France's aviation accident investigation bureau BEA released its final report this week on the May 2011 pitch trim runaway incident involving a Falcon 7X in Malaysia, which caused Dassault to temporarily ground the 7X fleet. The report reveals how the crew recovered from an unusual and dangerous attitude.
The pilot flying used his military experience and applied a procedure he had learned for bombing. When the pitch angle increased rapidly, he rolled the aircraft sharply to the right, applying a 40- to 80-degree bank angle for about 20 seconds, according to the report. This decreased the pitch angle and stabilized the aircraft’s speed.
The failure lasted two minutes and 36 seconds, after which the temperature of an electric motor exceeded its limit, triggering a bypass of the primary trim control system in favor of another chain of control. During this period, the trijet climbed from 13,000 to 22,000 feet and its calibrated airspeed dropped from 300 to 125 knots. The maximum pitch angle recorded was 41 degrees and the highest load factor was 4.6g.
Although the manufacturer did provide details on the cause of the problem at the time, the BEA report highlights organizational issues at industry and authority levels.