Problems on earlier SJ30-2 flight reported

 - October 9, 2007, 11:59 AM

The Sino Swearingen SJ30-2 that crashed in a remote area of Texas on the morning of April 26 was on the second in a series of flights to complete flutter certification before it suddenly rolled and went into an uncontrolled descent into the ground. Company test pilot Carroll Beeler, 59, was killed in the accident. No one else was aboard.

It is now known that the Williams-Rolls FJ44-2A-twinjet had problems on its first flight in the same series on the previous day. That flight was curtailed after the airplane encountered an uncommanded roll to the left and a possible encounter with Mach buffet. What follows below are excerpts from the NTSB’s May 16 preliminary report.

In addition to the uncommanded roll and buffet on April 25, Beeler also noted a discrepancy between his displayed airspeeds and those reported by a chase-plane pilot. Beeler later realized that he had incorrectly set up the airspeed display. When he thought he had completed a test point at indicated Mach 0.86, he had actually completed it at indicated Mach 0.878. Beeler also reported that the “rumble” he felt in conjunction with the left roll occurred at indicated Mach 0.855. (Beeler would have had to operate two cockpit switches to be able to display reference system airspeed. Failure to do so would have resulted in his reading a lower airspeed.)

To confirm that there wasn’t a mechanical problem with the airplane that may have caused the rumble, flight-test personnel assigned the second SJ30-2 test pilot, Chuck Walls, as a backseat observer in the Northrop T-38 chase plane for the next day’s (fatal) flight. The accident flight was also being monitored in a telemetry van.

Before the test flight, a mission briefing was conducted via conference call between the San Antonio-based personnel and the telemetry van personnel in Rock Springs, Texas. During the briefing, the project’s flutter consultant (a DER) noted that he had, during previous discussions, advised that for the purpose of flutter testing, if Beeler ran out of aileron or elevator trim, the tests could still be completed, even if the pilot had to hold aileron/elevator force to steady the airplane. He further stated, however, that continuation of the testing would never override the pilot’s decision as to whether the control forces were unacceptable or hazardous.

SJ30-2 N138BF, S/N 002, departed for the second flutter test on an IFR flight plan–in VMC–from San Antonio International Airport at 9:11 a.m. on April 26. The airplane climbed to 39,000 feet and set up for a shallow dive to accelerate to the Mach 0.884 (indicated) test point. When the airplane reached indicated Mach 0.875, Beeler called “Mark” on the radio to duplicate the previous day’s test point. Beeler then initiated a single pulse input to the elevator.

After checking the telemetry strips, the consultant then gave Beeler the go-ahead for a single pulse to the aileron, followed by another “Go” for a single pulse to the rudder. Telemetry van personnel noted that all the modes excited were “well damped.” Telemetry van personnel also reported that after the pulses were completed, Beeler said the uncommanded roll to the left–which had been experienced on the previous flight–did not occur. There was also no mention of a rumble. In addition, the chase-plane pilots confirmed that there were no mechanical anomalies evident on the airplane.

Beeler subsequently began to set up the SJ30-2 for the dive to reach Mach 0.884. Discussions between Beeler and telemetry van personnel indicated that this test point might be the last one of the mission due to fuel concerns, especially for the chase airplane.

Following telemetry lock, the airplane began a shallow dive. According to most of the participating personnel, before reaching the test point of indicated Mach 0.884, Beeler said that he had put in full trim and couldn’t let go. At indicated Mach 0.884, he called “Mark.” Each control surface was again pulsed, and the responses were again “well damped.”

After the final pulse, Beeler was cleared to the next test point, indicated Mach 0.894, but Beeler responded that the airplane was rolling to the right, and he couldn’t stop it. Telemetry was lost about 20 seconds later. The chase pilot called “get out” twice to Beeler, but he said that he couldn’t get out, that there were too many g’s. This was his last transmission. The airplane was at about 30,000 feet at this time and appeared to be in a shallow right bank, according to the chase-plane pilot.

Walls in the T-38 saw the SJ30-2’s nose to be “a little low,” and in an approximately 30-degree right bank after reaching Mach 0.884. A few seconds later, the test airplane entered a “barrel roll-type maneuver” to the right, then continued to roll, and increased its dive angle until it hit the ground at about 10 a.m. No parts were seen separating from the airframe as it descended. The chase airplane was not close enough for its crew to see the SJ30-2’s control positions.

When Walls saw the initial roll, his first thought was, “What did he do that for?” Then he saw that the airplane “came around and made another barrel roll. It was not around a point like an aileron roll; and it was not real fast; it looked lazy.”

The telemetry van was receiving reference system airspeed. One of the telemetry personnel said that as the accident sequence approached, the airplane’s airspeed readout was consistently between Mach 0.881 and 0.882. He subsequently noted that he did not believe the airplane exceeded Mach 0.882 before the telemetry signal was lost. (The airplane had achieved its planned Mmo of Mach 0.83 late last year without any reported anomalies.)

The wreckage was fragmented, with debris spread over an area of approximately nine acres, dispersed 360 degrees around the impact crater. Evidence of all flight control surfaces was found at the scene. There was no evidence of an in-flight fire or in-flight structural failure, and all fracture surfaces examined exhibited evidence of static overload. Control continuity could not be confirmed due to the severity of the impact damage.

Hard drives containing more than 450 flight parameters were on board the airplane, though they were destroyed in the crash. The telemetry van data included 27 parameters, most of which were accelerations. Additional parameters included Mach number, altitude, calibrated airspeed, magnetic heading and the positions of the ventral rudder, rudder and elevator. The NTSB is now evaluating this data.

Beeler held an ATP certificate with ratings for the Boeing 707, 727 and 747 and Airbus A300. He was also a retired Navy pilot with combat experience in the Vought F8J Crusader, and had subsequent flight-test experience with several major manufacturers. He was reported to have 12,000 hours of total flight time. Beeler joined Sino Swearingen in 1997, and he had logged 271 hours in the accident airplane and 331 hours in the company’s nonconforming prototype. He also piloted the second conforming prototype on its first flight in March.