UPDATE 1800 EDT U.S., July 7
A flight recorder from the crashed Bell Helicopter 525 has been recovered from the burnt wreckage and sent for readout to the NTSB's Washington, D.C. recorder lab; the recorder is not a hardened CVR/FDR but appears to be in good shape, according to the safety board. The NTSB has dispatched a total of six investigators from its Washington headquarters to Texas to support the crash probe, which is led by Investigator-in-Charge John Lovell.
The U.S. National Transportation Safety Board has dispatched an investigator-in-charge from its Washington, D.C. headquarters to lead the probe into yesterday’s fatal crash of a Bell 525 prototype in Texas.
Helicopter accidents normally are examined by individual NTSB investigators from one of its field offices throughout the U.S. (unless the crash involves a significant number of deaths). Often the board sends no investigator to a helicopter crash and relies on information gathered by an FAA inspector.
However, the safety board will elect to conduct a more comprehensive investigation if it believes a crash raises particular issues of interest. The 525 crash is noteworthy because it involves the first civil helicopter designed with full fly-by-wire (FBW) flight controls and it occurred during flight tests.
The 525 crash comes as the NTSB is supporting Italy’s investigation of the Oct. 30, 2015 crash of a Leonardo Helicopters AW609. That probe is focusing in part of what role idiosyncrasies in that civil tiltrotor’s flight control software played in the crash, which also killed both test pilots on board. Bell played a major role in developing and refining the AW609’s flight-control software.
The civil tiltrotor and the 525 are distinct aircraft with unique flight control systems, and there is no reason to draw a connection between the performance of those systems in the accidents. But the coincidence of the crashes may present an opportunity for the NTSB to examine how flight-control software for rotorcraft is designed, tested and certificated.
The 525 crashed shortly before noon local time near Italy, Texas, about 30 nm south-southwest of the flight’s launch point of Bell’s Xworx research facility at Arlington, Texas Municipal Airport. Bell engineers on the ground were gathering data on the flight via telemetry and a chase helicopter was following the test aircraft.
Bell said the crash killed both pilots on board. The aircraft was one of three prototypes of the “super-medium” twin that Bell is developing for the offshore support market and other applications. The company had been working toward FAA Part 29 certification of the 525 next year and first deliveries to customers in late 2017.
Photographs of the crash site show a concentrated field of debris that was heavily damaged by fire and a separate area of debris that includes the aft section of the 525’s tail boom, vertical stabilizer and at least portions of the tail rotor.
The main wreckage field includes the aircraft’s engine compartment and, close by it, a section of the tail boom. Nearby lie sections of aircraft skin, some of which appear untouched by fire.
The burn field in this area appears concentrated around the fuselage, although two burn lines extend radially from it. The engine compartment and tail boom section line on one of these radial lines.
The aft tail boom lies on unburnt ground, between two sets of trees. News reports say it is about 1,500 ft distant from the main wreckage.