Originally Posted by
sprite1
Ok. Interesting. Thanks. I’d say all those parameters were within limits, tbh.
Is the inherent requirement for pronounced nose-up trim due to small elevators? Or the number 2 engine’s thrust line?
As I mentioned previously, you can see what looks like elevators deflect upwards just as it passes abeam the videographer that’s standing on the apron to the south of the runway and then the thrust reduces.
sorry, can’t answer that one. Elevator effectiveness would be a contributing factor I would think. I went back and pulled the NTSB report on the SBA accident.
“A post accident inspection of the airplane revealed that all systems were operating within allowable tolerances. Post accident simulator testing revealed that when configured for takeoff in the accident conditions, stabilizer trim set to -5.5 degrees and V speeds set for 45,400 pounds, a delay of 2 to 4 seconds was noted from the time an up elevator input was made to the time the airplane reacted in pitch. When the simulator was configured with the stabilizer trim set to -7.0 degrees and the V speeds set for 46,480 pounds, there was no delay in airplane response to elevator input.”
”In a statement dated June 22, 2007, the pilot in command reported "...an interesting call was made by the chief test pilot at Dassault to our local investigative rep. He said that at gross weight takeoffs you will not get rotation at Vr (rotation speed) and [an] anomaly occurs with the Falcon 900. That it will only occur after holding the yoke full aft for 2 or more seconds.”
”According to information provided by Dassault representatives, the Civil Aviation Authority of the United Kingdom (CAA-UK) performed an evaluation of the MF900 Airplane Flight Manual (AFM), which resulted in the CAA-UK including in their AFM findings, “There must be a simple chart relating c.g. to take-off trim position.” (Refer to “Operation of Horizontal Stabilizer” chart attached). The CAA-UK requirement was taken into account and reflected in specific AFM pages for UK-registered aircraft, which included the MF900. Had such a chart been available and used prior to the accident flight’s take-off for a calculated c.g. of 15.73% MAC, the referenced stabilizer trim setting would have been between -7 and -7.5 degrees.”
I retired in 2010, I cannot recall such a chart existed for U. S. registered a/c, neither did the other two F900 drivers I’ve been corresponding with.
The first time it happened to us, we were at a higher weight, probably in the neighborhood of 48,000#. At that weight we experienced the delay described, just a couple seconds, but definitely unexpected. I made damn sure the rest of my guys knew. 49,000# is the maximum takeoff gross weight with no runway/2nd segment, or SID gradient limitations.