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Dassault Falcon 900EX crash, San Diego

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Dassault Falcon 900EX crash, San Diego

Old 15th Feb 2021, 18:35
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Dassault Falcon 900EX crash, San Diego

This past Saturday, 13th February, 2021, a Dassault 900EX Falcon was substantially damaged when it overran the runway at KMYF (San Diego, Calif., USA) during a rejected takeoff. All three gear legs were sheared off; however, miraculously, there were no serious injuries.

Here's a link to the Aviation Safety Network Report:
https://aviation-safety.net/database...?id=20210213-0

Here's a link to to the Kathryn's Report which includes links to videos of the crash:
Kathryn's Report: Dassault Falcon 900EX, N823RC / N718AK: Incident occurred February 13, 2021 at Montgomery-Gibbs Executive Airport (KMYF), Kearny Mesa, San Diego County, California

If those links prove to not be "active", just copy and paste to your browser.

Cheers,
Grog
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Old 15th Feb 2021, 18:39
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I've watched another video of a Dassault 900 EX takeoff and noted that there is considerable stabilizer nose up trim used. In the video supplied by Aviationking95, it appears that the stabilizer is trimmed flat, with perhaps even a bit of nose down trim dialed in. Again, referring to Aviationking95's video, at the approximately 0:37 mark, it appears that considerable nose up elevator is being used, yet, the aircraft does not rotate.

I've been wrong before, but this could be a case of a missed checklist item: the stabilizer trim setting.

Just my opinion/conjecture.

Cheers,
Grog
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Old 15th Feb 2021, 19:34
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Grog,
All (modern) jet aircraft are required to be equipped with a Takeoff Configuration Warning.
Elevator trim out of range is DEFINITELY ​​​​​​ one of the items that will trigger it.


Top of page 13:
https://www.smartcockpit.com/docs/F9...t_Controls.pdf
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Old 15th Feb 2021, 21:51
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Originally Posted by B2N2 View Post
Grog,
All (modern) jet aircraft are required to be equipped with a Takeoff Configuration Warning.
Elevator trim out of range is DEFINITELY ​​​​​​ one of the items that will trigger it.


Top of page 13:
https://www.smartcockpit.com/docs/F9...t_Controls.pdf
I totally agree, but, however rare, incidents and accidents due to aircraft takeoff misconfiguration continue to occur. A quick search of the internet reveals several crashes that have occurred over the years due to misconfiguration of wing flaps, slats, trim etc. Here is a link to a report of Bombardier CRJ rejected takeoff/overrun that occurred in January of 2010:

https://flightsafety.org/asw-article...ed-in-overrun/

Here's a link to an FAA "Safety Alert For Operators" (SAFO) dated November 25, 2014:

http://content.govdelivery.com/attac.../SAFO14005.pdf

Thank you for the link to the Systems Summary for the Dassault 900EX. As designed, it seems to be a foolproof system; however, there doesn't seem to be any safeguard or interlock system that cannot be ignored, disabled or "worked around" by human beings.

Cheers,
Grog

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Old 16th Feb 2021, 10:19
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Spanair Madrid 2008, flaps not set, config unknowingly disabled, delayed. Sadly all the holes lined up.
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Old 16th Feb 2021, 12:49
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I'm seeing "Takeoff runway length requirement for the 900EX is 5200' at maxGW and 28R at MYF is 4600'." in the comments on Kathryns report
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Old 16th Feb 2021, 20:43
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“I've watched another video of a Dassault 900 EX takeoff and noted that there is considerable stabilizer nose up trim used. In the video supplied by Aviationking95, it appears that the stabilizer is trimmed flat, with perhaps even a bit of nose down trim dialed in. Again, referring to Aviationking95's video, at the approximately 0:37 mark, it appears that considerable nose up elevator is being used, yet, the aircraft does not rotate.”



I flew a 900EX for 10 years. And I can tell you at heavy weights, full fuel, you need as much allowable (in the green band) nose up trim as possible. Full fuel runs the cg pretty far forward. And even with that much trim you’ll still have the yoke in your gut to achieve rotation, and that rotation will be much more sluggish that what you’ve been used to at much lighter weights. It’s a real eye opener if you’ve not experienced it beforehand!

Last edited by 7XDriver; 17th Feb 2021 at 01:58. Reason: Forgot to include quote from previous post
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Old 17th Feb 2021, 16:56
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Originally Posted by 7XDriver View Post
“I've watched another video of a Dassault 900 EX takeoff and noted that there is considerable stabilizer nose up trim used. In the video supplied by Aviationking95, it appears that the stabilizer is trimmed flat, with perhaps even a bit of nose down trim dialed in. Again, referring to Aviationking95's video, at the approximately 0:37 mark, it appears that considerable nose up elevator is being used, yet, the aircraft does not rotate.”



I flew a 900EX for 10 years. And I can tell you at heavy weights, full fuel, you need as much allowable (in the green band) nose up trim as possible. Full fuel runs the cg pretty far forward. And even with that much trim you’ll still have the yoke in your gut to achieve rotation, and that rotation will be much more sluggish that what you’ve been used to at much lighter weights. It’s a real eye opener if you’ve not experienced it beforehand!
I heard they were going to Hawaii. About 2,700 NM. Would they have had a full load of fuel?
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Old 17th Feb 2021, 17:16
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Beginning of the takeoff roll:

Actual overrun:
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Old 18th Feb 2021, 02:52
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Originally Posted by Old Boeing Driver View Post
I heard they were going to Hawaii. About 2,700 NM. Would they have had a full load of fuel?
probably not, I know nothing about their Weight and Balance numbers, Basic operating weight (BOW) etc. My own 900 for example, had a BOW of 26,300#, and cg 24.8% Mac. My old AFM shows a maximum T/O weight of 45,500#, based on 0’PA, 4,600’ runway @ 15°C, zero wind, zero slope, no anti ice. So, 45,500-26,300 leaves 19,200# for fuel and pax. Call the pax load @ 600#, leaves 18,800# fuel(200# taxi). The max fuel capacity for an EX is 21,000#. So if their BOW is anywhere close to mine +/-, they would have had a relatively forward cg, enough so that max allowable nose up trim would be not out of the question. 2,700nm is not a stretch for an EX, but in this case, there are no diversion airports. IIRC, KSAN-PHNL is one of the longest overwater routes. ETP’s in case of engine loss, or worse, pressurization problems that would force a lower altitude would add to fuel considerations.
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Old 18th Feb 2021, 06:26
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4500’ TORA is not much.

That take-off roll looked sluggish to me also. It just appeared it was being held back with weights or something.

Is the application of full/calculated take-off thrust on the brakes a common take-off procedure for these jets? It makes me think the crew felt it was going to be tight from the off.

edited to add; as the aircraft passes abeam the videographer standing on the ramp, you can see the elevators deflect upwards and then hear the engines move to idle. Appears the trim/nose heavy issue mentioned by others above could play a part.
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Old 18th Feb 2021, 11:04
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Originally Posted by sprite1 View Post
4500’ TORA is not much.

Is the application of full/calculated take-off thrust on the brakes a common take-off procedure for these jets? It makes me think the crew felt it was going to be tight from the off.
only if you’re runway limited. Usually a rolling takeoff if available runway exceeds BFL buy a good margin. BFL in the AFM are computed using T/O thrust set before brake release.

From my copy of the 900EX AFM, “Full takeoff thrust is set before brake release.”
Section 5, subsection 150, p3. Additionally there is a T/O CONFIG warning light on the MCS illuminates if:

Flaps more than 22°
Airbrakes not retracted
Slats retracted
Trim outside authorized range (-4.5° to -7.5°)
Park brake engaged
Uncommanded brake press in #2 system

this warning only triggered on the ground with at least one power lever > 82°PLA
accompanied by master caution and aural warn, “NO TAKEOFF” cannot be silenced as long as T/O Config is illuminated.

Last edited by 7XDriver; 18th Feb 2021 at 15:52. Reason: Added AFM notations
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Old 18th Feb 2021, 16:58
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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.
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Old 18th Feb 2021, 18:46
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Originally Posted by sprite1 View Post
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.
Yes I agree and, if we are looking at the same video (the one linked below), I had the below comments in another Forum (Kathryn's).

https://jetcareers.com/forums/thread.../#post-3044662

Notice that at 0:17 of the video, upward deflection of the elevators is not apparent; however, upward deflection is apparent starting at 0:18 in the video. I'm not expert on the Falcon 900EX, but in my recent reading, I've found information to the effect that the 900EX is pretty sensitive to improper takeoff stabilizer trim. Whether or not it was a factor in this crash, remains to be seen.

Another contributor ("Anonymous") to the Kathryn's discussion thread was able to blow up a frame in this video that showed the setting of the elevator trim relative to the painted marks on the vertical stabilizer Here's a copy of his post, including the link:

"Here is the CBS 8 video link, screen grab it at 29 seconds on 1080p and take into a photo editor":

The trim setting is exactly as that shown on page 13 of the Dassault Falcon 900EX Easy Systems Summary Manual (see B2N2's post above for the link to the manual). In light of 7XDriver's remarks above, that may not have been sufficient nose up elevator trim.

Cheers,
Grog

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Old 18th Feb 2021, 21:26
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Originally Posted by sprite1 View Post
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.

Last edited by 7XDriver; 18th Feb 2021 at 23:28. Reason: Info from the NTSB SBA investigation.
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Old 19th Feb 2021, 20:17
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Links to reports of the 2007 overrun at SBA:

The UK AFM chart for stab trim setting vs. CG was not in FAA AFMs at the time of the crash.
Full Docket :
https://data.ntsb.gov/Docket/?NTSBNumber=SEA07LA152

Summary:
​​​​​​https://reports.aviation-safety.net/...900_N914DD.pdf
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Old 23rd Feb 2021, 02:39
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Originally Posted by 7XDriver View Post
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.
I gotta make a correction! My statement re the wt/cg/stab trim chart is not totally correct! As chief pilot of a 10 man department I oversaw document revisions as they arrived. Two 900EX, and a G200. I would copy the revisions before having them inserted in the appropriate manuals, and email the revisions to the troops. This is a copy of that email, date 5/19/08

“Just received temp change # 90 to the AFM and # 29 to Operating Procedures Manual.

#90 is no big deal, DFJ revised the operations in Russian airspace and deleted the previous temp change regarding the same

#29 is regarding trim settings for takeoff with various C.G. settings and several notes pertaining to same. There is also a graph to set trim vs. C.G.

These are not in any of the appropriate manuals yet”

note the revision was to the operations manual not the AFM
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Old 18th Mar 2021, 15:46
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Here's a link to the NTSB Preliminary Report on this accident:

https://data.ntsb.gov/carol-repgen/a...ort/102629/pdf

It looks like this report was released just to "check a box" on some sort of check list form, because it says essentially nothing. It also appears that the author of the report did not bother to proof read his work.

Cheers,
Grog
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Old 19th Mar 2021, 11:55
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Originally Posted by capngrog View Post
Here's a link to the NTSB Preliminary Report on this accident:

https://data.ntsb.gov/carol-repgen/a...ort/102629/pdf

It looks like this report was released just to "check a box" on some sort of check list form, because it says essentially nothing. It also appears that the author of the report did not bother to proof read his work.

Cheers,
Grog
That's all any NTSB Preliminary report ever really says, bare bones situation statement, with in-depth analysis not until the Final report, months or a year later. I agree with the proofreading comment, though, you'd think they'd get that right.
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Old 11th May 2021, 14:42
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Does anybody knows what was the flaps setting?
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