http://https://youtu.be/Wbu6X0hSnBY

This guy - Harry Lordings, an ex USAF test pilot has an interesting presentation on VMCA. He's pretty critical of the ATSB investigation into the EMB 120 accident at Darwin suggesting that the ATSB did not understand the concept of VMCA.

He is suggesting that the Darwin accident was really caused by deficiencies in the aircraft manufacturers flight manual.

Lordings says that despite the pilots following published procedures and speeds that that the accident occurred due to a practice engine failure below the actual VMCA. He says that the aircrafts speed below VMCA is demonstrated by its lack of ability to maintain runway heading, since that is the very definition of VMCA.

The Essendon accident shares with the Darwin accident that a straight flight path was not able to be maintained despite the airspeed being significantly above the published VMCA.

Let's hope that the ATSB do a better job of engine investigation than the Whyalla accident, a better job of considering asymmetric issues than the Darwin accident and a better job of deriving airspeed than the Bankstown Mojave accident. For that matter the ATSB investigation of the engine issues of the Bankstown accident was superficial at best.

Whatever happened; the only pilots that think they would have dealt with the emergency better than Max are fooling themselves. There but for the grace of god....

It doesn't surprise me in the slightest. I flew 737's for many years and after reading an article on testing the CVR for one's own voice transmission, the very first 737 CVR I checked by calling "test test test" into the CVR microphone and expecting after two seconds to hear my own voice, revealed no voice. I snagged it in the maintenance record and a defect was found by the technicians and fixed. In fact this happened on numerous occasions on other 737's I flew yet the test needle indicated the CVR was serviceable.

Then I flew for a European airline that had recently bought new 737-500's
I flew one which only had about 40 hours since new. I decided to plug my headset into the CVR jack in the cockpit and check my own voice for clarity.

Guess what? No voice re-transmission. Over the next few months checked the CVRs on other new 737-500's and a couple of 737-400's of that airline and on some discovered identical defects on their CVR voice test. Others were perfectly clear speech re-transmissions and some where the speech was so muffled as to be useless. After those experiences I made it my own SOP to check the correct operation of the CVR before every flight. Over many years I found many CVR failed to record one's voice.

Just because the Boeing 737 (older types anyway) passed the FCOM Supplementary Procedures test of pushing the CVR test switch and receiving a tone through a headset plugged into the headset jack as well as noting the Monitor indicator in the Green band, it doesn't necessarily ensure your voice is recorded or legible.

ATSB states it will undertake "a review of the aircraft’s maintenance and operational records."

That's fine. Not forgetting of course, that not all defects are necessarily recorded in the maintenance release; even though many are legally supposed to be.

Was the M/R written up on fireproof paper? :ooh:

casa will find defects in the paperwork and crucify the operator/maintainer, no matter how minor the infraction, unless they are 'mates".

One of the deceased was the lawyer who took Enron to court. Another was a FBI agent.

If it had happened 10 years ago assassination might be a motive, but I doubt that if people wanted him dead they would wait some 15+ years.

While there are some 'interesting' deaths surrounding the Enron Collapse. Ken Lay who has to have been the most convenient heart attacks of all time, I doubt that in this instance it would be applicable. Why would they wait so long to knock him off? You would have to also consider what the FBI agent was up to. But again if they're retired what's the point? Usually people get tapped BEFORE they execute justice.

My money would be on some strange control system or engine failure.

This is neither the time nor place to vent your paranoia about the regulator and the ATSB.
Old Akro should consider this as well

Why is that Eddie?

Why can't Sunfish & Old Akro raise these points, here & now, on Pprune?

Finally sat down with google earth. If ATSB is right with liftoff point on 17 gives a ground run of about 3500ft or 1060m. That is dependent on using Tango and the full available.runway distance.

Five men dead, King Air crashed for no apparent reason. You work it out.

the point Eddie, is that the infractions will be prosecuted wether they are material to the accident or not. the decision to prosecute will be a political one as evidenced by the shameful treatment of Domenic James.

to put that another way, i would hate to have had anything to do with the maintenance of the aircraft in question because the possibility exists that i might end up a felon.

JT. You are correct , it is Harry Horlings. But his presentation lists being a graduate of the USAF test pilot school in his credentials.

Either way, it is yet another well credentialed overseas commentator finding fault with an ATSB report.

And Eddie, the reason is that it deserves note - right now- is that the ATSB has a long history of sloppy investigative work and of taking the easy way out and blaming the pilot, especially a dead one. The ATSB needs to be put on notice that it will not be accepted again.

Those who knew and respected Max need to be vigilant about the diligence of the ATSB report and the greater group of people who take interest in the quality of the ATSB work will be watching. This is the same organisation that was told by a senate committee to redo the Norfolk Island report and who recently yet again delayed it to the point that 8 years after the incident there is still not a final report.

The Essendon incident is going to be complex. A repeat of the substandard work that the ATSB has previously exhibited should not be tolerated.

"The Essendon incident is going to be complex. A repeat of the substandard work that the ATSB has previously exhibited should not be tolerated."

Hear, Hear Old Akro.

So over 24 hours has passed and you still not answered the question of fwd airspeed.
It is impossible to make the statment that the prop was at 2000 rpm with out knowing the airspeed to make the statement as fact.
Then even if the prop is at that speed its still not an indication of power being produced by the engine. Only the torque of the engine is a reflection of power being produced.
As for flap. Was it set, was it going down, was it being retracted.
The only thing that the initial report has relly given is the gear was down and locked.
The only thing with the ASTB is th hey will find weather true or not a reason/explanation for this accident they will not just say we dont know what happened. Also being the type of aircraft involved one would imagine that all maintenence has been done and as a general rule to a much higher standard than GA lower grade aircraft.

Huh? I'm no investigator, but my curoius mind would say that if you had slash marks on the ground, measured how far apart they are and you knew the speed at impact, you could infer the rotational speed of the prop.

Not really. It is just a blog from a guy who has a bee in his bonnet and finds fault in any report by any authority that does not focus above all else on the single issue of maintaining a zero slip angle of bank. ATSB, NTSB, AAIB, DTSB and any manufacturer who didn't change their manual after he wrote to them; he knows better than all of them of course.

You are not interested in airspeed because measurements are being taken from ground impact references (prop slash marks) which relate to GS.

The last data point gives a GS of 108 knots, which equals,

108*6080/60 ft/min = 10944

Four bladed prop - distance over five (one RPM) consecutive blade strikes I measure at 6.9 feet ie one complete prop rotation

Prop RPM then equals 10944/6.9 = 1,586 RPM
I used a mixture of Google Earth and the dimensions between ridges of the roof cladding to work numbers.

Connedrod, quite correct that you have no idea of the power being produced, though touchdown was with yaw about 25° and a 6° descent (rough figures).

I have been led to understand, from colleagues watching the take off roll, that it won't be a complex investigation.

As far as DJ is concerned, contrary to Sunfish, he was not prosecuted for anything. Most of his peers found his decision making appalling.

Megan, great analysis, you should be part of the ATSB team.

Do tell more..... flaps, reduced power? Am trying to think what else would be noticeable from the takeoff roll... ATSB did say that it was a longer takeoff roll than normal.

MQ
 

I knew Max many years ago so I joined here to observe the outcome (and post). I do hope the authorities get to the bottom of it all. It's the ones left behind that suffer for ever & a day:-(

Jay Hook?
 

I wonder if the J Hook did not disengage - so the gear was physically blocked from being selected up?

It's plausible to imagine the pilot getting distracted by the stuck gear and fumbling for the J Hook release. In this scenario he would have his head inside the cockpit - and hand off the power levers. This would be the worst time to experience a power lever creep back, or a sudden power lever closure, as discussed earlier in this thread.

It's a horrible thought - a nightmare- to imagine looking up in this situation to see you are low level, low speed, off the runway centre line and diverging towards the buildings.

Maybe the pilot decided to stay on the ground a little longer than normal flight manual lift off for weight, as a precaution to pick up more airspeed for controllability reasons in case of engine failure after lift off. Quite a common practice with some pilots flying light propeller twins.

Five POB, shouldn't imagine AUW would be a factor.
Sorry Squawk, can't say, won't say. Secret squirrel business.
Not in everyone's universe.

Ack. That makes more sense now.

Megan,

Hats off to you on your practical maths but can I ask what dimensions did you use for the roof cladding?

The ridges/corrugations in the cladding should be 30 cm apart. By my measurements the first five prop strikes occur over a distance of 1.82 metres or 5.97 feet. That yields an average prop rotation of 1833 rpm. As you'd expect the last five prop strikes occur over a slightly greater distance; about 1.89metres or about 6.21 feet by my measurements, yielding 1762 rpm.

I make the yaw to achieve the left and nose wheel gear marks nearly aligning as they do to be around 30°.

So what prop speed is it 2000rpm 1586 1833. So megans difference is nearly 25% ish. Thats a large difference is it not. Why is that important. Because one is in prop gov range and the other is not basically. This is an indication of the power being produced by that engine. Case in point you really cannot make any expectation of prop speed with out detail measurements this includes airspeed at inpact. If its slower than expected the inpact marks will be closer and vice versa.

The CVR is powered off the No 1 Dual Fed Bus, so named because it is powered by both the Left and Right Generator Buses.

The normal rpm control range of the primary governor, the green arc, is from 1,600 rpm to 2,000 rpm. I estimate that the average prop speed across the first five prop strikes to be 1833 rpm, megan has estimated it to be 1586 rpm; the difference between the two estimates is about 15%. megan's estimate is within 14 rpm (0.875%) of the lower green arc range, my estimate is on the the upper side of the middle of the range. By any reasonable assessment you'd say that the left prop was rotating in the normal range at impact.

Power is clearly a different story but the difference between the first and last sets of five strikes may be instructive; the average prop speed slowed by less than 4% after 11 increasingly deep strikes. That might suggest that the engine was producing power.

The shape of the strikes certainly indicates that the left propeller was not feathered so it is reasonable to infer that the left engine was producing more than 200 foot-pounds of torque otherwise the auto-feather system would have opened the dump valve and feathered the prop.

As has been explained to you previously airspeed is irrelevant to the calculations; the prop strikes are on an object fixed to the ground and we have the ground speed at impact from the ADS-B data as 108 knots.

So how do we account for so much (apparent) yaw to the left?

That is a very good question. If you review the dash-cam footage it looks like the airplane yaws through about 90° to the left in less than 2 seconds; as the airplane initially climbs into view it appears to be nose-up, climbing and oriented properly with the direction of flight along the extended centre line then very quickly we see it in profile, nose-down and descending. The flight path illustrated in the ATSB preliminary report might be a gently curving arc but the airplane appears to be oriented obliquely to it in the lateral axis; both the dash-cam and the the alignment of the nose and left landing gear strike marks bear that out. Unfortunately it's difficult, if not impossible, to determine the rudder position from the dash-cam footage.

For **** sake you arm chair quarterbacks need to shut you cake holes. You all have no idea whatsoever what happened. Let the ATSB finish their investigation.

And you all have no idea whatsoever as to what constitutes courteous and professional discourse so perhaps you might heed your own advice regarding holes, cake and shutting thereof.

On given info and B200 performance are we looking at sinister stuff? how many engine calls made and no evidence of any.

Not to be rude but it hit my thoughts.

zanthrus, you can always be relied upon to make some stupid post, whatever the thread. Now shut YOUR cake hole. No one knows exactly what happened, and we await the ATSB report, but in the mean time we are free to discuss.I used 700mm which is quoted as the coverage for a single sheet. I assumed that would have meant 350mm from ridge to ridge.From the manual.Note the last groundspeed, and we can assume the airspeed, given the wind was 23005, to be the same, was 108 knots. Recommendation from the good book for practice Vmca demonstration is a minimum of 5,000 feet, clearly not something to be trifled with.

Low side governor failure, P3 air leakage?

But the extrapolations from the prop strikes suggest the left engine and propellor were operating 'normally'. If they were, why would a reduction in airspeed below VMCA result in yaw to the left?

(And zanthrus, I generally refrain from following post-crash threads because they often degenerate into character assassinations of the pilot. But I don't see what's wrong with calmly discussing the mechanical and aerodynamic implications of various pieces of information such as the photos of the prop strikes and gear strikes.)

It may well have been the other way around; the yaw to the left may have caused the reduction in airspeed (and positive vertical speed).

Megan,

Could you post the photo that you have used for your calcs? The effective cover and ridge spacing is different for different profiles obviously but from the photos I've seen I can't say for sure which profile has been used. If I can I can give you the exact measurements.

That style/type of roof panelling comes in a range of widths; 305mm, 420mm, 620mm, 700mm, 762mm, 820mm, 840mm, 930mm. The 700mm panels have four ridges per width or 175mm ridge to ridge. I think an indication of the distance between the ridges can be gained from their alignment with the rectangular HVAC ducting (900mm) and the rooftop walkways (615mm).

P3 Air issue should result in hung start. But I guess you are referring to Pressure governing, ie the line running along the top of engine to the power turbine part of the CSU. Have experienced leakage here on a Caravan engine which resulted in topping out at about 1680 RPM.
This should show up on preflight run up.