Sino-Swearingen's first prototype SJ30-2 crashed on the second in a series of flutter certification flight tests, but the aircraft appeared to remain intact all the way to the ground, says the US National Transportation Safety Board. The crash, on 26April, near Loma Alta, Texas, killed test pilot Carroll Beeler.
On the second test run of the day, in a shallow dive at Mach 0.884, the aircraft began an uncommanded roll to the right that the pilot could not stop. The aircraft entered a descending barrel roll, with the g force preventing the pilot bailing out and the dive angle increasing until ground impact.
According to the NTSB's preliminary report, the first flutter mission, on the previous day, was terminated after an uncommanded roll to the left at an indicated M0.855, in conjunction with a rumble thought to be Mach buffet. After the flight, Beeler realised he had incorrectly set the airspeed display, so it had read M0.86 when the airspeed measured by the chase aircraft was M0.878.
After take-off on the second flutter mission, the SJ30-2 climbed to 39,000ft (11,900m) and entered a shallow dive. Beeler first duplicated the previous day's flight, making single-pulse aileron, elevator and rudder inputs at M0.875. There was no uncommanded roll and no mention of rumble, says the NTSB.
At the next test point, M0.884, the pilot reported he had put in full trim and could not let go of the controls. Each control surface was pulsed and responses were "well damped", he said. He was cleared to go to M0.894, but reported the aircraft was rolling to the right and he could not stop it. The crew of the chase aircraft said the SJ30-2 entered a "barrel-roll type manoeuvre" which continued to ground impact.
Source: Flight International
