter by a 75-foot line. Video evidence from the rescue showed that as the helicopter climbed away from the scene the net struck a pole, and the firefighter was ejected.
Conquest II Encounters Powerlines
Cessna 441 Conquest II, Sept. 5, 2016, Coorabie Airport, South Australia—The twin turboprop encountered powerlines on approach to Coorabie Airport in South Australia. The crew continued the approach to a successful landing with no injuries. The Australian Transport Safety Bureau is investigating.
MD500E Loses Blade Tip
MD Helicopters MD500E, Oct. 4, 2016, Waimea, Hawaii—A commercial pilot and two passengers were uninjured after an MD500E operated under Part 135 by Volcano Helicopters on a VFR flight sustained substantial damage to the main rotor while climbing out from a remote location in the Kohala Mountains near Waimea, Hawaii.
The pilot reported that he had just transported an external load to a remote location and retrieved two passengers to head back to a staging area. Before takeoff he jettisoned a 20-foot longline used to transport a load from the cargo hook by pressing the hook release switch. During the initial climb, at about 75 to 100 feet agl, the pilot experienced a moderate anomaly in the feel of the cyclic control, followed by a significant vertical vibration, and saw that the main rotor blade track had a substantial blade spread. The pilot performed a precautionary landing in a suitable area nearby.
Inspecting the blades after the landing, the pilot noted that a portion of the tip was missing from one of the main rotor blades, and that the blade was bent aft. Three blades exhibited scratch marks on their leading edges. The longline was not found in the helicopter or at the site. The helicopter has been recovered for further investigation.
Short Sherpa Nose Gear Collapses
Short SD3-60 Sherpa, Oct. 13, 2016, Missoula, Mont.—Two airline transport-rated pilots completing a VFR ferry flight from Kingman Airport, Kingman, Ariz., were uninjured after the nose gear of a Short SD3-60 Sherpa collapsed during landing at Missoula International Airport (KMSO) in Missoula, Mont. The United States Department of Agriculture (USDA) airplane supports the U.S. Forest Service.
The pilots reported that before landing they had an unsafe nose gear indication. After multiple unsuccessful attempts to get the nose gear to extend and indicate that it was down and locked, they landed and the nose gear collapsed on contact with the runway. Once the airplane came to a stop the flight crew evacuated. The underside of the fuselage near the nosewheel sustained minor damage.
Cessna 525 Runs Off The Runway In Pawtucket
Cessna 525, Oct. 13, 2016, North Central State Airport (KSFZ), Pawtucket, Rhode Island—A Cessna 525B was substantially damaged when it overran the runway after an instrument approach at North Central State Airport (KSFZ), Pawtucket, Rhode Island. The crew—a commercial pilot and an airline transport pilot—and four passengers were not injured. The eight-seat twinjet was manufactured in 2014.
The flight departed from Allegheny County Airport (KAGC), Pittsburgh, Penn., in IMC, operating under Part 91. The flight crew told the FAA after the accident that the weather was below approach minimums; however, as was their right they elected to continue the approach and descended below the clouds about 800 to 850 feet msl. The airplane was flying at 130 to 135 knots on the final approach leg to Runway 05, the crew told the NTSB.
Airport surveillance video showed the airplane touching down midfield on Runway 05, a 5,000-foot-long asphalt runway. Intermittent skid marks on the final 2,000 feet of runway were followed by marks where the airplane ran off the end of the runway and hit the localizer antenna, 300 feet beyond. The wings, fuselage and nose gear were substantially damaged.
Initial examination by an FAA inspector did not reveal any issues with the braking system. Weather at KSFZ about the time of the accident was reported as 200-foot overcast, three statute miles visibility with mist and calm wind.
Final Reports
Unlocked Collective During Preflight Test Behind Rooftop Accident
Airbus Helicopters AS350B2, March 18, 2014, Seattle—A pilot and his cameraman were killed and the occupant of an automobile was seriously injured when an Airbus AS350B2 news helicopter powered by a Turbomeca (Safran) Arriel 1D1 appeared to lift off and go out of control from a rooftop helipad in downtown Seattle. The NTSB determined that the loss of tail rotor and main rotor control was caused by a loss of hydraulic boost, possibly the result of a standard preflight check performed with the collective unlocked.
Because the helicopter was not equipped with a flight recording device there is no way to ascertain for sure what the pilot did during the preflight hydraulic checks or the status of the hydraulic system when the helicopter lifted off. Video footage from the helicopter pad showed that the helicopter lifted off and immediately yawed left, indicating a loss of tail rotor control. It completed one 360-degree rotation to the left in a near level attitude while climbing. As it continued to spin it pitched nose down and banked right, indicating a loss of main rotor control. The helicopter moved away from the rooftop helipad, lost altitude and hit a car on the street below. A post-crash fire consumed most of the fuselage and the forward section of the tailboom. All major structural components of the helicopter were found at the accident site, and there was no evidence of an in-flight failure of the airframe. Examination of the engine, main rotor and tail rotor systems revealed that they were all producing power/thrust at impact.
Unable to confirm flight control continuity because of fire and impact damage, the NTSB based its probable cause finding on a series of deductions. Logically it is most likely that the hydraulics lost pressure during the preflight hydraulic system accumulator check on activation of the hyd test button with the collective unlocked. If the collective was not locked during this check and the cyclic movements depleted one or more of the main rotor accumulators, the collective would have moved up rapidly. This uncommanded collective movement is caused by a design characteristic of the main rotor system in the AS350. Engaging the collective lock as per the preflight checklist prevents the uncommanded movement. If the pilot did not lock the collective and performed the accumulator check with the FFCL in the flight detent per an older version of the operator’s checklist that interviews with other company pilots indicate might have been on board, he might have experienced an uncommanded increase in collective and a marked heave of the helicopter. The pilot might have reacted by manually increasing collective pitch, resulting in an unplanned takeoff. Once airborne, the lack of hydraulic boost to the pedals would have resulted in an uncontrolled left yaw, and, as all three main rotor accumulators became depleted, the main rotor controls would have lost hydraulic boost, resulting in a rapid loss of control.
Pilots, Airport Staff, ATC Implicated in Falcon Fatal
Dassault Falcon 50EX, Oct. 20, 2014, Vnukovo International Airport, Moscow, Russia—Russia’s Interstate Aviation Committee (IAC) has determined that the fatal crash of a French-registered Dassault Falcon 50EX that hit a snowplow during takeoff from Moscow Vnukovo International Airport—killing three crewmembers and a passenger—was caused by airport workers, air traffic controllers and the jet’s pilots. Criminal charges were levied against seven controllers and airport workers, among them the snowplow driver, who was believed to have been intoxicated at the time of the collision.
The accident happened shortly before midnight in drizzle and mist. Two snowplows were working under the command of a supervisor who was in a car in the area. The supervisor lost sight of one of the snowplows. At the same time, the Falcon 50 was cleared for takeoff. Ten seconds after the crew had received permission to take off, the surface movement radar in the control tower showed one of the snowplows moving toward the active runway, and 14 seconds after the aircraft began its takeoff roll the crew saw a “car” crossing the runway (according to the CVR). The crew continued the takeoff and the jet lifted off the runway at about 134 knots. But the right wing and right landing gear collided with the snowplow, the airplane rolled inverted, hit the ground and burst into flames.
While the report blames airport workers and controllers for violations of procedure, failure of supervisory responsibilities, a breakdown of communications, lack of proper equipment on the snowplows and loss of situational awareness, it also accuses the flight crew of negligence, criticizing the pilots for continuing the takeoff when the captain saw the vehicle on the runway. The Falcon 50EX nosewheel steering, which can be controlled only from the left seat, was also implicated because it forces a transition of control amidst the already high workload of takeoff. Investigators added that the long wait for departure clearance and a desire to get home might have influenced the crew’s decision-making.
Engine Failed on Sikorsky S-76C
Sikorsky S-76C, July 11, 2013, Longford, Victoria, Australia—An S-76C passenger ferry departing the Snapper platform in the Bass Strait oil and gas fields for a return to Longford, Victoria, lost power from the number-two Turbomeca Arriel 1S1. The failure was attributed to the fracture of a second-stage high-pressure turbine blade that damaged adjacent blades, causing power loss and vibration. The helicopter descended rapidly to within 30 feet of the sea surface as the crew secured the failed engine. A positive rate of climb was established at that point and the helicopter flew back to Longford, escorted by other company helicopters, for a single-engine landing.
The engine manufacturer concluded that the failure was caused by a combination of metal fatigue, blade creep and oxidation deposits. While a definitive cause for the blade fracture has yet to be determined, blade material, dimensional and quality assurance checks have ruled out any deficiencies. The manufacturer reported that blades with more than 2,000 operating hours or 2,300 cycles can be more susceptible to failure. The manufacturer is in the process of identifying potentially affected blades. Given the number of similar blades in service and the number of hours flown, the failure rate is low. The Australian Transport Safety Bureau regards the associated safety risk as low.
In the absence of a conclusive cause of the blade fracture and remedial information, the operator imposed a service life limitation on its helicopters’ turbine assemblies fitted with the same blades. In addition, the engine manufacturer issued notifications to operators and introduced specific inspection requirements relevant to potentially affected turbine assemblies.