[Peetwo]

ATSB: The copy & paste Annex 13 AAI?

From page 54 of the UP King Air down thread - https://www.pprune.org/pacific-general-a...on-54.html - there was a bit of a ding-dong going on between Old Akro and resident troll/CASAsexual/HVH lover FGD??

Old Akro

Which incident are you referring to here, Old Akro?

Report WPR09LA451. B200 Kingair. The main wreckage was 4420 ft from the point of lift off at about 10 deg from the runway centre line. The rudder trim was full left AND elevator trim 9 degree nose up (should have been 2-3) AND the RH propeller " one half inch forward of the feather position" AND both power levers were one inch aft of the full power setting. AND the left condition lever was in the low idle position while the right condition lever was in the high idle position. 

The report notes: "The Hawker Beechcraft investigator stated that the position of the right propeller lever “…would cause the right engine to reach a higher torque because the propeller is now on the primary governor. The result would be a yaw in a left direction.” "

So, this aircraft should have had a much larger left yaw than ZCR, yet it basically crashed on runway heading, suggesting that the pilot had directional control. 

The NTSB report did not attribute a cause of the accident to any particular one of the mis-set controls, but the pilot said: " The pilot added that he had both hands on the yoke until the airplane crashed. " which infers that it was not the rudder correction that was his main struggle. 

By comparison with the US B200 which crashed 4420 ft from lift off 10 deg of runway, ZCR crashed about 1500 ft from lift off and about 40 deg from runway heading. There is no indication in the report that the US B200 climbed above 100 ft. ZCR achieved about 650 ft before descending. 

The two incidents barely seem analogous. and I think the US incident suggests that directional control can be maintained despite full left rudder trim. It would have been good if the ATSB tested this.

---

FGD135

Old Akro,

You are consistently misrepresenting and misquoting these reports. You're definitely pushing an agenda, but we're onto you.

Report WPR09LA451. B200 Kingair.

In your first post this morning, you stated that the pilot "did maintain directional control, despite full NL rudder trim". This is a misrepresentation. If you use Google Earth to look at the runway in question, and the two buildings this aircraft collided with, you will see that the veer to the left after takeoff appears almost identical to that by ZCR. That is not what most people would consider "maintaining directional control". My Google Earth is playing up, but if you want me to take some precise measurements for comparison with ZCR, I will find a way to do so.

The rudder trim was full left AND elevator trim 9 degree nose up (should have been 2-3) AND the RH propeller " one half inch forward of the feather position" AND both power levers were one inch aft of the full power setting. AND the left condition lever was in the low idle position while the right condition lever was in the high idle position.

The condition levers had no bearing on the outcome. The RH prop lever, however, may have had some bearing, but it must be noted that this was how the lever was found in the wreckage - no analysis appears to have been conducted as to whether it was in this position during the takeoff.

The report notes: "The Hawker Beechcraft investigator stated that the position of the right propeller lever “…would cause the right engine to reach a higher torque because the propeller is now on the primary governor. The result would be a yaw in a left direction.” "

This is not true. At best, the power output of the RH engine would have matched the LH, or it may have been less. It all depends on when the lever was put in that position, relative to when the takeoff torque was set.

If BEFORE the torque was set, then the pilot most likely advanced both power levers to the target takeoff torque (2,230 ft-lbs), as normal, but if the RH prop lever was in the reported position, then the RH RPM would not have come up to 2,000 RPM. It would have got to only about 1,800 (my estimate). In this case, the RH engine is actually producing LESS power than the LH.

If the lever was positioned AFTER the torque was set, then yes, the torque of the RH prop is increased - but the RPM is reduced, with the result that the power output is about the same. So, in neither case would the reported position of the RH prop lever have caused an increase in the NL yaw moment.

The pilot added that he had both hands on the yoke until the airplane crashed. " which infers that it was not the rudder correction that was his main struggle.

I imagine the tendency to roll L would be very strong in these instances, and with the low airspeed, may well have required full R aileron.

By comparison with the US B200 which crashed 4420 ft from lift off 10 deg of runway, ZCR crashed about 1500 ft from lift off and about 40 deg from runway heading. There is no indication in the report that the US B200 climbed above 100 ft...

As I stated above, the veered path appears almost identical to ZCR. The buildings in the US case were much closer, and appear to be lower. Until I make some measurements, it appears to me that the only difference between these two accidents was that the US aircraft was about 50-60 feet lower than ZCR at the same point.

I think the US incident suggests that directional control can be maintained despite full left rudder trim.

Disagree - and all the evidence disagrees with this assertion.

And on it goes until Lead Balloon steps in and puts a cap on the FGD bollocks...

Lead Balloon

We all have an ‘agenda’, FGD.

Your ‘agenda’ is to defend a report that reaches the oh-so-convenient conclusion that the only hole in the Swiss cheese was the pilot.

Others like me (and I suspect OA) have an ‘agenda’ of testing the reasoning and findings of an oh-so-compromised ATSB.

I for one do want you to “take some precise measurements [of the details of the B200 accident with report number WPR09LA451] for comparison with ZCR”, so please “find a way to do so” on google maps. I’m surprised that more detail of the US accident were not included in the ZCR report, if the path of the aircraft in US accident was, in fact, so similar to that of ZCR.

---

FGD135

As requested, I have done some work with Google Earth to compare the flight paths of VH-ZCR and N726CB, the latter being the King Air B200 that took off from Hayward Executive airport, California on 16/9/2009, with full nose-left rudder trim.


N726CB veered left after becoming airborne and struck the roof of a 10 metre high (estimate) building. The point of impact was 15 degrees off the runway azimuth, at a distance of 670 metres - measured from the lift-off point. I have assumed a distance of 500 metres for this takeoff roll (see attached image).

For the takeoff of VH-ZCR, I have drawn a line of the same vector onto the Essendon image, to see how close the two impact points are (see image).

The two points are about 150 metres apart. ZCR has veered more, which could be explained by its 15 knot greater airspeed at lift-off (assuming that N726CB rotated at a normal speed). The greater airspeed would give a greater initial nose-left yawing moment.

Another possible explanation: the pilot of N726CB had 37 year old knees, as compared to the 76 year old knees in ZCR.

The distance from lift-off to impact for N726CB was about 670 metres. For ZCR, this distance was about 620 metres.

The biggest unknown in this exercise has been the length of the takeoff run for N726CB. I have assumed 500 metres, but if that actual takeoff had got off to a more leisurely, rolling start, then this distance could have been closer to 600 metres, which would have put the endpoints of the two vectors within about 75 metres of each other.

---

Lead Balloon

Thanks FGD.

I acknowledge the similarities. But I don’t see too much precision in stuff like:

“I have assumed a distance of”,

“could be explained by”

“Another possible explanation”

“The biggest unknown”

“could have been closer”

All of your assumptions and reasoning may be reasonable. But they may also be wrong in fact.

The difference between our approaches is that all of your assumptions and reasoning are in one direction, to make the two incidents as similar as possible and thereby to ‘prove’ the two incidents had the same cause. My (and I suspect OA’s and others’) approach is to ask: What if your assumptions, possible explanations and known unknowns turned out to show substantial differences between the two incidents? Frankly, the latter approach is the one that ATSB should take, rather than jump to a conclusion then find as much stuff to support that conclusion, even if it means making assumptions that may be invalid and positing explanations that could be wrong.

I apologise if you’ve already answered these questions, but what is your theory as to who set the trim to full NL, when and why? I realise that these questions are irrelevant for those who consider there is only one hole in the Swiss cheese in this tragedy, but they are not irrelevant to others. You’ve said you don’t believe that the pilot set the rudder trim to full NL during pre-flight checks then failed to set it correctly due to distraction. If you are correct, it inexorably follows...

However my curiosity was piqued more by the 2009 US (Hayward Executive B200 occurrence) NTSB final investigation report...  

I am currently on my 2nd run through that report and it's associated pictorial/PDF evidence archive. Besides the fact that the occurrence pilot is extremely lucky to be alive, so far I am starting to get a very uneasy feeling about the so called 'similarities' of these two accidents...  

Anyway not wanting to sway opinion AP has instructed me to provide the links for other interested IOS member's independent and considered review...    

References: https://reports.aviation-safety.net/2009...N726CB.pdf & https://dms.ntsb.gov/pubdms/search/hitli...TXTSEARCHT=

Much..much MTF - P2